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1. (WO2017003312) NANOMATÉRIAU D'ARGENT DE COUCHE BIOCIDE POUR SURFACES POREUSES, ET PROCÉDÉ DE PRODUCTION DE NANOMATÉRIAU D'ARGENT DE COUCHE BIOCIDE
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Silver nanomaterial of biocidal layer for porous surfaces

and the production method of silver nanomaterial of biocidal layer

The subject of the invention is silver nanomaterial of biocidal layer for porous surfaces and the production method of silver nanomaterial of biocidal layer for porous surfaces. In particular, silver nanomaterial is designed for application on the surfaces of construction ceramic materials, plasters and building gypsum - to be used in utility and farming buildings where animals are kept.

The existing biocides are based on chemical compounds, mainly peroxides, chlorine compounds, detergents or strong acids. These compounds share a specific feature, i.e. their biological activity diminishes after a long time of use.

Another tested solution is the application of silver in biocides. Silver is one of the most efficient antimicrobial materials. The basic feature to differentiate silver and its compounds in their biocidal applications is their complex effects on pathogen cells. In case of bacteria, silver impact mainly the following elements:

- cell wall and its main building agent - peptidoglycan;

proteins of the cell wall;

- disulphide bonds and thiol groups in proteins that cause denaturation;

- active protein centres, including enzymes of key metabolic and breathing pathways;

DNA and RNA, causing the emergence of durable complexes and thus destroying their spatial structure.

However, the known silver biocides require re-application. This increases the amount of silver on the protected surface after each application. Hence, after each application of the new coat of the preparation, its amount and thus activity increases. A negative feature of this solution is the need to use quite significant doses of silver preparation. Also, it is necessary to protect the surface against biofilm formation and therefore silver is of limited application in animal rearing. In order to overcome the flaws of nanosilver materials and silver ions and hence to allow their broader applications, it is proposed to combine silver agents with compounds that stabilize or impart its performance.

In case of fungal pathogens and protozoa, the effect of silver is not that spectacular, although its influence on cell metabolism is very clear. As their cell walls contain chitosan, which bounds with metals to create durable complexes, these organisms demonstrate increased resistance to silver material. One of the ways to improve the effects of silver on fungal pathogens and protozoa is to use compounds that impart its penetration into the cells.

US 8 183 167 discusses the production of a textile material, based on natural and synthetic fibres containing silver nanoparticles. Due to its specific features, this material will show

biological activity against pathogens. Therefore, it is possible to obtain a composite, which will basically act as a self-disinfectant.

US 5 807 641 presents the way to obtain biocidal effect in ceramic materials containing nanosilver. In this case, nanosilver supported by anti-agglomeration substances. Therefore, it is possible to obtain on the surface a nanostructure that releases the ions of silver.

US 4 915 955 presents the production method of a disinfectant containing hydrogen peroxide and silver. Silver nanoparticles are synthetized with silver salts suspension stabilized with organic acids. Nanomaterial produced in this way is then stabilized with concentrated mineral acids and then mixed with hydrogen peroxide. Thanks to very high concentration of hydrogen peroxides, the silver and organic complex is kept in an ion form and also acts as biocide in the first step of its influence on pathogens.

EP 2 309 863 presents a concentrate for the production of disinfectant containing hydrogen peroxide and colloid silver, with additional of a stabilizer i.e. gum Arabic, gelatine, guar gum, carrageenan, pectins or combination thereof. The preparation demonstrates local concentration of nanoparticles, which are mixed with each other with a neutral organic material. The system is stabilized to its ion form with the addition of small amounts of mineral acids and perhydrol. Such a system demonstrates strong biocidal properties and keeps the silver material oxygenated.

The invention aims to introduce a composition containing silver nanomaterial to be placed on the protection surface and then to be durably bound with the substrate, i.e. active for a longer time. Silver nanomaterial should be imparted by the compounds that facilities its penetration into cell walls. Such a preparation could be used for permanent disinfection of surfaces along with durable protection against the growth of pathogens or biofilms.

The assumption behind the invention is to obtain silver nanomaterial to disinfect porous construction ceramic materials, plaster and building gypsum materials. Ultimately, the preparation containing such nanosilver could be used to produce biocidal film on the surface of walls, in particular in farming of poultry, pigs and cattle. The current intensive method of animal farming requires the use of chemical protection agents to prevent infections and thus to prevent animal deaths. One of the priorities is to limit the growth of microorganism, and specifically the pathogens, in animal rearing.

The essence of the nanomaterial in the invention is that the active biological factor is the composition of silver in varied degrees of oxidation - in the form of metallic silver and silver ions, in the proportions depending on the mutual relations of material ingredients, in the presence of the agents that boost and stabilize its biological activity, nanomaterial of 1000 grams contains silver in the amount fro 0.0001 gram to 10 grams, while 1 % to 40% of silver is in the ion form and the remaining part is metallic silver, hydrogen peroxide in the amount from 1 gram to 350 grams and also a penetrating agent, i.e. polyethylene glycol in the amount from 0.001 gram to 300 grams and stabilizers: potassium nitrate from 0.1 gram to 250 grams and

polyvinyl alcohol from 0.0000001 gram to 10 grams, while metallic silver creates complexes with polyvinyl alcohol and polyethylene glycol.

The invention consists in the fact that in the first step silver solution is produced by dissolving silver salts, preferably silver nitrate or silver acetate in the amount allowing to obtain from 0.0001 gram to 10 grams of silver in 1000 grams of water, with the addition of ethylene alcohol in the amount from 0.01 gram to 100 grams, which produces an unstable system of ions and metallic silver and then polyvinyl alcohol PVA is added to this solution in the amount from 0.001 gram to 1 gram for 1 gram of silver; in the second step silver ions and metallic particles and synthetized with polyvinyl alcohol PVA matrix and the system is stabilized by the addition of polyethylene glycol PEG in the amount from 0.001 gram to 300 grams and the reaction is promoted by sodium hydroxide or potassium hydroxide added in the amount from 0.0000005 gram to 8 grams, which results in the creation of a biocidal complex that acts on pathogens; in the third step potassium nitrate is added as stabilizer in the amount from 0.1 gram to 250 grams, in the fourth step the solution of hydrogen peroxide is added to stabilize the system in the amount that allows to obtain hydrogen peroxide content from 1 gram to 350 grams.

The main biologically active material of the colloid are silver nanoparticles in equilibrium with silver ions. Total silver concentration in colloid must not exceed 10,000 ppm. If higher, the material is chemically unstable and goes through spontaneous reduction producing macro-systems that then go though sedimentation. The best solution is to create colloid with total amount of silver under 4,000 ppm. In order for the colloid to stabilize, after instillation of nanoparticle synthesis promoter, a solution of hydrogen peroxide is used in such amount so as to obtain from 1 to 350 grams of pure hydrogen peroxide in 1000 grams of the colloid.

In order to gain higher penetration of pathogen cells, two preparations are applied. The task of the first one - polyvinyl alcohol - is to bind to the pathogen cell. Due to its specific characteristics, this polymer shows affinity to silver ions. Thus we gain local point increase in its concentration. The required concentration of this polymer ranges from 0.001 % to 10% against the amount of silver in the colloid. The second one - polyethylene glycol demonstrates affinity to cell membranes and increases their permeability. The system is also stabilized by silver/polyvinyl alcohol complex and thus the equilibrium of Ag/Ag+ in the colloid is achieved. Mutual synergy of these systems produces preparation with desired characteristics.

The size of silver nanoparticles is controlled through the time of sodium hydroxide or potassium hydroxide instillation, its concentration and the temperature of the reaction mixture. Due to the presence of chemical stabilizers of the colloid and the systems that bound to biological surfaces, the preparation demonstrated increased affinity to fungi and bacteria. It can be applied in the concentrated formula as well as diluted.

Due to their unique physical and chemical characteristics related to their size as well as considerable surface coverage as compared to their volume, nanomaterials are effective in small concentrations. A typical concentration unit in such materials is ppm, i.e. one part per million. In case of nanomaterials, it is possible to reach the desired target with the use of just trace amounts as compared to larger-sized materials. The material efficiency was demonstrated in silver concentration of 0.002 ppm.

The tests demonstrate the preparation is efficiency in eliminating the following bacteria:

Staphylococcus aureus, Eschericha coli, Salmonella typhi, Klebsiella pneumonia, Candida albicans, Aspergillus niger and Trichoderma koningi._

In line with the invention, apart from silver nanomaterial required for biocidal effect, the preparation also includes chemical compounds that do not act as biocides. In order to stabilize the colloid, the preparation also includes a compound that provides for continuous presence of silver ions. Compounds that improve nanosilver permeability through pathogen cell walls result in reduced amount of silver required for biocidal effect. Hence, it is possible to introduce into the cells the system with strong effects on cell metabolic pathways in lower concentration that would otherwise be required for nanosilver or silver ions. Consequently, the amount of nanosilver required for biological activity is reduced by as much as 60%. This results in savings on silver nanomaterial and lower costs of application.

Example 1

All chemical compounds used in the reaction must be of at least pure class. Specifically, the water used in the reaction should be free from chlorides, sulphates, thiol compounds or phosphates.

Devices:

homogenizer (rotomax)

set of laboratory glasses and polyethylene containers

analytical scales

hotplate

Raw materials:


* water solution

Preparation of input materials

0.00015748 grams of silver nitrate and 300 grams of water are weighted in a polyethylene container. They are placed in a homogenizer at 800 rotations/minute until complete dissolving of silver nitrate. Then 0.01 gram of ethanol is added. After that, the mixture should be heated up to 40° C, with continuous stirring over 30 minutes. Separately, 0.0000005 gram of potassium hydroxide is dissolved in 10 grams of water.

Obtaining @Ag/polyethylene glycol complex

At a constant temperature of 40°C, a mixture of polyethylene glycol (0.0001 gram) and water (9.9999 gram) is added in portions of 10 grams to the solution obtained in the previous step so that the total amount of added mixture is 100 grams. After thoroughly mixing, purified water is added to the solution to obtain total mass of 800 grams. Then 0.0000005 gram of potassium hydroxide previously dissolved in water is added to the solution, if more potassium hydroxide is added, the proportion of ion silver in the final preparation goes down. Then 0.000001 grams of 10% water solution of polyvinyl alcohol is added to the solution. Ultimately, 0.1 gram of potassium nitrate is added as well as 3.33333333 gram of 30% perhydrol is added and the mixture is topped up with water up to the total mass of 1000 gram.

1000 grams of the final product contains 0.0001 gram of solver, 1 gram of hydrogen peroxide, 0.001 gram of polyethylene glycol, 0.1 gram of potassium nitrate and 0.0000001 gram of polyvinyl alcohol.

The preparation is designed for frequent disinfection and protection of flat surfaces (laboratory tables, meat cutting tables, places exposed to fungi growth). Its composition allows multiple coating (once the work is finished). It is recommended for cleaning the feeders, drinkers and places exposed to bacteria growth.

Example 2

All chemical compounds used in the reaction must be of at least pure class. Specifically, the water used in the reaction should be free from chlorides, sulphates, thiol compounds or phosphates.

Devices:

homogenizer (rotomax)

set of laboratory glasses and polyethylene containers

analytical scales

Raw materials:


* water solution

Preparation of input materials

15.74765922 grams of silver nitrate and 100 grams of water are weighted in a polyethylene container. They are placed in a homogenizer at 900 rotations/minute until complete dissolving of silver nitrate. Then 100 grams of ethanol is added. After that, the mixture should be mixed for 45 minutes. Separately, 8 grams of potassium hydroxide is dissolved in 10 grams of water and 200 grams of polyethylene glycol.

Obtaining @Ag/polyethylene glycol complex

At a constant temperature of 50°C, polyethylene glycol in 10 grams portions is first added to the solution obtained in the previous step so that the total amount is 100 grans. Then 8 grams of potassium hydroxide previously dissolved in water and polyethylene glycol is added to the solution, if more potassium hydroxide is added, the proportion of ion silver in the final preparation goes down. Then 100 grams of 10% water solution of polyvinyl alcohol is added to the solution. Ultimately, 250 grams of potassium nitrate is added as well as 100 grams of 30% perhydrol is added and the mixture is topped up with water up to the total mass of 1000 gram.

1000 gram of the final product contains 10 grams of silver, 30 grams of hydrogen peroxide, 300 grams of polyethylene glycol, 250 grams of potassium nitrate and 10 grams of polyvinyl alcohol.

Example 3

All chemical compounds used in the reaction must be of at least pure class. Specifically, the water used in the reaction should be free from chlorides, sulphates, thiol compounds or phosphates.

Devices:

homogenizer (rotomax)

analytical scales

hotplate

set of laboratory glasses and polyethylene containers

Raw materials:


Preparation of input materials

15.74765922 grams of silver nitrate and 100 grams of water are weighted in a polyethylene container. They are placed in a homogenizer at 9000 rotations/minute until complete dissolving of silver nitrate. Then 20 grams of ethanol is added. After that, the mixture should be heated up to 50° C, with continuous stirring over 45 minutes. Separately, 8 grams of potassium hydroxide is dissolved in 40 grams of water and 3 grams of polyethylene glycol.

Obtaining @Ag/polyethylene glycol complex

At a constant temperature of 50°C, polyethylene glycol in 0.5 gram portions is first added to the solution obtained in the previous step so that the total amount is 3 grams. Then 8 grams of potassium hydroxide previously dissolved in water and polyethylene glycol is added to the solution, if more potassium hydroxide is added, the proportion of ion silver in the final preparation goes down. Then 5 grams of 10% water solution of polyvinyl alcohol is added to the solution. Ultimately, 20 grams of potassium nitrate and 700 grams of 50% perhydrol are added and the mixture is topped up with water up to the total mass of 1000 gram.

1000 gram of the final product contains 10 grams of silver, 350 grams of hydrogen peroxide, 5 grams of polyethylene glycol, 20 grams of potassium nitrate and 0.5 gram of polyvinyl alcohol.

The preparation produced this way is concentrated. Its application is recommended on the materials that are constantly exposed to biological factors, where it is difficult or impossible to run regular disinfection.

This product can also be diluted and applied to wood or woodgrain surfaces that are constantly exposed to humidity. For this purpose, the preparation should be dissolved in purified water at 1 :10 and applied on the protected surface by immersion or painting.

Example 4

Just like in previous examples, all chemical compounds used in the reaction must be clean and include no water. The water used in the reaction should be free from chlorides, sulphates, thiol compounds or phosphates. Preferably, distilled or purified water with conductivity below 15 mS should be used in the reaction. The chemical compounds used in the reaction must be of at least pure class.

Devices:

homogenizer (rotomax)

vacuum pomp

Buchner funnel with suction flask

analytical scales

set of laboratory glass and polyethylene containers

Raw materials:


Preparation of input materials

7.75 grams of silver acetate, 300 grams of water and 20 ml of 25% ammonia solution are weighted in a polyethylene container. They are placed in a homogenizer at 10,000 rotations/minute until complete dissolving of silver acetate. Then 140 grams of isopropyl alcohol is added. After that, the mixture should be heated up to 50° C, with continuous stirring over 30 minutes. Separately, 0.4 grams of potassium hydroxide is dissolved in 15 grams of water and 200 grams of polyethylene glycol.

Obtaining @Ag/polyethylene glycol complex

At a constant temperature of 40°C, the 1 : 1 mixture of 400 ml polyethylene glycol and water is added in portions of 25 ml. After thorough mixing, 700 grams of purified water is added to the solution. Then 5 ml of potassium hydroxide resulting from mixing of 0.4 grams of KOH with 4.6 grams of water is added to the solution, if more potassium hydroxide is added, the proportion of ion silver in the final preparation goes down. Then, with continuous stirring, 12 grams of 10% polyvinyl alcohol is added to the solution. Finally, the mixture is completed with 140 grams of 30% hydrogen peroxide, 140 grams of potassium nitrate is added and the solution is topped up with water up to 1 ,000 grams. The final product is sieved through the Buchner funnel to separate potential contaminants.

1 ,000 gram of the final product contains 5 grams of silver, 42 grams of hydrogen peroxide, 5 grams of ammonia, 1.2 grams of polyethylene glycol, 140 grams of potassium nitrate, 140 grams of isopropyl alcohol and 200 grams of polyvinyl alcohol.

The preparation produced this way is concentrated. Its application is recommended on the materials that are constantly exposed to biological factors, where it is difficult or impossible to run regular disinfection.

This product can also be diluted and applied to wooden or woodgrain surfaces that are constantly exposed to humidity. For this purpose, the preparation should be dissolved in purified water at 1 :10 and applied on the protected surface by immersion or painting.

The preparations can be applied on the surface cleaned from organic matter with a manual sprayer, mist maker and thermal mist maker in the facilities designed for animal farming. Before application, the product can be mixed with specialist carriers to facilitate its viscosity and to improve spraying efficiency. The contact time between the preparation and the surface required for biocidal effect is at least 20 minutes.

The preparation provides long-term protection (e.g. within the entire poultry production cycle) of farm building surfaces, which can be the potential source of harmful pathogens. The use of nanomaterials results in bio-degradation of fungi pathogens and protects the surface against the creation of biofilms. The nanomaterial is not biodegradable. Each application onto the protected surface results in nanomaterial accumulation, thus increasing its bioavailability and effect on pathogens.

The products can be used as:

- ready-made disinfectants, after prior preparation of diluted solution;

- preparations to protect construction wood against the growth of pathogens;

- preparations used to protect building ceramic materials against the growth of fungi;

- disinfectants for concrete, wood and polymer surfaces;

- addition to other disinfectants and cleaning agents.