Antimicrobial Applications of Nanosilica Derived from Rice Grain Husks

The silica obtained from rice husks can be extracted in several methods. One of those methods is digestion by strong bases. In this study, nanosilica material derived from rice husk (RH-SiO 2 ) was synthesized via digestion by sodium hydroxide. The sol–gel method was used to create RH-SiO 2 at room temperature. The silanol group and siloxane group were detectable in silica's infrared spectra at 3446 cm −1 and 1115 cm −1 , respectively. According to the analysis of nitrogen adsorption and desorption, nano-silica does have a specific surface area of 65.95 m 2 g −1 . The silica nanoparticles have a restricted 2–15 nm pore size distribution. Since there were no distinct and strong diffraction patterns in the XRD spectrum, the sample had to be amorphous. According to scanning electron micrographs (SEM), the particles and pores of nanosilica are randomly distributed but they have a tendency to be regular. Transmission electron micrographs (TEM) revealed a formation of spherical silica nanoparticles with an average diameter of 50 nm. Atomic force microscope (AFM) showed that the particles and pores of nanosilica are randomly distributed and they tend to be spherical regular particles. Thermogravemetric analysis (TGA/DTA) of the nanosilica material revealed two stages of mass loss, the first stage is the loss of water adsorbed physically/chemically on the surface of the silica, and the second stage is due to the decomposition of silanol Si–OH and its transformation into Si–O-Si siloxanes. In vitro, the antimicrobial was tested on streptococcus mutants and candida albicans in various concentrations of nanosilica suspension solutions. Streptococcus mutants and candida albicans were sensitive to nanosilica, and sensitivity increased as the concentration with a statistically significant difference, indicating that this material had antibacterial and antifungal activity.