Nanobiotechnology for health-care
 
Chitosan- graft -Polyacrylamide Hydrogels and its applications for controlled drug delivery
O. Nadtoka, P. Virych, N. Kutsevol, S. Nadtoka 
Taras Shevchenko National University of Kyiv. Volodymyrska Street, 64/13, Kyiv-01601, Ukraine. 
E-mail: oksananadtoka@ukr.net

Cross-linked grafted polysaccharides as hydrogels have various applications in different important scientific areas such as drug delivery, pharmaceutical field, waste water treatment, etc. [1]. Hybrid hydrogels have been synthesized by graft copolymerization reaction of сhitosan and аcrylamide using N,N-methylene-bis-acrylamide as a cross-linker and cerium ammonium nitrate as an initiator. FT-IR, TGA and DSC studies of hybrid сhitosan-graft-polyacryamide hydrogels were carried out to analyse its structure.
Swelling and sorption/desorption process of biologically active compounds into/out of hydrogels as an important factor for regulation of therapeutic concentrations in bacteria medium were studied. Methylene blue (МB) and chlorhexidine (ChH) were used as universal models of the active substances. Methylene blue is a cationic derivative of phenothiazine whereas chlorhexidine is a cationic bisbiguanide. The bactericidal effect is a result of the binding of this cationic molecules to negatively charged bacterial cell walls. At low concentrations of MB and ChH this results in a bacteriostatic effect. It was found that the rate of release of absorbed MB and ChH from the hydrogel is lower for samples with a higher concentration of chitosan. This feature can be used for the antibacterial prolonged action when using loaded hydrogels as a dressing material.

Figure 1. Chitosan-graft-polyacrylamide.
The antimicrobial efficacy in solid medium against wild strains S. aureus was registered. Thus, prepared hydrogel composites can be used as promising materials for wound dressings.
1. O. Nadtoka, N. Kutsevol, V. Krysa, B. Krysa, Mol. Cryst. Liq. Cryst.  672 (1) (2018) 1.