Enhancing physico-mechanical and antibacterial properties of natural rubber using synthesized Ag-SiO2 nanoparticles.

The incorporation of the prepared Ag-SiO2 core-shell particles in natural rubber matrix was investigated on antibacterial and mechanical properties of resulting composites. Significant antibacterial effect against S. aureus (Gram positive) and P. aeruginosa (Gram negative) was observed and achieved inhibition growth up to 85 and 90%, respectively, after 24 h depending on the amount of Ag-SiO2 core-shell. It was found that SiO2 acted as crosslinking agent and controlling the amount of silver release. UV-vis spectra and TEM, XRD showed Ag-SiO2 core-shell particles formation. SEM, FTIR, XRD and mechanical analysis showed uniform distribution of Ag-SiO2 core-shell into rubber matrix with enhanced tensile strength.

Synthesis and characterization of nanosilver-silicone hydrogel composites for inhibition of bacteria growth.

PURPOSE: Nanosilver-silicone hydrogel (NAgSiH) composites for contact lenses were synthesized to asses the antimicrobial effects. METHODS: Silicone hydrogel (SiH) films were synthesized followed by impregnation in silver nitrate solutions (10, 20, 30, 40, 60, 80ppm) and in-situ chemical reduction of silver ions using sodium borohydride (NaBH4). The silver nano particles (AgNPS) were identified by UV-vis absorption spectroscopy, Energy-dispersive X-ray spectroscopy (EDX) mapping and EDX spectrum. Physico-mechanical and chemical properties of NAgSIH films were studied. The antimicrobial effect of the hydrogels against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus was evaluated. The numbers of viable bacterial cells on NAgSiH surface or in solution compared to control SiH were examined. RESULTS: The NAgSiH films were successfully synthesized. FTIR results indicated that AgNPS had no effect on the bulk structure of the prepared SiH films. From TGA analysis, NAgSiH(R80) and SiH(R0) films had the same maximum decomposition temperature (404°C). UV-vis absorption spectroscopy and EDX mapping and spectrum emphasized that AgNPS were in spherical shape. The maximum absorption wavelength of NAgSiH films were around 400nm. The light transmittance decreased as the concentration of AgNPS increased, but still greater than 90% at wavelength around 555nm. The Young's modulus increased gradually from 1.06MPa of SiH(R0) to highest value 1.38MPa of NAgSiH(R80). AgNPS incorporated into SiH films reduced the bacterial cell growth and prevented colonization. Groups NAgSiH(R60,R80) demonstrated an excellent reduction in bacterial viability in solution and on the SiH surface. CONCLUSIONS: NAgSiH composites were successfully synthesized and possessed an excellent antimicrobial effects.