Background and objective: Silver nanoparticles are interested in antimicrobial studies due to their significant inhibitory effect. Despite the widespread research in this regard, preparation of water-dispersible and stable silver nanoparticles has not been solved sufficiently. At this work, fabrication, characterization, and antimicrobial activity of silver-decorated polymeric nanocomposite based on a pH-responsive thiol-end capped ABC triblock copolymer is presented.
Materials and methods: PAA-b-PDMAEMAQ-b-PCL-SH triblock copolymer was firstly synthesized by combination of ring-opening polymerization and reversible addition fragmentation chain transfer polymerization techniques. For preparation of silver-decorated nanocomposite, the triblock copolymer was self-assembled into polymer micelles with 20 nm diameter. Then, Ag nanoparticles were incorporated into the core of micelles when reducing agent of sodium borohydride was added. The Ag-doped nanocomposite was characterized by Fourier transform infrared, ¹H nuclear magnetic resonance, UV-VIS spectroscopy, laser scattering technique, and transmission electron microscopy. Antimicrobial activity of the silver-doped nanocomposite was examined against Bacillus cereus, Staphylococcus aureus, Escherichia coli,and Candida albicans at three concentrations of 10, 25, and 50 mg/ml.

Results and conclusion: The least and highest antagonisms were observed against E. coli by inhibition diameters of 4, 28 and 32 mm and C. albicans by inhibition diameters of 58, 101 and 119 mm for three concentrations of 10, 25, and 50 mg/ml, respectively. Among bacteria, the highest inhibition was observed for S. aureus by 45, 51 and 59 mm inhibition diameter induced by the three tested concentrations of the nanocomposite. It was accounted as 29, 34 and 40 mm inhibition diameter for B. cereus. Other than antimicrobial property, the synthesized silver nanocomposite could be introduced for de novo drug delivery system in cancer therapy by using both hydrophobic and hydrophilic anticancer drugs due to its physicochemical properties.