Green fabrication, characterization of silver nanoparticles using aqueous leaf extract of Ocimum americanum (Hoary Basil) and investigation of its in vitro antibacterial, antioxidant, anticancer and photocatalytic reduction

Abstract

Green fabrications of metallic nanoparticles are rapidly developing the research era, due to their broad spectrum of applications in the field of biomedical sciences. In the present study, the green fabrication of silver nanoparticles (AgNPs) has been demonstrated by a highly stable, biocompatible, and environmental friendly aqueous leaf extract of Ocimum americanum for their antibacterial, anticancerous, and photocatalytic dye degradation efficiency. The synthesized AgNPs were confirmed by UV–Visible spectroscopy, which indicates the surface plasmon resonance λmax band at 435 nm. The FE-SEM and HR-TEM micrographs showed spherical shaped AgNPs, and EDX analysis confirmed the crystalline purity of green fabricated AgNPs. Fourier transform infrared (FT-IR) technique indicated the presence of active functional groups such as O‒H, C˭C, C‒H, C‒N involved in the reduction and surface capping agent of green fabricated AgNPs. The XRD analysis of synthesized AgNPs showed the face-centered cubic (fcc) crystalline structure. The DLS measurement showed average particle size of distribution was 48.25 nm and Zeta potential value at −20.2 mV revealed high stability of fabricated AgNPs. Further, the synthesized AgNPs has exhibited potential antibacterial activity against pathogenic Gram +ve and Gram −ve bacteria and in-vitro antioxidant activity assessed by DPPH, H2O2 and reducing power assays. The in-vitro cytotoxic effects of fabricated AgNPs against A549 lung cancer cells displayed apoptotic cell death confirmed by fluorescent staining techniques and the cellular apoptotic induction of G0/G1 cell cycle arrest confirmed with the flow cytometry analysis. On the other hand, the AgNPs exhibited efficient photocatalytic dye degradation of eosin yellow (EY) under sunlight and UV-irradiation method. The AgNPs did not lyse the hemoglobin from human red blood cells and showed its biocompatibility on human cells. Herein, the present study proves an effective, economical, and multifunctional AgNPs for improved therapeutic and catalytic applications.