Synthesis and characterisation of gold nanoparticles using Mentha piperita leaf extract: a green, non-toxic and rapid method

Abstract

Eco-friendly synthesis of gold nanoparticles (AuNPs) using Mentha piperita leaf extract was addressed in this work. Different extract concentrations (0.5, 1.0 and 1.5% w/v) were used for the synthesis of AuNPs. Reaction rate increased with temperature and leaf extract concentration; however, prolonged heating might affect negatively the AuNPs synthesis. AuNPs in colloid state were synthesised in acid pH (between 2.5 and 3.1), with potentials for charged surface between –21.8 and –24.1 mV, these colloids were highly stable for a storage time of four weeks. Bioreduction has generated AuNPs with spherical and triangular shape and size range between 3–26 nm for all concentrations of leaf extract, indicating a weak dependence of the nanoparticle size on extract concentrations. The present work, thus, offers a simple, rapid and non-toxic process for the synthesis of AuNPs that would potentially be used in different areas such as foods, cosmetic, medicine, electronics and polymer science.