Nanobiotechnology for health-care
Urotropine-containing antibacterial nanocomposite materials and their physico-chemical properties
Skurikhina O.1, Kozakevych R.2, Liubatska O.1, Murlanova T.1, Vakuliuk P.1, Lupatsii M.1, Furtat I.1, Tertykh V.2, Golub A.1
1National University of Kyiv-Mohyla Academy, 2 Skovoroda Str., Kyiv, 04070, Ukraine. Email: tanmurlanova@gmail.com

2Chuiko Institute of Surface Chemistry of the NAS of Ukraine
17 General Naumov Str., 03164, Kyiv, Ukraine

The wound cleansing from a pathogenic microbial medium and the effective removal of the wound exudate are the main factors should be taken into cosideration for the effective treatment of wound infections. One of the promising directions of functional antimicrobial agents development is the creation of nanocomposites based on pyrogenic silica due to its biocompatibility, purifying action and unique physico-chemical properties. The use of pyrogenic silica as a carrier of drugs, provides not only delivery of antimicrobial agents, but also ensures the second crucial factor in wound healing - effective removal of the wound exudate, wound cleansing and balanced hydration [1].
Nanocomposites based on highly dispersed pyrogenic silica, urotropine, and combined nanocomposites containing both ornidazole and urotropine with different concentrations of active components in nanocomposites were obtained in the research. The concentration of each antibacterial component was 2% and 4% for one component and for mixed nanocomposites, respectively. The presence of ornidazole and urotropine on the surface of modified nanocomposites was confirmed using the method of IR spectrometry. The kinetics of desorption of active components from the nanocomposite surface was investigated by the method of adsorption spectrophotometry (for ornidazole-containing nanocomposites) and titrimetry (for urotropine-containing) for all samples for 12 hours. Analyzing the kinetics of desorption for 2AU (A=aerosil, U=urotropine) and 4AU samples, it can be concluded that a larger part of urotropine is desorbed into the solution during the first hour. This phenomenon can be explained by the weakness of binding the modifier on the surface. By analyzing the kinetics of desorption for samples 2-2AUO (O=ornidazole) and 4-4AUO it can be concluded that a larger part of medications (ornidazole and urotropine) is desorbed into the solution for the first two hours. The release of antimicrobial substances for composites with a combined composition is two times slower than for samples 2AU and 4AU with pure urotropine.
The antimicrobial activity of the obtained nanocomposites was investigated for the following strains: Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli. It was shown that the antimicrobial effect was greater while using nanocomposites based on ornidazole and urotropine, than the effect of nanocomposites with only one active compound, due to the phenomenon of synergy. The effect of nanocomposites with both ornidazole and urotropine and urotropine only on bacterial cells during 2-hour contact led to a slight reduction of CFU (colony forming units) number. The prolongation of contact between nanocomposites and bacterial cells resulted into increasing antimicrobial effect. In case of using both types of nanocomposites only 0.01 % of staphylococcal cells have survived, moreover, the complete inhibition of growth of Escherichia coli cells was observed. The effect of nanocomposite with ornidzole and urotropine caused complete inhibition of growth of both tested gram-negative bacterial strains. These observations brought us to conclusion that the extension of contact time between nanocomposites and bacterial cells led to increasing antimicrobial effect of nanocomposites. The synergy of ornidazole and urotropine in the nanocomposite resulted into stronger antimicrobial effect against gram-negative bacteria.

1.	Murlanova T., Kotsiuda S., Vakuluk P., Golub A. Nanocomposites based on ornidazole and pyrogenic silica for the treatment of complicated wounds // Scientific notes of NaUKMA. Natural Sciences. – 2017. – 197, p. 53-57.