Green synthesis of silver nanoparticles using Hyptis suaveolens (L.) Poit leaf extracts, their characterization and cytotoxicity evaluation against PC-3 and MDA-MB 231 cells

The green synthesis of nanoparticles using plant extracts is an efficient eco-friendly approach. The present study is aimed at investigating the green synthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Hyptis suaveolens and evaluation of their cytotoxicity against cancer cells. The formation of AgNPs upon incubation of AgNO3 with leaf extract was identified by color change (yellow to brown), further confirmed by characteristic UV-visible absorbance peak at 436nm. The Extended dispersive X-ray spectroscopy in turn confirmed elemental silver content in green synthesized AgNPs (G.S.AgNPs). The scanning and transmission electron microscopy revealed randomly dispersed spherical shaped particles in a size range of 20-80nm. The X-ray diffraction spectroscopy has shown distinct Bragg diffraction peaks corresponding to the planes of face centered cubic lattice, indicating crystalline nature of G.S.AgNPs. The Dynamic light scattering spectroscopy has shown average size distribution of NPs ranging from 80 to 207nm, certainly higher as it measures the size of entire complexion of organic capping layer with the nanoparticle. The Zeta potential of G.S.AgNPs in water was found to be -13.7mV, reflecting their higher stability. Further, the Fourier transform infrared spectroscopy revealed the leaf extract's phenolic compounds and certain proteins responsible for the biological reduction of Ag+ and stabilization of AgNPs. The MTT assay has shown prominent cytotoxic activity of G.S.AgNPs against PC-3 and MDA-MB 231 cells with IC50 values of 63.16 and 52.49g/ml respectively. Overall, the study clearly indicates efficient synthesis of AgNPs, which can have a scope for the application in cancer therapy.