Effect of cationic polyelectrolyte on the structure and antimicrobial activity of silver-containing nanocomposites based on interpolyelectrolyte complexes with a pectin anionic component

This paper investigates the structure, morphology and antimicrobial properties of silver-containing nanocomposites based on interpolyelectrolyte complexes (IPEC) of pectin with polyethylenimine, cationic starch or chitosan as a cationic polyelectrolyte. The reduction of silver ions was carried out by thermochemical technique by heating of the interpolyelectrolyte–metal complexes, which in turn prepared by adsorption of ions on IPEC. The chemical reduction was also performed using ascorbic acid as reductant. The temperature and time needed to produce the nanocomposites at which completely reduction of silver ions occurs are 150 °C and 30 min. It is revealed that during thermochemical reduction depending on the type of cationic polyelectrolyte (PEI, cationic starch, chitosan), silver nanoparticles with an average size of 4.1, 5.3 and 4.7 nm, respectively, are formed. Various mechanisms of thermochemical reduction for interpolyelectrolyte–metal complexes containing polymers with aminogroups or polymers with the glucopyranose units are considered. It is found that the silver-containing nanocomposites, formed by thermochemical reduction, exhibited higher antimicrobial activity against strains of S. aureus and E. coli than ones obtained using ascorbic acid.