WO2020260560A1

WO2020260560A1 - Photo-sterilizable medical device

Info

Publication number: WO2020260560A1
Application number: PCT/EP2020/067991
Authority: WO
Inventors: Guillermo Orellana Moraleda; Francisco Amaro Torres; Miguel GÓMEZ MENDOZA; Ana Belén DESCALZO LÓPEZ
Original assignee: Universidad Complutense De Madrid
Priority date: 2019-06-28
Filing date: 2020-06-26
Publication date: 2020-12-30
Also published as: ES2801524A1; ES2801524B2

Abstract

The present invention relates to a tubular medical device comprising a longitudinal outer surface; a longitudinal inner surface; and a material comprised between the two longitudinal surfaces with an index of refraction, n _c _, ≥ 1.340; characterized in that at least one of the two longitudinal surfaces of the device comprises a photosensitizer covalently linked to said surface. This tubular medical device allows for the easy, rapid, and effective sterilization of its surface after irradiation with an external light source.

Description

PHOTO-STERILIZABLE MEDICAL DEVICE

Field of the Invention

The present invention relates to a sterilizable medical device that can be sterilized by irradiation, more specifically a tubular medical device comprising a biocidal coating inhibiting the formation of a biofilm, thereby preventing its formation or eliminating microorganisms from said biofilm after irradiation with a light source.

Background of the Invention

Among healthcare-associated infections, those caused by invasive devices in hospital care are among the most important, especially in critical patients. The use of tubular medical devices such as catheters, urinary tubes, endotracheal tubes, parenteral nutrition tubes, mechanical ventilation tubes, and other central catheters, including for hemodialysis, accounts for a considerable percentage of catheter-associated infections (CAI), including catheter- associated urinary tract infections (CAUTI) with a morbimortality increased by between 10 and 20%, in addition to prolonging hospital stays and increasing economic costs generated by the disease. The latest ENVIN-Helics report, issued in 2018 ( Estudio Nacional de Vigilancia de Infection Nosocomial en Servicios de Medicina Intensiva 2018; Sociedad Espanola de Medicina Intensiva Critica y Unidades Coronarias (SEMICYUC): 2019; p 96), which analyzes nosocomial infections in internal medicine services from 219 intensive care units (ICUs) in Spain, covering 27,514 patients, reflects the human and economic magnitude of the problem: 1.53 episodes of infection for every 1000 days of central venous catheter. Out of a total of 1631 episodes of infection recorded in said period, 30.47% correspond to ventilator-associated pneumonia, 30.23% to urethral tube-associated infection, and 12.39% to central venous catheter. In general, catheter-related bloodstream infection (CRBSI) are more common outside the Intensive Care Unit (ICUs) (Guembe et al., The Journal of Hospital Infection 2015, 90, 135- 41). Additional aspects of the problem are the costs and risks for the patient that are inherent to the removal and replacement of the tubular medical device, in the event of a suspected infection, in addition to the costs of the material itself and analyses thereof.

Among the characteristics that are typical of each type of tubular medical device, in accordance with the type of patient and the handling thereof, the possibility of developing an infection correlates with the number of days said device is in contact with the patient. The existing contamination pathways are both through the outer surface of the device (generally at the point of insertion into the body) and the intraluminal surface. In the first case, it is associated with components of the skin microbiota, which change their status from commensal to opportunistic pathogen and may progress towards the tip of the device and subsequently develop into bacteremia that could progress to a more severe local or systemic infection. Said type of infection normally occurs in the first days after insertion of the device. Moreover, it is the most common pathway in ventilator-associated pneumonias, due to the existence of air sterilization filters that reduce the risk of intraluminal contamination. The intraluminal contamination generally originates when manipulating the connections of the device, for example, a catheter.

A system which allows effectively auto-sterilizing a device (for example, a catheter) implanted in the patient, especially an ICU patient, would represent a considerable economic savings, in addition to the evident benefit for the patient. Furthermore, it would account for a lower consumption of antibiotics and a reduction in the occurrence of multi-antibiotic resistant bacterial strains. The main microorganisms responsible for the mentioned infections are Gram negative bacteria (e.g. Escherichia coli and Pseudomonas aeruginosa ); among Gram-positive bacteria, Staphylococcus epidermidis, Staphylococcus aureus, and Enterococcus faecalis, as well as Candida albicans among fungemias, are important in CAIs.

As a solution to this problem, there are microbicidal catheter coatings (Zhang and Warner, Antimicrobial Coatings and Modifications on Medical Devices, Springer International Publishing, 2017; Singha et al. Acta Biomaterialia 2017, 50, 20-40) for a wide range of antiseptic agents or antibiotics (Islas et al., Int. J. Pharm. 2015, 488, 20-28; Saini et al. Biofouling 2016, 32, 511— 522; Zuniga-Zamorano et al., Radiation Physics and Chemistry 2018, 142, 107-114). The inclusion of silver particles (Leuck et al. American J. of Infection Control 2015, 43, 260-265) or conjugation to chlorhexidine (Tenke et al., Current Opinion in Infectious Diseases 2014, 27, 102-107), antibiotic peptides (Cirioni et al. Peptides 2006, 27, 1210-1216), coatings comprising quaternary ammonium salts (Carmona-Ribeiro and De Melo Carrasco, International J. of Molecular Sciences 2013, 14, 9906-9946) or silane derivatized with a quaternary ammonium group (Isquith et al. Applied Microbiology 1972, 24, 859-863), or triclosan^® (Silva Paes Leme et al. Canadian J. of Microbiology 2015, 61 , 357-365), as well as photoactive agents (documents US20110218139 and WO2012005396), may be mentioned as representative examples of the foregoing.

The photodynamic effect is based on the biocidal effect on microorganisms resulting from the combination of light, molecular oxygen, and a dye (referred to as“photosensitizer”) capable of absorbing said light and photochemically reacting with said molecular oxygen dissolved in water or naturally present in the atmosphere surrounding the photosensitizer (Nyokong and Ahsen, Eds.,“Photosensitizers in Medicine Environment and Security”, Springer, Dordrecht, NL, 2012; Dryden et al., Journal of Global Antimicrobial Resistance 8 (2017) 186-191 ; Mesquita et al., Molecules 2018, 23, 2424-2470).

Photosensitizers are dyes which, under illumination at a suitable wavelength, generate variable amounts of “singlet” molecular oxygen (¹C>2) and other reactive species from the molecular oxygen present in the biological media and in tissues as described, for example, in Nonell and Flors (Editors),“Singlet Oxygen: Applications in Biosciences and Nanosciences”, Vol. 1 , Royal Society of Chemistry, Cambridge, UK, 2016. This process is“photocatalytic”, insofar as the photosensitizer is not consumed in the photochemical reaction.

International patent application W02012005396A1 describes a catheter and method for manufacturing same, provided with a fluorescent photosensitizing agent immobilized on the inside of the catheter wall. However, (i) the described immobilization by swelling does not prevent the loss of part of the sensitizer to the tissues adjacent to the place where the catheter is inserted from occurring; and (ii) the transport efficiency of the reactive oxygen species (biocidal species) into (the lumen) or out of the catheter is very low (the lifetime of the reactive species, such as the“singlet” molecular oxygen, for example, is just a few microseconds, as described by Nonell and Flors (Editors), “Singlet Oxygen: Applications in Biosciences and Nanosciences”, Vol. 1 , Royal Society of Chemistry, Cambridge, UK, 2016; therefore most of these reactive species will not manage to escape from inside the catheter wall because said wall is generally from one to two mm thick).

Patent application US2001047195A1 describes a medical device with an internal surface and an external surface (such as a catheter, for example) provided with an“optical fiber” or light conductor extending along at least one segment of the wall of the device. Furthermore, the application indicates the existence of a photosensitizer “coating” or “embedded” in said surfaces. However, it does not solve the problem of the loss of the photosensitizer with continued use, and it requires the use of an external light guide, which considerably complicates the manufacture and use of the resulting catheter or medical device.

Patent application US2014039418A1 describes the possibility of incorporating a photosensitizer in a catheter, sterilizable by the use of light. However, this document does not contemplate the problem of the loss of the sensitizer with continued use either.

Patent application US 2017050996 A1 discloses the possibility of covalently incorporating a photosensitizer on different substrates, including a catheter.

International PCT application WO 2013035913 A1 describes a stent comprising a photosensitizer molecule. US 2009130049 A1 describes polymeric medical devices that can be functionalized with phthalocyanines.

However, the prior art does not disclose how to achieve sterilization of the entire surface of a medical device without the necessity of irradiating the entire surface. The prior art is silent regarding the irradiation of the medical devices in such a way that the entire surface of the medical device generates reactive oxygen species.

Therefore, there is still a need to provide a tubular medical device capable of being sterilized in a very simplified manner so as to prevent bacterial contamination and formation of biofilms on the surface of said device (and, with it, infection of the patient) when implanted for a long time in the patient, over the entire time the device is implanted.

In this context, the inventors have surprisingly found a solution to the enormous challenge that is how to prevent bacterial contamination and the formation of biofilms on the surface of a tubular medical device (and, with it, infection of the patient) implanted for a long time in the patient, over the entire time the device is implanted. The tubular medical devices herein described are based on the binding of photosensitizing molecules to at least one of the walls of the device, which are activated by illumination making use of the transmission of light from a low-cost high-density external source (for example, light-emitting diodes or LEDs, or laser diodes) along the device by total internal reflection. By tapping into the phenomenon of light propagation by total internal reflection, the photosensitizers which are covalently bound to the surface of the device can be excited by the so-called evanescent wave, namely, the fraction of light that leaks out of the waveguide material during the travel along it by total internal reflection. This has the advantage that the device of the invention can be sterilized by irradiating it from at least one single point, optionally at one end of the device, wherein said single irradiation point can be outside the body of the subject and still achieve the excitation (thus sterilization) of the surface of the entire device, including parts of the device that are inserted in the body (hence, in a dark environment).

Brief Description of the Invention

The present invention relates to the inclusion of a coating in a tubular medical device, which can be activated to carry out a microbicidal effect in short but highly effective periods and which guarantees continuous auto-sterilization of the device. The coating is innocuous to higher organisms but deleterious to microorganisms. The coating imparts the device with a universal microbicidal effect, even over pathogens that are multi- or pan-resistant to clinical antibiotics, with zero induced resistances, minimal or null toxicity for the patient but sufficient to perform its microbicidal function. The coating imparts microbicidal action to the device and can be activated when desired, without any need for the replacement of the device during the patient’s hospitalization. The gist of the invention lies in the possibility of achieving sterilization of a tubular medical device wherein the majority of its length is in the dark, for example when it is inserted in a patient

Therefore, a first aspect of the invention relates to a tubular medical device comprising:

- a longitudinal outer surface;

- a longitudinal inner surface; and

- a material comprised between the two longitudinal surfaces with an index of refraction, n_c, ³ 1.34;

characterized in that at least one of the two longitudinal surfaces of the device comprises a photosensitizer covalently linked to said surface, wherein the photosensitizer and said surface are arranged so that the photosensitizer is excited by an evanescent wave propagating in said material.

In a second aspect, the invention relates to a tubular medical device comprising:

- a longitudinal outer surface;

- a longitudinal inner surface; and

wherein at least one of the two longitudinal surfaces of the device comprises a photosensitizer covalently linked to said surface, for use in the treatment and/or prevention of a disease caused by pathogen-induced infections, wherein said treatment and/or prevention is achieved by evanescent wave excitation of said photosensitizer.

The tubular medical device, as defined in the claims, allows being readily and effectively sterilized. Therefore, a third aspect of the invention contemplates a sterilization method for sterilizing the medical device of the invention, characterized in that it comprises the step of irradiating the device with an irradiation source at a wavelength comprised between 350 and 800 nm at an angle of incidence ³ critical angle Q. The critical angle Q is such that it allows the longitudinal propagation of the incoming radiation by means of total internal reflection at the material surface of the light along the material constituting the device. The longitudinal propagation of radiation excites the photosensitizer by way of the radiation evanescent wave, which in turn generates reactive oxygen species in the presence of molecular oxygen (O2). Likewise, the invention also contemplates the preparation of the tubular medical device. Therefore, a fourth aspect defines a preparation method for preparing a tubular medical device according to the invention, characterized in that it comprises the steps of:

a. subjecting a tubular medical device comprising a longitudinal outer surface, a longitudinal inner surface, and a material comprised between the two longitudinal surfaces with an index of refraction, n_c, ³ 1.340, to an oxidizing medium;

b. reacting at least one of the oxidized surfaces obtained in step a) with a bifunctional spacer chain; and

c. reacting a photosensitizer with at least one of the functionalized surfaces obtained in step b).

A fifth aspect of the invention contemplates a kit comprising the tubular medical device of the invention and an external light source, wherein the light source is preferably selected from the group consisting of a laser light, a laser diode, or a light-emitting diode source. It may further comprise instructions for irradiating the device in order to achieve excitation of the photosensitizer by an evanescent wave generated by a beam of light propagating longitudinally by total internal reflection.

Finally, a sixth aspect of the invention contemplates the use of the medical device of the invention, or of the kit of the invention, in a sterilization procedure that substantially involves total internal reflection of light to achieve photosensitizer excitation.

Brief Description of Figures

Figure 1. ¹C>2 decay (monitored through its emission at 1265 nm after excitation at 532 nm, 1 mJ/pulse, averages of 40 pulses) of: 1. Non-functionalized silicone catheter; 2. Silicone catheter functionalized with APTES; 3. Silicone catheter, without pre-treatment, placed in contact with a photosensitizer solution; 4. Silicone catheter bonded to the PdPFPP sensitizer through APTES, submerged in water; and 5. Silicone catheter bonded to the PdPFPP sensitizer through APTES. All the measurements were taken uncovered (in the presence of air).

Figure 2. ¹C>2 decay (monitored through its emission at 1265 nm after excitation at 532 nm with a Nd:YAG laser, 1 mJ/pulse, 2 nanosecond pulses) of a silicone catheter sample, bonded to the PdPFPP sensitizer through APTES, after 50, 200, 350, 600, and 1000 pulses of irradiation.

Figure 3. Number of colony forming units (CFUs) of P. aeruginosa after incubation on silicone discs: 1. Control; 2. Silicone disc treated according to the invention, protected from light; and 3. Silicone disc of the invention after 60 min of irradiation with a 532 nm diode laser (100 mW, 12 V). The asterisks indicate significant differences (p < 0.001) between the functionalized catheter with respect to the control according to the Student t-test.

Figure 4. Number of CFUs of P. aeruginosa after incubation on silicone discs: 1. Silicone disc treated with APTES irradiated with a 532 nm diode laser (100 mW, 12 V); 2. Silicone disc treated with APTES without irradiation; 3. Silicone disc treated with APTES and with PdPFPP without irradiation; 4. Silicone disc treated with APTES and with PdPFPP irradiated with a 532 nm diode laser (100 mW, 12 V).

Figure 5. Number of CFUs of P. aeruginosa, E. coli, and S. epidermidis after irradiation in total internal reflection of different silicone discs exemplifying the catheters of the invention after 30 minutes of irradiation with a 532 nm diode laser (100 mW, 12 V) wherein: 1. Silicone disc treated with APTMS and contaminated with P. aeruginosa ; 2. Silicone disc treated sequentially with APTMS and PdPFPP according to the method of the present invention, contaminated with P. aeruginosa ; 3. Silicone disc treated with TDTMS and contaminated with P. aeruginosa ; 4. Silicone disc treated with TDTMS and PdPFPP according to the method of the present invention, contaminated with P. aeruginosa ; 5. Silicone disc treated with APTMS and contaminated with E. coli ; 6. Silicone disc treated with APTMS and PdPFPP according to the method of the present invention, contaminated with E. coir, 7. Silicone disc treated with TDTMS and contaminated with E. coli ; 8. Silicone disc treated with TDTMS and PdPFPP according to the method of the present invention, contaminated with E. coir, 9. Silicone disc treated with APTMS and contaminated with S. epidermidis ; 10. Silicone disc treated with APTMS and PdPFPP according to the method of the present invention, contaminated with S. epidermidis ; 11. Silicone disc treated with TDTMS and contaminated with S. epidermidis ; 12. Silicone disc treated with TDTMS and PdPFPP according to the method of the present invention, contaminated with S. epidermidis.

Detailed Description of the Invention

The present invention is based on coating a tubular medical device with a photosensitizer. The essential requirements for being able to carry out the invention are defined by the following first aspect:

A tubular medical device comprising:

- a longitudinal outer surface;

- a longitudinal inner surface; and

The tubular medical device has applications compatible with the human body, therefore it will be surrounded by aqueous or gaseous media. The index of refraction of these media is, preferably, below 1.34 (water has an index of 1.33). When n_c is greater than the index of refraction of the external medium surrounding it, n,, the phenomenon of total internal reflection occurs, which allows the internal propagation of an incident beam of light along the device, wherein the radiation is propagated in said material comprised between the two longitudinal outer and inner surfaces of the device.

Thus, the medical device of the invention is suitable for being coupled to a light source of a wavelength comprised between 350 and 800 nm said light source being arranged to irradiate the device at an angle of incidence ³ critical angle Q. Preferably, the light source is arranged to irradiate at least one of said surfaces of the device at an angle of incidence > critical angle Q.

The critical angle Q is the smallest angle of incidence that yields total reflection such that it allows the propagation of radiation by means of total internal reflection of the light along the longitudinal direction of the material comprised between the two longitudinal surfaces of the device.

In turn, since the radiation is propagated subjected to the phenomenon of total internal reflection, it causes an evanescent wave (also called evanescent field) from the interface where the index of refraction changes (the surface of the material), the range of which is on the order of magnitude of the wavelength of the propagated wave (Ahmad and Hench, Biosensors and Bioelectronics 2005, 20, 1312-1319). An evanescent field or evanescent wave is a near-field standing wave with an intensity that shows an exponential decay with the distance to the interface where it was produced. The intensity of evanescent waves decays exponentially with the distance to the interface at which they are formed. Evanescent waves are formed when sinusoidal waves are (internally) reflected off an interface at an angle greater than the critical angle so that total internal reflection occurs.

Therefore, in a preferred embodiment the evanescent wave is responsible for the excitation of the photosensitizer. Nevertheless, the photosensitizer may also be excited by additional means of direct irradiation (wherein irradiation is propagated by a means other than the tubular medical device). After excitation, the photosensitizer generates reactive oxygen species responsible for the biocidal effect.

In contrast to a polymer coating containing a photosensitizer, or unlike a photosensitizer embedded in the wall of a device by swelling of the material constituting it, the covalent linking of a photosensitizer to at least one of the surfaces of the tubular medical device of the present invention allows the formation of a monolayer, or at most a few layers, of photosensitizer molecules on the surface of the device. This allows arranging the photosensitizer at a distance from the surface of the device which allows the optimization of the absorption of energy from the evanescent wave.

Tubular medical device

The term“photosensitizer” refers to a molecule, particularly a dye which, after the absorption of visible light with a wavelength suitable for same, generates an excited electron state of said dye and which, during its excited state lifetime, is capable of giving or transferring its excess energy to another molecule present in the surrounding medium, an excited state thereof being obtained. In the present case, the photosensitizer is a dye having a long-lived triplet excited state as the most stable excited state. If the photosensitizer in the excited triplet state collides with molecular oxygen, singlet molecular oxygen (abbreviated in the literature as “singlet oxygen”) is generated.

Therefore, in a particular embodiment of the present invention, the photosensitizer generates reactive oxygen species.

The proximity of the photosensitizer to the surface of the device, as a consequence of said covalent bonding, combined with a suitable value of n_c, yields several advantages:

(i) Excitation of the photosensitizer along the entire device;

The light propagated by total internal reflection through the core of the material constituting the tubular medical device produces an evanescent wave field, because in each of the reflections of the propagating light against the device/fluid, device/air, or device/tissue interface, said light penetrates the exterior of the material at a length in the order of magnitude of the wavelength of the light travelling through said material (for example, in the case of green light, the mean penetration distance is about 550 nm). The photon density decreases exponentially with the distance to the surface of the material. Therefore, upon irradiating the device with an external excitation source, excitation of the photosensitizer along substantially the entire longitudinal surface of the device is achieved. (ii) No losses of the photosensitizer;

The covalent bonding of the photosensitizer to one of the surfaces of the tubular medical device prevents the photosensitizer from washing out, escaping or migrating from the surface of the device to the fluids or tissues in direct contact with said surface(s), even though the device remains inserted in the patient for many days, guaranteeing the safety of the device of the invention.

and,

(iii) Better biocidal efficacy;

The extreme thinness of the monolayer or multilayer of photosensitizer molecules immobilized on at least one of the surfaces of the device (a few nanometers thick) allows a high proportion of the singlet molecular oxygen and other reactive species generated by the photosensitizer upon illumination to effectively reach the biological target (viruses, fungi, or bacteria gradually adhering to the surface of the device to finally form a bacterial biofilm that is extremely resistant to removal or inactivation), because the singlet molecular oxygen in water only travels less than 200 nm before being deactivated to molecular oxygen and losing its biocidal properties. The biocidal nature of said reactive species prevents colonization of the surface by live pathogenic microorganisms and formation of the corresponding bacterial biofilm on the outer and/or inner surface of the material, preventing the infections caused by said microorganisms.

In the context of the present invention, a“tubular medical device” is to be considered as any device or apparatus having a substantially tubular shape, which can be applied in medicine, particularly for insertion in a mammal. Said device shall comprise at least one material defining an inner surface and an outer surface.

Therefore, in a particular embodiment of the present invention, a tubular medical device is a catheter, bladder tube, gastric tube, urinary tube, endotracheal tube, or a stent. In the context of the present invention, the tubular medical device is preferably made up of flexible polymer material, more preferably transparent or semi-transparent, such as silicone, polyvinylpyrrolidone, polyvinyl chloride, polycarbonates, acrylates, polystyrenes, polyethylene terephthalate, polyamides, polyurethanes, fluoropolymers, and combinations thereof.

The term“stent” is recognized in the art as a flexible tube made of a plastic material, optionally provided with an extendable mesh used for opening arteries, veins, and other ducts in the body (for example, the urethra). The term“biofilm” is used for defining an organized microbial ecosystem consisting of one or several species of microorganisms associated with a surface and embedded in a matrix generally of polysaccharides. In the present case,“biofilm” refers to a biofilm of microorganisms, preferably bacteria or fungi, present on the surface of a tubular medical device.

For the tubular medical device of the invention to be sterilizable according to the method of the invention, the material comprised between the two longitudinal surfaces must have an index of refraction, n_c, ³ 1.34. Nevertheless, one skilled in the art will know that the phenomenon of total internal reflection occurs only when n_c, > n,. Therefore, in a particular embodiment, n_c ³ 1.35, n_c ³ 1.36, n_c ³ 1.37, n_c ³ 1.38, and preferably n_c ³ 1.39.

The index of refraction values described in the present application are values represented with a degree of approximation of two decimal places. Therefore, n_c, ³ 1.34 means that the index of refraction is greater than or equal to 1.34, including all values with three decimal places comprised between 1.335 and 1.344.

In a particular embodiment compatible with the preceding embodiments, n_c £ 1.80, preferably n_c £ 1.70, more preferably n_c £ 1.60.

Therefore, in the present invention, 1.34 £ n_c £ 1.80, more preferably 1.35 £ n_c £ 1.70, even more preferably 1.36 £ n_c £ 1.60.

The index of refraction (or refractive index) of the material constituting the tubular medical device of the invention is represented as the standard value measured at 589 nm, at room temperature and ambient pressure. The values of the refractive indexes of the materials are of common general knowledge, being found, for example, in Brandrup et al. (Editors), Polymer Handbook, 4^th edition, Wiley, 2003. Nevertheless, the index of refraction may be obtained by means of the ASTM D542-14 method for measuring the index of refraction of polymer materials, for example. Furthermore, the index of refraction may be measured using, for example, a J457 refractometer (Rudolph Research Analytical).

In the present invention, the material comprised between the two longitudinal surfaces can be the material defining the two surfaces. In this context, at least one of the two longitudinal inner or outer surfaces is a surface comprising the same material as the material comprised between the two longitudinal surfaces.

In a particular embodiment, said material is a polymer material selected from the group consisting of silicone, polyvinylpyrrolidone, polyvinyl chloride, polycarbonates, acrylates, polystyrenes, polyethylene terephthalate, polyamides, polyurethanes, fluoropolymers, and combinations thereof. In a preferred embodiment, the tubular medical device of the invention is characterized in that the material constituting it is silicone, polyvinylpyrrolidone, polyvinyl chloride, polyurethane, or a fluoropolymer, preferably silicone. Non-limiting examples of fluoropolymers include PFA (a tetrafluoroethylene (TFE) and a perfluoroalkyl vinyl ether (PAVE) copolymer) or PTFE (polytetrafluoroethylene).

Since the material comprised between the two longitudinal surfaces of the device can be the material defining at least one or both of the surfaces of the device, the surfaces may also comprise a polymer material selected from the group consisting of silicone, polyvinylpyrrolidone, polyvinyl chloride, polycarbonates, acrylates, polystyrenes, polyethylene terephthalate, polyamides, polyurethanes, fluoropolymers, and combinations thereof, preferably silicone, polyvinylpyrrolidone, polyvinyl chloride, or a fluoropolymer, more preferably silicone.

In a preferred embodiment, the tubular medical device is made of silicone.

In a particular embodiment, the medical device of the invention is characterized in that a photosensitizer is covalently linked to at least one of the two surfaces through a bifunctional spacer chain. In another particular embodiment, the photosensitizer is covalently linked to one of the two longitudinal surfaces through a bifunctional spacer chain. In yet another particular embodiment, the photosensitizer is covalently linked to each of the two longitudinal surfaces through a bifunctional spacer chain.

The medical device of the invention is tubular. Therefore, it is characterized by a hollow cannula of variable diameter, a wall of variable thickness, and two terminals, characterized in that they are a connector suitable for introducing or removing biological fluids, solids, gases, liquids, or solutions.

Therefore, the present invention also contemplates the photosensitizer being able to be covalently linked to at least one of the two terminals of the tubular medical device, identically to how it would be linked to at least one of the two longitudinal surfaces.

The bifunctional spacer chain facilitates the covalent functionalization of at least one of the surfaces of the tubular medical device of the invention with a photosensitizer. Additionally, the spacer chain is such that the photosensitizer is at a non-arbitrary distance from said surface of the device.

The skilled person will readily understand that the functionalized surface will comprise at least one layer of bifunctional spacer molecules but can also comprise further layers. This means that the photosensitizer may be covalently bound to the surface of the device via one or more spacer molecules. In a particular embodiment, the spacer chain is such that the photosensitizer molecules are at a mean distance from the functionalized surface comprised between 0.5 and 200 nm, preferably between 0.5 and 100 nm, preferably between 0.5 and 50 nm, more preferably between 0.5 and 20 nm and even more preferably between 0.5 and 10 nm. The thickness of the spacer layer can be measured by means of techniques known to the skilled person, for example by techniques including XPS, AFM or ellipsometry. Preferably, the distance is determined by XPS. Particularly, the bifunctional spacer chain is a molecule with two reactive functional groups, preferably having a different reactivity relative to one another.

In a particular embodiment of the invention, the bifunctional spacer chain is an alkoxysilane. In a preferred embodiment, the alkoxysilane is preferably selected from aminosilanes, vinylsilanes, acyloxysilanes, glycidoxysilanes, acryloxysilanes, methacryloxysilanes, epoxysilanes, halosilanes, cyclic azasilanes, isocyanatesilanes, isothiocyanatesilanes, hydroxysilanes, and mercaptosilanes. The invention also contemplates the possibility of using more than one type of bifunctional spacer chain.

In a particular embodiment, the alkoxysilane is an aminosilane. In a preferred embodiment, the aminosilane is selected from the group consisting of 3-aminopropyltrimethoxysilane (APTMS), 3-aminopropyltriethoxysilane (APTES), 3-aminopropyldiethoxymethylsilane, 3- aminopropyldimethylethoxysilane, 2,9-diazanonyltriethoxysilane, 12,15- diazapentadecyltrimethoxysilane, 4,7-diazaheptyltrimethoxysilane, 4,7,10- triazadecyltrimethoxysilane (TDTMS), and combinations thereof.

An alkoxysilane is a compound that readily reacts with a surface previously subjected to an oxidizing environment, which preferably generates -OH groups in said surface. In a particular embodiment, at least one of the surfaces of the tubular medical device is treated with oxygen, nitrogen, helium or argon plasma, or atmospheric plasma, or an excimer lamp to facilitate reaction with the bifunctional spacer chain.

In a preferred embodiment, the at least one of the oxidized surfaces is the outer (or external) surface of the tubular medical device.

In the device of the present invention, at least one of the surfaces comprises a covalently linked photosensitizer. As described above, the photosensitizer is a species that generates singlet oxygen through an excited triplet state. Therefore, in a particular embodiment any photosensitizer generating an excited triplet state is a photosensitizer that can be used in the invention. In a preferred embodiment, the photosensitizer is selected from the group consisting of porphyrins, phthalocyanines, Ru(ll), Pd(ll), and Pt(ll) complexes, boron dipyrromethenes, quinone, anthraquinone, acridine, and coumarin derivatives, xanthene derivatives such as fluorescein, eosin, rose bengal, and erythrosine, thiazine derivatives such as methylene blue, and combinations thereof. More preferably, the photosensitizer is selected from porphyrins.

When the photosensitizer is a porphyrin, said porphyrin is preferably selected from a metalloporphyrin selected from the group consisting of Protoporphyrin IX, octaethylporphyrin derivatives, meso-tetraphenylporphyrin derivatives such as meso-tetra(2- fluorophenyl)porphyrin, meso-tetra(3-fluorophenyl)porphyrin and meso- tetra(pentafluorophenyl)porphyrin, and combinations thereof. In a preferred embodiment, the photosensitizer is a meso-tetra(pentafluorophenyl)porphyrin.

The metal present in the metalloporphyrin can be selected from the group consisting of Pt(ll), Pd(ll), Zn(ll), Fe(ll), Co(ll), Ni(ll), Ru(ll), Ti(ll), Cr(ll), Cu(ll), Si(IV), and combinations thereof, preferably being selected from Pd(ll).

In a preferred embodiment, the photosensitizer is covalently linked on the outer surface of the tubular device. More preferably, the photosensitizer is covalently linked through a bifunctional chain, selected from an alkoxysilane. The invention also contemplates the possibility of the photosensitizer being covalently linked to the inner surface of the tubular device, being covalently linked to the two inner and outer surfaces of the tubular device, as well as to the two surfaces and to the terminal region (or regions) of the device.

In a preferred embodiment of the invention, the tubular medical device comprises:

- a longitudinal outer surface;

- a longitudinal inner surface; and

- a material comprised between the two longitudinal surfaces with an index of refraction, n_c, comprised between 1.34 and 1.80;

characterized in that at least one of the two longitudinal surfaces of the device comprises a Pd(ll) porphyrin covalently linked to said surface through an alkoxysilane.

In a more preferred embodiment of the invention, the tubular medical device comprises:

- a longitudinal outer surface;

- a longitudinal inner surface; and

- a material comprised between the two longitudinal surfaces with an index of refraction, n_c, comprised between 1.35 and 1.70;

characterized in that at least the longitudinal outer surface of the device comprises Pd(ll) meso- tetra(pentafluorophenyl)porphyrin covalently linked to said surface through an aminosilane.

In an even more preferred embodiment of the invention, the tubular medical device is a silicone catheter characterized in that at least the outer surface of the catheter comprises Pd(ll) meso- tetra(pentafluorophenyl)porphyrin covalently linked to said surface through an aminosilane.

Medical use of the device

The medical device of the invention comprises a medium suitable for the propagation of light by total internal reflection and generation of an evanescent wave. Said evanescent wave is utilized for excitation of a photosensitizer which is covalently bonded at a non-arbitrary distance from the surface of said material. Upon excitation, the photosensitizer generates reactive oxygen species which sterilize the medical device and kill, or avoid the presence of, pathogenic microorganisms lying on the medical device. The gist of the invention is that the medical device can be easily sterilized while inserted inside a mammal, preferably a human, where normally the device is in a dark environment. Therefore, in a second aspect, the invention relates to a tubular medical device comprising:

- a longitudinal outer surface;

- a longitudinal inner surface; and

Preferably, the evanescent wave excitation of the photosensitizer is achieved by irradiating the device with a light source of a wavelength comprised between 350 and 800 nm, at an angle of incidence ³ critical angle Q.

All of the particular and preferred embodiments related to the medical device of the invention are also equally applicable to the device of the invention for use in the treatment and/or prevention of a disease caused by pathogen-induced infections. Preferably, the device is for use in the prevention of a disease caused by pathogen-induced infections.

In a preferred embodiment, the disease caused by pathogen-induced infections is a disease caused by a medical tubular device infection, preferably a catheter induced infection.

Exemplary pathogens are viruses, fungi and bacteria, including multidrug resistant bacteria. The pathogens are those such as Staphylococcus aureus, Pseudomonas aeruginosa, co-agulase negative staphylococci, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumanii, Serratia marcescens, Enterobacter, Citrobacter, Stenotrophomonas maltophilia, Acinetobacter, Burkholderia cepacia, yeasts, no filamentous fungus, Candida sp. Preferably, these are Escherichia coli, Staphylococcus epidermidis, Pseudomonas aeruginosa.

Exemplary pathogen-induced infections are those caused by any pathogen found in the skin flora and include Urinary tract infections such as a Catheter-Associated Urinary Tract Infection, a catheter- related bloodstream infection, sepsis or phlebitis. Other infections include tracheobronchial infection, pneumonia, ventilator-associated pneumonia or ventilator-associated tracheobronchitis.

Sterilization method

A third aspect of the invention contemplates the sterilization method of the medical device of the invention. This method is characterized in that it comprises the step of irradiating the tubular medical device of the invention with an irradiation source of wavelength comprised between 350 and 800 nm at an angle of incidence ³ critical angle Q. The critical angle Q is such that it allows the longitudinal propagation of radiation by means of total internal reflection of the light along the material constituting the device.

This aspect is also related to a method of treating and/or preventing a disease caused by pathogen-induced infections in a subject, which method comprises irradiating the tubular medical device of the invention with an irradiation source of wavelength comprised between 350 and 800 nm at an angle of incidence ³ critical angle Q. Preferably the subject is a mammal, more preferably a human.

One skilled in the art familiar with the phenomenon of total internal reflection knows that the angle of incidence of Q is the critical angle of incidence of a beam of light which determines when the total internal reflection of said beam of light in a material with an index of refraction n_c, in contact with another material with a lower index of refraction, begins to occur. The Snell’s law describes this phenomenon and allows calculating the critical angle.

One of the advantages of the present invention is that the tubular medical device can be comfortably sterilized by applying a beam of light, at no risk to the user or, where appropriate, the patient, which once irradiation starts, the sterilization takes place immediately. Therefore, in a particular embodiment the sterilization method of the invention is characterized in that it is carried out while the medical device is being used. In other words, it is carried out while the medical device is implanted (or inserted) in a patient.

The irradiation of the tubular medical device may be performed such that less than 50%, less than 40% less than 30%, less than 20%, less than 10% of the device length is exposed to direct irradiation. In this context, direct irradiation is that which is not an evanescent wave irradiation. Preferably, the irradiation of the device is performed such that less than 10% of the medical device length is exposed to direct irradiation, even more preferably less than 5%.

In a preferred embodiment, the excitation is performed using one or several light-emitting diode(s) or laser diode(s) coupled to the tubular medical device. By way of example, the coupling may be achieved, for instance, by attaching the said commercial light source(s) to an axially hollow metal block (e.g. stainless steel or aluminum for refrigeration purposes, while the fluid can still pass through the metal block towards/from the tubular medical device shaft). The edge of the metal block allows leak-proof attachment of the tubular medical device shaft, such as a catheter shaft, endowed with the covalently bonded photosensitizer dye on its surface; the other edge allows connection to a hollow tube for introducing or evacuating the fluid(s) into the patient. Each said light source seats on a straight hole, optionally containing one or a set of lenses, that allows the beam of light to reach the tubular medical device side with an angle ³ critical angle (Q) of the tubular medical device used calculated by the Snell’s law.

The light source needed to achieve excitation of the photosensitizer has to be capable of emitting in the visible wavelength range, necessarily within the absorption range of the photosensitizer, and preferably with an emission at a wavelength close to the maximum absorption, or at one of the maximum absorptions, of the photosensitizer.

Therefore, in a preferred embodiment the radiation comes from at least one laser light, at least one laser diode, or at least one light-emitting diode source. More preferably, the radiation source is at least one laser diode.

According to the present invention, irradiation is carried out in the visible range, therefore the irradiation source emits in a wavelength comprised between 350 and 800 nm, preferably the emission range is such that the maximum intensity overlaps with the maximum absorption of the photosensitizer. The invention contemplates narrower irradiation ranges, particularly between 370 nm and 700 nm, between 400 nm and 650 nm, between 450 nm and 600 nm, preferably between 500 nm and 600 nm.

The duration of the irradiation time will be that needed to reduce or remove the biofilm built up on the tubular medical device, such as an indwelling catheter, or to prevent the formation thereof. Therefore, the invention contemplates continuous or pulsed irradiation times, for a total time that ranges between 1 and 120 min, between 1 and 80 min, between 2 and 80 min, between 5 and 80 min, preferably between 10 and 80 min, more preferably between 15 and 60 min. Depending on the type of use that is conferred to the tubular medical device, irradiation may be repeated such that the device is sterilized at least one time a day, at least two times a day, at least three times a day, or at least four times a day. Alternatively, an irradiation protocol of at least one time every two days, every three days, every four days or every week is also contemplated herein.

The sterilization method of the present invention includes generating singlet oxygen species or other reactive oxygen species, the oxidation potential of which combined with its electrophilic nature means that said species readily react with another molecule they encounter in their path. Singlet oxygen species are species with very short lifetimes; therefore, they do not have the capacity to diffuse or spread out more than an average distance of -200 nm in water. The sterilization method of the invention relates to the sterilization of a surface of a tubular medical device of the invention, comprising a photosensitizer on its surface. This allows generating in situ a highly reactive and, accordingly, lethal environment for any type of microorganism. In a particular embodiment, the sterilization method of the invention allows reducing a biofilm built up on at least one of the surfaces of the medical device.

Depending on the irradiation time (and the subsequent generation of reactive oxygen species), the method may, in a first step, reduce the concentration of viruses, fungi or bacteria or other microorganisms making up a biofilm and, if irradiated for a longer time, completely kill said microorganisms built up on said surface. Therefore, in a particular embodiment, the sterilization method of the invention is characterized in that it prevents formation or growth, reduces or removes a biofilm from at least one of the surfaces of the medical device. Preferably, the sterilization method of the invention is characterized in that it prevents formation of the biofilm.

Preparation method for preparing the device

The invention also contemplates the preparation of the tubular medical device of the invention, therefore in a fourth aspect a preparation method for preparing a tubular medical device according to the invention is defined, characterized in that it comprises the steps of:

One skilled in the art will easily know what conditions to use to achieve a medium capable of oxidizing at least one of the surfaces of the device. As an example of an oxidizing medium, an oxygen, nitrogen, helium or argon plasma or atmospheric plasma, or an excimer lamp, is contemplated. Preferably, the oxidizing medium is oxygen plasma or nitrogen plasma. In a preferred embodiment, the oxygen plasma is an etching plasma generated in a RIE (Reactive Ion Etching) device. Alternatively, an ozone atmosphere produced, for example, by a corona discharge method is also contemplated herein as oxidizing medium. If an oxygen plasma is used, for example, one skilled in the art will know what conditions are needed to achieve oxidation of the surface to be oxidized, consulting for example the teachings of the prior art (Hillborg et al. Polymer 2000, 41 , 6851-6863; Bhattacharya et al. J. Microelectrom. Sys. 2005, 14(3), 590-597; Hemmila et al. Applied Surface Science 2012, 258, 9864-9875). In a particular embodiment, after a first oxidizing treatment, the tubular medical device is optionally flipped over inside the chamber and then submitted to a second oxidizing treatment. This optional step ensures that the entire surface of the device is exposed to the oxidizing environment.

In a particular embodiment of the preparation method for preparing the device of the invention, it is contemplated that the device is subjected to said oxidizing medium for 1 , 5, 10, 15, 20, 25, or 30 minutes, preferably between 1 and 15 minutes.

In a particular embodiment of the preparation method for preparing the device of the invention, the at least one oxidized surface comprises at least part of its surface oxidized, specifically at least 10%, at least 20%, at least 30%, at least 40%, at least 50% of its surface, at least 60% of its surface, at least 70% of its surface, at least 80% of its surface, and at least 90% of its surface (in area) oxidized. In another particular embodiment, the at least one oxidized surface is oxidized in between 50 and 100% of its total area.

The method of the invention allows obtaining the tubular medical device of the invention, which is the device described in detail above. Therefore, all the features described above for the tubular medical device are applicable to the features of the preparation method. For example, the preparation method contemplates, inter alia, that the tubular medical device comprises a material the index of refraction, n_c, of which is comprised between 1.34 and 1.80, or even between 1.35 and 1.70.

As described above for the device, in one embodiment of the method of its preparation, the bifunctional spacer chain is an alkoxysilane. Preferably, the alkoxysilane is an aminosilane selected from the group consisting of 3-aminopropyltrimethoxysilane, 3- aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 3- aminopropyldimethylethoxysilane, 2,9-diazanonyltriethoxysilane, 12,15- diazapentadecyltrimethoxysilane, 4,7-diazaheptyltrimethoxysilane, 4,7,10- triazadecyltrimethoxysilane, and combinations thereof. In a preferred embodiment of the preparation method for preparing the device of the invention, the bifunctional spacer chain is added to the device in step b) in the presence of an organic solvent, preferably selected from acetonitrile, dimethylsulfoxide, dimethylformamide, N- methylpyrrolidone, or combinations thereof. A preferred organic solvent is acetonitrile.

In the present invention, the bifunctional spacer chain must react with the oxidized surface of the tubular medical device. For this reason, the inventors have discovered that the swelling of the material constituting the tubular medical device is a phenomenon that must be avoided as it would give rise to the problems described above: i) loss of part of the sensitizer due to a weak attachment; ii) generation of reactive oxygen species in a region far from the surface where the biofilm may build up; and iii) absorption of the radiation that is propagated along the device, reducing the intensity of the propagated light. These three effects together contribute to a loss of biocidal efficacy since it would give rise to: i) a smaller amount of available photosensitizer; ii) a lower concentration of reactive oxygen species in the area of interest; and iii) a loss of radiation intensity along the device.

In this context, in a preferred embodiment step b) does not involve the swelling of the tubular medical device. In a preferred embodiment, step b) is not carried out in the presence of an organic solvent selected from pentane, hexane, cyclohexane, heptane, ether, or ethyl acetate. In a preferred embodiment, step b) is not carried out in the presence of an organic solvent selected from chloroform, toluene, dioxane, acetone, isopropanol, butanol, ethanol, pentane, hexane, cyclohexane, heptane, ether, or ethyl acetate.

In a preferred embodiment of step b), the reaction between the bifunctional chain and the oxidized surface is carried out under stirring. The reaction time needed to achieve functionalization of the oxidized surface may vary depending on the bifunctional chain. However, one skilled in the art may determine, for example by means of contact angle measurements, the time needed to achieve suitable functionalization. In a particular embodiment, step b) is carried out for 3-84 hours, for 6-84 hours, for 12-84 hours, preferably for 12-72 hours. The reaction may be carried out at a controlled temperature, for example, at a temperature comprised between 15 and 45 °C, between 20 and 40 °C, but the reaction temperature is preferably comprised between 22 and 37 °C. In a particular embodiment, the reaction temperature of step b) does not exceed 45 °C, preferably does not exceed 40 °C, even more preferably does not exceed 37 °C.

In a particular embodiment of the preparation method for preparing the device of the invention, the method comprises an additional step, b1), performed between steps b) and c), comprising the optional step of cleaning the functionalized surface to remove any residues of the bifunctional chain not covalently bonded to at least one of the oxidized surfaces. A preferred example for carrying out this optional step of step b1) is subjecting the tubular medical device to an ultrasonic bath for a time comprised between 1 and 10 minutes, preferably for 1 and 5 minutes.

Step b1) further comprises a second optional step which comprises drying the tubular medical device. Preferably, the device is dried uncovered. In another embodiment, the device is dried at a temperature comprised between 25 and 60 °C, preferably between 25 and 50 °C, more preferably between 30 and 40 °C.

As described above for the device of the invention, in a particular embodiment of the method of its preparation the photosensitizer is selected from the group consisting of porphyrins, phthalocyanines, Ru(ll), Pd(ll), and Pt(ll) complexes, boron dipyrromethenes, quinone, anthraquinone, acridine, and coumarin derivatives, xanthene derivatives such as fluorescein, eosin, rose bengal, and erythrosine, thiazine derivatives such as methylene blue, and combinations thereof. Preferably, the photosensitizer is a porphyrin.

Step c) of reacting a photosensitizer with at least one of the functionalized surfaces obtained in step b) also contemplates the use of an organic solvent. In this context, step c) is carried out in acetonitrile, dimethylsulfoxide, dimethylformamide, N-methylpyrrolidone, or combinations thereof. A preferred organic solvent is acetonitrile.

However, in step c) it is also important to avoid the swelling of the material of the tubular medical device for the reasons explained above for step b). In this context, in a preferred embodiment step c) does not involve the swelling of the tubular medical device. In a preferred embodiment, step c) is not carried out in the presence of an organic solvent selected from pentane, hexane, cyclohexane, heptane, ether, or ethyl acetate. In a preferred embodiment, step c) is not carried out in the presence of an organic solvent selected from chloroform, toluene, dioxane, acetone, isopropanol, butanol, ethanol, pentane, hexane, cyclohexane, heptane, ether, or ethyl acetate.

The reaction time needed to achieve the reaction between the photosensitizer and the bifunctional chain depends on the nature of the reagents. However, one skilled in the art may determine, for example by means of contact angle measurements or by means of lifetime measurements (see examples), the time needed to achieve the reaction. In a particular embodiment of step c), the reaction is carried out for at least 6, 12, 24, 36, 48, or 60 hours. Preferably, step c) is carried out for 72 hours. The reaction of step c) may be carried out at a controlled temperature, for example, at a temperature comprised between 15 and 45 °C, between 20 and 40 °C, but the reaction temperature is preferably comprised between 22 and 37 °C. In a particular embodiment, the reaction temperature of step c) does not exceed 45 °C, preferably does not exceed 40 °C, even more preferably does not exceed 37 °C. Step c) comprises an optional step of washing the obtained material. If performed, washing is preferably carried out with the aid of ultrasounds. The solvents preferred for the optional washing are acetonitrile, methanol, ethanol, dimethylsulfoxide, dimethylformamide, N-methylpyrrolidone, or combinations thereof.

In a preferred embodiment of the preparation method of the invention, said method is characterized in that it comprises the steps of:

a. subjecting a tubular medical device comprising a longitudinal outer surface, a longitudinal inner surface, and a material comprised between the two longitudinal surfaces with an index of refraction, n_c, ³ 1.340, to an oxidizing medium of oxygen or nitrogen plasma;

b. reacting at least one of the oxidized surfaces obtained in step a) with an alkoxysilane; b1. optionally washing the device obtained in step b) and optionally leaving it to dry; and c. reacting a porphyrin with at least one of the silanized surfaces obtained in step b).

The invention also contemplates a tubular medical device that can be obtained according to the preparation method of the invention. Said device is a device comprising:

- a longitudinal outer surface;

- a longitudinal inner surface; and

characterized in that at least one of the two longitudinal surfaces of the device comprises a photosensitizer covalently linked to said surface.

Kit

The invention relates to a tubular medical device functionalized with a photosensitizer. For the tubular medical device to be sterilized according to the method of the invention, the device is irradiated with an external irradiation source, preferably at a specific angle. Therefore, a fifth aspect of the invention contemplates a kit comprising the tubular medical device of the invention, an external light source, wherein the light source is preferably selected from the group consisting of a laser light, a laser diode, or a light-emitting diode source. The kit may further comprise instructions for irradiating the device in order to achieve excitation of the photosensitizer by an evanescent wave generated by a beam of light propagating longitudinally by total internal reflection.

The light source can be integrated in the tubular medical device or can alternatively be coupled to the device by means of, for example, a wave guide such as an optical fiber.

Uses

The medical device of the invention is particularly useful in achieving a simple and low-cost self sterilization effect upon irradiation.

Therefore, a sixth aspect of the invention contemplates the use of the medical device of the invention, or of the kit of the invention, in a sterilization procedure that substantially involves total internal reflection of light to achieve photosensitizer excitation.

Examples.

One skilled in the art will understand that the method of the invention for chemically bonding the photosensitizing dye through a covalent bond can be applied to the entire tubular medical device or preferably to an outer and/or inner region or segment of the device where microbial biofilms leading to patient infections most often occur.

Example 1. Oxidation of a tubular medical device

In this example, the tubular medical device was selected from a silicone catheter and the at least one surface to be oxidized was the outer surface of the catheter.

The outer surface of the catheter was activated by introducing chemical functional groups capable of later reacting with the desired spacer. This functionalization was performed, in the present example, by treatment with oxygen plasma (also referred to as reactive ion etching or RIE) using the PlasmaPro NGP80 RIE device sold by Oxford Instruments (Yatton, Bristol, UK). To that end, silicone catheters, in the present example, standard 2-way Foley-type catheters manufactured and marketed by Mediplus (Bucks, UK), were introduced in the RIE chamber. Once a vacuum was obtained in the RIE chamber, the catheters were treated for 10 min with oxygen plasma, using an O2 flow of 20 seem, with a radio frequency power of 50 W and at a pressure of 50 mTorr for 10 min.

Example 2. Introduction of a bifunctional spacer chain

In this example, the oxidized catheter of Example 1 was treated with the primary aminosilane 3- aminopropyltriethoxysilane (APTES; Merck, Darmstadt, Germany).

In detail, the catheter was introduced in a solution of 2 mmol L ¹ of APTES in acetonitrile (HPLC grade, Merck), for 72 hours, under orbital shaking at 37 °C. The catheter was subsequently submerged in acetonitrile and placed in an ultrasonic bath (Proclean 2.0DS, Ulsonix, Germany) for 2 minutes to remove any residue of non-chemically bonded silane. It was then taken out of the bath and left to dry uncovered. Under these conditions, the inventors consider that Si-O- Si(CH2)3NH2 bonds are generated between the hydroxyl groups introduced in Example 1 and the aminosilane used in this example.

Example 3. Reaction of a photosensitizer with the silanized surface

In this example, the catheter silanized with APTES according to Example 2 was treated with a photosensitizer capable of covalently reacting with the distal amino group of the APTES spacer molecule. The following reaction scheme is not intended to be interpreted as a precise representation of the invention but rather to provide a pictorial general representation of what the functionalized surface is thought to be like.

Specifically, the catheter was introduced in a solution in acetonitrile (HPLC grade) of 0.2 mmol L ¹ of palladium(ll) meso-tetra(pentafluorophenyl)porphyrin (PdPFPP, manufactured and sold by

Frontier Scientific, Logan, Utah, USA) for 72 h under constant orbital shaking, at 37 °C and protected from light.

Finally, it was slightly dried and subjected to ultrasounds for 1 min in acetonitrile and followed by 2 min in ethanol (Merck) to remove sensitizer residues.

Once dry, the catheter was stored in the dark until use.

The inventors consider that this reaction allows forming a covalent chemical bond between the amino terminal group of APTES and one or more of the perfluorinated rings of PdPFPP. The layer of photosensitizer anchored to the surface by means of this method is so thin that it cannot be observed by the naked eye or with a conventional spectrophotometer. Its presence on the surface of the catheter was verified by the production of singlet oxygen (both uncovered and submerged in water equilibrated with air) when a 532 nm laser pulse (2-3 ns) was applied and the decay of the emission signal of said reactive oxygen species at 1265 nm was monitored in real time (Edinburgh Instruments FL900 Luminescence Kinetic Spectrometer, Edinburgh, UK) (Figure 1).

From the singlet oxygen species decay represented in Figure 1 , the dramatic increase in the measured lifetime can be observed, which confirms the presence of the photosensitizer on the surface of the catheter.

Figure 2 depicts the decay of the singlet oxygen species according to the same method as in Figure 1 , but wherein each curve represents 50, 200, 350, 600, and 1000 pulses of irradiation. The results do not vary, which means that the photosensitizer is stable after irradiation (1000 pulses are equivalent to 14 J cm^-1 of green light).

Example 4. Antibacterial activity of the device of the invention

To evaluate antibacterial activity, the bacterial species which most often cause catheter- associated infections according to the epidemiological data of the European Centre for Disease Prevention and Control (ECDC) and the Sociedad Espanola de Medicina Preventiva, Salud P iblica e Higiene have been selected. Therefore, the species Escherichia coli CECT515 strain and Staphylococcus epidermidis CECT4183 strain, have been used as examples of Gram negative and Gram-positive bacteria, respectively, and Pseudomonas aeruginosa FA022 strain for its high biofilm forming capacity on catheters and other surfaces.

In this example, the antibacterial activity of the catheter of Example 3 was evaluated according to two different ways of irradiating the catheter:

a) Tests with perpendicular illumination of the catheter.

Discs of about 0.5 cm² were used as the catheter surface model, with said discs being punched from the surface of a silicone catheter prepared according to the preceding example, i.e., with covalently bonded PdPFPP, and from an untreated catheter (control). The discs were sterilized with 70% ethanol immediately before performing each test. Each disc was contaminated with P. aeruginosa (about 100 pL of a suspension of 10⁵ cells/mL in LB liquid medium (Merck)), supplemented with 0.2% glucose (Merck). To promote bacteria adhesion and colonization, the discs were incubated in a humid chamber for 2 h at 37 °C. After this time, the non-adherent cells were removed by gently washing the discs with 0.9% saline (NaCI). The discs were then introduced in a closed Petri dish acting as a humid chamber during illumination. Before closing the dish, 50 mI_ of 0.9% saline were added onto the surface of each disc.

The samples were illuminated for 60 minutes with a green diode laser (532 nm, 100 mW, model 532MD-100-12V, Lilly Electronics, Wuhan, Hubei, R.P. China) placed outside the closed Petri dish at 3 cm from the sample. In this test, the outer surface of the catheter where bacteria were adhered was illuminated. The number of viable bacteria remaining on the disc after illumination was determined by plating and colony forming units (CFUs) counting.

To that end, after illumination, each silicone disc was introduced in a microcentrifuge tube with 1 mL of 0.9% saline. With a vortex, the cells were separated from the disc and serial dilutions of this cell suspension were plated in LB agar medium. The plates were incubated at 37 °C for 20 hours and the number of CFUs was counted in each plate to determine the number of viable cells in each disc.

Figure 3 shows the count of CFUs of P. aeruginosa in the discs of the present example, where bar 1 represents the control disc, bar 2 represents the silicone disc treated according to the preceding example, and bar 3 represents the same disc but irradiated. A reduction of the microbial load by 5 orders of magnitude can be observed when the photosensitizer is illuminated for 60 min (bar 3). However, irradiation does not affect the viability of the bacteria adhered to the unfunctionalized silicone disc (bar 1) or to the functionalized silicone disc incubated in the dark (bar 2).

A parallel test irradiating the silicone discs (with or without photosensitizer) for 0, 30, 60, and 90 minutes is depicted in Figure 4. It is verified that there is no biocidal effect in the absence of the photosensitizer.

b) Tests with illumination along the catheter.

The catheters of the present example were contaminated following the same method described in the preceding section but contaminating them with E. coli and S. epidermidis in addition to P. aeruginosa.

Like in the preceding section, discs of about 0.5 cm² were used as the catheter surface model, with said discs being punched from the surface of a silicone catheter prepared according to the preceding example, but instead of APTES, APTMS and TDTMS were used as the spacer chains. The illumination in this case was performed along the disc taken from the silicone catheter with the 532 nm green diode laser located outside the Petri dish at 3 cm from the disc edge, in such a way that the radiation is propagated in total internal reflection along the catheter wall. The number of viable bacteria was determined by plating and CFUs counting, as described above. Figure 5 shows the results obtained by applying this methodology, in which the CFUs count in silicone catheter discs contaminated with P. aeruginosa (bars 1-4), E. coli (bars 5-8), or S. epidermidis (bars 9-12) can be observed.

Bars 1 , 3, 5, 7, 9, and 11 represent the control discs (without photosensitizer) irradiated for 30 minutes. Bars 2, 4, 6, 8, 10, and 12 represent the discs with a photosensitizer and irradiated for 30 minutes. Bars 1 , 2, 5, 6, 9, and 10 represent discs functionalized with APTMS (with or without photosensitizer). Bars 3, 4, 7, 8, 11 , and 12 represent discs functionalized with TDTMS (with or without photosensitizer).

It is demonstrated that there is no biocidal effect without a photosensitizer. The bacterial load is significantly reduced (by 3 to 6 orders of magnitude) only in those discs containing the covalently bonded photosensitizer following the illumination thereof (bars 2, 4, 6, 8, 10, and 12). In contrast, irradiation does not affect viability of the bacteria adhered to the silicone discs lacking photosensitizer (bars 1 , 3, 5, 7, 9, and 11).

It is verified in this test that the photosensitizer has a biocidal effect (3 to 6 orders of magnitude) on both Gram-negative bacteria (P. aeruginosa, bars 2 and 4; E. coli, bars 6 and 8) and Gram-positive bacteria (S. epidermidis, bars 10 and 11).

Claims

1. A tubular medical device comprising:

a. a longitudinal outer surface;

b. a longitudinal inner surface; and

c. a material comprised between the two longitudinal surfaces with an index of refraction, n_c, ³ 1.340;

characterized in that at least one of the two longitudinal surfaces of the device comprises a photosensitizer covalently linked to said surface, wherein the photosensitizer and said surface are arranged so that the photosensitizer is excitable by an evanescent wave propagating in said material.

2. The medical device according to claim 1 , wherein the distance between the photosensitizer and said surface is from 0.5 to 200 nm.

3. The medical device according to any one of claims 1 or 2, characterized in that it is suitable for being coupled to a light source of a wavelength comprised between 350 and 800 nm, said light source being arranged to irradiate the device at an angle of incidence ³ critical angle Q, and characterized in that the photosensitizer generates reactive oxygen species, wherein Q is such that it allows the longitudinal propagation of radiation by means of total internal reflection of the light along the material constituting the device.

4. The medical device according to any one of claims 1 to 3, characterized in that the photosensitizer is covalently linked to said at least one of the two longitudinal surfaces through a bifunctional spacer chain.

5. The medical device according to claim 4, characterized in that the bifunctional spacer chain is an alkoxysilane, preferably selected from aminosilanes, vinylsilanes, acyloxysilanes, glycidoxysilanes, acryloxysilanes, methacryloxysilanes, epoxysilanes, halosilanes, cyclic azasilanes, isocyanatesilanes, isothiocyanatesilanes, hydroxysilanes, and mercaptosilanes.

6. The medical device according to claim 5, characterized in that the alkoxysilane is an aminosilane selected from the group consisting of 3-aminopropyltrimethoxysilane, 3- aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 3- aminopropyldimethylethoxysilane, 2,9-diazanonyltriethoxysilane, 12,15- diazapentadecyltrimethoxysilane, 4,7-diazaheptyltrimethoxysilane, 4,7,10- triazadecyltrimethoxysilane, and combinations thereof.

7. The medical device according to any one of claims 1 to 6, characterized in that said material comprised between the two longitudinal surfaces is a polymer material selected from the group consisting of silicone, polyvinylpyrrolidone, polyvinyl chloride, polycarbonates, acrylates, polystyrenes, polyethylene terephthalate, polyamides, polyurethanes, fluoropolymers, and combinations thereof.

8. The medical device according to claim 7, characterized in that said material is silicone.

9. The medical device according to any one of claims 1 to 8, characterized in that the photosensitizer is selected from the group consisting of porphyrins, phthalocyanines, Ru(ll), Pd(ll), and Pt(ll) complexes, boron dipyrromethenes, quinone-, anthraquinone-, acridine-, and coumarin-derivatives, xanthene derivatives such as fluorescein, eosin, rose bengal, and erythrosine, thiazine derivatives such as methylene blue, and combinations thereof.

10. The medical device according to any one of claims 1 to 9, characterized in that the photosensitizer belongs to the group of porphyrins.

11. The medical device according to any one of claims 1 to 10, characterized in that the photosensitizer is a metalloporphyrin selected from the group consisting of Protoporphyrin IX, octaethylporphyrin derivatives, meso-tetraphenylporphyrin derivatives such as meso-tetra(2-fluorophenyl)porphyrin, meso-tetra(3- fluorophenyl)porphyrin, and meso-tetra(pentafluorophenyl)porphyrin, and combinations thereof.

12. The medical device according to any one of claims 1 to 11 , characterized in that the photosensitizer is a metalloporphyrin wherein the metal is selected from the group consisting of Pt(ll), Pd(ll), Zn(ll), Fe(ll), Co(ll), Ni(ll), Ru(ll), Ti(ll), Cr(ll), Cu(ll), Si(IV), and combinations thereof.

13. The medical device according to any one of claims 1 to 12, characterized in that the photosensitizer is a metalloporphyrin wherein the metal is Pd(ll).

14. The medical device according to any one of claims 1 to 13, characterized in that said medical device is selected from the group consisting of a catheter, bladder tube, gastric tube, urinary tube, endotracheal tube, and stent.

15. The medical device according to any one of claims 1 to 14, characterized in that one of the two longitudinal surfaces of the device comprising a covalently linked photosensitizer is the outer surface of the tubular device.

16. A tubular medical device comprising:

a. a longitudinal outer surface;

b. a longitudinal inner surface; and

characterized in that at least one of the two longitudinal surfaces of the device comprises a photosensitizer covalently linked to said surface, for use in the treatment and/or prevention of a disease caused by pathogen-induced infections, wherein said treatment and/or prevention is achieved by evanescent wave excitation of said photosensitizer.

17. A method for sterilizing a medical device according to any of claims 1 to 15, characterized in that it comprises the step of irradiating the device with an irradiation source with a wavelength comprised between 350 and 800 nm at an angle of incidence ³ critical angle Q, wherein Q is such that it allows the longitudinal propagation of radiation by means of total internal reflection of the light along the material constituting the device.

18. The sterilization method according to claim 17, characterized in that said method is carried out while the medical device is being used.

19. The sterilization method according to any one of claims 17 or 18, characterized in that the radiation comes from at least one laser light, at least one laser diode, or at least one light-emitting diode source.

20. The sterilization method according to any one of claims 17 to 19, characterized in that it prevents formation or growth, reduces or removes a biofilm from at least one of the surfaces of the medical device.

21. A method for preparing a medical device according to any of claims 1 to 15, characterized in that it comprises the steps of:

a. subjecting a tubular medical device comprising a longitudinal outer surface, a longitudinal inner surface, and a material comprised between the two longitudinal surfaces with an index of refraction, n_c, ³ 1.340, to an oxidizing medium; b. reacting at least one of the oxidized surfaces obtained in step a) with a bifunctional spacer chain; and

22. The method according to claim 21 , characterized in that the oxidizing medium is selected from oxygen, nitrogen, helium or argon plasma or atmospheric plasma, or an excimer lamp.

23. The method according to any one of claims 21 or 22, characterized in that the bifunctional spacer chain is an alkoxysilane.

24. The method according to claim 23, characterized in that the alkoxysilane is an aminosilane selected from the group consisting of 3-aminopropyltrimethoxysilane, 3- aminopropyltriethoxysilane, 3-aminopropyldiethoxymethylsilane, 3- aminopropyldimethylethoxysilane, 2,9-diazanonyltriethoxysilane, 12,15- diazapentadecyltrimethoxysilane, 4,7-diazaheptyltrimethoxysilane, 4,7,10- triazadecyltrimethoxysilane, and combinations thereof.

25. The method according to any one of claims 21 to 24, characterized in that the photosensitizer is selected from the group consisting of porphyrins, phthalocyanines, Ru(ll), Pd(ll), and Pt(ll) complexes, boron dipyrromethenes, quinone-, anthraquinone-, acridine-, and coumarin-derivatives, xanthene derivatives such as fluorescein, eosin, rose bengal, and erythrosine, thiazine derivatives such as methylene blue, and combinations thereof.

26. A kit comprising a medical device according to any of claims 1 to 15 and an external light source, wherein the light source is preferably selected from the group consisting of a laser light, a laser diode, or a light-emitting diode source.

27. The kit according to claim 26, further comprising instructions for irradiating the device in order to achieve excitation of the photosensitizer by an evanescent wave generated by a beam of light propagating longitudinally by total internal reflection.

28. The kit according to anyone of claims 26 or 27, wherein the light source is either integrated in the device or coupled to the device.

29. The kit according to anyone of claims 26 to 28, wherein the light source is coupled to the device by means of a wave guide, preferably an optical fiber.

30. Use of the medical device according to anyone of claims 1 to 15, or of the kit according to anyone of claims 26 to 29, in a sterilization procedure that involves total internal reflection of light to achieve photosensitizer excitation.