WO2022018678A1

WO2022018678A1 - Nanoparticles, nanofunctionalised substrate and device with antiviral and/or antibacterial and/or antifungal photocatalytic activity

Info

Publication number: WO2022018678A1
Application number: PCT/IB2021/056631
Authority: WO
Inventors: Giovanni Baldi; Laura Niccolai; Marco Bitossi; Giada Lorenzi
Original assignee: Colorobbia Consulting S.R.L.
Priority date: 2020-07-24
Filing date: 2021-07-22
Publication date: 2022-01-27
Also published as: EP4185340A1

Abstract

The invention relates to the use of nitrogen-doped TiO₂ (TiO₂-N) nanoparticles activatable by UV light and/or visible light and/or sunlight, of a substrate nanofunctionalised with said nanoparticles and of a device comprising said substrate and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, for killing a virus and/or fungi and/or bacteria. The invention also relates to a method for killing said virus and/or said fungi and/or said bacteria, comprising the steps of: (A) providing said nanoparticles or (A') said substrate or (A") said device; (B) placing said nanoparticles or (B') said substrate or (B") said device in contact with said virus and/or said fungi and/or said bacteria; and (C) irradiating said nanoparticles or (C')/(C") said substrate with a source of UV light and/or visible light and/or sunlight.

Description

“Nanoparticles, nanofunctionalised substrate and device with antiviral and/or antibacterial and/or antifungal photocatalytic activity”

DESCRIPTION

FIELD OF THE INVENTION

The present invention fits into the field of photocatalytic degradation for disinfection and/or sanitisation applications. In particular, the present invention relates to the use of nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight, a substrate nanofunctionalised with said nanoparticles and a device comprising said substrate for killing viruses and/or fungi and/or bacteria. The present invention also relates to a method for killing said virus and/or said fungi and/or said bacteria.

PRIOR ART

Infectious diseases, i.e. diseases caused by pathogenic agents that come into contact with an individual, still today represent one of the main causes of disability and/or death worldwide. In particular, viruses, fungi and bacteria, which can be transmitted from person to person or from animals to people, represent a problem that is of increasing concern in today’s society. One need only consider, for example, the infections acquired in care settings (such as, for example, in hospitals, long-term care facilities, outpatient facilities, home care, etc.) and which often represent the most frequent and most serious complication in the field of health care, also in the most developed countries with high standards of hygiene. In particular, as regards bacteria, the spread of antibiotic-resistant bacteria is particularly worrying, both in hospital settings, where ample use is often made of antibiotics and personnel/visitors (potential carriers of bacteria) and patients (often immunocompromised) are often in close contact, and, for example, in the context of livestock farming. In the latter case, in fact, antibiotics are often administered in massive amounts to animals, also healthy ones, in order to prevent infections that could impair their growth or cause diseases. In this case, therefore, antibiotic-resistant bacteria could develop which are potentially transmittable also to humans, for example, by ingestion of food products derived from the animals themselves. Among them, for example, bacteria both of the species Escherichia coli and Staphylococcus aureus are often responsible for this phenomenon of resistance, and can have a role in transferring this resistance to humans precisely through food. In order to have a complete picture of the situation and the risks tied to the spread of infectious diseases, it is also important to consider that, in the past few decades, globalisation, the concentration of a large number of people in increasingly crowded urban spaces and the increasing ease of international travel have greatly contributed to the spread of pathogenic agents over a short period and in different parts of the world. One need only consider, for example, coronaviruses (CoVs), which have been responsible for various epidemics since 2002, caused by SARS-CoV-1 , MERS-CoV and, at present, SARS-CoV-2 (COVID-19), the causative agent of the most recent pandemic (2019-2020). In particular, SARS-CoV-2, also because of its high virulence and ability to cause high mortality, has become an unprecedented global public health emergency. Coronaviruses are enveloped positive-sense RNA viruses belonging to the family Coronaviridae and the order Nidovirales and are considered the largest positive- sense RNA viruses, with genomes ranging from 27 to 32 kb. CoVs are the cause of a variety of respiratory, gastrointestinal and central nervous system diseases both in humans and in animals, and are capable of adapting to new environments by mutation and recombination. The transmission of these viruses, as in the case of bacteria or fungi, can occur through contact with or close proximity to an infected person, or through contact with infected objects or surfaces and subsequent transmission of the pathogenic agent through contact with the nose, mouth or eyes. These pathogenic agents are in fact capable of surviving in the environment for hours or days (and in some cases for months), contaminating surfaces, medical equipment or environmental media such as water or air in general. Moreover, transmission may also occur through asymptomatic individuals, thus making it extremely difficult to control the spread of the disease. In the light of the above, it appears clear that the emergence of new diseases, such as, precisely, SARS, MERS or COVID-19, or of bacteria that are increasingly resistant to antibiotics, has created new global paradigms of public health and challenged even the most efficient health care systems due to the lack of specific drugs and/or potential therapies. For this reason, at the present state of the art, in the absence of effective drugs and/or therapies for treating patients, interventions to combat the outbreak of such new diseases are mostly based on controlling and preventing the spread of the relevant pathogenic agents. In this area there is a growing need to be able to perform a rapid disinfection and sanitisation of both public and private environments and spaces, such as, for example, means of transport, hospitals, schools, offices, shops, restaurants, etc. In particular, there remains the challenge of being able to provide a method that enables viruses and/or fungi and/or bacteria to be killed whether they are deposited on surfaces or are present in the air and transported by aerosol droplets in closed environments, in a rapid, inexpensive manner and without risks and/or contraindications for the operator. In the prior art there are numerous publications regarding the study of the action of photocatalysis against viruses and bacteria. In this area, as reported for example by H. A. Foster et al. (“Photocatalytic disinfection using titanium dioxide: spectrum and mechanism of antimicrobial activity”, Applied Microbiology and Biotechnology, 90, 1847-1868 (2011)), numerous studies have been conducted on the potential antiviral and antibacterial activity of titanium dioxide (PO2), one of the best known photocatalysts normally used to reduce polluting agents such as nitrogen oxides (NO, NOx, NO2) and volatile organic compounds (VOCs). Titanium dioxide-based photocatalysts show numerous advantages, including the modest cost, high availability, nontoxicity, chemical and thermal stability and high oxidative power of Ti02. However, the largest disadvantage of using such titanium dioxide-based photocatalysts is that they are active only if irradiated by a suitable light source having a wavelength in the interval of the ultraviolet region (l=350-400 nm), due to the relatively high band-gap energy of TiC>2 (Eg = 3.0-3.2 eV), which only absorbs light with a wavelength of less than about 387 nm. Given that, until recent times, the know-how regarding photocatalysis has led to the prevalent use of activation by ultraviolet light (UVA/UVB), nothing is to be found in the prior art with regard to the killing of viruses and bacteria by titanium dioxide with light having a wavelength also in the visible spectrum. The only publications regarding the killing of viruses and/or fungi and/or bacteria using photocatalysis with visible light relate, in fact, to photocatalysts comprising other substances, such as, for example, the ones described by K. Takehara (“Inactivation of avian influenza virus H1N1 by photocatalyst under visible light irradiation”, Virus Research, Vol. 151 (1), 2010, pp. 102-103), in which use is made of platinum-doped tungsten oxide for the inactivation of the avian influenza virus H1 N1. In this context, the technical task at the basis of the present invention is to propose an optimised alternative to photocatalysts for killing viruses and/or fungi and/or bacteria, in particular by providing a photocatalyst that works with both UV light and visible light, as well as sunlight, and which has the same effectiveness as or a greater effectiveness than the photocatalysts known in the art and can be adapted to cover different substrates. In particular, the present invention enables the problems of the prior art to be solved through the use of a photocatalyst based on nitrogen-doped titanium dioxide (T1O2-N) nanoparticles with photocatalytic activity to kill viruses and/or fungi and/or bacteria, in a short time, without emissions of contaminants (as occurs, for example, in the case of ozone sanitisation devices) and which is active in both the UV and visible light spectra, thus overcoming the high costs and problems of accessibility tied to the use of UV lamps, such as, for example, the production of O3.

SUMMARY OF THE INVENTION

The present invention relates to the use of nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight, a substrate nanofunctionalised with said nanoparticles, a device comprising at least one substrate nanofunctionalised with said nanoparticles and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, for killing a virus and/or fungi, said fungi being selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium and a combination thereof; and/or bacteria, said bacteria being selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae and a combination thereof.

The present invention also relates to a method for killing said virus and/or said fungi and/or said bacteria, comprising the steps of:

(A) providing said T1O2-N nanoparticles or (A’) said nanofunctionalised substrate or (A”) said device;

(B) placing said nanoparticles or (B’) said nanofunctionalised substrate or (B”) said device in contact with said virus and/or said fungi and/or said bacteria; and

(C) irradiating said nanoparticles or (C’) said substrate with a source of UV light and/or visible light and/or sunlight; or (C”) irradiating said at least one substrate comprised within said device with said light source.

According to any one of the embodiments of the invention, said virus is preferably selected in the group consisting of: Coronaviridae, Bacteriaofagi, Caliciviridae, Picornaviridae, Reoviridae, Adenoviridae, Astroviridae, Anelloviridae, Pramixoviridae, Poxviridae, Filoviridae, Orthomyxoviridae, hepatitis virus, and a combination thereof. Preferably, said virus and/or said fungi and/or said bacteria are comprised within a fluid, preferably air and/or water and/or a body fluid, or are present on a surface, preferably adsorbed onto said surface. According to a particularly preferred embodiment of the invention, said T1O2-N nanoparticles comprise at least a brookite crystalline phase in an amount of 10 to 99 % by weight relative to the weight of the nanoparticles and a rutile crystalline phase in an amount of 25 to 90% by weight relative to the weight of the nanoparticles; more preferably, said T1O2-N nanoparticles further comprise an anatase crystalline phase in an amount of 1 to 10 % by weight or 25 to 90% by weight relative to the weight of the nanoparticles.

For the purposes of the present invention, said amount of the brookite crystalline phase, from “10 to 99% by weight”, means that said brookite crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, such as, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%,

37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%,

52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%,

67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%,

81%, 83%, 94%, 95%, 96%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%,

97%, 98%, 99%.

For the purposes of the present invention, said amount of the rutile crystalline phase, from “25 to 90% by weight”, means that said rutile crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, such as, for example, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%,

53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%,

68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 81%,

83%, 94%, 95%, 96%, 87%, 88%, 89%, 90%.

For the purposes of the present invention, said amount of the anatase crystalline phase, from “1 to 10 % by weight or 25 to 90% by weight”, means that said anatase crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, such as, for example, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%,

54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%,

69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 81%, 83%,

94%, 95%, 96%, 87%, 88%, 89%, 90%.

Preferably, said PO2-N nanoparticles have a nitrogen doping content comprised between 1 and 5% by weight relative to the weight of the nanoparticles. According to a preferred embodiment of the invention, said substrate is selected in the group consisting of: a substrate of ceramic, polymeric or textile material, nonwoven fabric, metal, glass, paper and cardboard material, or a combination thereof. Preferably, said substrate comprises a plurality of channels and/or cells suitable for the passage of a fluid, said channels and/or cells having a cross section preferably selected from among circular, hexagonal, square, triangular, rectangular and a combination thereof, and identifying a path for the fluid having a variable geometry; said substrate preferably having a structure selected from among: a stratified structure, an interwoven structure, a fabric weave structure and a honeycomb structure, preferably characterised by a CPSI (cells per square inch) value of from 40 to 120, and a combination thereof. According to one embodiment, the present invention relates to the use of nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight, a substrate nanofunctionalised with said nanoparticles, a device comprising at least one substrate nanofunctionalised with said nanoparticles and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, for killing a pathogenic agent, said pathogenic agent preferably being selected from viruses and/or bacteria and/or fungi as described in the present patent application. According to one embodiment, the present invention also relates to a method for killing said pathogenic agent, comprising the steps of:

(A) providing said PO2-N nanoparticles or (A’) said nanofunctionalised substrate or (A”) said device;

(B) placing said nanoparticles or (B’) said nanofunctionalised substrate or (B”) said device in contact with said pathogenic agent; and

BRIEF DESCRIPTION OF THE FIGURES

Figures 1A and 1 B show SEM images, in two different magnifications, of a detail of the surface of the nanofunctionalised substrate, i.e. the substrate coated by T1O2-N nanoparticles obtained as described in Example 2.

DETAILED DESCRIPTION OF THE INVENTION

For the purposes of the present invention, the expressions “nitrogen-doped T1O2 (T1O2- N) nanoparticles” or “nitrogen-doped titanium dioxide (T1O2-N) nanoparticles” refer to (photocatalytic) nanoparticles doped exclusively with nitrogen. Such expressions therefore exclude so-called “co-doping”, that is, the simultaneous presence of two or more doping elements/agents, such as, for example in the case of nitrogen-rare earth doping or the like.

The terms “suspension of nanoparticles” and “nanoparticle suspension”, for the purposes of the present invention, are considered synonymous and refer to a mixture in which finely divided solid nanoparticles are dispersed in a solvent, for example water and/or alcohol, so that they are not sedimentable or, after a possible sedimentation, are easily re-dispersible.

The term “nanoparticle coating”, for the purposes of the present invention, means a coating comprising nanoparticles or consisting of nanoparticles.

The term “polymeric material” or “plastic material” means, for the purposes of the present invention, a wide range of synthetic or semi-synthetic, high-molecular weight polymeric organic compounds, which are malleable and can thus be modelled into solid objects. Said polymeric organic compounds can be pure (co)polymers or comprise other substances aimed at improving the properties and reducing the costs thereof, such as, for example organic and/or inorganic additives.

For the purposes of the present invention, the term “(co)polymer” is used to indicate both polymers, also called homopolymers, i.e. macromolecules whose polymeric chain contains repetitive units obtained from the union of monomers of only one type, and copolymers, i.e. macromolecules whose polymeric chain contains repetitive units obtained from the union of monomers of two or more different types.

For the purposes of the present invention the term “transparent” refers to the physical property of transparency, i.e. the property which allows light to pass through a material. In particular, for the purposes of the present invention a material is defined “transparent” if it transmits light and enables a clear observation of an object through it.

The term “translucid” refers to the physical property of translucency, which allows light to pass through a material in a diffused manner.

In particular, for the purposes of the present invention a material is defined as “translucid” if it transmits light by diffusing it but is not transparent, i.e. if said material does not enable a clear observation of an object observed through it.

The term “opaque” refers to the physical property of opacity, which does not allow light to pass through a material. In particular, for the purposes of the present invention, a material is defined as “opaque” if it does not transmit light, i.e. if it is impenetrable to light and thus totally prevents the observation of an object through it.

The term “substrate nanofunctionalised with nitrogen-doped T1O2 nanoparticles” and synonyms mean a substrate that comprises said nanoparticles. Said nanoparticles can be present within the material/materials that forms/form the substrate or can form/be present within a nanoparticle coating that covers (totally or partly) at least one surface of the substrate, be it an inner and/or outer surface.

The expression “inner and/or outer surface of the substrate” means, for the purposes of the present invention, any surface of the substrate, whether it is visible from the outside (outer surface) or, in the case of a more complex geometry and/or shape of the substrate comprising, for example, cavities, channels and/or interstices, not visible from the outside (inner surface). By way of example, a substrate produced with the shape and geometry of a hollow sphere will have an outer surface visible to the observer and an inner surface facing towards the hollow internal space and thus not directly visible to the observer.

According to one embodiment of the invention, the term “substrate” is to be understood as a synonym of “support”. Similarly, the expressions containing the term “substrate” described in the present patent application (i.e. “nanofunctionalised substrate” etc.), according to one embodiment of the invention, are to be understood as containing the term “support” (i.e. “nanofunctionalised support”, etc.).

The term macroroughness” means the property possessed by a surface of a body consisting of geometric micro imperfections, intrinsic or resulting from machining; such imperfections, measured by means of a roughness tester or by observation with an electron microscope, generally appear in the form of depressions and/or scratches, of variable shape, depth and direction and having a size in the order of micrometres or millimetres.

The term “nanoroughness” means the property, measured by means of an electron microscope, tied to the presence of nanoparticles within a material and/or as a coating on the surface thereof, and which renders the surface thereof “rough” on a nanometric scale, i.e. a surface that exhibits imperfections in the form of protuberances, mountains and valleys having a size in the in the order of nanometres.

The term “UV light” means ultraviolet radiation, i.e. the range of electromagnetic radiation with a wavelength immediately below that of light visible to the human eye and immediately above that of X-rays, i.e. with a wavelength comprised between about 10 and about 380 nm.

The term “visible light” means visible radiation, i.e. the range of electromagnetic radiation with a wavelength immediately above that of ultraviolet radiation and immediately below that of infrared radiation, i.e. with wavelength comprised between about 380 and about 720 nm.

The term “sunlight” means solar radiation, i.e. the radiant energy emitted in interplanetary space by the sun, which comprises electromagnetic radiation at various wavelengths. In particular, about 50% of solar radiation is emitted in the infrared region (NIR, near the visible region and comprised between about 750 nm and about 1500 nm), about 5% in the ultraviolet region and the rest in the visible region.

For the purposes of the present invention, the term “fluid” refers to a material (i.e. a substance or a mixture of several substances) which deforms unlimitedly (flows) if subjected to a shear strain, irrespective of the entity of the latter. The term “fluid” is therefore used to indicate the state of matter that comprises liquids, aeriform substances (gases), plasma and plastic solids.

The subject matter of the present invention relates to a use of nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. According to one embodiment, the present invention relates to a use of nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight for killing a pathogenic agent, said pathogenic agent preferably being selected from among said virus and/or said fungi and/or said bacteria, as described in the present patent application. According to one embodiment of the invention, said T1O2-N nanoparticles activatable by UV light and/or visible light and/or sunlight are in the form of a powder, preferably calcined powder. For the purposes of the present invention the expressions “nanoparticles in the form of a (calcined) powder” or “(calcined) nanoparticle powder” are to be understood as synonyms. According to another embodiment of the invention, said T1O2-N nanoparticles activatable by UV light and/or visible light and/or sunlight are in the form of a suspension in a solvent, preferably selected in the group consisting of: an organic solvent, water or a mixture thereof. Preferably, said organic solvent is selected in the group consisting of: ethyl alcohol, acetone, glycol, preferably selected in the group consisting of: diethylene glycol (DEG), polyethylene glycol (PEG), monopropylene glycol (MPG), monoethylene glycol (MEG), and a combination thereof; or a mixture thereof. Preferably, said organic solvent comprises a mixture of ethyl alcohol and at least one glycol, or a mixture of acetone and at least one glycol; said at least one glycol, preferably being selected in the group consisting of: diethylene glycol (DEG), polyethylene glycol (PEG), monopropylene glycol (MPG), monoethylene glycol (MEG), and a combination thereof. According to one embodiment, said solvent comprises a mixture of said organic solvent and water, preferably a mixture of at least one glycol and water; said at least one glycol, preferably being selected in the group consisting of: diethylene glycol (DEG), polyethylene glycol (PEG), monopropylene glycol (MPG), monoethylene glycol (MEG), and a combination thereof. Preferably, said PO2-N nanoparticles are present in said suspension in an amount comprised between 0.1 and 20% by weight, preferably between 1 and 10% by weight relative to the total weight of the suspension. Preferably, in the embodiment wherein said solvent does not comprise or does not consist of glycol, said suspension of PO2-N nanoparticles activatable by UV light and/or visible light and/or sunlight has a density comprised between 0.6 and 1 g/cm³, more preferably between 0.7 and 0.9 g/cm³ and, preferably, a viscosity comprised between 0.8 and 1.3 mPa*s, more preferably between 0.9 and 1.1 mPa*s, measured at 25 °C. Preferably, in the embodiment wherein said solvent comprises or consists of glycol, said suspension of PO2-N nanoparticles activatable by UV light and/or visible light and/or sunlight has a density comprised between 0.6 and 1.1 g/cm³, more preferably between 0.7 and 0.9 g/cm³ and, preferably, a viscosity comprised between 30 and 80 mPa*s, more preferably between 35 and 75 mPa*s, measured at 25 °C. According to one embodiment of the invention, said T1O2-N nanoparticles activatable by UV light and/or visible light and/or sunlight are comprised within a colour coating or a paint. Preferably, according to any one of the embodiments described above, said T1O2-N nanoparticles have a size between 30 and 150 nm, more preferably between 35 and 100 nm, even more preferably between 48 and 150 nm, even more preferably between 48 and 100 nm, even more preferably between 30 and 50 nm, even more preferably between 30 and 80 nm, even more preferably between 48 and 90 nm, measured as a Z-average with the DLS technique (Dynamic Light Scattering, Malvern Instruments). The range of 30-150 nm means that the nanoparticles have a Z-average equal to a whole or decimal number comprised between 30 and 150 nm, with a polydispersity index less of than 0.3, preferably comprised between 0.21 and 0.29, more preferably comprised between 0.216 and 0.286. Such polydispersity values indicate an excellent uniformity in the size of the nanoparticles. Therefore, if for example the Z- average value of the nanoparticles is equal to 49.9 with a polydispersity index of 0.221, this means that the nanoparticles are evenly distributed from a dimensional viewpoint and that almost all of them have an average diameter of about 49.9 nm. Preferably, the amount of doping nitrogen present in said T1O2-N nanoparticles is comprised between 1 and 5% by weight, preferably between 1.5 and 3% by weight relative to the total weight of the nanoparticles. Without wishing to be bound to any theory, the Applicant has nonetheless found said T1O2-N nanoparticles activatable by UV light and/or visible light and/or sunlight have a considerable photocatalytic activity, in particular a considerable activity of oxidative photocatalysis, since, under irradiation (with UV light and/or visible light and/or sunlight), said nanoparticles become a powerful oxidant and show to be surprisingly and particularly effective in killing a virus and/or fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or bacteria, said bacteria being selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. According to an even more preferred embodiment, said T1O2-N nanoparticles have, as determined by X-ray diffraction analysis, at least a brookite crystalline phase in an amount of 10 to 99% by weight relative to the weight of the nanoparticles.

Preferably, said T1O2-N nanoparticles further have a rutile crystalline phase. Even more preferably, said T1O2-N nanoparticles that have at least a brookite crystalline phase and a rutile crystalline phase, also further have an anatase crystalline phase. In one embodiment, said T1O2-N nanoparticles have a brookite crystalline phase in an amount of 90 to 99% by weight relative to the weight of the nanoparticles, the remaining amount to 100% being a rutile and/or anatase crystalline phase. In one embodiment, said T1O2- N nanoparticles have at least two crystalline phases of T1O2: a brookite crystalline phase in an amount of 10 to 99% by weight relative to the weight of the nanoparticles and a rutile crystalline phase (and/or an anatase crystalline phase) in an amount of 25 to 90% by weight relative to the weight of the nanoparticles.

For the purposes of the present invention, said amount of the brookite crystalline phase from “10 to 99% by weight” means that said brookite crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes as described above.

For the purposes of the present invention, said amount of the rutile and/or anatase crystalline phase from “25 to 90% by weight” means that said rutile and/or anatase crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, as described above.

In one embodiment, said T1O2-N nanoparticles have at least two crystalline phases ofPO2: a brookite crystalline phase in an amount of 10 to 75% by weight relative to the weight of the nanoparticles and a rutile crystalline phase (and/or an anatase crystalline phase) in an amount of 25 to 90% by weight relative to the weight of the nanoparticles. For the purposes of the present invention, said amount of the brookite crystalline phase from “10 to 75% by weight” means that said brookite crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, such as, for example, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%,

23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%,

38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%,

53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%,

68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%.

In one embodiment, said PO2-N nanoparticles have a rutile crystalline phase (and/or an anatase crystalline phase) and a brookite crystalline phase, each preferably present in an amount equal to about 50% by weight relative to the weight of the nanoparticles. In a particularly preferred embodiment, said PO2-N nanoparticles have three crystalline phases of PO2: a brookite crystalline phase in an amount of 20 to 75%, an anatase crystalline phase in an amount of 35 to 80% and a rutile crystalline phase in an amount of 35 to 40% by weight relative to the weight of the nanoparticles. For the purposes of the present invention, said amount of the brookite crystalline phase from “20 to 75% by weight” means that said brookite crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, such as, for example, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%,

48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%,

63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%.

For the purposes of the present invention, said amount of the anatase crystalline phase from “35 to 80% by weight” means that said anatase crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, such as, for example, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%,

63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%,

78%, 79%, 80%.

For the purposes of the present invention, said amount of the rutile crystalline phase from “35 to 40% by weight” means that said rutile crystalline phase can be present in an amount equal to any value comprised between the two aforesaid extremes, such as, for example, 35%, 36%, 37%, 38%, 39%, 40%.

According to a particularly preferred embodiment, the present invention relates to the use - for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof - of nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight comprising at least a brookite crystalline phase in an amount of 10 to 99% by weight, preferably from 10 to 75% by weight relative to the weight of the nanoparticles and a rutile crystalline phase in an amount of 25 to 90% by weight relative to the weight of the nanoparticles, more preferably said T1O2-N nanoparticles further comprising an anatase crystalline phase in an amount of 1 to 10 % by weight or 25 to 90% by weight relative to the weight of the nanoparticles. The presence of significant amounts of the brookite crystalline phase within the (photocatalytic) T1O2-N T1O2 nanoparticles according to the embodiments described above brings considerable advantages as regards the photocatalytic properties of said nanoparticles when used to kill a virus and/or to kill fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or to kill bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof, according to the present invention. Without wishing to be bound to any theory, the better activity of the brookite phase compared to the other two crystalline phases of PO2 can be linked to the fact that, since the photocatalytic activity depends on the number of PO2 molecules per cell units, and the brookite phase has a greater cell volume, it has a larger amount of surface oxygen available for photocatalysis and therefore for killing said virus and/or said fungi and/or said bacteria. According to one embodiment, the present invention relates to a use of nitrogen-doped PO2 (PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof, said nanoparticles being in combination with at least one further virucidal and/or bactericidal and/or fungicidal agent, preferably selected from among: a source of silver (in the form of a silver salt, e.g. a silver nitrate or sulphate, or silver nanoparticles), manganese oxide (IV) (MnC>2) nanoparticles, zinc oxide (ZnO) nanoparticles, a source of copper (in the form of a copper salt, e.g. a copper nitrate or sulphate, or copper nanoparticles), and a combination thereof. Preferably, in said embodiment, said PO2-N nanoparticles are as previously described. Preferably, in said embodiment, said PO2-N nanoparticles are in combination with said at least one further virucidal and/or bactericidal and/or fungicidal agent in the form of a mixture (suspension) in a solvent, preferably in an organic solvent, for example ethyl alcohol, acetone or glycol, preferably selected in the group consisting of: diethylene glycol (DEG), polyethylene glycol (PEG), monopropylene glycol (MPG), monoethylene glycol (MEG), and a combination thereof, or mixtures thereof, or in water, or in a mixture of water and an organic solvent, or in the form of a powder mixture. Preferably, said organic solvent comprises a mixture of ethyl alcohol and at least one glycol, or a mixture of acetone and at least one glycol. According to one embodiment, said solvent comprises a mixture of said organic solvent and water, preferably a mixture of water and at least one glycol. Preferably, said at least one glycol is selected in the group consisting of: diethylene glycol (DEG), polyethylene glycol (PEG), monopropylene glycol (MPG), monoethylene glycol (MEG), and a combination thereof. In this manner it is possible to obtain an antiviral and/or antibacterial and/or antifungal activity, due to the presence of the silver and/or Mn02 and/or zinc oxide and/or copper, also in the absence of UV light and/or visible light and/or sunlight. In this embodiment, the amount of silver and/or Mn02 and/or ZnO and/or Cu present in the suspension or final powder mixture (in combination with said PO2-N nanoparticles) is preferably greater than 20 ppm. Preferably, according to one embodiment, said nitrogen-doped PO2 ( PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight as previously described are obtained/obtainable in the form of a calcined powder by means of the process described in WO2019/211787 of the same Applicant, entirely incorporated herein by reference, which comprises the steps of: a) preparing a suspension of PO2 nanoparticles in water; b) adding a nitrogen doping agent to the suspension and mixing until homogeneous; c) drying the suspension to which the nitrogen doping agent was added until obtaining a powder with a moisture residue comprised between 0 and 15% by weight; d) subjecting the dried powder to calcination at a temperature comprised between 400 and 600 °C, thereby obtaining nitrogen-doped PO2 (PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight in the form of a calcined powder.

Said nitrogen-doped PO2 (PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight are preferably obtained/obtainable in the form of a suspension, if, in addition to steps a)-d) described above, the process comprises the further steps of: e) subjecting the calcined powder obtained in step d) to grinding in a solvent, thereby obtaining a suspension of PO2-N nanoparticles activatable by UV light and/or visible light and/or sunlight in a solvent; f) diluting the suspension of step e) with further solvent. Preferably, the suspension of T1O2 nanoparticles in water of step a) is a stable suspension prepared according to the process described in W0200788151 of the same Applicant, entirely incorporated herein by reference.

In particular, the suspension of PO2 nanoparticles in water of step a) is a suspension ofPO2 nanoparticles having a size comprised between 30 and 50 nm, measured with methods known in the art, such as FEG-SEM (scanning electron microscopy), TEM (transmission electron microscopy) and DLS (Dynamic Light Scattering). The polydispersity index of the nanoparticles is less than 0.3, preferably comprised between 0.21 and 0.29, more preferably between 0.216 and 0.286. The concentration of T1O2 nanoparticles suspended in water is comprised between 1 and 10% by weight, preferably between 2 and 8% by weight relative to the weight of the suspension. The suspension of nanoparticles is stable for very long periods without manifesting phenomena of coagulation or conglomeration. Therefore, said suspension can be prepared with the process of W0200788151 and then stored, also for a long time, before being used in step (a). The process for obtaining the suspension of T1O2 nanoparticles in water, preferably in anatase crystalline form, comprises a first step in which a titanium alkoxide in water is subjected to acid hydrolysis at a temperature comprised between 15 and 95 °C and for a time comprised between 12 hours and 72 hours, in the presence of a non-ionic surfactant, preferably Triton X-100. The titanium alkoxide is selected from among titanium methoxide, titanium ethoxide, titanium normal- propoxide, titanium isopropoxide, titanium normal-butoxide and titanium isobutoxide. The preferred alkoxide is titanium propoxide. The mineral acid used for the acid hydrolysis of the titanium alkoxide is selected from among: hydrochloric acid, nitric acid, sulphuric acid, perchloric acid, hydrobromic acid and hydrogen iodide. In step b), a nitrogen doping agent selected from an inorganic ammonium salt and an organic nitrogen compound is added to the suspension of T1O2 nanoparticles in water, preferably in anatase crystalline form. The nitrogen doping agent is preferably selected from ammonium citrate and triethanolamine. Ammonium citrate has provided better results in terms of process and ease of drying of the suspension than triethanolamine and is thus the preferred nitrogen doping agent. The nitrogen doping agent is added to the aqueous suspension of T1O2 nanoparticles in an amount preferably comprised between 2 and 6% by weight, preferably between 3 and 5% by weight. Preferably, the addition of the nitrogen doping agent to the aqueous suspension of T1O2 nanoparticles takes place under stirring and the formation of a white gel is observed. The suspension is then kept under stirring for a time preferably comprised between 4 and 24 hours, that is, until a homogeneous white suspension is obtained. The suspension obtained preferably comprises from 4 to 8% by weight of T1O2 and from 6 to 30% by weight of nitrogen relative to the weight of TiC>2. The suspension preferably comprises from 5 to 7% by weight of T1O2 and from 8 to 25% by weight of nitrogen relative to the weight of TiC>2. The suspension obtained preferably comprises T1O2 nanoparticles having a size comprised between 48 and 150 nm, measured as the Z-average with DLS (Dynamic light scattering, Malvern Instruments). The range of 48-150 nm means that the nanoparticles have a Z-average equal to a whole or decimal number comprised between 48 and 150 nm, with a polydispersity index of less than 0.3, preferably comprised between 0.21 and 0.29, more preferably between 0.216 and 0.286. Such polydispersity values indicate an excellent uniformity in the size of the nanoparticles of the suspension. Therefore, if for example the Z-average of the nanoparticles is equal to 49.9 with a polydispersity index of 0.221 , this means that the suspension comprises very uniform nanoparticles, almost all of which have an average diameter of about 49.9 nm. The suspension of T1O2 nanoparticles also comprising the nitrogen doping agent thus obtained is subjected to drying in step c) by means of the spray-drying technique, or electric or gas ovens, or by heating with microwaves. The latter treatment is to be preferred, since the process shows to be more efficient and faster compared to the use of the conventional spray-drying technique; furthermore, the treatment with microwaves makes it possible to obtain a powder with a lesser degree of aggregation/agglomeration, which makes the subsequent optional grinding step (step e)) more efficient. The drying temperature is preferably comprised between 100 and 150 ^QC, preferably between 110 and 140 ^QC. Drying can last from 10 to 24 hours, preferably from 15 to 20 hours. At the end of drying, one obtains a very fine powder with a moisture residue comprised between 0 and 15% by weight and good flowability. The particle size of the powder is preferably less than 20 pm, more preferably less than 15 pm, calculated with laser diffraction using a Sympatec HELOS (Model H0969). Preferably, 99% of the powder particles have a size of less than 15 pm and 90% of the powder particles have a size of less than 11 pm. More preferably, 50% of the powder particles have a size of less than 5.5 pm and 10% of the powder particles have a size of less than 2 pm. The calcination of step d) preferably takes place at a temperature comprised between 450 and 500 °C. Preferably, heating is carried out by treating the dried powder in a muffle furnace or by means of microwaves. The latter treatment is to be preferred, since the process shows to be more efficient and faster compared to conventional heating in a muffle furnace; furthermore, the treatment with microwaves makes it possible to obtain a powder with a lesser degree of aggregation/agglomeration, which makes the subsequent optional grinding step (step e)) more efficient. The calcination is preferably carried out for a time comprised between 1 and 2 hours, more preferably with a ramp of 1 or 2 hours to arrive at the calcination temperature. The heating gradient can be comprised between 7 and 14 ^QC per minute. During the calcination, the nitrogen doping of T1O2 takes place; the nitrogen penetrates into the T1O2 nanoparticles, positioning itself in a substitution position within the crystal lattice of the T1O2 and/or in an interstitial position, that is, within the crystal planes of the TiC>2. The calcined powder is obtained as a powder of nitrogen-doped T1O2 (T1O2-N) nanoparticles and, for the purposes of the present invention, it is also called “nanoparticle powder”. The calcined powder is obtained as an aggregate powder of nitrogen-doped T1O2 (T1O2-N) which, according to X-ray diffraction analysis, has at least a brookite crystalline phase in an amount of 10 to 99% by weight relative to the weight of the calcined powder. In one embodiment said calcined powder further comprises a rutile crystalline phase. In one embodiment, the calcined powder comprising at least a brookite crystalline phase and a rutile crystalline phase further comprises an anatase crystalline phase as well. In one embodiment, the calcined powder comprises from 90 to 99% by weight, relative to the weight of the calcined powder, of a brookite crystalline phase of T1O2, the remaining amount to 100% being a rutile and/or anatase crystalline phase. In one embodiment, the calcined T1O2-N powder comprises at least two crystalline phases of T1O2: a brookite crystalline phase in an amount of 10 to 99% by weight relative to the weight of the calcined powder and a rutile crystalline phase (and/or an anatase crystalline phase) in an amount of 25 to 90% by weight relative to the weight of the calcined powder. In one embodiment, the calcined T1O2-N powder comprises at least two crystalline phases of T1O2: a brookite crystalline phase in an amount of 10 to 75% by weight relative to the weight of the calcined powder and a rutile crystalline phase (and/or an anatase crystalline phase) in an amount of 25 to 90% by weight relative to the weight of the calcined powder. In one embodiment, the calcined powder comprises a rutile crystalline phase (and/or an anatase crystalline phase) and a brookite crystalline phase, each preferably present in an amount equal to about 50% by weight relative to the weight of the calcined powder.

In one embodiment, the calcined powder comprises three crystalline phases of the T1O2: a brookite crystalline phase in an amount of 20 to 75%, an anatase crystalline phase in an amount of 35 to 80% by weight relative to the weight of the calcined powder and a rutile crystalline phase in an amount of 35 to 40% by weight relative to the weight of the calcined powder. The calcined powder has a degree of purity greater than 95% by weight, preferably equal to or greater than 99% by weight, since the diffraction analysis did not reveal the presence of phases other than the crystalline phases of T1O2 described above.

For the purposes of the present invention, the aforesaid ranges of the amount of brookite, rutile and anatase crystalline phases mean that said crystalline phases can be present in an amount equal to any value comprised between the two aforesaid extremes of the aforesaid ranges, as described above.

Preferably, said calcined powder obtained in step d), has an amount of doping nitrogen present in the TiC>2 comprised between 1 and 5% by weight, preferably between 1.5 and 3% by weight, relative to the total weight of the calcined powder. Without being bound to any theory, the Applicant deems that the formation of a calcined powder of nitrogen doped TiC>2 comprising at least one brookite crystalline phase is ascribable mainly to the use of the TiC>2 suspension obtained with the process of W0200788151 , but probably also to a combination between the use of this starting product, and the drying and calcination steps as just described. The presence of the brookite phase is a surprising and unexpected result, considering that the starting product consists essentially of T1O2 in the anatase phase. The brookite phase brings some considerable advantages as regards the photocatalytic properties of the T1O2-N nanoparticles, in particular proving to be particularly efficient in the use for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae,

Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. In the use for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof, according to the present invention, the calcined powder as previously described can be used as such or subjected to further treatments. Preferably, said calcined powder can be subjected to wet grinding and then re-dispersed in a solvent, according to steps e) and f) described below. Alternatively, the calcined powder can be finely dispersed with or without a grinding and dilution pre treatment according to steps e) and f), within colour coatings and paints used to coat floors, walls or exterior and/or interior surfaces, for example of buildings, in order to render them antiviral and/or antibacterial and/or antifungal, and thus capable of killing viruses and/or fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae,

Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof.

Preferably, said nitrogen-doped PO2 (PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight are obtained/obtainable in the form of a suspension, if, in addition to steps a)-d) described above, the process comprises the further steps of: e) subjecting the calcined powder obtained in step d) to grinding in a solvent, thereby obtaining a suspension of PO2-N nanoparticles activatable by UV light and/or visible light and/or sunlight in a solvent; f) diluting the suspension of step e) with further solvent.

In step e) the calcined powder is preferably subjected to grinding in a high-energy ball mill with the aid of a solvent, for example water, acetone, ethyl alcohol or mixtures thereof. The grinding takes place at a speed preferably comprised between 1000 and 2000 rpm for a time comprised between 30 and 120 minutes, more preferably between 80 and 100 minutes. At the end of the grinding one obtains a very concentrated suspension in the solvent, with concentration values of the T1O2-N nanoparticles comprised, for example, between 15 and 30% by weight. In particular, the suspension obtained after grinding is a suspension of T1O2-N nanoparticles in an organic solvent, for example ethyl alcohol or acetone or mixtures thereof, or in water, or in mixtures of water and an organic solvent. The size of the nanoparticles is preferably comprised between 48 and 150 nm, measured as a Z-average with DLS (Dynamic light scattering, Malvern Instruments). The range of 48-150 nm means that the nanoparticles have a Z-average equal to a whole or decimal number comprised between 48 and 150 nm, with a polydispersity index of less than 0.3, preferably comprised between 0.21 and 0.29, more preferably between 0.216 and 0.286. Such polydispersity values indicate an excellent uniformity in the size of the nanoparticles of the suspension. Therefore, if for example the Z-average value of the nanoparticles is equal to 49.9 with a polydispersity index of 0.221 , this means that the suspension comprises very uniform nanoparticles, almost all of which have an average diameter of about 49.9 nm. The suspension obtained at the end of step e) can be too concentrated and have a rheology that is not suitable for some industrial applications, above all for applications on substrates. For this reason, the process as described above preferably also comprises a subsequent step f), wherein the suspension is further diluted in the same solvent, preferably in an organic solvent or water or mixtures thereof, such as, for example ethyl alcohol, acetone, water or mixtures thereof. The final concentration of the T1O2-N powder in the solvent is thus preferably brought to values comprised between 0.1 and 20% by weight, preferably between 1 and 10% by weight. For applications on substrates, in particular, the rheology of the suspension is preferably characterised by a density comprised between 0.6 and 1 g/cm³, more preferably between 0.7 and 0.9 g/cm³ and, preferably, by a viscosity comprised between 0.8 and 1.3 mPa*s, more preferably between 0.9 and 1.1 mPa*s, measured at 25 °C. In the event that a suspension with these rheological characteristics is not obtained from the grinding and subsequent dilution, it is possible to modulate density and viscosity by adding suitable additives known in the art for this type of function, for example carboxymethylcellulose and glycols. The rheology of the suspension is important in order to be able to use the suspension, preferably on an industrial scale, in particular in order to be able to apply the suspension to substrates of varying nature by means of the “spray coating”, “flow coating”, “dip coating”, “spin coating”, “Meyer bar coating”, “gravure coating”, “knife coating”, “kiss coating”, “die coating” or “film transfer” techniques. In one embodiment of the invention, during step f) of diluting the suspension, it is possible to add to the suspension of T1O2-N nanoparticles at least one further virucidal and/or bactericidal and/or fungicidal agent such as, for example a source of silver (in the form of a silver salt, e.g. a silver nitrate or sulphate, or silver nanoparticles), manganese oxide (IV) (MnC>2) nanoparticles, zinc oxide (ZnO) nanoparticles, a source of copper (in the form of a copper salt, such as, for example a copper nitrate or sulphate, or copper nanoparticles), or a mixture thereof. In this manner one obtains a suspension in a solvent that has antiviral and/or antibacterial and/or antifungal activity, due to the presence of the silver and/or zinc oxide and/or copper, even when not irradiated by UV light and/or visible light and/or sunlight. In this embodiment, the amount of silver and/or MnC and/or ZnO and/or Cu present in the final suspension is preferably greater than 20 ppm. The suspension of T1O2-N nanoparticles obtained at the end of the process as described above comprises nanoparticles with the same crystalline phases as shown in the calcined powder. The percentages by weight indicated are to be understood as percentages by weight of the crystalline phase relative to the weight of the nanoparticles. Preferably, the T1O2-N nanoparticles in suspension have a nitrogen doping content preferably comprised between 1 and 5% by weight, preferably between 1.5 and 3% by weight relative to the weight of the nanoparticles. The suspension of T1O2-N nanoparticles is a suspension in a solvent, preferably ethyl alcohol, acetone, water or mixtures thereof. According to one embodiment, the T1O2-N nanoparticles are present in the suspension in an amount comprised between 0.1 and 20% by weight, preferably between 1 and 10% by weight, preferably in an alcoholic organic solvent, water or mixtures thereof, such as, for example ethyl alcohol or mixtures thereof with water. The solvent is thus present in an amount comprised between 80 and 99.9% by weight. The suspension of T1O2-N nanoparticles can be defined as a ready-to-use suspension, as it has chemical and physical characteristics, e.g. rheology, such as to enable it to be used without further treatments to coat substrates by means of the coating techniques listed above. Furthermore, the suspension thus obtained is stable for over 6 months without the formation of precipitates or phase separations. The subject matter of the present invention also relates to a use of a substrate nanofunctionalised with nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. According to one embodiment, the present invention also relates to a use of a substrate nanofunctionalised with nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight for killing a pathogenic agent, said pathogenic agent preferably being selected from among said virus and/or said fungi and/or said bacteria, as described in the present patent application. Preferably, said nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight are as previously described. Preferably, said nanofunctionalised substrate is entirely or partly coated with said nitrogen-doped PO2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight, and/or comprises said nanoparticles within it. More specifically, the expression “entirely or partly coated with nitrogen-doped PO2 nanoparticles”, means that said nanoparticles form/are present within a nanoparticle coating that entirely or partly coats at least one surface of the substrate, be it an inner and/or outer surface. “Entirely coated” means that the substrate has all inner and/or outer surfaces coated with the nitrogen-doped PO2 nanoparticles. In other words, the inner and/or outer surfaces of the substrate have, overall, a percentage of coverage greater than 95%, preferably greater than 98%. “Partly coated” means that the inner and/or outer surfaces of the substrate have, overall, a percentage of coverage less than 95%, preferably less than 98%. In this case, for example, only some of the surfaces of the substrate may be coated with the nitrogen-doped PO2 nanoparticles. The nanoparticle coating preferably has a thickness, measured by means of an electron microscope, comprised between 1 and 5 pm, preferably between 1.5 and 3 pm, more preferably between 1.8 and 2.6 pm. The expression “comprising within it nitrogen-doped T1O2 nanoparticles” means that said nanoparticles are present within the material/materials forming the substrate. Preferably, both in the embodiment wherein said nanofunctionalised substrate is entirely or partly coated with said T1O2-N nanoparticles and in the embodiment wherein it comprises them within it, said nanofunctionalised substrate comprises an amount of T1O2-N nanoparticles comprised between 1 and 10 g/m², preferably between 2 and 8 g/m², even more preferably between 4 and 7 g/m². According to one embodiment, said substrate nanofunctionalised with nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight further comprises at least one virucidal and/or bactericidal and/or fungicidal agent preferably selected from among: a source of silver (in the form of a silver salt, e.g. a silver nitrate or sulphate, or silver nanoparticles), manganese oxide (IV) (MnC>2) nanoparticles, zinc oxide (ZnO) nanoparticles, a source of copper (in the form of a copper salt, e.g. a copper nitrate or sulphate, or copper nanoparticles); and a combination thereof. Preferably, said at least one further virucidal and/or bactericidal and/or fungicidal agent is comprised, together with the nitrogen-doped T1O2 nanoparticles, within a nanoparticle coating that entirely or partly coats at least one surface of the substrate, be it an inner and/or outer surface. Alternatively, said at least one further virucidal and/or bactericidal and/or fungicidal agent in turn forms a complete or partial coating on said PO2-N nanoparticle coating. Alternatively, said at least one further virucidal and/or bactericidal and/or fungicidal agent is comprised, together with the nitrogen-doped PO2 nanoparticles, within the material/materials forming the substrate. In this manner one obtains a nanofunctionalised substrate that has antiviral and/or antibacterial and/or antifungal activity, due to the presence of the silver and/or MnC>2 and/or zinc oxide and/or copper, even when not irradiated by UV light and/or visible light and/or sunlight. In this embodiment, the amount of silver and/or MnCte and/or ZnO and/or Cu present as a coating of the and/or comprised within the substrate is preferably greater than 20 ppm. Preferably, said substrate is selected in the group consisting of: a substrate of ceramic material, preferably said ceramic material being selected from among cordierite, mullite, alumina and a combination thereof; a substrate of polymeric material, said polymeric material preferably comprising at least one (co)polymer selected from among: PMMA (polymethylmethacrylate), PA (polyamide), PC (polycarbonate), PLA (polylactic acid), PET (polyethylene terephthalate), PE (polyethylene), PVC (polyvinyl chloride), PS (polystyrene), acrylonitrile styrene acrylate (ASA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol (PET-g), polyurethane (PU), polypropylene (PP), copolyester, and a combination thereof; a substrate of textile material, nonwoven fabric, metal, glass, paper and cardboard material, or a combination thereof. According to a preferred embodiment, said substrate is a substrate selected from among: cordierite, mullite, alumina, acrylonitrile butadiene styrene (ABS) and polyethylene terephthalate glycol (PET-g), preferably acrylonitrile butadiene styrene (ABS). Said nanofunctionalised substrate can preferably be obtained/obtainable by means of any process known in the art which enables a complete or partial coating with the nitrogen-doped T1O2 nanoparticles (as previously described, optionally in combination with at least one further virucidal and/or bactericidal and/or fungicidal agent), or which enables the inclusion of said nanoparticles within the material/materials forming the substrate itself, said process preferably being selected from among the techniques of: “spray coating”, “flow coating”, “dip coating”, “spin coating”, “Meyer bar coating”, “gravure coating”, “knife coating”, “kiss coating”, “die coating” or “film transfer”, optionally followed by a calcination step; 3D printing, injection moulding, extrusion, or a combination thereof. Preferably, said nanofunctionalised substrate is opaque, translucid or transparent. According to a preferred embodiment, said nanofunctionalised substrate is translucid or transparent so as to be able to advantageously exploit up to 100% of the luminous radiation (i.e. UV light and/or visible light and/or sunlight) when it is incident on the substrate and can thus be respectively diffused by or passes through the substrate, thereby obtaining superior photocatalytic performances (in terms of killing said virus and/or said fungi and/or said bacteria) of the T1O2-N nanoparticles activatable by UV light and/or visible light and/or sunlight as previously described. According to an even more preferred embodiment, the nanofunctionalised substrate is transparent. Preferably, according to any one of the embodiments described above, said nanofunctionalised substrate comprises a plurality of channels and/or cells suitable for the passage of a fluid. Preferably, said channels and/or cells have a cross section with variable geometry, preferably selected from among circular, hexagonal, square, triangular, rectangular and a combination thereof. More preferably, said channels and/or cells identify a path for a fluid, said path having a variable geometry. Said path is preferably selected from among linear, tortuous, spiral or a combination thereof. According to one embodiment, said nanofunctionalised substrate has a structure selected in the group consisting of: a stratified structure, an interwoven structure, a fabric weave structure and a honeycomb structure, preferably with a variable cell number and/or shape, said shape being for example selected from among circular, hexagonal, square, triangular, rectangular and a combination thereof. According to one embodiment, the nanofunctionalised substrate can comprise several layers in variable numbers and sizes, each layer preferably having a structure as previously described. The nanofunctionalised substrate according to this embodiment preferably comprises at least two layers joined to each other by means of an interlock mechanism or with a plug system. The selection of the number of layers and the assembly thereof and of their structure will vary according to the fluid-dynamic characteristics it is desired to obtain. According to a preferred embodiment, the nanofunctionalised substrate has a honeycomb structure. In other words, said substrate with a honeycomb structure comprises a matrix of walls, preferably thin walls, which define a plurality of parallel conduits that are open at both ends so as to allow the passage of a fluid, preferably air and/or water. Advantageously, said plurality of conduits defines a plurality of oxidation sites in which, through the activation of the photocatalytic properties of the T1O2-N nanoparticles activatable by UV light and/or visible light and/or sunlight comprised within the material(s) forming the substrate itself and/or in the form of a coating of said walls, there occurs an effective killing, by an incident photon, of a virus and/or of fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or of bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae,

Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. Said honeycomb structure is preferably characterised by a CPSI (cells per square inch) value comprised between 40 and 120, preferably between 50 and 100, more preferably between 50 and 70, even more preferably between 55 and 65. According to one embodiment of the invention, said nanofunctionalised substrate is a substrate made of polymeric material characterised by a nanoroughness, measured by means of an electron microscope, comprised between 10 and 50 nm and a macroroughness, measured by means of an electron microscope, comprised between 100 and 600 pm, wherein said nano- and macroroughness is diffused internally and/or superficially. Preferably, said nanoroughness is comprised between 20 and 40 nm and said macroroughness is comprised between 200 and 300 pm. The expression “nano-/macroroughness diffused internally and/or superficially” means that said substrate can exhibit said nanoroughness and macroroughness in every part thereof, i.e. both on at least one inner and/or outer surface of the substrate and incorporated within the polymeric material forming the substrate (observable and measurable, in the latter case, by sectioning the substrate). Without wishing to be bound to any theory, it is possible to hypothesise that said macroroughness is connected to the polymeric material and/or the processing thereof to obtain the substrate itself. Preferably, said processing is selected in the group consisting of: the 3D printing, injection moulding and extrusion techniques, optionally followed by further operations suitable for creating macroroughness. As regards the nanoroughness, by contrast, it is possible to hypothesise that said nanoroughness derives from the functionalisation of the substrate with the T1O2-N nanoparticles as described above (optionally in combination with at least one further virucidal and/or bactericidal and/or fungicidal agent as previously described) which, once in contact with the polymeric material characterised by said macroroughness, become organised so as to create a characteristic nanoroughness. With regard to the embodiments which envisage that said T1O2-N nanoparticles are present (i.e. comprised) within said polymeric material or that they are present both therewithin and in the form of a nanoparticle coating, in this case one can speak of nanoroughness that is both internally and superficially diffused. With regard to the embodiment which envisages that said PO2-N nanoparticles are present solely in the form of a nanoparticle coating on at least one inner and/or outer surface of said substrate, in this case one can speak only of superficially diffused nanoroughness. Without wishing to be bound to any theory, the Applicant has surprisingly found that, thanks to the combination of said nanoroughness comprised between 10 and 50 nm and of said macroroughness, measured by means of an electron microscope, comprised between 100 and 600 pm, it is possible to obtain a nanofunctionalised substrate made of polymeric material in which there is perfect compatibility between the PO2-N nanoparticles as described above (optionally in combination with at least one further virucidal and/or bactericidal and/or fungicidal agent as previously described) with which the substrate is nanofunctionalised and the polymeric material itself. Said compatibility is connected to the amount of PO2- N nanoparticles as described above (optionally in combination with at least one further virucidal and/or bactericidal and/or fungicidal agent as previously described) that can effectively functionalise the substrate and, consequently, the photocatalytic performances thereof. Said compatibility makes it possible, in fact, to have a better anchorage of said nanoparticles to the substrate and to be able not only to effectively functionalise the substrate with large amounts of PO2-N nanoparticles as described above (optionally in combination with at least one further virucidal and/or bactericidal and/or fungicidal agent as previously described), but also to maintain the latter effectively adherent thereto, thus ensuring a long-lasting photocatalytic activity with high performances resulting in the effective killing of a virus and/or of fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or of bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. Furthermore, thanks to the specific nano- and macroroughness values according to this preferred embodiment of the substrate, it is possible to assure an effective dose of said PO2-N nanoparticles (optionally in combination with at least one further virucidal and/or bactericidal and/or fungicidal agent as previously described) present both within it and in the form of a nanoparticle coating on the at least one inner and/or outer surface of the substrate. In particular, according to a particularly preferred embodiment, thanks to the nanoroughness and macroroughness values previously described, said substrate can be effectively coated with a nanoparticle coating of the aforesaid thickness, which proves to be advantageously compatible and adherent to the underlying polymeric material over an extended period of time. Preferably, according to the embodiment wherein said nanofunctionalised substrate is a substrate of polymeric material, said nanofunctionalised substrate can be obtained/obtainable by means of a process comprising the steps of:

(i) preparing a substrate of polymeric material, having at least one inner and/or outer surface, by means of a technique selected in the group consisting of: 3D printing, injection moulding or extrusion of a polymeric material, said polymeric material possibly being a polymeric material comprising the T1O2-N nanoparticles as described above within it;

(ii) applying, on the at least one inner and/or outer surface of the substrate obtained in step (i), a suspension of PO2-N nanoparticles as previously described, wherein said nanoparticles are preferably present in the suspension ad a concentration comprised between 1 and 30% weight/weight, by means of a technique selected in the group consisting of: “spray coating”, “flow coating”, “dip coating”, “spin coating”, “Meyer bar coating”, “gravure coating”, “knife coating”, “kiss coating”, “die coating” and “film transfer”; with the condition that, if the PO2-N nanoparticles are present within the polymeric material in step (i), step (ii) can optionally be omitted.

In the embodiments wherein said T1O2-N nanoparticles are present within the polymeric material forming the substrate or wherein said PO2-N nanoparticles are present both within the polymeric material and in the form of a nanoparticle coating, the polymeric material comprising PO2-N nanoparticles used in step (i) is preferably a polymeric nanocomposite material. Said polymeric nanocomposite material is preferably obtained by compounding, i.e. by adding a powder comprising the PO2-N nanoparticles as previously described to the polymeric material, preferably in the form of pellets, and subsequently extruding either the nanofunctionalised substrate made of polymeric material or, alternatively, a polymeric nanocomposite thread, which is subsequently processed by means of a 3D printing or injection moulding technique in order to produce the nanofunctionalised substrate made of polymeric material as previously described. In the embodiment wherein the substrate is further nanofunctionalised with at least one further virucidal and/or bactericidal and/or fungicidal agent, it is possible to add, during said compounding, said at least one further virucidal and/or bactericidal and/or fungicidal agent selected from among: a source of silver (in the form of a silver salt, e.g. a silver nitrate or sulphate, or silver nanoparticles), manganese oxide (IV) (MnC ) nanoparticles, zinc oxide (ZnO) nanoparticles, a source of copper (in the form of a copper salt, e.g. a copper nitrate or sulphate, or copper nanoparticles); and a combination thereof. Advantageously, the possibility of being able to functionalise the polymeric material before processing it to produce the nanofunctionalised substrate makes it possible to standardise production so as to obtain different nanofunctionalised substrates comprising the same amount of PO2-N nanoparticles and to use them effectively to kill a virus and/or to kill fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or to kill bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. Advantageously, this embodiment further enables a second functionalisation to be carried out, optionally, by coating the substrate (already nanofunctionalised in step (i) in which the T1O2-N nanoparticles are present within the polymeric material) with a nanoparticle coating through the application of a suspension of T1O2-N nanoparticles, as previously described.

Preferably, the substrate prepared according to step (i) can undergo a further treatment adapted to impart further macroroughness. Said further treatment is preferably selected in the group consisting of: laser treatment, embossing of the mould, and a combination thereof. The mould itself can be designed and constructed so that the desired roughness is formed precisely during the mechanical action of pressing and the subsequent extraction from the mould. This proves particularly advantageous in the event that the substrate is prepared with the injection moulding or extrusion techniques, which impart to the substrate macroroughness values that are generally lower than those required by the present invention. According to a particularly preferred embodiment, in the above-described step (i), the substrate is prepared by means of 3D printing. Advantageously, the operation of forming the substrate by means of 3D printing effectively produces a macroroughness which, though in the case of traditional applications it represents a problem, being undesirable, in this case constitutes an advantage, as it makes it possible to effectively increase the compatibility between the polymeric material of the substrate and the T1O2-N nanoparticles and thus to increase the activity of killing said virus and/or said fungi and/or said bacteria performed by the nanofunctionalised substrate according to the present invention. Preferably, the suspension of PO2-N nanoparticles of the above-described step (ii) is as previously described. In order to ensure better applications on the substrate, the rheology of said suspension is preferably characterised by a density comprised between 0.6 and 1 g/cm³, more preferably between 0.7 and 0.9 g/cm³, and by a viscosity comprised between 0.8 and 1.3 mPa-s, more preferably between 0.9 and 1.1 mPa-s, measured at 25 °C. Without wishing to be bound to any theory, the Applicant has nonetheless surprisingly found that, with the same weight of the applied suspension of PO2-N nanoparticles, the amount of nanoparticles effectively adhering to the substrate and, therefore, functionalising the substrate, shows to be considerably higher (preferably comprised between 1 and 5 g/m², preferably between 1.5 and 3 g/m², more preferably between 1.8 and 2,6 g/m²) in the case of the nanofunctionalised substrate as described above, characterised by a nanoroughness, measured by means of an electron microscope, comprised between 10 and 50 nm and a macroroughness, measured by means of an electron microscope, comprised between 100 and 600 pm, wherein said nano- and macroroughness is diffused internally and/or superficially, as compared to a substrate made of the same polymeric material, but having different nanoroughness and macroroughness values. In the embodiment wherein the substrate is further nanofunctionalised with at least one further virucidal and/or bactericidal and/or fungicidal agent, it is possible to add to the suspension of PO2-N nanoparticles of step (ii) at least one further virucidal and/or bactericidal and/or fungicidal agent selected from among: a source of silver (in the form of a silver salt, e.g. a silver nitrate or sulphate, or silver nanoparticles), manganese oxide (IV) (MnC ) nanoparticles, zinc oxide (ZnO) nanoparticles, a source of copper (in the form of a copper salt, e.g. a copper nitrate or sulphate, or copper nanoparticles), or a combination thereof. Preferably, before step (ii) as described above, according to a preferred embodiment, a further step (ii’) can be carried out. Said step (ii’) is a step of pre-activating the substrate obtained in the previously described step (i) by immersion in an organic solvent, for an immersion time comprised between 0.1 and 50 minutes and a subsequent heat treatment at a temperature comprised between 30 and 60 °C. Preferably, said organic solvent is selected in the group consisting of: acetone, ethyl alcohol, isopropyl alcohol, methyl alcohol and a combination thereof. More preferably, said organic solvent is acetone. Said immersion time is preferably comprised between 1 and 10 minutes. Said heat treatment is preferably carried out at a temperature comprised between 35 and 55 °C. Advantageously, said pre-treatment step (ii’) proves to be effective in further increasing the compatibility between the polymeric material of the substrate and the subsequent nanoparticle coating, thus further increasing the adhesion of said coating to the substrate and consequently improving, over time, the photocatalytic performance thereof and the killing of a virus and/or of fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or of bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof. According to one embodiment, after step (ii), a further step (iii) can be carried out. Said step (iii) is a step of subjecting the substrate obtained to a heat treatment at a temperature comprised between 30 and 90 °C, for a treatment time comprised between 0.5 and 3 hours. Said temperature is preferably comprised between 35 and 55 °C. Said treatment time is preferably comprised between 0.5 and 2 hours. Advantageously, the heat treatment step (iii) makes it possible to assure a further improved adhesion of the nanoparticle coating to the substrate. Advantageously, the choice of the material of the substrate according to this preferred embodiment makes it possible not only to obtain, by means of 3D printing, injection moulding or extrusion techniques, a substrate with variable geometries, thicknesses and shapes which can be modulated according to need, but also to adjust the optical properties thereof. In particular, according to a particularly preferred embodiment, the nanofunctionalised substrate is translucid or transparent, even more preferably transparent. The Applicant has found that modulating the parameters listed above (shape, thickness, geometry, degree of opacity/translucency/transparency of the substrate, degree of roughness imparted to the substrate by the presence of TiC -N nanoparticles comprised within it and/or in the form of a nanoparticle coating) makes it possible to vary and optimise the properties and the performance of the substrate itself, in terms of killing said virus and/or said fungi and/or said bacteria, as it is possible to modulate the time of contact of said virus and/or said fungi and/or said bacteria with the nanofunctionalised substrate, the amount of T1O2-N nanoparticles present in and/or on the substrate and the percentage of luminous radiation that irradiates, possibly passing through the support itself or being diffused thereby. Furthermore, the Applicant has found that modulating the nano- and macroroughness values makes it possible to assure an effective adhesion of the nanoparticle coating, which otherwise is generally scarcely compatible with a substrate made of polymeric material and has a tendency to peel and come detached, thus deteriorating, over time, the performance of the substrate in terms of killing said virus and/or said fungi and/or said bacteria. Preferably, according to the embodiment wherein said nanofunctionalised substrate is a substrate made of ceramic material, preferably selected in the group consisting of: cordierite, mullite, alumina and a combination thereof, said nanofunctionalised substrate can be obtained/obtainable by means of the process described in WO2018/207107 of the same Applicant, entirely incorporated herein by reference, which comprises the steps of:

(1) synthesising an aqueous suspension of PO2 nanoparticles;

(2) adding a nitrogen doping agent to said suspension, thereby producing a suspension comprising said PO2 nanoparticles and said nitrogen doping agent;

(3) applying said suspension to at least one application surface of a substrate, thereby forming a nanoparticle coating, said coating being a partial or complete coating;

(4) subjecting said substrate to a heating cycle.

Preferably, said steps (1) and (2) correspond to steps a) and b) of the process described in WO2019/211787 of the same Applicant, as previously described.

According to one embodiment, step (3) comprises a first sub-step (3a) of applying said suspension comprising said PO2 nanoparticles and said nitrogen doping agent to at least one application surface of the substrate, for example by means of a spraying process, and a second sub-step (3b) of applying a flow of compressed air onto said at least one application surface so as to remove any excess nanoparticle coating that may have been deposited. Alternatively, it is possible to apply the suspension comprising said PO2 nanoparticles and said nitrogen doping agent (also called “doping suspension”) by means of dip coating or flow coating processes or applications typical of the ceramic field, such as veil-glazing, screen printing, bell-glazing, air brushing or digital injection. Preferably, the heating cycle of step (4) of subjecting the substrate to a heating cycle is carried out after a period of rest of the substrate itself, by heating it to a temperature between 490 °C and 510 °C. Advantageously, during the heating cycle (also called the calcination step), the doping of the titanium dioxide with the nitrogen from the nitrogen doping agent takes place and the nitrogen penetrates into the T1O2 nanoparticles, positioning itself in a substitutional position within the PO2 crystalline lattice and/or in an interstitial position, that is, within the PO2 crystalline planes. In the case in which a static furnace is used, the heating cycle is preferably carried out with a temperature variation coefficient of 50 °C/h for a period of ten hours, reaching a maximum temperature of about 500 °C. However, in the case in which a continuous run furnace is used, a 3-hour heating cycle can be implemented, with a preheating step, a 500 °C heating step and a cooling step, with a running speed of about 4 m/h. In general, it can be observed that the heating cycle is of a duration substantially ranging from 2 to 11 hours, depending on the type of heating device used. The subject matter of the present invention further relates to a device for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof; said device comprising at least one nanofunctionalised substrate and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm. According to one embodiment, the subject matter of the present invention also relates to a device for killing a pathogenic agent; said pathogenic agent preferably being selected from among said virus and/or said fungi and/or said bacteria, as described in the present patent application; said device comprising at least one nanofunctionalised substrate and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm. Preferably, said at least one nanofunctionalised substrate and said at least one light source are arranged in such a way that the radiation emitted by said at least one light source irradiates at least partly, preferably entirely, the nanofunctionalised substrate. In other words, it can be affirmed that said device comprises said at least one nanofunctionalised substrate “associated” with said at least one light source. Preferably, said nanofunctionalised substrate is as previously described. Preferably, said nanofunctionalised substrate is “activated” by irradiation with light (i.e. radiation) having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm, preferably when the device, and hence the at least one light source, are switched on. Without wishing to be bound to any theory, it is nonetheless possible to maintain that irradiation with a radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm, brings about the activation of the photocatalytic properties of the T1O2-N nanoparticles that are present as a coating (complete or partial) of the substrate and/or comprised therewithin, thus enabling the killing of said virus and/or said fungi and/or said bacteria. In one embodiment, said device is a filtration device that enables the decontamination of a fluid, preferably air and/or water and/or a body fluid, from said virus and/or said fungi and/or said bacteria comprised within said fluid. According to this embodiment, said filtration device further comprises at least one system for ventilation and/or the distribution of a fluid, preferably air and/or water and/or body fluid, configured to allow the passage of said fluid within said filtration device, preferably favouring contact with and/or the passage through the at least one nanofunctionalised substrate. In one embodiment, said filtration device comprising at least one nanofunctionalised substrate as described above and at least one light source, is characterised in that said at least one nanofunctionalised substrate completely surrounds and/or incorporates said at least one light source, said at least one light source preferably being positioned so as not to obstruct the flow of the fluid, preferably air and/or water and/or body fluid, during its passage within the device. In one embodiment, said device is a lighting apparatus. Preferably, said lighting apparatus comprises a substrate for one or more lighting elements having inner and/or outer light diffusion surfaces, characterised in that said inner and/or outer surfaces are partly or entirely coated with the PO2-N nanoparticles as previously described (optionally in combination with at least one further virucidal and/or biocidal agent as previously described).

According to this embodiment, therefore, the at least one nanofunctionalised substrate and the at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm, coincide. Alternatively, said lighting apparatus can comprise at least one nanofunctionalised substrate as previously described and a support for one or more lighting elements, having inner and/or outer light diffusion surfaces, characterised in that said inner and/or outer surfaces are partly or entirely coated with the PO2-N nanoparticles as previously described (optionally in combination with at least one further virucidal and/or biocidal agent as previously described). According to this embodiment, therefore, not only does said device comprise the at least one nanofunctionalised substrate as described above, but the at least one light source is also nanofunctionalised. Preferably, said lighting apparatus as described above, can also be integrated with a system for ventilation and/or the distribution of a fluid, preferably air and/or water and/or body fluid, configured to allow the passage of said fluid within said device (i.e. lighting apparatus), preferably favouring contact with and/or the passage through the at least one nanofunctionalised substrate. According to this embodiment, said device can also be defined as a “filtering lighting apparatus”. Preferably, the lighting apparatus as described above can be an LED panel, a projector, a light bulb or a furnishing object, such as, for example a ceiling light fixture, a lamp (fixed or movable) or a chandelier. In one embodiment said lighting apparatus comprises a plurality of lighting elements (for example LEDs) organised in a chain-like succession. In one embodiment, light diffusion shields are present in a position below or above the aforesaid chain of lighting elements. Preferably, according to any one of the previously described embodiments, said at least one light source is selected from a light source, preferably an LED, with a colour temperature comprised between 3000 and 7000 K, preferably between 3000 and 6000 K, more preferably between 6000 and 7000 K. Said at least one light source preferably further has an irradiance comprised between 70 and 100 W/m². Said at least one light source preferably further has a yield in terms of luminous flux comprised between 500 and 1000 Im. In the embodiment wherein the substrate is further nanofunctionalised with at least one virucidal and/or bactericidal and/or fungicidal agent as previously described, said device therefore has, in addition to a photocatalytic activity for killing said virus and/or said bacteria and/or said fungi, also a virucidal and/or bactericidal and/or fungicidal activity in the absence of irradiation by a source of light (UV light and/or visible light and/or sunlight), that is, for example when at least one light source comprised in the device itself is not in action. Advantageously, the Applicant has found that, given the versatility of the process and the materials used to produce the nanofunctionalised substrate, according to one embodiment, it is possible to advantageously miniaturise said substrate and, consequently, the device that will comprise it, preferably the filtration device. Furthermore, the Applicant has found that, given the possibility of choosing thicknesses and the possibility of varying the geometries of the substrate as described above (for example by creating an internal design of the substrate providing for multiple paths that advantageously make it possible to increase the contact time of said virus and/or said fungi and/or said bacteria present in the fluid to be treated), it is possible to obtain an optimisation of the fluid- dynamic system of the device and obtain an effective killing of said virus and/or said fungi and/or said bacteria. The present invention also relates to a method for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof; said method comprising the steps of:

(A) providing nitrogen-doped TiC>2 (Ti02-N) nanoparticles activatable by UV light and/or visible light and/or sunlight;

(B) placing said nitrogen-doped TiC>2 nanoparticles in contact with said virus and/or with said fungi and/or with said bacteria;

(C) irradiating said nanoparticles with a source of UV light and/or visible light and/or sunlight.

According to one embodiment, the present invention also relates to a method for killing a pathogenic agent; said pathogenic agent preferably being selected from among said virus and/or said fungi and/or said bacteria, as described in the present patent application; said method comprising the steps of:

(B) placing said nitrogen-doped TiC>2 nanoparticles in contact with said pathogenic agent;

Preferably, said TiC -N nanoparticles are as previously described. Preferably step (B) of “placing” said nitrogen-doped TiC>2 nanoparticles in contact with said virus and/or with said fungi and/or with said bacteria, for the purposes of the present invention, is to be understood as a step in which said virus and/or said fungi and/or said bacteria “enter spontaneously into contact” or “are placed in contact” (for example by an operator/individual and/or by conveying a flow of a fluid comprising said virus and/or said fungi and/or said bacteria over said nanoparticles, etc.) or else “are in contact by chance” with said nanoparticles, so that said nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight can be able to perform their killing activity against said virus and/or said fungi and/or said bacteria. In this context, for the purposes of the present invention, the expression “virus and/or fungi and/or bacteria in contact with said nitrogen-doped PO2 nanoparticles”, means that said virus and/or said fungi and/or said bacteria are on the surface of said nanoparticles, preferably being adsorbed onto it. According to one embodiment, the source of UV light and/or visible light and/or sunlight of step (C) is a light source as previously described. The subject matter of the present invention also relates to a method for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof; said method comprising the steps of:

(A’) providing a substrate nanofunctionalised with nitrogen-doped TiC>2 (Ti02-N) nanoparticles activatable by UV light and/or visible light and/or sunlight;

(B’) placing said nanofunctionalised substrate in contact with said virus and/or with said fungi and/or with said bacteria;

(C’) irradiating said nanofunctionalised substrate with a source of UV light and/or visible light and/or sunlight.

(B’) placing said nanofunctionalised substrate in contact with said pathogenic agent;

(C’) irradiating said nanofunctionalised substrate with a source of UV light and/or visible light and/or sunlight. Preferably, said nanofunctionalised substrate is as previously described. Preferably, step (B’) of “placing” said nanofunctionalised substrate in contact with said virus and/or with said fungi and/or with said bacteria, for the purposes of the present invention, is to be understood as a step in which said virus and/or said fungi and/or said bacteria “enter spontaneously into contact” or “are placed in contact” (for example by an operator/individual and/or by conveying a flow of a fluid comprising said virus and/or said fungi and/or said bacteria over said nanoparticles, etc.) or else “are in contact by chance” with said substrate nanofunctionalised with nitrogen-doped T1O2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight, so that said nanoparticles can be able to perform their killing activity against said virus and/or said fungi and/or said bacteria. In this context, for the purposes of the present invention, the expression “virus and/or fungi and/or bacteria in contact with said nanofunctionalised substrate”, means that said virus and/or said fungi and/or said bacteria are on at least one surface, be it an inner and/or outer surface, of said substrate nanofunctionalised with said nanoparticles, more preferably being adsorbed onto the surface of said nanoparticles. According to one embodiment, the source of UV light and/or visible light and/or sunlight of step (C’) is a light source as previously described. The subject matter of the present invention also relates to a method for killing a virus and/or for killing fungi selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium, and a combination thereof; and/or for killing bacteria selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae, and a combination thereof; said method comprising the steps of:

(A”) providing a device comprising at least one substrate nanofunctionalised with nitrogen-doped TiC>2 nanoparticles and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm;

(B”) placing said device in contact with said virus and/or with said fungi and/or with said bacteria;

(C”) irradiating said at least one nanofunctionalised substrate with said light source. According to one embodiment, the present invention also relates to a method for killing a pathogenic agent; said pathogenic agent preferably being selected from among said virus and/or said fungi and/or said bacteria, as described in the present patent application; said method comprising the steps of:

(A”) providing a device comprising at least one substrate nanofunctionalised with nitrogen-doped PO2 nanoparticles and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm;

(B”) placing said device in contact with said pathogenic agent;

(C”) irradiating said at least one nanofunctionalised substrate with said light source. Preferably, said device is as previously described. Preferably, step (B”) of “placing” said device in contact with said virus and/or with said fungi and/or with said bacteria, for the purposes of the present invention, is to be understood as a step in which said virus and/or said fungi and/or said bacteria “enter spontaneously into contact” or “are placed in contact” (for example by an operator/individual and/or by conveying a flow of a fluid comprising said virus and/or said fungi and/or said bacteria over said nanoparticles, etc.) or else “are in contact by chance” with said device comprising at least one substrate nanofunctionalised with nitrogen-doped PO2 (PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight, so that said nanoparticles can be able to perform their killing activity against said virus and/or said fungi and/or said bacteria. In this context, for the purposes of the present invention, the expression “virus and/or fungi and/or bacteria in contact with said device”, means that said virus and/or said fungi and/or said bacteria are on at least one surface, be it an inner and/or outer surface of said at least one substrate nanofunctionalised with said nanoparticles comprised in the device, more preferably being adsorbed onto the surface of said nanoparticles. For the purposes of the present invention, in this embodiment, “light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm” is to be understood as synonymous with “source of UV light and/or visible light and/or sunlight”. According to a preferred embodiment of the present invention, the irradiating step (C), (C’) or (C”) is carried out for a period of time comprised between 0.5 and 48 hours, preferably between 1 and 12 hours, more preferably between 2 and 8 hours.

Preferably, according to any one of the embodiments previously described, said virus is selected in the group consisting of: Coronaviridae, preferably Orthocoronavirinae, more preferably alphacroronavirus (alpha-CoV), even more preferably HCoV-229E and HCoV-NL63, betacoronavirus (beta-CoV), even more preferably OC43, HKU1 , SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2;

Bacteriophages, preferably Myoviridae, Siphoviridae, Podoviridae, Cystoviridae, Microviridae, more preferably FC174;

Caliciviridae, preferably Norovirus;

Picornaviridae, preferably Enterovirus, Echovirus, Rhinovirus and Coxsakievirus, even more preferably Coxsakievirus B, Enterovirus C, even more preferably poliovirus;

Reoviridae, preferably Rotavirus, more preferably Rotavirus A, Rotavirus B, Rotavirus C, Rotavirus D, Rotavirus and, Rotavirus F, Rotavirus G, Rotavirus H, Rotavirus I, Rotavirus J;

Adenoviridae, preferably Adenovirus, more preferably Atadenovirus, Aviadenovirus, lchtadenovirus, Mastadenovirus, Siadenovirus;

Astroviridae, preferably Avastrovirus, more preferably Avastrovirus 1 , Avastrovirus 2, Avastrovirus 3;

Anelloviridae, preferably Alphatorquevirus, more preferably Torque teno virus 1 ; Pramixoviridae, preferably respiratory syncytial virus (RSV) and parainfluenza virus;

Poxviridae, preferably Orthopoxvirus, more preferably Variola virus;

Filoviridae, preferably Ebolavirus;

Orthomyxoviridae, preferably Alphainfluenzavirus, Betainfluenzavirus, Deltainfluenzavirus, Gammainfluenzavirus, influenza virus A, influenza virus B, H 1 N1 and H5N1 ; hepatitis virus, preferably hepatitis virus A (FIAV), hepatitis virus B (FIBV), hepatitis virus C (FICV), hepatitis virus D (FIDV), hepatitis virus E (HEV); and a combination thereof.

Preferably, said virus is selected in the group consisting of:

- Coronaviridae, preferably Orthocoronavirinae, more preferably alphacoronavirus (alpha-CoV), even more preferably FICoV-229E and FICoV-NL63, betacoronavirus (beta-CoV), even more preferably OC43, HKU1 , SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2;

- Poxviridae, preferably Orthopoxvirus, more preferably Variola virus;

- Filoviridae, preferably Ebolavirus; - Orthomyxoviridae, preferably Alphainfluenzavirus, Betainfluenzavirus, Deltainfluenzavirus, Gammainfluenzavirus, influenza virus A, influenza virus B, H1 N1 and H5N1 ;

- hepatitis virus, preferably hepatitis virus A (HAV), hepatitis virus B (HBV), hepatitis virus C (HCV), hepatitis virus D (HDV), hepatitis virus E (HEV); and a combination thereof.

Preferably, said virus is selected in the group consisting of:

- alphacoronavirus (alpha-CoV), preferably HCoV-229E and HCoV-NL63, betacoronavirus (beta-CoV), preferably OC43, HKU1 , SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2;

- Orthopoxvirus, preferably Variola virus;

- Filoviridae, preferably Ebolavirus; and a combination thereof.

Preferably, said virus is selected in the group consisting of: HCoV-229E, HCoV-NL63, OC43, HKU1 , SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2, preferably SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2, even more preferably SARS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2, even more preferably Bovine coronavirus (BCoV) and SARS-CoV-2.

Preferably, according to any one of the embodiments previously described, said fungi are selected in the group consisting of:

- Cladosporium, preferably Cladosporium cladosporioides and Cladosporium herbarum;

- Microsporum, preferably Microsporum audouinii, Microsporum felineum, Microsporum ferrugineum and Microsporum minutissimum;

- Aspergillus, preferably Aspergillus fumigatus, Aspergillus sydowii and Aspergillus usus;

- Penicillium, preferably Penicillium corylophilum, Penicillium chrysogenum, Penicillium glabrum, Peniciullium corylophilum and Penicillium marneffei;

- Mucor, preferably Mucor hiemalis;

- Rhizopus, preferably Rhizopus oryzae and Rhizopus nigricans,

- Cryptococcus, preferably Cryptococcus neoformans, Cryptococcus laurentii and Cryptococcus albidus;

- Exophiala, preferably Exophiala jeanselmei, Exophiala dermatitidis, Exophiala hongkongensis, Exophiala phaeomuriformis, Exophiala pisciphila, Exophiala werneckii;

- Candida, preferably Candida albicans, Candida auris, Candida dubliniensis, Candida glabrata, Candida lusitaniae, Candida parapsilosis and Candida tropicalis;

- Fusarium, preferably Fusarium oxysporum; and a combination thereof.

Preferably, said fungi are selected in the group consisting of: Cladosporium cladosporioides, Cladosporium herbarum, Microsporum audouinii, Microsporum felineum, Microsporum ferrugineum, Microsporum minutissimum, Aspergillus fumigatus, Aspergillus sydowii, Aspergillus usus, Penicillium corylophilum, Penicillium chrysogenum, Penicillium glabrum, Peniciullium corylophilum, Penicillium marneffei, Mucor hiemalis, Rhizopus oryzae, Rhizopus nigricans, Cryptococcus neoformans, Cryptococcus laurentii, Cryptococcus albidus, Exophiala jeanselmei, Exophiala dermatitidis, Exophiala hongkongensis, Exophiala phaeomuriformis, Exophiala pisciphila, Exophiala werneckii, Candida albicans, Candida auris, Candida dubliniensis, Candida glabrata, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Fusarium oxysporum and a combination thereof.

Preferably, according to any one of the embodiments previously described, said bacteria are selected in the group consisting of:

- Streptococcaceae, preferably Streptococcus, more preferably Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus faecalis and Streptococcus mutans;

- Bacillaceae, preferably Bacillus, more preferably Bacillus subtilis, Bacillus anthracis, Bacillus oleronius, and Bacillus cereus,

- Clostridiaceae, preferably Clostridium, more preferably Clostridium difficile, Clostridium perfringens, Clostridium tetani and Clostridium botulinum;

- Enterococcaceae, preferably Enterococcus, more preferably vancomycin- resistant Enterococcus spp. (VRE), Enterococcus faecalis and Enterococcus Faecium;

- Staphylococcaceae, preferably Staphylococcus, more preferably Staphylococcus auricularis, Staphylococcus capitis, Staphylococcus caprae, Staphylococcus cohnii, Staphylococcus lugdunensis, Staphylococcus saprophyticus,

Staphylococcus aureus, even more preferably methicillin-resistant

Staphylococcus aureus (MRSA), even more preferably coagulase-negative staphylococci (CNS), even more preferably Staphylococcus epidermidis;

- Pseudomonadaceae, preferably Pseudomonas, more preferably Pseudomonas aeruginosa and Pseudomonas fluorescens;

- Legionellaceae, preferably Legionella, more preferably Legionella pneumophila;

- Campylobacteraceae, preferably Arcobacter, preferably Arcobacter butzleri;

- Moraxellaceae, preferably Acinetobacter, preferably Acinetobacter Baumannii;

- Enterobacteriaceae, preferably Enterobacter, Salmonella, more preferably Salmonella enterica, Klebsiella, more preferably Klebsiella pneumoniae, Klebsiella granulomatis, Shigella, more preferably Shigella dysenteriae and Shigella flexneri, Escherichia, more preferably Escherichia Coli;

- Micrococcaceae, preferably Micrococcus, more preferably Micrococcus luteus;

- Mycobacteriaceae, preferably Mycobacterium, more preferably Mycobacterium tuberculosis, Mycobacterium africanum, Mycobacterium leprae, Mycobacterium marinum, Mycobacterium paratuberculosis and Mycobacterium ulcerans;

- Spirochaetaceae, preferably Treponema, preferably Treponema pallidum, Treponema carateum, Treponema pertenue and Treponema endemicum;

- Leptospiraceae, preferably Leptospira, preferably Leptospira interrogans, Leptospira kirschneri, Leptospira noguchii, Leptospira alexanderi, Leptospira weilii, Leptospira genomospecies 1 , Leptospira borgpetersenii, Leptospira santarosai, Leptospira kmetyi; and a combination thereof.

Preferably, said bacteria are selected in the group consisting of: Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus faecalis, Streptococcus mutans, Clostridium difficile, Clostridium perfringens, Clostridium tetani, Clostridium botulinum, Staphylococcus aureus, preferably methicillin- resistant Staphylococcus aureus (MRSA), coagulase-negative staphylococci (CNS), preferably Staphylococcus epidermidis, Legionella pneumophila, Enterobacter, Salmonella enterica, Klebsiella, preferably Klebsiella pneumoniae and Klebsiella granulomatis, Shigella, preferably Shigella dysenteriae and Shigella flexneri, Escherichia, preferably Escherichia Coli, Mycobacterium tuberculosis, Mycobacterium africanum, Mycobacterium leprae, Mycobacterium marinum, Mycobacterium paratuberculosis and Mycobacterium ulcerans, Treponema pallidum, Treponema carateum, Treponema pertenue, Treponema endemicum, and a combination thereof. Preferably, said bacteria are selected in the group consisting of: Staphylococcus aureus and Escherichia, more preferably methicillin-resistant Staphylococcus aureus (MRSA) and Escherichia Coli.

Preferably, according to any one of the embodiments previously described, said virus and/or said fungi and/or said bacteria are comprised within a fluid, preferably air and/or water and/or a body fluid, preferably selected from among blood, blood plasma, blood serum, ear wax, faeces, urine, sperm, vaginal secretions, mucus, sebum, sweat, tears, pus, or a combination thereof. According to a particularly preferred embodiment, said virus and/or said fungi and/or said bacteria are comprised within a current/flow of air, preferably within an aerosol. According to a particularly preferred embodiment, said virus and/or said fungi and/or said bacteria are comprised within a fluid selected from among: a sneeze, breath, a cough or saliva of an individual and/or an animal. According to one embodiment, said virus and/or said fungi and/or said bacteria are present on a surface, preferably adsorbed onto said surface. Without wishing to be bound to any theory, the Applicant has nonetheless found that the use of the nitrogen-doped PO2 nanoparticles activatable by UV light and/or visible light and/or sunlight, or of a substrate nanofunctionalised with said nanoparticles, or of a device comprising said nanofunctionalised substrate and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, as described above, according to the present invention, proves to be particularly effective, as it makes it possible to obtain a killing of said virus and/or said fungi and/or said bacteria (when said virus and/or said fungi and/or said bacteria are present either on a surface or in a fluid/aerosol) at a percentage greater than 80%, preferably greater than 95%, more preferably greater than 96%, even more preferably greater than 97%, even more preferably greater than 97.55%, even more preferably greater than 97.99%, even more preferably greater than 98%, even more preferably greater than 98.55%, even more preferably greater than 98.99%, even more preferably greater than 99% even more preferably greater than 99.55%, even more preferably greater than 99.99%. Similarly, the method according to the present invention also proves to be particularly effective, as it makes it possible to obtain a killing of said virus and/or said fungi and/or said bacteria at a percentage greater than 80%, preferably greater than 95%, more preferably greater than 96%, even more preferably greater than 97%, even more preferably greater than 97.55%, even more preferably greater than 97.99%, even more preferably greater than 98%, even more preferably greater than 98.55%, even more preferably greater than 98.99%, even more preferably greater than 99% even more preferably greater than 99.55%, even more preferably greater than 99.99%. Preferably, said killing percentage is greater than 80%, preferably greater than 95%, more preferably greater than 96%, even more preferably greater than 97%, even more preferably greater than 97.55%, even more preferably greater than 97.99%, even more preferably greater than 98%, even more preferably greater than 98.55%, even more preferably greater than 98.99%, even more preferably greater than 99% even more preferably greater than 99.55%, even more preferably greater than 99.99%, after 1 hour, preferably after 4 hours, of activation of said nanoparticles (or of said substrate nanofunctionalised with said nanoparticles) by the UV light and/or visible light and/or sunlight or, in other words, after irradiation of said nanoparticles (or of said substrate nanofunctionalised with said nanoparticles) with a source of UV light and/or visible light and/or sunlight, preferably, with a light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm. Preferably, in the embodiment regarding the killing of a virus, more preferably of a virus selected from among HCoV- 229E, HCoV-NL63, OC43, HKU1 , SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2, preferably SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2, even more preferably SARS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2, even more preferably Bovine coronavirus (BCoV) and SARS-CoV-2, said killing percentage is greater than 99% even more preferably greater than 99.55%, even more preferably greater than 99.99%, after 1 hour, preferably after 4 hours, of activation of said nanoparticles (or of said substrate nanofunctionalised with said nanoparticles) by the UV light and/or visible light and/or sunlight or, in other words, after irradiation of said nanoparticles (or of said substrate nanofunctionalised with said nanoparticles) with a source of UV light and/or visible light and/or sunlight, preferably, with a light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm. For the purposes of the present invention, the expression “irradiating PO2-N nanoparticles with a source of UV light and/or visible light and/or sunlight” is equivalent to saying that said P02-N nanoparticles, activatable by UV light and/or visible light and/or sunlight, are “activated” and therefore capable of performing their photocatalytic activity, in particular their photocatalytic activity of killing said virus and/or said fungi and/or said bacteria. Similarly, the expression “irradiating a nanofunctionalised substrate with a source of UV light and/or visible light and/or sunlight” is equivalent to saying that said substrate, being nanofunctionalised with said T1O2-N nanoparticles activatable by UV light and/or visible light and/or sunlight, is “activated”, or rather, said nanoparticles that completely or partly coat said substrate and/or are comprised within it, are “activated” and thus capable of performing their photocatalytic activity, in particular their photocatalytic activity of killing said virus and/or said fungi and/or said bacteria. In the case of the embodiment of the present invention relating to the killing of viruses selected in the group consisting of: HCoV-229E, HCoV- NL63, OC43, HKU1 , SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS- CoV-2, preferably SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS- CoV-2, even more preferably SARS-CoV, Bovine coronavirus (BCoV) and SARS-CoV- 2, even more preferably Bovine coronavirus (BCoV) and SARS-CoV-2, or a combination thereof, without wishing to be bound to any theory, it is nonetheless possible to maintain that the use, according to the present invention, of the PO2-N nanoparticles activatable by UV light and/or visible light and/or sunlight (or of a substrate nanofunctionalised with said nanoparticles or of a device comprising at least one such nanofunctionalised substrate, as described above) could be particularly effective in preventing the spread of respiratory diseases deriving from said viruses, thanks to the synergistic action of not only killing the viruses but also reducing other contaminants such as, for example, NOx, COV and SOV, normally present in the air in both indoor and outdoor environments. It is in fact well known that exposure to indoor and outdoor atmospheric pollution - and in particular to nitrogen oxides (NO and NO2) - can cause a set of adverse health effects and create factors of risk for/predispositions to respiratory diseases, in some cases worsening the situation of patients who come into contact with the aforesaid virus. EXAMPLES

EXAMPLE 1 - Synthesis of an aqueous suspension comprising T1O2 nanoparticles and a nitrogen doping agent.

806.0 g of ammonium citrate dibasic are added to 19,194.00 g of an aqueous suspension containing 6% titanium dioxide (PH000025), obtained through the synthesis described in document W02007088151 , in a 20 L reactor under stirring and at room temperature. After 24 hours of mixing, the formation of a white suspension containing 0.498% nitrogen and 5.76% T1O2 (which corresponds to 8.6% by weight of nitrogen relative to T1O2) are observed. The size of the nanoparticles in the suspension obtained was measured by DLS (Dynamic Light Scattering, Malvern Instruments), and a Zaverage value (which corresponds to the hydrodynamic diameter D_z, hence the particle size) equal to 49.9 nm was obtained, with a polydispersity index (Pdl) of 0.221. EXAMPLE 2 - Production of a nanofunctionalised substrate

100.0 g of the suspension obtained as per example 1 were applied, using the dip coating technique, on a 15x15x2 cm substrate of ceramic material (cordierite) with a honeycomb structure (having a weight of about 336 g). Said operation entails the immersion of the substrate in the suspension for about 1 minute; it is then positioned on a grid so that the excess material (i.e. the suspension comprising T1O2 nanoparticles and ammonium citrate dibasic) can be collected and reused. The substrate thus prepared was subjected to a firing cycle in a continuous electric oven at 500 °C for 3 hours with the belt speed set on 4 m/h. After firing, the amount of nitrogen-doped titanium dioxide nanoparticles deposited was about 6 g, corresponding to about 1.75 ± 0.05 % by weight relative to the total weight of the nanofunctionalised substrate. Figures 1A and 1 B present SEM images that show a detail of the surface of the nanofunctionalised substrate, i.e. of the substrate coated by T1O2-N nanoparticles, at two different magnifications. In particular, as may be observed from the magnification in figure 1 B, said T1O2-N nanoparticles coating the substrate have a size of about 50 nm, in accordance with the value of the nanoparticle size determined in the suspension obtained according to Example 1. For the subsequent analyses of the killing of viruses and bacteria, flat rectangular samples with a size of 2x6 cm (12 cm²) were taken from the nanofunctionalised substrate.

EXAMPLE 3 - Production of a device comprising a nanofunctionalised substrate

The 15x15x2 cm substrate made of ceramic material (cordierite) with a honeycomb structure, functionalised with T1O2-N nanoparticles as described in Example 2, was inserted into an air filtration device further comprising a COOL WFIITE LED with a power of 25 W (disposed in such a way as to completely irradiate the substrate) and a ventilation system (serving to favour the passage of air within the device, thus favouring its contact with and passage through the substrate having a honeycomb structure. EXAMPLE 4 - Virus and bacteria kill tests

The kill tests were carried out by the certified laboratories of Eurofins Biolab Sri, Vimodrone (Milan), Italy. The tests were carried out using a COOL WFIITE LED with a power of 25 W as the light source for irradiating the substrates.

EXAMPLE 4.1 - Contact test on antibacterial activity against Escherichia coli K12 DSM11250

The activity of the nanofunctionalised substrate according to the present invention (i.e. obtained as per example 2) in terms of killing Escherichia coli K12DSM11250 was tested according to standard ISO 22196:2011 (Measurement of antibacterial activity on plastics and other non-porous surfaces); the method was duly modified and adapted as reported here. The tests were performed by placing Escherichia coli in direct contact on samples taken from nanofunctionalised substrates obtained as per example 2 and on analogous non-nanofunctionalised substrates (control). The results were recorded at contact times (contact between Escherichia coli and substrates) of t=0 minutes (to), t=1 hour (t-i), t=4 hours (t4) and t=8 hours (ts).

Identification and maintenance of test strains.

Cultures of the following microorganisms were used: Escherichia coli K12 DSM11250. The bacterial strains were kept frozen. Prior to use, the strains were transplanted into TSA slants 4 times at most and, after incubation, they were refrigerated at 5 °C ± 3 °C. Prior to use, the bacterial strains were transplanted into TSA slants two consecutive times and incubated at 35 ±1 °C for 18-24 hours.

Materials and Methods

The validity of the culture media and reagents was checked before beginning the analysis. The following culture media and reagents were used for the test:

- Tryptone Water

- Water for injection (WFI)

- Culture medium TSB (Tryptone Soy Broth)

- Culture medium TSA (Tryptone Soy Agar)

- CEN neutraliser

- Lecithin = 3 g

- Polysorbate 80 = 30 g

- Sodium thiosulphate = 5 g

- L-histidine = 1 g

- Saponin = 30 g

- Tryptone-treated water = q.s. to 1000 ml

- Suspension medium = 1/500 dilution of TSB in WFI

The validity of the instruments and equipment was verified before beginning the analysis. Ordinary microbiology laboratory equipment was used for the test, and in particular:

- Climate chamber set at a temperature of 35 °C ± 1 °C and RFI>90% (RH = relative humidity).

Preparation of the test inoculum In the first two hours after the start of the test, a loop of the test bacteria was transferred into 20 ml of the suspension medium (1/500 dilution of TSB in WFI) and evenly dispersed. The suspension was adjusted to a concentration of about 1 - 5 x 10⁶ cfu/ml, with a target concentration of 2.5 x 10⁶ cells/ml; the concentration was verified with the “pour-plate” method. The viable bacteria were quantified by means of 1 :10 serial dilutions in Tryptone water and plated in duplicate in TSA at 35 °C ± 1 °C for 24-72 hours.

Samples

The tests were performed on 2 cm x 6 cm rectangular samples taken from nanofunctionalised substrates obtained as per example 2 and analogous non- nanofunctionalised substrates (control samples).

Analysis

Each sample was separately positioned in a sterile Petri dish. 0.1 ml of the test inoculum previously prepared was inoculated onto the surface of the samples. The test inoculum was covered with a square film of about 324 mm², which was delicately pressed to ensure that the test inoculum would spread to the edges of the film, but not go beyond. The Petri dishes with the inoculated samples were incubated at 35 °C ± 1 °C with a RH >90% (RH=relative humidity) for the pre-established contact time and exposed to the light of the COOL WHITE LED lamp so as to activate the antimicrobial surface. The non-nanofunctionalised samples used as a control were not exposed to the light of the lamp. At to both the non-nanofunctionalised samples and functionalised samples were immersed in 10 ml of neutraliser and, after mechanical stirring, viable microorganisms were recovered in order to determine the baseline. The viable bacteria were quantified by means of 1 :10 serial dilutions in Tryptone water and plated in duplicate in TSA at 35 °C ± 1 °C for 24-72 hours.

At each designated contact time, three samples were processed at the same time to. Calculation method

For every sample, the number of viable bacteria recovered per cm² was calculated according to the equation:

N = (100 x C x D x V)/A where

N is the number of viable bacteria recovered per cm² per sample;

C is the average number of plates for the duplicated plates;

D is the dilution factor for the counted plates; V is the volume, in ml, added to each sample;

A is the surface, in mm2, of the covering film.

The average number of viable bacteria recovered for each sample series was calculated and this value was expressed in two significant digits. Test validity requirements

In order for the test validity conditions to be satisfied, the logarithmic value of the number of viable bacteria recovered immediately after inoculation from the control samples must meet the following requirement:

(Lmax - Lmin)/(Lave) < 0.2 When the test is deemed to be valid, the antibacterial activity is calculated with the following formula:

R = (Ut - Uo) - (At - Uo) = Ut - At where

R is the antibacterial activity; Uo is the mean of the Log of the number of viable bacteria recovered at to from the control sample;

Ut is the mean of the Log of the number of viable bacteria, recovered at the contact time t from the control sample

At is the mean of the Log of the number of viable bacteria, recovered at the contact time t from the nanofunctionalised sample according to the present invention.

Results

All of the validity criteria listed above were satisfied.

The number of viable bacteria in the test inoculum, the number of viable bacteria recovered from every sample, the number of viable bacteria per cm², the values Uo, Ut and At, and the antibacterial activity calculated are shown in the following tables: Table 1 and Table 2.

Table 1

Table 2

On the basis of the results obtained, given that the value of the antibacterial activity can be used to characterise the effectiveness of an antibacterial agent, it may be affirmed that the nanofunctionalised substrate obtained as per example 2 is active against Escherichia coli K12 DSM 11250 and causes a reduction in the bacterial count of Log1.70 and > Log2.34 after 4 and 8 hours of contact (between the substrate and the Escherichia coli), respectively, under the experimental conditions adopted.

EXAMPLE 4.2 - Test of antibacterial activity against Escherichia coli K12 in an aerosol In addition to the contact kill tests described in Example 4.1 , the activity of the nanofunctionalised substrate according to the present invention (i.e. obtained as per example 2) in terms of killing Escherichia coli K12DSM11250 was also tested in the case of an aerosol of Escherichia coli K12DSM11250. The tests were carried out inside an Airlock chamber with a volume of 1 m³ for a nebulisation time of 30 minutes. The tests were carried out in triplicate (Replicate 1 , Replicate 2 and Replicate 3) using a device comprising a nanofunctionalised substrate obtained as per example 3 and a non- nanofunctionalised substrate made of ceramic material (cordierite) with a honeycomb structure as the control sample. The results were recorded at contact times (contact between Escherichia coli and the substrates, after nebulisation) of t = 0 minutes (to; immediately after nebulisation) and t = 4 hours (t4; 4 hours after nebulisation). Identification and maintenance of the test strains.

Cultures of the following microorganisms were used: Escherichia coli K12 DSM11250. The bacterial strains were kept frozen. Prior to use, the strains were transplanted into TSA slants 4 times at most and, after incubation, they were refrigerated at 5 °C ± 3 °C. Prior to use, the bacterial strains were transplanted into TSA slants two consecutive times and incubated at 35 ± 1 °C for 18-24 hours.

Materials and Methods

The validity of the culture media and reagents was checked before beginning the analysis. The following culture media and reagents were used for the test: - Tryptone Water

- Water for injection (WFI)

- Culture medium TSB (Tryptone Soy Broth)

- Culture medium TSA (Tryptone Soy Agar) - CEN neutraliser

- Lecithin = 3 g

- Polysorbate 80 = 30 g

- Sodium thiosulphate = 5 g

- L-histidine = 1 g - Saponin = 30 g

- Tryptone-treated water = q.s. to 1000 ml

- Suspension medium = 1/500 dilution of TSB in WFI

Preparation and count of the test bacterial suspension

For each replicate (Replicate 1 , Replicate 2 and Replicate 3), a bacterial suspension of Escherichia coli K12 DM11250 at a concentration of 1.5 - 5.0 x10⁷ cfu/ml was diluted up to 10⁵ and 10⁶ decimal dilutions. The concentration of every dilution was verified with the “pour-plate” method in duplicate (X and X’). The number of colony forming units per ml was determined after 48 hours of incubation at 37 °C ± 1 °C and a calculation was made of the actual count of the test microbial suspension, expressed as the value N, and shown in the following Tables 3.1 , 3.2 and 3.3.

Table 3.1 - Replicate 1

Table 3.2 - Replicate 2

Table 3.3 - Replicate 3

Preparation of the test chamber (for each nebulisation)

The surfaces of the test chamber were sanitised with wipes soaked in a 6% H2O2 solution before and after the execution of every test, then dried with sterile wipes after 30 minutes of exposure to the H2O2. 6 contact plates were used to check for microbial contamination after the sanitisation treatment. The contact plates were incubated at 30 °C-35 °C for 2 days and then at 20 °C-25 °C for 5 days. The results of the microbial test on the test chamber after the sanitisation treatment before and after the execution of every test are shown, by way of example, for Replicate 1 and only for the tests with the device comprising the nanofunctionalised sample, in Tables 4.1 and 4.2. As for the replicates of the experimental tests (Replicate 2 and Replicate 3) and in the case of the tests with the control sample, similar results were obtained and in all cases the microbial test was passed.

Table 4.1 - Microbial test on the test chamber after the sanitisation treatment (prior to the start of the experimental tests; i.e. prior to the start of Replicate 1 for the tests with the device comprising the nanofunctionalised sample)

Table 4.2 - Microbial test on the test chamber after the first test (Replicate 1) with the device comprising the nanofunctionalised sample

The sterilised Collison nebu iser - filled with bacterial suspension - was connected to the test chamber by means of a sterilised glass tube for aerosol delivery, surrounded by a thermostatic water bath in order to obtain a temperature within the aerosol of 20 °C ± 5 °C. The Collison nebuliser was connected to the air flow system. The test chamber and the content thereof were exposed to the bacterial aerosol for 30 minutes. The level of environmental contamination after the opening of the test chamber and sanitisation were monitored during the experimental stage in order to validate the sanitisation procedure using 6 test plates placed outside the test chamber. The plates were incubated at 30 °C-35 °C for 2 days and then at 20-25 °C for 5 days. The results of the microbial test on the environment outside the test chamber during nebulisation are shown in Table 5. In this case as well, the results of the microbial test are shown, by way of example, only for Replicate 1 and only for the test with the device comprising the nanofunctionalised sample. As for the other replicates of the experimental tests (Replicate 2 and Replicate 3) and in the case of the tests with the control sample, similar results were obtained and in all cases the microbial test was passed.

Table 5 - Microbial test outside the test chamber during the first test (Replicate 1) with the device comprising the nanofunctionalised sample.

Tests

The device obtained according to Example 3 was positioned inside the test chamber near the nebulisation delivery tube and was switched on (i.e. by turning on the LED light and the ventilation system) for at least one hour before the start of the test. Subsequently, a bacterial suspension of Escherichia coli K12 as described above was nebulised inside the test chamber for 30 minutes. 8 sterile TSA plates were inserted into the test chamber as settling plates and distributed in such a way as to cover the entire base surface. The plates were opened shortly before the chamber was closed in order to sample and record the bacteria touching the bottom surface of the chamber during the exposure time (considering a sufficiently homogeneous exposure of the aerosolised inoculum). After 30 minutes, the nebulisation was stopped and the device was left on for a contact time of 4 hours. At the end of the set contact time, the 8 settling plates were recovered and incubated for at least 48 hours at 37 °C ± 1 °C in order to measure the contamination by microorganisms. The number of CFU/plate (Na) was determined. Three experimental tests were carried out (Replicate 1 , Replicate 2 and Replicate 3). Furthermore, a control experiment was carried out using a substrate made of ceramic material (cordierite) having a honeycomb structure, but not functionalised and not inserted within a device (Nc), in order to measure the initial microbial contamination inside the test chamber. A bacterial suspension of Escherichia coli K12 as described above was nebulised inside the test chamber for 30 minutes. 8 sterile TSA plates were inserted into the test chamber as settling plates and distributed in such a way as to cover the entire base surface. The plates were opened shortly before the chamber was closed in order to sample and record the bacteria touching the bottom surface of the chamber during the exposure time (considering a sufficiently homogeneous exposure of the aerosolised inoculum). After 30 minutes, the nebulisation was stopped and the 8 settling plates were recovered and incubated for at least 48 hours at 37 °C ± 1 °C in order to measure the contamination by microorganisms. The number of CFU/plate (Nc) as determined.

Calculations

The reduction in viability was calculated according to the following formula: R = Nc - Na where:

R = % Reduction in viability

Nc = number of cfu/plate in the non-functionalised control at time 0 Na = number of cfu/plate in the nanofunctionalised test sample at the set contact time. Results

The results obtained for each replicate are shown in the following tables 6.1 , 6.2 and

6.3.

Table 6.1 - Replicate 1

Table 6.2 - Replicate 2

Table 6.3 - Replicate 3

The percentage reduction in viability after 4 hours of contact (following 3 0l minutes of nebulisation of the bacterial suspension) for each of the 3 replicates carried out with the device comprising the nanofunctionalised sample is shown in Table 7.

Table 7

On the basis of the results obtained, it may be affirmed that the device comprising a substrate nanofunctionalised with PO2-N nanoparticles obtained as per example 3 shows activity against Escherichia coli K12 DSM 11250 and causes a mean reduction of 99.14% in the viability of the microorganism after 4 hours of contact time, following 30 minutes of nebulisation of a suspension containing said microorganism, under the experimental conditions adopted.

EXAMPLE 4.3 - Contact test on antiviral activity against Bovine Coronavirus (BCoV)

The viral strain used for the test was BCoV Bovine coronavirus; strain: S379 Riems; cell line: PCT cells (Ovis aries), code CCLV-RIE 11. BCoV is a virus used as a surrogate for SARS-related viruses, as it belongs to the same genus, Betacoronavirus 1 , and has shown a susceptibility similar to that of formulations of the World Health Organisation (WHO) in published studies. For this reason, BCoV is considered as a certified reference model for carrying out experimental tests and studying the behaviour of viruses vis-a-vis chemical and physical agents.

The activity of the nanofunctionalised substrate according to the present invention (i.e. obtained as per example 2) in terms of killing Bovine Coronavirus was tested according to standard ISO 21702:2019 (Measurement of antibacterial activity on plastics and other non-porous surfaces); the method was duly modified and adapted as reported here. The tests were carried out by direct contact of 12 cm² (2x6 cm) BCoV flat rectangular samples taken from nanofunctionalised substrates obtained as per example 2 and analogous non-nanofunctionalised substrates (control samples). The tests were carried out in triplicate (Replicate 1 , Replicate 2 and Replicate 3), both in the case of the nanofunctionalised substrates (nanofunctionalised samples) and in the case of the control samples (non-functionalised). The results were recorded at contact times (contact between BCoV and substrates) of t=4 hours (t4). The tests were carried out at room temperature (25 °C ± 1 °C) and under conditions of RH (relative humidity) > 90%. Validity and effectiveness criteria

Test on the cytotoxicity of the sample examined: the sample under examination was not cytotoxic, that is, its contribution in terms of CPE was not visible in the test. Assay of virus infectivity (virus titration): the minimum titre of the starting viral suspension was sufficiently high to allow at least a theoretical reduction in virus infectivity of 4 LogTCID5o. Test on viral infectivity (functionalised substrate and control): the amount of infective particles recovered immediately after inoculation from the non-functionalised samples (control) was comprised between 5 and 6LogTCID5o; the amount of infective particles recovered from every non-functionalised sample (control) after 24 hours of contact was not greater than 3LogTCID5o. Test on host cell susceptibility to the virus and suppression of the antiviral activity (neutralisation): the difference in the mean value of TCID50 between the cell cultures treated with the functionalised samples or with the control samples and then with the viral inoculum and those treated only with the viral inoculum (negative control) was < 0.5 LogTCIDso. Precision of the virus control among the three replicates: the maximum difference in the value of TCID50 between the cell cultures treated with the viral inoculum recovered from the 3 different control samples of the 3 different replicates was < 0.5 Log. Antiviral effectiveness: the Log ReductionTCID5o (R) factor was calculated according to standard ISO 21702:2019, i.e. by subtracting the mean LogTCIDso of the nanofunctionalised sample (At) from the mean LogTCIDso of the control sample (Ut) at the selected contact time (t4 = 4 hours). The LogTCIDso was calculated with the Spearman-Karber method.

Results The mean of the results obtained for each replicate is shown in the following Table 8. Table 8

On the basis of the results obtained, it may be affirmed that the substrate nanofunctionalised with T1O2-N nanoparticles obtained as per example 2 shows activity against BCoV and causes a complete reduction (i.e. >99.9%) in the viral load after a contact time of 4 hours under the experimental conditions adopted.

Claims

1. Use of nitrogen-doped PO2 (T1O2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight for killing a virus and/or fungi and/or bacteria, wherein:

- said virus is selected in the group consisting of: Coronaviridae, Bacteriophages, Caliciviridae, Picornaviridae, Reoviridae, Adenoviridae, Astroviridae, Anelloviridae, Pramixoviridae, Poxviridae, Filoviridae, Orthomyxoviridae, hepatitis virus, and a combination thereof; and/or

- said fungi are selected in the group consisting of: Cladosporium, Microsporum, Aspergillus, Penicillium, Mucor, Rhizopus, Cryptococcus, Exophiala, Candida, Fusarium and a combination thereof; and/or

- said bacteria are selected in the group consisting of: Streptococcaceae, Bacillaceae, Clostridiaceae, Enterococcaceae, Staphylococcaceae, Pseudomonadaceae, Legionellaceae, Campylobacteraceae, Moraxellaceae, Enterobacteriaceae, Micrococcaceae, Mycobacteriaceae, Spirochaetaceae, Leptospiraceae and a combination thereof.

2. Use of a substrate nanofunctionalised with nitrogen-doped PO2 (PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight according to claim 1 for killing said virus and/or fungi and/or bacteria.

3. Use of a device for killing said virus and/or fungi and/or bacteria, comprising at least one substrate nanofunctionalised with nitrogen-doped PO2 (PO2-N) nanoparticles activatable by UV light and/or visible light and/or sunlight according to claim 2, and at least one light source configured to emit radiation having a wavelength comprised between 10 and 1500 nm, preferably between 250 and 600 nm.

4. Use according to any one of claims 1-3, wherein:

- said virus is selected in the group consisting of: FICoV-229E, FICoV-NL63, OC43, HKU1 , SARS-CoV, MERS-CoV, Bovine coronavirus (BCoV) and SARS-CoV-2, Variola virus, Ebolavirus, Alphainfluenzavirus, Betainfluenzavirus, Deltainfluenzavirus, Gammainfluenzavirus, Influenza virus A, Influenza virus B, H 1 N 1 and H5N 1 , hepatitis A virus (FIAV), hepatitis B virus (FIBV), hepatitis C virus (FICV), hepatitis D virus (FIDV), hepatitis E virus (HEV), or a combination thereof; and/or

- said bacteria are selected in the group consisting of: Streptococcus pneumoniae, Streptococcus pyogenes, Streptococcus agalactiae, Streptococcus faecalis, Streptococcus mutans, Clostridium difficile, Clostridium perfringens, Clostridium tetani, Clostridium botulinum, Staphylococcus aureus, preferably methicillin-resistant Staphylococcus aureus (MRSA), coagulase-negative staphylococci (CNS), preferably Staphylococcus epidermidis, Legionella pneumophila, Enterobacter, Salmonella enterica, Klebsiella, preferably Klebsiella pneumoniae and Klebsiella granulomatis, Shigella, preferably Shigella dysenteriae and Shigella flexneri, Escherichia, preferably Escherichia Coli, Mycobacterium tuberculosis, Mycobacterium africanum, Mycobacterium leprae, Mycobacterium marinum, Mycobacterium paratuberculosis and Mycobacterium ulcerans, Treponema pallidum, Treponema carateum, Treponema pertenue, Treponema endemicum, and a combination thereof; and/or

- said fungi are selected in the group consisting of: Cladosporium cladosporioides, Cladosporium herbarum, Microsporum audouinii, Microsporum felineum, Microsporum ferrugineum, Microsporum minutissimum, Aspergillus fumigatus, Aspergillus sydowii, Aspergillus usus, Penicillium corylophilum, Penicillium chrysogenum, Penicillium glabrum, Peniciullium corylophilum, Penicillium marneffei, Mucor hiemalis, Rhizopus oryzae, Rhizopus nigricans, Cryptococcus neoformans, Cryptococcus laurentii, Cryptococcus albidus, Exophiala jeanselmei, Exophiala dermatitidis, Exophiala hongkongensis, Exophiala phaeomuriformis, Exophiala pisciphila, Exophiala werneckii, Candida albicans, Candida auris, Candida dubliniensis, Candida glabrata, Candida lusitaniae, Candida parapsilosis, Candida tropicalis, Fusarium oxysporum or a combination thereof.

5. Use according to any one of claims 1-4, wherein said virus and/or said fungi and/or said bacteria is/are comprised within a fluid, preferably air and/or water and/or a body fluid.

6. Use according to any one of claims 1-5, wherein said nitrogen-doped T1O2 nanoparticles comprise at least a brookite crystalline phase in an amount of 10 to 75% by weight, relative to the weight of the nanoparticles, and a rutile crystalline phase in an amount of 25 to 90% by weight relative to the weight of the nanoparticles; more preferably said T1O2-N nanoparticles further comprise an anatase crystalline phase in an amount of 1 to 10% by weight or 25 al 90% by weight, relative to the weight of the nanoparticles.

7. Use according to any one of claims 1-6, wherein said nitrogen-doped PO2 nanoparticles have a nitrogen doping content comprised between 1 and 5% by weight, preferably between 1.5 and 3% by weight relative to the weight of the nanoparticles.

8. Use according to any one of claims 2-7, wherein said nanofunctionalised substrate is a substrate selected in the group consisting of: a substrate of ceramic material, said ceramic material preferably being selected from among cordierite, mullite, alumina and a combination thereof; a substrate of polymeric material, said polymeric material preferably comprising at least one (co)polymer selected from among: PMMA (polymethylmethacrylate), PA (polyamide), PC (polycarbonate), PLA (polylactic acid), PET (polyethylene terephthalate), PE (polyethylene), PVC (polyvinyl chloride), PS (polystyrene), acrylonitrile styrene acrylate (ASA), acrylonitrile butadiene styrene (ABS), polyethylene terephthalate glycol (PET-g), polyurethane (PU), polypropylene (PP), copolyester, and a combination thereof; a substrate of textile material, nonwoven fabric, metal, glass, paper and cardboard material, or a combination thereof.

9. Use according to any one of claims 2-8, wherein said nanofunctionalised substrate is a substrate comprising a plurality of channels and/or cells suitable for the passage of a fluid, said channels and/or cells having a cross section preferably selected from among circular, hexagonal, square, triangular, rectangular and a combination thereof, and identifying a path for the fluid having a variable geometry, said path preferably being selected from among linear, tortuous, spiral or a combination thereof; said substrate preferably having a structure selected from among: a stratified structure, an interwoven structure, a fabric weave structure and a honeycomb structure, preferably characterised by a cells per square inch (CPSI) value of from 40 to 120, preferably from 50 to 100, more preferably from 50 to 70, even more preferably from 55 to 65, and a combination thereof.