Antimicrobial activity of organic–inorganic hybrid films based on gelatin and organomodified silicones

Abstract

Gelatin–siloxane hybrid films containing antimicrobial agents were prepared in the two-step procedure. First, gelatin was chemically modified with organomodified silicones containing epoxy (S1) and both epoxy and fluoroalkyl groups (S2). Next, antimicrobial agents such as lysozyme, EDTA, and nisin, in various concentrations, were introduced into obtained hybrid solution, prior to solvent casting of the films. Antimicrobial activity of prepared samples, as well as neat gelatin and gelatin–siloxane hybrid as a reference, was investigated using a modified agar diffusion method against several bacterial strains (Aeromonas hydrophila, Bacillus subtilis, Escherichia coli) and opportunistic fungus (yeast species Candida albicans). Prepared gelatin–siloxane films were characterized using FT-IR, thermal and SEM analysis. Mechanical properties and swelling behavior of the samples were also investigated. The influence of type and amount of organosilicon compound used for modification of gelatin, as well as type and concentration of applied active agent on antimicrobial activity, was determined. We observed higher antimicrobial activity for all synthesized gelatin–siloxane hybrids than for unmodified gelatin with lysozyme, nisin, and EDTA prepared as comparison. Moreover, samples obtained with siloxane containing fluoroalkyl groups (S2) showed higher resistance to microbial agents than hybrids with S1 siloxane. Hybrid films showed also better water stability than neat biopolymer.