Enhanced mechanical properties and bactericidal activity of polypropylene nanocomposite with dual-function silica-silver core-shell nanoparticles

Abstract

Dual-function silica-silver core-shell (SiO2@Ag) nanoparticles (NPs) with the core diameter of 17 ± 2 nm and the shell thickness of about 1.5 nm were produced using a green chemistry. The SiO2@Ag NPs were tested in vitro against gram-positive Staphylococcus aureus (S. aureus) and gram-negative Escherichia coli (E. coli), both of which are human pathogens. Minimal inhibitory concentrations of the SiO2@Ag NPs based on Ag content are 4 and 10 μg mL-1 against S. aureus and E. coli, respectively. These values are similar to those of Ag NPs. SiO2@Ag NPs were for the first time incorporated to a commodity polypropylene (PP) polymer. This yielded an advanced multifunctional polymer using current compounding technologies i.e., melt blending by twin-screw extruder and solvent (toluene) blending. The composite containing 5 wt % SiO2@Ag NPs (0.05 wt % Ag) exhibited efficient bactericidal activity with over 99.99% reduction in bacterial cell viability and significantly improved the flexural modulus of the PP. Anodic stripping voltammetry, used to investigate the antibacterial mechanism of the composite, indicated that a bactericidal Ag+ agent was released from the composite in an aqueous environment.