Justicia adhatoda L. mediated green synthesis of silver nanoparticles and assessment of their antioxidant, hydrogen peroxide sensing and optical properties

Abstract

ABSTRACT In this report, a green synthesis practice has been adopted to fabricate silver nanoparticles (AgNPs) using Justicia adhatoda L. leaf extract (JALE). The phytosynthesized AgNPs present a characteristic SPR peak at 446 nm. Comparative FTIR analyses of JALE and AgNPs revealed the input of phytochemicals in the reduction, capping and stabilisation of J. adhatoda-mediated silver nanoparticles (JA@AgNPs). The crystalline nature and face-centred cubic lattice plane of JA@AgNPs were explained by XRD. SEM and TEM revealed a spherical shape having about ~19 nm mean NPs size. JA@AgNPs displayed significant inhibition potency against DPPH and ABTS free radicals and thus could be convenient in biomedical applications. Furthermore, the green-synthesised JA@AgNPs presented SPR-based colorimetric detection of H2O2 with exceptional sensing, which exhibited its usefulness in accessing reactive oxygen species in biological samples and waterbodies. The bandgap energy of JA@AgNPs was calculated as 3.3 eV, which revealed its semiconductor behaviour.