Process optimization for green synthesis of gold nanoparticles mediated by extract of Hygrophila spinosa T. Anders and their biological applications

Plant extract-mediated green synthesis of gold nanoparticles (AuNPs) and their biomedical application is currently gaining huge interest in the field of nanotechnology. In the present study, AuNPs were synthesized using Hygrophila spinosa aqueous extract (HSAE). The formation of AuNPs was confirmed by observing color change and characteristic absorbance peak for surface plasmon resonance by UV–Vis spectroscopy. Different reaction parameters such as HSAE concentration, salt concentration, pH, reaction time and temperature were optimized for biosynthesis of AuNPs. The NPs were characterized for particle size, surface morphology, crystallinity, elemental composition and surface functionalities. Cytotoxicity of the AuNPs was studied against different cancer cell lines by MTT assay and antioxidant potential as total antioxidant capacity was also evaluated. The biosynthesized AuNPs were small in size and negatively charged. Phytochemical screening of HSAE, and FTIR spectrum of synthesized AuNPs demonstrated participation of various groups of chemical compounds as capping and stabilizing agents in biosynthesis of AuNPs. The green synthesized AuNPs exhibited significantly higher anticancer activity compared to HSAE against breast, ovarian, glioblastoma/brain and multi-drug resistant ovarian cancer cell lines. Antioxidant activity of the synthesized AuNPs was less than HSAE. The biosynthesized AuNPs could be studied further to access their potency in the treatment and imaging of various cancers.