Synthesis of biogenic silica nanoparticles from rice husks for biomedical applications

Silica nanoparticles have numerous potential applications and can be manufactured in several forms, including fumed silica, colloidal silica, silica gel, and silica aerogel. However, biogenic silica is an excellent alternative to synthetic silica because of its variable structure, density, and composition. Among the available agricultural bioresources, rice husk is considered to be a cost-effective and non-metallic bio-precursor for biogenic silica nanoparticle synthesis. In this investigation, we synthesized biogenic silica nanoparticles (bSNPs) using rice husk as a precursor. Under pressurized conditions, the rice husk was acid pretreated to remove inorganic impurities and induce the hydrolysis of organic substances. Residues from the acid pretreatment were calcinated at different temperatures for 1 h. The structure and morphology of the synthesized biogenic nanoparticles were analyzed using transmission electron microscopy (TEM). Fourier transform infrared (FT-IR) spectra of the synthesized samples showed O–Si–O stretching vibrations between 1056 and 1078 cm−1. The X-ray diffraction patterns of the bSNPs showed the presence of amorphous biogenic silica. The TEM images suggested that irregular particles with dimensions between 10 and 30 nm had formed. During the calcination process, the primary particles were aggregated; however, upon increasing the calcination temperature, the sizes of the primary particles decreased. The biological properties of bSNPs were studied by MTT assay and by assessing cellular morphological changes in human mesenchymal stem cells (hMSc). The cell viability studies revealed that the bSNPs had excellent hMSc biocompatibility. Our results revealed that these bSNPs can be used in bone tissue engineering.