Biogenic synthesis and characterization of silver nanoparticles using strobilanthes crispus and in-vitro determination of antioxidant activity

The aim of this study was to determine the antioxidant activity of biogenic synthesized silver nanoparticles (AgNPs) using Strobilanthes crispus. The formation of AgNPs using S.crispus was confirmed by using characterization techniques included UV-Vis spectrum, FTIR, XRD, SEM and EDS analysis. Sunlight was used as catalyst to induce the bioreduction of silver ion. Optical observation of colour changes from mixture of S.crispus and silver nitrate solution was pre-confirmation step for formation of AgNPs. UV-Vis spectroscopy showed 448 nm surface plasmon resonance (SPR) peak of silver has proved the synthesis of AgNPs. FTIR analysis showed the 0-H group, C-H group, N-H group and C-O-C group which are found responsible in bioreduction and stabilization of AgNPs. XRD analysis showed crystalline face centered cubic structure of synthesized AgNPs. SEM showed the size of synthesized AgNPs was less than 5 µm. EDS showed the elemental composition of AgNPs was 77.28% silver and 22.72 % chlorine in weight percentage. Through DPPH assay, both S.crispus leaf extract and synthesized AgNPs showed moderate antioxidant activity. Further study on mechanism of action of synthesized AgNPs using S.crispus is necessary to develop clinical diagnostics and application of targeted drug delivery.