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Students of Samara University have developed effective inexpensive in production and safe for human health antimicrobial coating that can be applied on fabric. Clothes or dressings made of such fabric can significantly reduce risks of development and distribution of infections and accelerate healing of patient wounds that is especially important when providing medical care in field conditions.
The invention is based on the unique technology of application of bactericide coating composed of natural polymers and silver nanoparticles on a textile material. Antimicrobial composite includes a combination of various agents with high bacteriostatic and fungistatic action. They prevent the in-take of nutritional substances from the environment by microbes and thus effectively terminate the development of bacteria and fungi. Unlike other similar antimicrobial fabrics that contain silver, the coating made by the Samara technology is more stable, preserves antimicrobial activity much longer and for its products less amount of noble metal is required, which as a result reduces the total cost of production.
“We developed and tested innovation antibacterial coating based on modified natural polymers with branched molecular structure and silver nanoparticles that are embedded into a polymer matrix. Such approach allows effectively retain nanoparticles on the surface of the fabric, which makes the coating more durable and preserving its antimicrobial properties for a longer period of time. In addition, our technology requires a small amount of silver-containing substances, by about 10 times less that usual, which makes the production cheaper. There are no analogues of antimicrobial fabric with such characteristics in Russia,” told Viktoria Salakhova, Master-Degree Student of the Department of Biochemistry, Biotechnology, and Bioengineering of the Institute of Natural and Mathematical Sciences of Samara University.
Traditional fabrics are very favorable medium for growth and reproduction of pathogenic microorganisms, namely various bacteria and fungi. As a rule, fabrics are characterized by porous structure that retains moisture, for example sweat, well. In average, under favorable for nutrition and reproduction conditions, only one bacterial cell fallen into sweaty tissue can consider itself as a parent of a whole population of bacteria consisting of about 1 million cells after seven hours. Thus, it is very important to ensure sterility of fabric and devices made of it when providing medical care in hospitals, especially in field conditions.
Silver “nano bullets” and “fur coat” for nanoparticles
Silver has been used as a disinfecting agent from the most ancient times. Even Hippocrates advised to treat ulcers on skin with silver powder. Silver dishes protected people against infections: for example, during well-known trip of Aleksandr Makedonsky in India due to large-scale outbreak of intestinal diseases military leaders who drink from silver glasses were almost not affected unlike simple soldier the dishes of whom were made of tin. Compounds of silver as solutions were actively used for treating wounds in XIX and XX centuries until the epoch of antibiotics has begun. However, massive use of antibiotics resulted in appearance of bacteria resistant to many drugs, while bacteria have not still been able to develop resistance as regard to silver.
In XXI century, silver was again return to the field of fight against microbes but at present it is already used as nanoparticles. As modern scientists have been established, silver nanoparticles have a very high activity as regard to a wide spectrum of microbes, even when using low doses: the complete inhibition of bacterial growth can occur at the concentration of 32 milligrams of nanoparticles per one liter. In case of contact of silver nanoparticles with bacteria, reactive oxygen intermediates are formed, which break bacterial membrane and damage proteins and DNA of bacteria. They are some kind of silver “nano bullets” for “vampire” microbes.
In the world, a lot of types of antibacterial fabrics were created, which contain silver nanoparticles, but most of these inventions have a substantial disadvantage. The point is that silver nanoparticles due to their properties dislike deeply to stay alone for a long period of time and constantly strive to “stick together,” connect with other nanoparticles while forming unions and agglomerations. When using chemical language, silver nanoparticles are extremely prone to aggregation. Cause of aggregation is the nanoparticle striving to take a more stable position. When merging, properties of nanoparticles are changed, antimicrobial effect weakens (according to scientists, the smaller nanoparticle is, the stronger its effect on microbes is), thus silver microparticles in agglomerations become less effective for treatment of fabric.
In order to prevent “sticking” of nanoparticles, various substances)(stabilizers) are used, which “gown” nanoparticles just as “fur coat” while depriving them of the opportunity to connect each other. However, this also hides a problem: as a rule, such “fur coats” turn out to be toxic to human body. During experiments, Samara researchers developed an optimal, according to them, substance (stabilizer) that both prevents “sticking” of particles and is absolutely safe for human and the environment. The base for this substance was isolated from brown coals. Details of the composition of this substance has not disclosed to the general public yet, as a patent to this invention has not been received yet.
“This polymeric compound after modification, as shown by experiments, effectively reduces and retains silver nanoparticles without worsening their antimicrobial properties. Complex aggregates of various functional groups of the matrix with metal nanoparticles are formed. In addition to silver nanoparticles, we suppose to include copper nanoparticles in future as well. As advantages of our coating, we can call protection from bacterial carry-over, prolonged antimicrobial effect, reduction of risk of contact infection, as well as prevention of appearance of bad odors caused by bacteria and most importantly safety to human,” noted Aleksandr Kuks, Master-Degree Student of the Department of Biochemistry, Biotechnology, and Bioengineering of the Institute of Natural and Mathematical Sciences of Samara University.
This innovation coating was named “Nanoguardian.” Students developed a technology of coating application, produced pilot samples of antimicrobial fabric, and tested them. During testing, the Samara invention showed a sufficient efficacy as regard to fight against various bacteria. In the future, it is planned to create a plant for producing such fabric and market the product.
