Novel approach to synthesis of silver nanoparticles in interpolyelectrolyte complexes based on pectin, chitosan, starch and their derivatives

The effect of the chemical structure of interpolyelectrolyte complexes (IPEC) based on polymers of natural origin (pectin(-) chitosan(+), pectin(-) cationic starch (starch(+)), carboxymethylcellulose (CMC-) cationic beta-cyclodextrin (beta-CD+), anionic starch (starch(-))-cationic starch (starch(+)) on the structure, morphology, thermomechanical and antimicrobial properties of silver-containing nanocomposites obtained by thermochemical reduction of Ag+ ions in interpolyelectrolyte-metal complexes (IMC) was studied. Thermochemical reduction of Ag+ ions in the IMC bulk for 30 min at 150 degrees C led to formation of silver-containing nanocomposites and this fact was confirmed by wide-angle X-ray scattering method. Transmission electron microscopy showed that different sized of silver nanoparticles were formed depending on the chemical structure of IPEC. The average size of silver nanoparticles was found to be 4.7 nm for pectin(-)-Ag-chitosan(+); 5.3 nm for pectin(-)-Ag-starch+; 6.3 for CMC--Ag-beta-CD+ and 9 nm for starch(-)-Ag-starch(+), correspondingly. The nanocomposites having smaller average nanoparticle size exhibited higher antimicrobial activity against S. aureus and E. coli strains. Pectin(-)-Ag-chitosan(+) nanocomposites formed by thermochemical reduction of Ag+ ions showed that the diameter of the inhibition zone against S. aureus and E. coli strains was 19.7 and 32.6 mm, respectively, whereas these values were 15.6 and 14 mm, respectively, for the same nanocomposites obtained by chemical reduction using ascorbic acid.