Bactericidal coatings for implants and not only
MSU scientists have created materials with bactericidal properties
Scientists of Lomonosov Moscow State University have created durable and non-toxic polymer coatings capable of destroying up to 99.999% of pathogenic microorganisms. The research was supported by a grant from the Russian Science Foundation (RNF) and published in the journal Materials Science and Engineering (Nuzhdina et al., Simple and versatile method for creation of non-leaching antimicrobial surfaces based on cross-linked alkylated polyethyleneimine derivatives).
Today, the so-called cationic antiseptics are quite popular, for example, miramistin, chlorhexidine, octenicept. They are not toxic to humans, and their aqueous solutions have excellent bactericidal activity. In the course of the study, the authors obtained water-insoluble polymers and coatings based on them, which act by a similar mechanism, and also have high bactericidal activity.
The authors of the work note that the main purpose of the study is to create materials whose surface has bactericidal properties. The development can be applied, among other things, when creating implantable medical devices, the surface of which is resistant to the formation of biofilms – a variety of microorganisms located on a certain surface. "According to various estimates, the frequency of complications (secondary infections) in the use of medical devices (orthopedic implants, catheters) associated with the formation of biofilms reaches 10-20% of cases. Therefore, it is very important that they are non–toxic to the tissues of the human body, and at the same time, quickly and effectively cause lysis (dissolution) of pathogenic microorganisms," comments Ivan Bessonov, co-author of the study, executor of the RNF grant, junior researcher at the Department of Bioengineering of the Faculty of Biology of Lomonosov Moscow State University.
Orthopedic implant with bactericidal coating. Source: Ivan Bessonov
In addition, according to the researchers, the results obtained will help in the creation of materials that can effectively absorb prokaryotic cells or individual structural fragments of their cell walls on their surface, and can also be used to clean reservoirs from cyanobacteria and microalgae, which are often the cause of serious environmental consequences.
"We have established general patterns between the chemical structure of polymers (length of alkyl substituents, degree of substitution, degree of crosslinking) and properties – bactericidal activity and solubility in water," says Ivan Bessonov. According to the scientist, it was also important to obtain highly active and poorly soluble compounds: coatings based on them will be washed off the longest, which means they will be the most durable.
In the course of the study, the authors obtained a series of several dozen new compounds (based on a synthetic polymer – polyethylenimine) and coatings based on them. They were studied using various physicochemical methods, including NMR (nuclear magnetic resonance spectroscopy) and IR spectroscopy. The value of the wetting edge angle and the degree of water washability were also evaluated. In addition, the researchers studied their bactericidal properties. To do this, Petri dishes with coatings based on the obtained polymers were seeded with microbes of Staphylococcus aureus and Pseudomonas aeruginosa. Next, the experts measured the number of colony-forming units.
It turned out that compared with the control, the indicator of the number of these bacteria was 1,000-1,000,000 times lower. Thus, it turned out that in combination with low solubility and high activity, according to a decrease in the number of CFU (the number of bacteria forming colonies in one milliliter of medium), this result indicates a "contact-active" mechanism of action.
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15.11.2016