Green synthesis and biomedicinal applications of silver and gold nanoparticles functionalized with methanolic extract of <i>Mentha longifolia</i>

Abstract

This study deals with facile and rapid synthesis of silver nanoparticles (AgNPs) and Gold nanoparticles (AuNPs) using <i>Mentha longifolia</i> leaves extracts (MLE). The synthesized AgNPs and AuNPs were characterized by UV-visible spectroscopy (UV-Vis), Fourier transformed infra-red spectroscopy (FT-IR), atomic force microscopy (AFM) and transmission electron microscopy (TEM) techniques. The phytochemical analysis showed the presence of bioactive secondary metabolites, which are involved in the synthesis of nanoparticles (NPs). The surface plasmon resonance (SPR) observed at 435 and 550 nm, confirmed the green synthesis of AgNPs and AuNPs, respectively. The TEM images showed poly dispersed and round oval shapes of Ag and Au NPs with an average particles size of 10.23 ± 2 nm and 13.45 ± 2 nm, respectively. TEM results are in close agreements with that of AFM analysis. The FT-IR spectroscopy revealed the presence of OH, -NH₂ and C = O groups, which involved in the synthesis of NPs. The MLE and their AgNPs and AuNP exhibited good <i>in vitro</i> antibacterial and anti-oxidant activities. Moreover, MLE and NPs also showed <i>in vivo</i> analgesic activities in mice, and excellent sedative properties in open field test paradigm.