Nanostructured silica particles from Cymbopogon flexuosus (Nees ex Steud.): extraction, characterization and study of their blend with osteoporotic drugs

Abstract

Cymbopogon flexuosus (lemongrass) is one of the potential herbaceous sources for the extraction of silica. Silica plays a vital role in formation of bone and its maintenance by improving the quality of the bone matrix and facilitating bone mineralization. This work presents the extraction of silica nanoparticles from different parts of lemongrass such as root, stem and leaf. IR spectra of all the three extracts confirmed the presence of siloxane and silanol linkage. The SEM analysis revealed the SiNPs from root, stem and leaves to be aggregates of tubular, fibrous and spherical structures, respectively. Significant differences were observed in elemental composition of SiNPs as determined by EDAX. Optimization of the acid leaching process further enhanced the yield by around 30% from leaves. EDAX revealed significant differences in the elemental composition. The DLS histogram showed a size distribution of 62.4 nm validating Zetasizer evaluation having PdI of 0.127. The work also reports the screening of drugs through in silico approach wherein the drug risedronate showed ideal parameters satisfying the Lipinski’s rule of 5. Further, the cytotoxicity of SiNPs and SiNPs with risedronate (drug) was tested on HUVEC and Saos-2 cell lines. The SiNPs showed lesser IC50 value in comparison with risedronate and SiNPs with risedronate tested on both the cell lines. LDH assay elaborated prominent cell leakage by risedronate-anchored SiNPs which is found significant in comparison with bare SiNPs. Treatment of the osteoporotic cells with risedronate/silica blend (1:1000) revealed efficient deposition of calcium and drug in the cells as determined by microscopic observations. Drug release studies of SiNPs with risedronate were performed. FTIR indicated the presence of siloxane (Si–O–Si) and silanol (Si–OH) functional groups. In vitro study of different ratios of risedronate with silica on Saos-2 cell lines was performed to determine the mineralization potential of the combinatorial drug. It was found that the cells incubated with 0.6 mg/ml and 0.8 mg/ml of risedronate with silica showed efficient deposition of calcium inside the cells. The wild variety of Cymbopogon flexuosus could be a potential source for the extraction of SiNPs, which finds much use in biomedical applications.