Seaweed Sargassum wightii mediated preparation of zirconia (ZrO2) nanoparticles and their antibacterial activity against gram positive and gram negative bacteria.

In the present study, a facile and green combustion method has been optimized for the synthesis of zirconia (ZrO2) nanoparticles using marine brown alga (seaweed), Sargassum wightii (S. wightii). Structural, optical and photoluminescence properties of the prepared ZrO2 nanoparticles were studied using XRD, FTIR, HR-TEM, UV-vis and PL spectroscopy. The average grain size of the nanoparticles calculated from the XRD pattern was around 4.8 nm which exhibits tetragonal structure. TEM results showed that the synthesized nanoparticles were uniformly monodispersed without aggregation. Formation of zirconia nanoparticles were confirmed by FTIR studies. The PL spectra exhibit broad emission peaks at the interface of UV and visible regions which can be assigned to the ionized oxygen vacancy in the material. Antibacterial activity of the synthesized zirconia nanoparticles was studied against gram positive and gram negative bacterial strains using agar well diffusion method. The prepared zirconia nanoparticles show significant antibacterial effect against Bacillus subtilis, Escherichia coli and Salmonella typhi due to their large surface area by their nanosize.