Green synthesis and characterization of silver nanoparticles using Indigofera aspalathoides leaf extract and study of its Antibacterial, Antioxidant, and Anti-cancerous activities

Indigofera aspalathoides is an indigenous medicinal plant with copious phytochemical and pharmacological benefits. The crude extract from the leaves of Indigofera apalathoides aids in the bioreduction of silver nitrate into silver ions which results in the formation of colloidal silver nanoparticles. Critical physio-chemical parameters such as temperature, pH, substrate ratio (ratio of leaf extract and silver nitrate solution) and incubation time were optimized to increase the yield and efficiency of the nanoparticle formation. Synthesized nanoparticles were then characterized by performing a set of spectral analyses such as UV, FTIR, XRD, SEM, EDAX and AFM, later its bioactivity was also assessed. Characteristic UV-Vis absorption peak (λmax) at the range of 360-390 nm indicated silver nanoparticle formation and XRD pattern revealed the crystalline nature, while the average grain size was estimated to be 68.5 nm using Scherrer’s formula. SEM image clearly depicted the square shaped silver nanoparticles, which were synthesized using Indigofera aspalathoides leaf extract. Confirmation of formation of silver nanoparticles were carried out using EDAX spectrum. IC 50 value of free radical scavenging occurred at a lower concentration of 300 µg/ml, while a maximum inhibition zone of 13 mm was recorded against pathogenic bacterial strains and 6.7 mm was recorded against pathogenic fungal strains. Further, the silver nanoparticle cytotoxicity analysis was also carried out using MCF 7 cell line and IC 50 was found out to be 5.9 µg/ml. Silver nanoparticles which are green synthesized using the aqueous extract of Indigofera aspalathoides proved as an effective broad-spectrum antibiotic as well as an efficient antioxidant and an anti-cancerous agent.