WO2013174356A1

WO2013174356A1 - Antibacterial layer active against pathogenic bacteria, particularly against the mrsa bacterial strain, and the method of its production

Info

Publication number: WO2013174356A1
Application number: PCT/CZ2012/000129
Authority: WO
Inventors: Irena SLAMBOROVA; Veronika ZAJICOVA; Petr EXNAR; Ivan Stibor
Original assignee: Technicka Univerzita V Liberci
Priority date: 2012-05-23
Filing date: 2012-12-10
Publication date: 2013-11-28
Also published as: CZ2012339A3; EP2852630A1; CZ303861B6

Abstract

The invention concerns an antibacterial layer active against pathogenic bacteria, particularly against the MRSA bacterial strain, composed of the hybrid polymer of 3-(trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide, with an addition of soluble silver, copper and zinc salts, and possibly also with an addition of titanium dioxide nanoparticles. The hybrid polymer may also include an addition of soluble chromium(lll) and/or vanadium salts, or up to 90 mol.% of 3-(trialkoxysilyl)propyl methacrylate may be replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane. Furthermore, the invention concerns the production of an antibacterial layer active against pathogenic bacteria, particularly against the MRSA bacterial strain, by applying the sol, prepared using a sol-gel method, to the substrate surface, and by subsequent polymerization of the layer. The sol is made of 3- (trialkoxysilyl)propyl methacrylate, titanium(IV) alkoxide, soluble silver, copper and zinc salts, a radical catalyst of polymerization, alcohol as the solvent, water and nitric acid as the catalyst of polycondensation of the inorganic part of the hybrid grid so that the molar ratio of 3-(trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide in the reaction mixture is 95:5 to 50:50; the content of silver, copper and zinc compounds (converted to metals in dry mass) was Ag 0.1 to 5 %w, Cu 0.1 to 10 %w, and Zn 0.1 to 5 %w; content of the radical catalyst of polymerization was 0.2 to 10 %w per dry mass weight, and the molar ratio of water content k = [H₂O]/[alkylalkoxysilane + titanium(IV) alkoxide] was in the range from 1.6 to 2.8, while upon application and evaporation of the solvent, the sol is polymerized using heat at 80 °C to 200 °C for 30 min to 6 hours or by photoinitiated polymerization for 1 s to 3 hours.

Description

Antibacterial layer active against pathogenic bacteria, particularly against the MRSA bacterial strain, and the method of its production

Field of the invention

The invention concerns an antibacterial layer active against pathogenic bacteria, particularly against the MRSA bacterial strain.

The invention also concerns the way in which the antibacterial layer active against pathogenic bacteria, particularly against the MRSA bacterial strain, is created, i.e. by applying a sol prepared using the sol-gel method onto the substrate surface and by subsequent polymerization of the layer.

Background of the invention

At present, the threat of infections caused by pathogenic bacteria, particularly the resistant pathogenic bacterium MRSA (Methicillin-Resistant Staphylococcus Aureus), is a worldwide problem. In particular, hospital patients at ICUs and bed wards are threatened, but other hospital areas are no exceptions, either. This pathogenic bacterium can spread in many different ways, in air, water, foods or contact with contaminated surfaces. Classical disinfection procedures cannot be applied in a complex manner in the entire area of ICUs or operating theatres. Available physical methods (steam, high temperature, irradiation) and chemical methods (chlorinated products) are either ineffective or destroy also the environment together with the undesirable bacteria. Given that diseases caused by pathogenic bacteria, particularly by the resistant pathogenic bacterium MRSA, are curable only with great difficulty, an essential condition is that such bacterial strains should be completely eliminated in medical institutions.

An antibacterial layer active against pathogenic bacteria, particularly against the MRSA bacterial strain, has been known from the CZ patent No. 303250; the layer is formed by the hybrid polymer 3-(trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide with an addition of silver and copper nitrates. Furthermore, the hybrid polymer in its expedient embodiment contains titanium dioxide nanoparticles, and up to 70 mol. % of 3-(trialkoxysilyl)propyl methacrylate is replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane. Based on the CZ patent No. 303250, the way of creating the antibacterial layer active particularly against the MRSA bacterial strain and other pathogenic bacteria consists in applying a sol prepared using the sol-gel method onto the substrate surface and in subsequent heat processing of the layer, while the sol is made of 3-(trialkoxysilyl)propyl methacrylate, titanium(IV) alkoxide, silver nitrate, copper(ll) nitrate, radical catalyst of polymerization, alcohol as the solvent, water and nitric acid as the catalyst of polycondensation of the inorganic part of the hybrid grid so that the molar ratio of 3-(trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide in the reaction mixture is 95:5 to 50:50, the content of silver and copper compounds (upon conversion as metals in dry mass) is 0.1 to 5 %w of Ag and 0.1 to 10 %w of Cu, the content of the radical catalyst of polymerization 0.2 to 10 %w per dry mass weight, and so that the molar ratio of water content k = [H₂0]/[alkylalkoxysilane + titanium(IV) alkoxide] is in the range of 1.6 to 2.8, while upon application and evaporation of the solvent, the sol is heat processed at 80 °C to 200 °C for 30 min up to 6 hours. In this process, the 3-(trialkoxysilyl)propyl methacrylate is 3-(trimethoxysilyl)propyl methacrylate (TMSPM), and the titanium(IV) alkoxide is the titanium(IV) isopropoxide. Dibenzoyl peroxide (BPO) is used as the radical catalyst of polymerization. Photoactive titanium dioxide nanoparticles are added to the sol during its preparation, in an amount corresponding to the dry mass weight : titanium dioxide nanoparticles weight ratio 99:1 to 25:75. Upon application and evaporation of the solvent, the sol is heat processed at 150 °C for 2 to 4 hours. Up to 70 mol. % of 3-(trialkoxysilyl)propyl methacrylate is replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane.

However, the need of improving antibacterial properties (efficacy) of the antibacterial layer even further has been seen in certain application, as well as the need to expand the possibilities of polymerizing the layer, done exclusively by heat polymerization, by additional possibilities.

Therefore the aim of the invention is to improve antibacterial activity of antibacterial layers active against pathogenic bacteria, particularly against the MRSA bacterial strain, and thus to allow for sufficiently stable application of layers also on materials not very resistant against heat, for example, plastic materials, by expanding the possibilities of polymerizing the layer.

Object of the invention

The aim of the invention has been achieved using an antibacterial layer whose substantial characteristic is that it is formed by the hybrid polymer of 3- (trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide with an addition of nitrates, acetylacetonates or other salts of silver, copper and zinc. According to the expedient embodiment, soluble salts of chromium(lll) and/or vanadium can also be added besides the aforementioned salts of silver, copper and zinc, which increase antibacterial activity of the prepared layer even further. According to another expedient embodiment, nanoparticles of photoactive titanium dioxide can be added to the layer, which increase even further the already high antibacterial effects of the layer. Based on yet another expedient embodiment, a part of 3- (trialkoxysilyl)propyl methacrylate can be replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane.

In essence, the antibacterial layer is formed as follows: the initial sol is prepared using the sol-gel method from 3-(trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide with an addition of the salts of silver, copper and zinc, and possibly also salts of chromium(lll) and/or vanadium; subsequently, the sol is applied in the form of a layer onto the surface of any object to be protected. When volatile ingredients evaporate, the layer is stabilized, in terms of mechanical properties and resistance against removal from the surface of the protected object, using heat-initiated polymerization at 80 °C to 200 °C or photoinitiated polymerization. Based on an expedient embodiment, nanoparticles of photoactive titanium dioxide can be added to the sol in the process of its preparation, which increases even further the already high antibacterial effects of the layer. According to another expedient embodiment, a part of 3-(trialkoxysilyl)propyl methacrylate can be replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane. The solution is based on creating an antibacterial layer on the basis of 3- (trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide. The addition of photocatalytic nanoparticles of titanium dioxide only supports and extends antibacterial efficacy of the resulting layer while antibacterial efficacy of the resulting layer is given by its primary creation and not by addition of photocatalytic nanoparticles of titanium dioxide. The resulting enhanced antibacterial properties are due to the synergic effect of titanium atoms in the inorganic grid of the hybrid polymer and ions or nanoparticles, respectively, of silver, copper, zinc, chromium(lll) and vanadium, possibly supported by the photocatalytic effect of titanium dioxide nanoparticles. The intensive antibacterial properties are manifested when the layer is irradiated with UV-A in the region of 315 nm to 380 nm; however, only the light of fluorescent tubes in the visible region suffices to maintain antibacterial properties of the surfaces. This layer can be applied on surfaces of glass, ceramics, metals and plastic materials. The antibacterial properties remain preserved also upon repeated washing or sterilization (verified after 50 cycles of washing and 20 cycles of extreme sterilization at 125 °C for 1 hour, respectively), which is another very important property of the layers.

Description of embodiments

The invention will be described using an example of the technological procedure of creating the layer, and also using examples of antibacterial activity of the layer based on the invention.

The initial sol is prepared using a modified sol-gel method based on dissolving 3-(triaikoxysilyl)propyl methacrylate (it is expedient to use 3- (trimethoxysilyl)propyl methacrylate TMSPM) and titanium(IV) alkoxide (it is expedient to use titanium(IV) isopropoxide IPTI) with an addition of soluble silver, copper and zinc salts (nitrates are expedient) and with an addition of the radical catalyst of polymerization (dibenzoyl peroxide BPO is expedient for heat-initiated polymerization, while for photoinitiated polymerization, bis(2,4,6- trimethylbenzoyl)phenylphosphine oxide is expedient) in a suitable alcohol (ethanol or isopropyl alcohol is expedient), with subsequent addition of an acid (nitric acid is expedient) with water so thai, the molar ratio of 3- (trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide is 95:5 to 50:50, so that the content of silver, copper and zinc compounds (converted to metals in dry mass) is Ag 0.1 to 5 %w, Cu 0.1 to 10 %w, and Zn 0.1 to 5 %w, so that the amount of the radical catalyst of polymerization is 0.2 to 10 %w per weight of the dry mass, and so that the molar ratio of water content k = [H20]/[alkylalkoxysilane + titanium(IV) alkoxide] reaches the values of k = 1.6 to 2.8. Besides silver, copper and zinc, adding Cr 0.1 to 5 %w and/or V 0.1 to 5 %w (converted to metals in dry mass) to the initial reaction mixture in the form of soluble salts is expedient.

Furthermore, nanoparticles of titanium dioxide with photocatalytic activity (ratio of the dry mass weight : titanium dioxide nanoparticles of 99:1 to 25:75) can be added to the prepared sol. Based on an expedient embodiment, up to 90 mol.% of 3-(trialkoxysilyl)propyl methacrylate in the reaction mixture can be replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane. The prepared sol (possibly with nanoparticles of titanium dioxide dispersed in the sol using ultrasound) is then applied on the surface of any substrate intended for antibacterial adaptation as a layer (by pulling up, centrifugation or spraying), and when the solvent evaporates, the created layer is polymerized using heat- or photoinitiated polymerization. The heat-initiated polymerization is done at 80 °C to 200 °C (the temperature of 150 °C is expedient) for 30 min to 6 hours (the duration of 3 hours is expedient).

The choice of heat- or photoinitiated polymerization depends on heat resistance of the substrate to which the layer has been applied, i.e. on thermal resistance of the object to be protected by the antibacterial layer created.

For example, photoinitiated polymerization is more suitable for polypropylene with thermal resistance up to 80 °C, while heat-initiated polymerization at 150 °C can be chosen for more resistant substrates, etc.

A fluorescent tube or lamp that irradiates (besides others also) UVA or UVB light can be used as a source of radiation for photoinitiated polymerization for 1 s to 3 hours, while the necessary time of exposure is given by the used catalyst .specific distribution of energies of the used source of radiation, and by radiation intensity at the place of the layer.

By processing as described above, a slightly porous, inorganic-organic layer of hybrid polymer with immobilized silver, copper and zinc (ions, atoms or nanoparticles) and possibly with chromium and vanadium (ions) and titanium dioxide nanoparticles is created.

Porosity of the prepared layer is necessary for its functionality (antibacterial properties) because if the metal particles (ions, atoms or nanoparticles) and titanium dioxide nanoparticles are completely enclosed in the volume of the material of the layer, the layer would show virtually no or very low antibacterial activity.

Below, the invention is described using several specific examples of embodiment; however, the examples do not document all possibilities of the invention, serve only to provide a closer description of the invention for its practical use, and shall be clear from the text for any ordinary specialist having knowledge about the invention.

Example 1

The initial sols were prepared using a modified sol-gel method. See Table 1 for the overview of reaction mixtures for sol preparation based on the invention and for the composition of comparative reaction mixtures for Example 1. The term dry mass shall be understood as the material of the hybrid polymer layer created, which remains upon application to, and subsequent polymerization on the substrate - any protected object, thus without volatile ingredients. The weight of any added nanoparticles of photoactive titanium dioxide is not calculated in the dry mass. The calculated amounts of 3-(trimethoxysilyl)propyl methacrylate (hereinafter TMSPM) or an equimolar mixture of methyl methacrylate and tetraethoxysilane, titanium(IV) isopropoxide (hereinafter IPTI), silver nitrate, copper(ll) nitrate and zinc nitrate were, together with dibenzoyl peroxide 0.1 g (hereinafter BPO), HN0₃ 0.2 ml (c = 2 mol.dm^"3) and additionally calculated amount of water (to achieve the required molar ratio of k = [H₂0]/[alkylalkoxysilane + titanium(IV) alkoxide]), dissolved in isopropyl alcohol, to - ^~ achieve the total volume of 55 ml. After hydrolysis and partial polycondensation of the alkoxy groups, the sols were ready to be applied to substrates. If any nanoparticles of photoactive titanium dioxide were to be added, the weighed amount of nanoparticles was poured in the finished sol and dispersed using ultrasound.

Upon sol application to the substrates (slides) by centrifugation, the samples were left in the laboratory setting to let the isopropyl alcohol evaporate, and subsequently they were subjected to heat-initiated polymerization of methacrylate groups in the dryer at 150 °C for 3 hours.

Antibacterial properties of the prepared layers were tested using MRSA bacterial strains (Methicillin-Resistant Staphylococcus Aureus ATCC 33591 , ATCC 33592), and also on the bacterial strains of Escherichia Coli (ATCC 9637), Staphylococcus Aureus (ATCC 1260), Acinetobacter baumanii (ATCC 17978), Pseudomonas aeruginosa (ATCC 31480), Proteus vulgaris (ATCC 29905) and Proteus mirabilis (ATCC 35659). The bacterial inoculum, prepared in advance, in the physiological solution with the concentration of 10⁸ CFU/ml of bacterial suspension, was used to prepare the concentration of 10⁵ CFU/ml of bacterial suspension by its dilution using the physiological solution. Subsequently, a drop of this bacterial suspension, 250 μΙ, was applied onto the sample. The tested samples with applied bacterial suspension were then irradiated under the fluorescent tube Philips special (Actinic BL F15T8, UV-A region of radiation, range 315-400 nm). The samples of the bacterial cultures were inoculated into Petri dishes containing blood agar. The dishes with inoculated bacterial cultures were incubated in a thermostat at 37.5 °C for 24 hours.

Table 1: Composition of reaction mixtures used for sol preparation (layers A to K were comparative; layers 1 to 7 were based on the invention).

Layer Molar Ag Cu Zn c of the k ratio weight ratio content content content sol ratio of

TMSPM : [w% in [w% in [w% in dry mass IPTI dry dry dry : nano · mass] mass] mass] particles

A 100 : 0 0 0 0 5.63 2.35 100 : 0

B 100 : 0 0 0 0 5.63 2.35 40 : 60

C 100 : 0 10 0 0 5.66 2.15 100 : 0

D 100 : 0 0 10 0 5.59 2.20 100 : 0

E 100 : 0 5 5 0 5.62 2.17 100 : 0

F 100 : 0 5 5 0 5.62 2.17 40 : 60

G 85 : 15 3 0 0 5.45 2.29 100 : 0

H 85 : 15 3 0 0 5.45 2.29 40 : 60

1 85 : 15 3 3 0 5.59 2.14 100 : 0

J 85 : 15 3 3 0 5.59 2.14 40 : 60

K 85 : 15 a 3 3 0 5.59 2.14 100 : 0

1 85 : 15 3 3 3 5.96 2.23 100 : 0

2 85 : 15 3 3 3 5.96 2.23 40 : 60

3 85 : 15 a 3 3 3 5.67 2.21 100 : 0

4 85 : 15 3 1 1 5.77 2.29 100 : 0

5 85 : 15 3 1 1 5.77 2.29 40 : 60

6 70 : 30 1 6 2 5.48 2.24 100 : 0

7 70 : 30 1 6 2 5.48 2.24 40 : 60

Legend

c of the sol ... sol concentration [g of dry mass per 100 g of the sol]

k ratio ... molar ratio k = [H₂0]/[alkylalkoxysilane + titanium(IV) alkoxide] a ... TMSPM 50 mol. % was replaced with equimolar mixture of methyl methacrylate and tetraethoxysilane

Dependence of the number of bacterial colonies on irradiation period was observed in the incubated samples, and the period of 100% inhibition (when bacterial colonies on the agar disappear) was determined if the needed period of irradiation was lower than 180 minutes. The results obtained for selected bacterial strains are summarized in Table 2. Results for the other bacterial strains were similar. The results indicate that none of the comparative samples A to G showed 100% inhibition at least for some bacterial strain(s) within 180 minutes of UV-A irradiation under the used experimental conditions. Among the comparative samples, only samples H to K (H with titanium dioxide nanoparticles; I to K based on CZ patent 303250 with Ag + Cu combination) showed 100% inhibition for the tested bacterial strains within 180 minutes of irradiation. However, the times needed to achieve 100% inhibition were considerably longer than for samples 1 to 7 based on this invention.

Example 2

Initial sols based on the invention were prepared using a modified sol-gel method, using the procedure as described in Example 1. The overview of composition of reaction mixtures for preparing the sols for Example 2 his presented in Table 1 , layers 1 to 3. In layers 1 UV to 3UV, the used dibenzoyl peroxide was replaced with bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide. When the sol had been applied to the substrates (glass, poly(methyl methacrylate), stainless steel) by immersion, centrifugation or spraying, the samples were left in the laboratory setting to let isopropyl alcohol evaporate. Layers 1 to 3 were subsequently subjected to heat-initiated polymerization in the dryer (glass and stainless steel at 150 °C for 3 hours, poly(methyl methacrylate) at 100 °C for 3 hours). Layers 1 UV to 3UV were subjected to photoinitiated polymerization using UV-A radiation emitted by the fluorescent tube Philips special (Actinic BL F15T8, UV-A region of radiation, range 315-400 nm) for 2 hours.

Antibacterial properties of the prepared layers were tested using the identical procedure as in Example 1. Besides UV-A irradiation (range 315-400 nm), irradiation using a common fluorescent tube was also tried. Results for layers on glass obtained after UV-A irradiation are summarized in Table 3; results for layers on glass after irradiation using common fluorescent tube light are presented in Table 4. Results obtained for the sample with poly(methyl methacrylate) substrate and stainless steel substrate were similar. Tha obtained results confirm that layers polymerized using both heat- and photoinitiated polymerization provide virtually identical results. This indicates that both ways of polymerization can be used for antibacterial layers based on the invention with no loss of activity. Polymerization using UV-A radiation provides advantages for large surfaces where the layer is applied by spraying, or for plastic materials showing low resistance (for example, polypropylene, etc.).

Table 2: Results of determining the time for 100% inhibition after UV-A irradiation (layers A to K were comparative; layers 1 to 7 were based on the invention).

Layer Molar Ag Cu Zn Weight Irradiation period ratio conten conten conten ratio of necessary for TMSPM : t [w% t [w% t [w% dry mass

IPTI in dry in dry in dry : nano- 100% inhibition mass] mass] mass] particles [min]

MRSA E. Coli St.

Aureus

A 100 : 0 0 0 0 100 : 0 n n n

B 100 : 0 0 0 0 40 : 60 n n n

C 100 : 0 10 0 0 100 : 0 n n n

D 100 : 0 0 10 0 100 : 0 n n n

E 100 : 0 5 5 0 100 : 0 n n n

F 100 : 0 5 5 0 40 : 60 n n n

G 85 : 15 3 0 0 100 : 0 n n n

H 85 : 15 3 0 0 40 : 60 85 160 140

I 85 : 15 3 3 0 100 : 0 50 155 160

J 85 : 15 3 3 0 40 : 60 50 140 140

K 85 : 15 a 3 3 0 100 : 0 55 150 160

1 85 : 15 3 3 3 100 : 0 35 120 120

2 85 : 15 3 3 3 40 : 60 30 100 105

3 85 : 15 a 3 3 3 100 : 0 35 110 120 4 85 : 15 3 1 1 100 : 0 40 120 120

5 85 : 15 3 1 1 40 : 60 35 100 110

6 70 : 30 1 6 2 100 : 0 45 130 130

7 70 : 30 1 6 2 40 : 60 40 120 120

Legend n ... no inhibition determined within minute 180 a... TMSPM 50 mol. % was replaced with equimolar mixture of methyl methacrylate and tetraethoxysilane

Table 3: Results of determining the time for 100% inhibition for samples on glass after UV-A irradiation.

See Table 1 for the legend. Table 4: Results of determining the time for 100% inhibition for samples on glass after irradiation using common fluorescent tube light.

See Table 1 for the legend.

Example 3

Initials sols based on the invention were prepared using a modified sol-gel method, using the procedure as described in Example 1. The sol for layer 1 in Table 1 was used as initial; in addition, chromium(lll) nitrate and/or vanadyl acetylacetonate were added to the reaction mixture in an amount corresponding to the content (converted to the element) as presented in Table 5. When the sol had been applied to glass by immersion, the samples were left in the laboratory setting to let isopropyl alcohol evaporate, and subsequently, they were subjected to heat-initiated polymerization in the dryer at 150 °C for 3 hours.

Antibacterial properties of the thus prepared layers were tested using the identical procedure as in Example 1. Results with layers on glass obtained after UV-A irradiation are summarized in Table 5. The obtained results confirm that layers containing Cr(lll) and/or V exhibit virtually identical times needed to achieve 100% inhibition against MRSA strain; however, they are slightly better against the other tested bacterial strains. Table 5: Results of determining the time for 100% inhibition for samples on glass after UV-A irradiation.

Layer Molar ratio Cr V Weight Irradiation period

TMSPM : content content ratio of necessary for

IPTI [w% in [w% in dry mass

dry dry : nano- 100% inhibition mass] mass] particles [min]

MRSA E. Coli St.

Aureus

1 85 : 15 0 0 100 : 0 35 120 120

8 85 : 15 2 0 100 : 0 35 100 100

9 85 : 15 0 2 100 : 0 35 90 110

10 85 : 15 1 1 100 : 0 30 90 100

Claims

PATENT CLAIMS

1. Antibacterial layer active against pathogenic bacteria, particularly against the bacterial strain MRSA, characterized by being made of hybrid polymer created by the reaction of 3-(trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide with an addition of soluble silver, copper and zinc salts, and possibly also with an addition of titanium dioxide nanoparticles.

2. Antibacterial layer based on Claim 1 , characterized by the fact that the hybrid polymer contains an addition of soluble chromium(lll) and/or vanadium salts.

3. Antibacterial layer based on Claim 1 , characterized by the fact that up to 90 mol.% of 3-(trialkoxysilyl)propyl methacrylate has been replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane.

4. The method used to create the antibacterial layer active against pathogenic bacteria, particularly against the bacterial strain MRSA, by applying the sol, prepared using the sol-gel method, to the substrate surface, and by subsequent polymerization of the layer, characterized by the sol being prepared of 3- (trialkoxysilyl)propyl methacrylate, titanium(IV) alkoxide, soluble silver, copper and zinc salts, radical catalyst of polymerization, alcohol as the solvent, water and nitric acid as the catalyst of polycondensation of the inorganic part of the hybrid grid so that the molar ratio of 3-(trialkoxysilyl)propyl methacrylate and titanium(IV) alkoxide in the reaction mixture is 95:5 to 50:50; the content of silver, copper and zinc compounds (converted to metals in dry mass) was Ag 0.1 to 5 %w, Cu 0.1 to 0 %w, and Zn 0.1 to 5 %w; content of the radical catalyst of polymerization was 0.2 to 10 %w per dry mass weight, and the molar ratio of water content k = [H₂0]/[alkylalkoxysilane + titanium(IV) alkoxide] was in the range from 1.6 to 2.8, while upon application and evaporation of the solvent, the sol is polymerized using heat at 80 °C to 200 °C for 30 min to 6 hours or by photoinitiated polymerization for 1 s to 3 hours.

5. The method based on Claim 4, characterized by the fact that soluble compounds of chromium(lll) and/or vanadium (converted to metals in dry mass) are moreover added to the sol during its preparation, in amounts of Cr 0.1 to 5 %w and/or V 0.1 to 5 %w.

6. The method based on Claim 4, characterized by the fact that 3- (trimethoxysi!yl)propyl methacrylate (TMSPM) is used as 3-(trialkoxysilyl)propyl methacrylate, and titanium(IV) isopropoxide is used as titanium(IV) alkoxide.

7. The method based on Claim 4 or 5, characterized by the fact that nitrates are used as the soluble salts of silver, copper, zinc and chromium(lll), and acetylacetonate is used as the soluble salt of vanadium.

8. The method based on Claim 4, characterized by the fact that dibenzoyl peroxide (BPO) is used as the radical catalyst of polymerization for heat polymerization, and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide for photoinitiated polymerization.

9. The method based on Claim 4, characterized by the fact that photoactive nanoparticles of titanium dioxide are added to the sol during its preparation, in an amount corresponding to the ratio of dry mass weight : weight of titanium dioxide nanoparticles 99:1 to 25:75.

10. The method based on Claim 4, characterized by the fact that up to 90 mol.% of 3-(trialkoxysilyl)propyl methacrylate is replaced with an equimolar mixture of methyl methacrylate and tetraalkoxysilane.

11. The method based on Claim 4, characterized by the fact that upon application and evaporation of the solvent, the sol is subjected to heat-initiated polymerization at 150 °C for 2 to 4 hours or photoinitiated polymerization for 1 to 60 min.