Hydrogels as template nanoreactors for silver nanoparticles formation and their antimicrobial activities

Silver nanoparticles were synthesized and stabilized using the hydrogel template method. The synthesized hydrogels were composed of acrylamide and styrene sulfonic acid sodium salt monomers with different molar ratios. The copolymer with the highest ionic monomer content was interpenetrated with different chitosan concentrations. The main goal of this study was to evaluate the antimicrobial activity of the prepared hydrogels. The formation of silver nanoparticles within the swollen hydrogel was mainly due to an ion exchange process via the sulfonate and amino groups of the hydrogels. The surface morphology showed a uniform distribution of silver nanoparticles throughout the hydrogel structure. These nanoparticles had face-centered-cubic unit cell structure and dimensions less than 70 nm, as determined by X-ray and UV-visible spectroscopy, respectively. To investigate the antimicrobial activities of the prepared composites, their inhibitory effect was evaluated against bacteria, fungi, and yeasts. Increasing the ionic monomer and chitosan content enhanced both the swelling properties and the antimicrobial activities of these composites. The results clarified that the most sensitive strain was Bacillus subtilis.