Azadirachta indica based biosynthesis of silver nanoparticles and evaluation of their antibacterial and cytotoxic effects

Abstract

Due to the growing threat to the environment by the climate change, the development of sustainable and environmental friendly methods for the preparation of metallic nanoparticles (NPs) is highly desirable. Herein, we demonstrate a simple and eco-friendly method for the preparation of silver nanoparticles (AgNPs) using Azadirachta indica leaf extract and aqueous solution of silver nitrate (AgNO3). The effect of concentration of leaf extract and temperature on the synthesis of AgNPs is studied. It was revealed that 1 mM of AgNO3, leaf extract concentration of 60 mg/mL, 30 min of reaction time and a temperature 85 °C were found to be optimum for the synthesis good quality AgNPs. The formation of AgNPs was confirmed by UV–Vis analysis, where the UV spectrum exhibited a highest absorption peak at ∼410 nm corresponding to the surface Plasmon Resonance (SPR) of the AgNPs. Furthermore, the antibacterial activity of biosynthesised AgNPs was investigated and the inhibitory concentrations of 0.5 µg/mL for Escherichia coli and 1.0 µg/mL for Staphylococcus aureus were found. Besides, the in vitro cytotoxicity investigation of biosynthesized AgNPs against human acute lymphoblastic leukemia cells via MTT assay showed that the minimum inhibitory concentration of 15.6 µg/mL was required. Therefore, the eco-friendly and cost effective synthesis of AgNPs has potential for biomedical applications and this method can be used for the large scale production of AgNPs. Keywords: Azadirachta indica, AgNPs, Biosynthesis, Antimicrobial activities, Cytotoxicity