COMPARISON OF ANTIBACTERIAL PROPERTIES BETWEEN CHITOSAN STABILIZED SILVER AND ZINC OXIDE NANOPARTICLES IMMOBILIZED ON WHITE SILICA BEADS

Most preparation of both silver (Ag) and zinc oxide (ZnO) nanoparticles (NPs) was relatively complicated. We proved a more straightforward method not only in the nanoparticle synthesis but also in their immobilization on the solid support. Since both the metal nanoparticles have antibacterial activities, comparing the efficacy and the preparation cost is still interesting to explore. TEM images show both colloidal chitosan stabilized-Ag NPs and ZnO NPs have dispersed and nano-size particles. The immobilized Ag NPs and ZnO NPs on white silica beads (SiG chi-Ag NPs and SiG chi-ZnO NPs) were successfully fabricated with appropriate techniques and suitable characteristics for antibacterial air filter materials. The colloidal and the immobilized metal NPs have high antibacterial properties against Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. The inhibition zone diameter of SiG chi-ZnO NPs and SiG chi-Ag NPs against S. aureus and E. coli were relatively similar but needed about ten times more weight zinc than silver to kill the bacteria at a similar inhibition zone size. Silver is ten times more expensive than zinc, but it is relatively simpler to prepare SiG chi-Ag NPs than to formulate SiG chi-ZnO NPs. The cytotoxicity of silver is more than ten times higher compared to zinc cytotoxicity. Therefore, it was reasonable to substitute silver with zinc nanoparticles for antibacterial air filter material.