Resumen
Green synthesis of silica nanoparticle from cow dung ash is a promising prospect due to the low-cost and environmental friendliness coupled with the ability to manipulate its physicochemical properties. Silica nanoparticles yield of around 76% was obtained via acid/base treatments of grey-coloured cow dung ash using NaOH and H2SO4 respectively. Field-Emission Scanning Electron Microscopy analysis shows that the silica nanoparticles are amorphous, agglomerated, near-spherical in shape with even distribution of shapes and sizes. The average size of the silica nanoparticles is around 35 nm. Silicon and oxygen are the two major components which make-up 79.72 wt% of silica nanoparticles. Fourier Transform Infrared peaks of silanol group, traces of water molecule, siloxane stretching, Si-O bending vibrations and out of plane Si-O bending vibrations were identified in the silica nanoparticles. An absorption spectrum for silica nanoparticles is observed at 240 nm with a band gap energy of 5.1 eV in Ultraviolet-Visible Spectroscopy analysis. Through Dynamic Light Scattering analysis, the mean size of the silica nanoparticles is found to be 361.68 nm with a polydispersity index of 0.171. Thermogravimetric Analysis confirms the thermal stability of the silica nanoparticles with only 4% of weight loss at elevated temperatures. Silicon and oxygen are found to be prominent in silica nanoparticles based on X-ray Photoelectron Spectroscopy analysis. Sharp and intensive peak is apparent at 2? = 19.09° which indicates the presence of crystalline quartz in the silica nanoparticles structure based on X-ray Diffraction analysis. Antimicrobial potential of the silica nanoparticles were evaluated using disc diffusion assay. Unmodified silica nanoparticles did not display any antimicrobial activity against B. subtilis and E. coli while silica nanoparticles that have been modified with (3-Aminopropyl) triethoxysilane and Glutaraldehyde and attached with Ampicillin on the surface showed sensitivity against the same microorganisms. This study has shown the potential of green synthesis of highly pure silica nanoparticles that can act as a drug carrier.