CA3201620A1

CA3201620A1 - Methods of inactivating microbiological contamination

Info

Publication number: CA3201620A1
Application number: CA3201620A
Authority: CA
Inventors: Trond Heldal
Original assignee: Osmotex AG
Current assignee: MYANT SWISS AG
Priority date: 2020-11-18
Filing date: 2021-11-17
Publication date: 2022-05-27
Also published as: GB202018143D0; JP2023552688A; WO2022106448A1; KR20230104276A

Abstract

The invention relates to methods of inactivating microbiological contamination using a textile or membrane which can generate a contamination-inactivating amount of ozone, chlorine or a reactive oxygen species. The textile or membrane comprises at least two electrically conductive elements or networks. The textile or membrane preferably forms part of a protective face mask, for example a medical or surgical face mask. A voltage effective to generate a microbiological contamination-inactivating amount of the inactivating species is applied between said conductive elements or networks.

Description

Methods of inactivating microbiological contamination The invention relates to methods of inactivating microbiological contamination using a textile or membrane which can generate a contamination-inactivating amount of ozone, chlorine or a reactive oxygen species.
Background to the invention One of the major routes of contagion for bacteria and viruses, including SARS
CoV-2, the infectious agent for COVI D-19, is via surfaces in public areas, offices or hospitals, on which viruses can survive for weeks. Furthermore, bacteria, viruses and other contamination can adhere to garments, gloves and face masks, which may be of significance in controlling hospital infection.
Many other physical surfaces are, or can be, covered by textile materials, including seating and interior panels in offices or public transport or light walls and delimiters in offices.
The present invention concerns an electronic disinfection textile or membrane material which can potentially be used on most types of surfaces and can be incorporated into garments, gloves and face masks.
Ozone and hydrogen peroxide are widely used for sterilization, for instance in water purification. While toxic in higher concentrations, both of these agents are used in medicine, including for their antiviral and antibacterial effect as well as other beneficial effects, e.g. to the human skin. An advantage of ozone and hydrogen peroxide is that they break down to oxygen and water after short time. Both disinfecting agents are in broad industrial use, and there is a significant volume of published research on their effects. For example, a strong reduction in the presence of 12 different viruses (three orders of magnitude reduction in concentration) has been demonstrated, using a concentration of 20-25 ppm of ozone at high air humidity (>90%), see Hudson JB, Sharma M, Vimalanathan S, Development of a Practical Method for Using Ozone Gas as a Virus Decontaminating Agent in Ozone: Science &
Engineering, vol. 31, p. 216-223 (2009).

2 Ozone concentrations of 0.5-2 ppm have been reported to be sufficient for "purification or ultra-purification of water for different purposes (e.g., pharmaceutical and electronic industries, water bottling process, etc.)" (see Da Silva LM, Franco DV, Goncalves IC, Sousa LG (2009) In: Gertsen N, Sonderby L (eds) Water purification.
Nova Science Publishers Inc., New York; and Tchobanoglous G, Burton FL, Stensel HD (2003) Wastewater engineering: treatment and reuse, 4th edn. Metcalf & Eddy Inc., New York). See also De Sousa et al. in J. Environmental Chem. Eng. 4 (2016), pages 418-427 for an electrochemical ozone generator.
Chlorine is also well known as a sterilising agent, for example in the form of hypochlorite-based bleaches. The "active chlorine" content of such bleaches is used as a unit of concentration, whereby one gram of a 100% active chlorine bleach has the quantitative bleaching capacity as one gram of free chlorine.
A dressing for preventing bacterial infection to an open wound is disclosed in WO 2017/011635. The dressing uses electrochemically generated H202 to achieve its anti-biofilm effect and comprises conductive layers separated by an insulating layer, a voltage then being applied between the conductive layers to generate from water in the layer adjacent to the wound. A modified wound dressing, in which hypochlorous acid is generated as an alternative to H202, is also discussed.
A protective mask to cover at least the mouth area of a wearer, and through a gauze filter section of which a sodium hypochlorite solution can be conducted, is disclosed in DE 10 2009 021 394 Al. The sodium hypochlorite solution for use in the mask is generated in an external electrolysis cell mounted on an accompanying pair of safety glasses.
Summary of the invention One embodiment of the invention provides a method of inactivating microbiological contamination at a locus, said locus comprising a textile or membrane comprising at least two electrically conductive elements configured to allow an electric current to pass between said elements via an intervening liquid medium, the textile or membrane further comprising an aqueous liquid on a surface or within the interior of said textile or membrane and in electrical contact with said conductive elements to provide said intervening medium;

3 wherein the method comprises applying between the at least two conductive elements a voltage effective to generate a microbiological contamination-inactivating amount of an inactivating species selected from ozone, chlorine and reactive oxygen species.
A further embodiment of the invention provides a method of inactivating microbiological contamination at a locus, the method comprising contacting said locus with a textile or membrane comprising at least two electrically conductive elements configured to allow an electric current to pass between said elements via an intervening liquid medium, the textile or membrane further comprising an aqueous liquid on a surface or within the interior of said textile or membrane and in electrical contact with said elements to provide said intervening medium;
wherein the surface of said textile or membrane contacted with said locus comprises a microbiological contamination-inactivating amount of an inactivating species selected from ozone, chlorine and reactive oxygen species.
A yet further embodiment of the invention provides a protective face mask comprising a textile or membrane, said textile or membrane comprising at least two electrically conductive elements formed of conductive yarn or conductive ink.
Another embodiment of the application provides a bag comprising a textile or membrane, said textile or membrane comprising at least two electrically conductive elements formed of conductive yarn or conductive ink.
A further embodiment of the application provides an interior or upholstery textile or membrane, said textile or membrane comprising at least two electrically conductive elements formed of conductive yarn or conductive ink.
Detailed description The invention utilises a flexible textile (i.e. woven material) or membrane (i.e.
continuous material) comprising at least two electrically conductive elements.
When the textile or membrane is wetted and a suitable voltage is applied between the electrically conductive elements, a microbiological contamination-inactivating amount of an inactivating species selected from ozone, chlorine and reactive oxygen species is generated.

4 For application of a suitable voltage the conductive elements are connected to an electric signal generator, either in a fixed manner or temporarily.
The electrochemical generation of reactive oxygen species or chlorine requires the presence of water or another aqueous liquid in the textile or membrane.
The water or other liquid can be applied to the textile or membrane when required, for example by spraying from an external source, or it may be absorbed directly from the surrounding air if a more hygroscopic material has been incorporated into or impregnated on the textile layer. Depending on the use to which the textile or membrane is being put, the frequency of application of water or other liquid may need to be higher or lower, thus in certain applications the area being treated may require regular spraying so as to provide continuous inactivation of microbiological contamination. For example, spraying once per hour, twice per hour or three times per hour may be appropriate.
In other applications it may only be necessary to spray the textile or membrane with water, and apply a suitable voltage to generate the inactivating species, at less frequent intervals, such as once, twice or three times a day in connection with periodic cleaning of the potentially contaminated area.
In a yet further embodiment, for example a protective face mask to be worn by a user, the humidity generated by the breathing of the user may be sufficient to generate the necessary water. Under these circumstances, continuous inactivation of the microbiological contamination can be achieved by application of a continuous or suitably pulsed voltage across the intermediate layer.
The conductive elements in the textile or membrane utilised in the invention are typically selected from conductive carbon, or steel or silver or other metal yarn.
The presence of metal ions released from the conductive elements may enhance the production of reactive oxygen species, for example via the Fenton Reaction illustrated in steps (1)-(3) below:

5 2Cu+ + 202(40 2Cu2+ 202- 0) 202- 2H+ -----* I-1:02 +02 (2) Cu+ + I-I2 0- Cu2+ + + Off _ Therefore, conductive elements comprising metals such as Cu or Ag are preferred in the textile or membrane according to the invention, to enhance the sterilizing effect of the material.
The electrical conductors of the present invention may be metals or alloys, such as silver or copper and related alloys, or stainless steel. They may contain or be coated with boron doped diamond or Ebonex (a non-stoichiometric titanium oxide).
The conductive elements may be linear or in the form of a network. Linear elements may run across one dimension of a textile or membrane, for example the width or length of the textile or membrane, or may be formed into a pattern to increase the length of conductive element incorporated into the textile or membrane.
For example, an undulating or other wave pattern may be created, provided the at least two conductive elements remain in a configuration permitting an electrical current to flow between them, i.e. are configured at least partly in parallel with each other.
Alternatively, the conductive elements may be networks incorporated into the textile or membrane during its manufacture.
Preferably at least two of the conductive elements in the textile or membrane are spaced apart from each other by a spacing of less than 1mm along at least 10%
of their respective lengths, or more preferably along at least 50% of their respective lengths.
Conductive elements can be incorporated into a woven or knitted structure as it is formed, and in this case they may be comprise a conductive yarn. Such yarns are known per se and typically are made up of metallic fibres, for example stainless steel or silver yarn.

6 Alternatively a conductive yarn can be sewn or embroidered into an already formed textile.
A further possibility is to apply a conductive ink to a textile or membrane by a printing process to form a linear or networked conductive element. Conductive inks according to the invention will contain graphite or other conductive materials, such as silver, in a printable ink base.
The textile or membrane supporting the conductive elements is electrically insulating and can be any fabric or continuous sheet material conventionally used in the protective face masks, medical and surgical garments, other protective garments, cleaning pads, carpets, furniture covers and architectural features described in detail below.
Specific examples include cotton and linen fabrics for use in breathable items such as face masks, and other synthetic materials such as non-woven fabrics, electro-spun membranes, or melt processable web glues.
The textile may also be coated or impregnated with an ion-conductive material which, for example when wetted, can provide the required conductivity between the conductive elements.
Suitable ion conductive materials include the sulfonated fluoropolymers which are, for example, commercially available from The Chemours Company under the name "Nafion", i.e. tetrafluoroethylene-perfluoro-3,6-dioxa-4-methyl-7-octenesulfonic acid copolymers.
Alternative ion conductive materials are sulfonated "pentablock" copolymers with a t-butyl styrene, hydrogenated isoprene, sulfonated styrene, hydrogenated isoprene and t-butyl styrene (tBS-Hl-SS-Hl-tBS) structure, which are commercially available from Kraton Performance Polymers under the name "Nexar".
One particularly useful embodiment of the invention is a construction in which the textile or membrane forms a sterilisable cover for a face mask, for example a medical or surgical face mask, protecting at least the nose and mouth area of a wearer. The face mask is thus potentially rendered reusable, or alternatively the lifetime of the face mask can be extended, as microbiological contamination can be

7 inactivated with the cover in situ or the cover can be removed for separate treatment.
The protection of the wearer will also be better, as compared to wearing a mask without the cover, because contamination accumulating in the mask and possibly being released by skin contact or breathing can be inactivated.
Other medical or surgical garments and personal protective equipment may likewise benefit from incorporation of a textile or membrane according to the present invention, or contact with a textile or membrane according to the invention, in order to inactivate microbiological contamination.
The invention will also find application in other areas requiring regular or occasional sterilisation or cleaning, so as to prevent infection where multiple users come into contact with an object or surface. Potential uses include garments and protective wear for use outside the medical or surgical environments described above. Additionally, utilisation in transportation, in offices and in public places is envisaged: for example, a seat can include one or more arm rests which contain, or are cleaned with, a textile or membrane according to the invention.
Thus, a further feature of the invention is an interior or upholstery textile or membrane, said textile or membrane comprising at least two electrically conductive elements formed of conductive yarn or conductive ink, namely a textile or membrane for use in the interior of a room and in particular as a component of the upholstery of furniture.
Treatment of microbiological contamination on architectural features such as walls and light walls/delimiters, or on frequently used items such as tables, desks, door handles and the handles or surfaces of office equipment, is also included within the invention.
A portable pad or carpet made of the materials according to the invention can be carried by a user, for example on airplanes or public transport, in rental cars or ride-hailing vehicles, or at offices, and powered by a power bank or USB
charger.
A sterilizing bag in various different sizes can be formed of the materials according to invention and can be used to sterilize small items such as mobile phones or standard face masks, as well as for more bulky items such as groceries.

8 Thus, a bag with an optional closure can be partly or completely formed of the textile or membrane with conductive elements according to the invention, and is configured to generate ozone, chlorine or a reactive oxygen species within the space enclosed by the bag when connected to an electric signal generator as discussed above.
The microbiological contamination addressed by the invention can be bacterial contamination, or viral contamination, or any other form of contamination spread by airborne droplets, by contact or by other known routes. Of particular relevance at present is SARS CoV-2, the infectious agent for the disease COVI
D-19, but other contamination is addressed by the methods and articles according to the invention, such as influenza viruses, common cold viruses, mycobacteria (the causative agent of TB) and infectious fungi and spores.
The invention uses an inactivating species selected from ozone, chlorine and reactive oxygen species, which it has unexpectedly been found can be produced in effective amounts when a suitable voltage is applied to the textile or membrane according to the invention. A voltage of 0.3 or 0.7 to 10.0 V is generally suitable, for example, to provide the desired current which may be either a continuous direct current or a pulsed direct current. Preferable the voltage is from 0.3 to 2.5 V and more preferably the voltage is from 0.5 to 2.0 V, or alternatively 0.6 to 1.2 V, in order to produce effective amounts of the inactivating species.
Alternatively a low-frequency or long-period alternating current can have a amplitude or maximum voltage between 0.3 and 10.0 V, for example between 0.6 and 1.5 V, with a square pulse signal with signal period between 1 second and minutes, preferably between 10 seconds and 10 minutes. Alternatively, the signal can have a sinusoidal or other shape and/or may include periods of zero voltage, for example of duration 5 minutes, spaced at regular intervals, for example every hour.
Reactive oxygen species are known and are generally regarded as including inter alia superoxide anions, hydrogen peroxide and hydroxyl radicals. Of these, hydrogen peroxide is the most commonly generated in the textile or membrane according to the invention and is the most useful in treating microbiological contamination. Suitable amounts of hydrogen peroxide are generally 1% to 90%
by weight in aqueous solution, for example 1% to 5% or from 3% to 10% by weight in aqueous solution.

9 Furthermore, ozone can be generated in the textile or membrane according to the invention alongside, or instead of, the reactive oxygen species described above.
A suitable concentration of ozone for inactivating microbiological contamination is 0.01 to 100 ppm by weight in water, for example 0.1 to 5.0 ppm, and/or 0.5 to ppm by weight in air, for example 20 to 25 ppm.
The electrochemistry of the invention will now be described in more detail, along with specific embodiments where one or other of the inactivating species may be preferred.
Electrolysis of water normally yields one or more of the compounds H2, 02, H202 and 03 as well as oxygen radicals as intermediate products. In the presence of chlorides (which are commonly present in tap water) it is also possible to generate chlorine / hypochlorites through the process known as electrochlorination.
This generally takes place at a higher voltage, above 2.2V. One may optimize the system to preferentially release certain of these components. Generally, 03 production is favoured when using an anode material with high overpotential for 02 formation, such as Ebonex (a non-stoichiometric titanium oxide), boron doped diamond or lead oxide.
Using a carbon cathode favours the production of H202. Using noble metals such as Pt or Pd for the anode favours 02 production.
The reaction voltages in the following schemes give a guide to voltage ranges for each process. Aided by this, the selection of electrode material and applied potential can be used to selectively optimize the system for formation of certain compounds. The electrode material can be applied as a coating to electrodes made of steel, copper or other metal. Whilst 03 can be produced at 0.28V and H202 at 0.55V, production of active chlorine requires at least 2.2V under standard conditions, and is favoured by the use of noble metals at the anode.

CA

0320162C21023-""
-a) Case of water reduction to Hydrogen at the cathode - Reaction at the cathode (pH=7) 2H20 + 2e- ¨> H2 + 20H- E (H20/H2) = - 0.41 V/SHE
- Possible reactions at the anode 2H20¨> 02+ 4H+ +4e- E (02/H20) = 0.81 V/SHE
3H20 4 03 + 6W + 6e- E (03/H20) = 1.09 V/SHE
2H20 4 H202 + 2W + 2e- E
(H202/H20) = 1.36 V/SHE
Compound Calculated thermodynamic cell potential of formation 02 E (02/H20) - E (H20/H2) = 0.81 ¨ (-0.41) = 1.22 V
03 E (03/H20) - E (W/H2) = 1.09¨ (-0.41) = 1.50 V
H202 E (H202/H20) - E (W/H2) = 1.36 ¨(-0.41) = 1.77 V
b) Case of oxygen reduction to water at the cathode - Reaction at the cathode (pH=7) 02 + 4 H+ + 4e- ¨> 2H20 E (02/H20)= 0.81 V/SHE
- Possible reactions at the anode (pH=7) 2H20¨> 02+ 4H+ +4e- E (02/H20) = 0.81 V/SHE
3H20 4 03 + 6W + 6e- E (03/H20) = 1.09 V/SHE
2H20 4 H202 + 2W + 2e- E (H202/H20) = 1.36 \ONE

Compound Calculated thermodynamic cell potential of formation 02 E (02/H20) - E (02/H20) = 0.81 ¨ (0.81) = 0.0 V
03 E (03/H20) - E (02/H20) = 1.09¨ (0.81) = 0.28 V
H202 E (H202/H20) - E (02/H20) = 1.36¨ (0.81) = 0.55 V
C) Case of oxygen reduction to H202 at the cathode - Reaction at the cathode (pH=7) 02 + 2H+ + 2e- ¨> H202 E (02/H202) = 0.29 V /SHE
- Possible reactions at the anode (pH=7) 2H20¨> 02+ 4H+ +4e- E (02/H20) = 0.81 V/SHE
3H20 4 03 + 6W + 6e- E (03/H20) = 1.09 WSHE
2H20 4 H202 + 2W + 2e- E (H202/H20) = 1.36 \ONE
Compound Calculated thermodynamic cell potential of formation 02 E (02/H20) - E (02/H202) = 0.81 ¨ (0.29) = 0.52 V
03 E (03/H20) - E (02/H20) = 1.09¨ (0.29) = 0.80 V
H202 E (H202/H20) - E (02/H20) = 1.36¨ (0.29) = 1.07 V
Electrochlorination Anode: 2 Cl- ¨> 012 + 2e- requires a potential of 1.36 Volt (V) Cathode: 2 H20 + 2e- ¨> 2 OH- + H2 requires a potential of -0.8277 Volt (V) Reaction voltage: 2.1877 V.

Examples of specific applications:
= for a textile designed to sterilize a volume of air, e.g. inside a bag with a significant air-filled volume or inside a room, it would be preferable to optimize for ozone production. Ozone gas would then fill the air space.
= for sterilization of the textile itself and objects in direct contact, it would be preferable to optimize for H202 production as this will be retained in the liquid.
Small amounts of ozone produced in the textile will not lead to any appreciable concentration in the air, which may be an advantage in applications close to the human body, in face masks, etc.
= chlorination by use of a higher voltage will be of interest if an enhanced effect is needed, e.g. for sterilizing larger volumes of water, high concentrations of virus, in the presence of dirt or turbid water, etc.
Microbiological contamination coming into contact with the material of the invention will be inactivated by the generated ozone, chlorine and/or reactive oxygen species. In order to enhance the effect, an antimicrobial coating can be included in, or coated onto, the electrically conductive textile or membrane of the invention.
Examples include ion conductive and ion exchange compounds with fixed positive, or negative, or both positive and negative, charges. Especially, cationic species such as alkyl ammonium ions, cationic peptides, polymers with quaternary ammonium moieties such as chitosan or polymers with grafted positively charged groups can be effective. Optionally, such coatings can be mixed with a conductor such as graphene powder, other carbon or metal powder or fibres to maintain a high surface conductivity. Due to the electrical properties of such coating, synergistic effects with the electric field may be obtained, creating a stronger sterilizing effect than either the fabrics of the invention without such coatings, or the coatings when applied onto conventional materials such as standard textiles.
The electrochemical generation of ozone, chlorine and hydrogen peroxide is known in the art, but is put to an unexpected use in the methods and articles of the present invention.

Claims

13

1. A method of inactivating microbiological contamination at a locus, said locus comprising a textile or membrane comprising at least two electrically conductive elements configured to allow an electric current to pass between said elements via an intervening liquid medium, the textile or membrane further comprising an aqueous liquid on a surface or within the interior of said textile or membrane and in electrical contact with said conductive elements to provide said intervening medium;
wherein the method comprises applying between the at least two conductive elements a voltage effective to generate a microbiological contamination-inactivating amount of an inactivating species selected from ozone, chlorine and reactive oxygen species.

2. A method of inactivating microbiological contamination at a locus, the method comprising contacting said locus with a textile or membrane comprising at least two conductive elements configured to allow an electric current to pass between said elements via an intervening liquid medium, the textile or membrane further comprising an aqueous liquid on a surface or within the interior of said textile or membrane and in electrical contact with said conductive elements to provide said intervening medium;
wherein the surface of said textile or membrane contacted with said locus comprises a microbiological contamination-inactivating amount of an inactivating species selected from ozone, chlorine and reactive oxygen species.

3. The method of claim 1 or claim 2 where at least two conductive elements in the textile or membrane are spaced apart from each other by less than 1mm along at least 10% of their respective lengths.

4. The method of claim 1 or claim 2 wherein the textile is a woven or knitted structure and at least one of the conductive elements comprises a conductive yarn.

5. The method of claim 1 or claim 2 wherein at least one of the conductive elements comprises a conductive yarn embroidered or sewn into a textile.

6. The method of claim 1 or claim 2 wherein at least one of the conductive elements is formed by conductive ink printing or lithography.

7. The method of claim 1 or claim 2 wherein the textile or membrane is impregnated or coated with an ionically conductive polymer.

8. The method of any preceding claim, wherein the microbiological contamination is bacterial contamination.

9. The method of any preceding claim, wherein the microbiological contamination is viral contamination.

10. The method of claim 9, wherein the viral contamination is SARS CoV-2.

11. The method of any preceding claim, wherein said locus is a protective face mask.

12. The method of any preceding claim, wherein the applied voltage is from 0.3 to 10.0 V.

13. The method of claim 12, wherein the applied voltage is from 0.5 to 2.0 V.

14. The method of any preceding claim, wherein an alternating voltage is applied between the conductive elements.

15. The method of claim 14, wherein the alternating voltage has a waveform with a period between 10 seconds and 10 minutes and a maximum amplitude between 0.3 and 10.0 V.

16. The method of any preceding claim, wherein the reactive oxygen species is selected from ozone and hydrogen peroxide.

17. The method of claim 1 or claim 2, wherein the locus is a bag for sterilizing objects, a protective face mask, protective clothing or an interior or upholstery textile or membrane.

18. A protective face mask comprising a textile or membrane, said textile or membrane comprising at least two conductive elements formed of conductive yarn or conductive ink.

19. A face mask according to claim 18, wherein the conductive elements are connected to an electric signal generator such that, in use, a voltage can be applied between the conductive elements.

20. A bag comprising a textile or membrane, said textile or membrane comprising at least two electrically conductive elements formed of conductive yarn or conductive ink.

21. A bag according to claim 20, wherein the conductive elements are connected to an electric signal generator such that, in use, a voltage can be applied between the conductive elements.

22. An interior or upholstery textile or membrane, said textile or membrane comprising at least two electrically conductive elements formed of conductive yarn or conductive ink.

23. An interior or upholstery textile or membrane according to claim 22, wherein the conductive elements are connected to an electric signal generator such that, in use, a voltage can be applied between the conductive elements.