Synthesis and Structural Characterization of SiO₂ Nanoparticles Using Extract of <i>Gracilaria Crassa</i> Via Green Chemistry Approach

Biologically synthesized nanoparticles via biological entities are produced with less negative impact on the environment and without expensive chemicals, which have biocompatibility and are eco-friendly. Gracilaria crassa is a well-known marine red alga that is edible and unique and is the commercial source of agar and agarose production. In this work, Gracilaria crassa-mediated SiO₂ NPs were synthesized by the green synthesis method. In order to characterize the physicochemical properties of the synthesized SiO₂ NPs, a variety of microscopic and spectroscopic approaches were used, including imaging with Field emission scanning electron microscopy, Energy-dispersive X-ray analysis, UV spectrophotometry, X-ray diffraction analysis, Fourier-transform infrared spectroscopy, Zeta potential, and Thermo gravimetric analysis. These results shown that Gracilaria crassa-mediated SiO₂ NPs were amorphous nature, negatively charged -15.5 mV and spherical shape in size of 20-50 nm. The antioxidant capacity of synthesised SiO₂ NPs was examined by 2,2-Diphenyl-1-picrylhydrazyl assay and it observed as IC₅₀ value of 49.4 μg/mL denotes that could counteract the production of free radicals and oxidative stress. The characteristics of the synthesized Gracilara crassa-mediated SiO₂ NPs suggest their application as potential antioxidant agents.