Green synthesis of Ag, Au and Ag-Au bimetallic nanoparticles using Stigmaphyllon ovatum leaf extract and their in vitro anticancer potential

Abstract Noble metals nanoparticles have shown interesting prospects towards biomedical applications, and their bimetallic counterparts are envisaged to be more promising. In this study, the Stigmaphyllon ovatum leaf extract was used for the synthesis of silver, gold and silver-gold bimetallic nanoparticles (AgNPs, AuNPs and Ag-Au BNPs) in an aqueous medium. Surface plasmon bands were obtained at 420, 550 and 542 nm for the AgNPs, AuNPs and Ag-Au BNPs respectively. Only one absorption band was observed in the spectra of the bimetallic nanoparticles, which suggested the formation of a nanoalloy. Particle sizes of about 24, 80 and 15 nm were obtained for the AgNPs, AuNPs and Ag-Au BNPs respectively. The effect of the nanoparticles on Human cervical carcinoma (HeLa) cells revealed cytotoxic effects towards the growth of the carcinoma cells with the IC50 values of 5.75 × 10−16, 9.1 × 10−9 and 0.0027 µM for the Ag-Au BNPs, AgNPs and AuNPs, respectively. The nanoparticles were excellently efficient compared to the standard drug, 5-fluorouracil with an IC50 value of 40 µM. These nanoparticles however opened up new perspectives in research and may provide promising alternative approaches for nano-drug development in the next generation of effective anticancer drugs.