Size-Dependent Surface Plasmon Resonance of Green Synthesized Gold Nanoparticles Using <i>Mangifera indica</i> Fruit Peel Extract

Abstract

Gold nanoparticles (AuNPs) have been studied for various applications due to their adjustable surface plasmon resonance (SPR) properties and facile synthesis. AuNP production has predominantly relied on synthetic chemicals to reduce and stabilize gold precursors. There is an increasing demand for environmentally friendly synthesis methods due to ecological concerns. This work introduced a green synthesis approach using Mangifera indica fruit peel extract. Obtained through maceration of dried fruit peels, this extract served as a reducing agent for gold precursors at 80°C. We obtained varying sizes of AuNPs by manipulating the initial concentration of gold ions: 0.1mM, 0.25mM, and 0.5mM. The UV-vis spectroscopy results confirmed the signature SPR peak for AuNPs around 530 nm, with peak shifts highly dependent on the gold ion concentration. The dynamic light scattering (DLS) measurements revealed hydrodynamic diameters of 89.5 nm, 121.5 nm, and 144.5 nm for the various concentrations. The Fourier transform (FTIR) analysis identified the role of inherent phenols and flavonoids in gold precursor reduction. This study emphasizes the potential of Mangifera indica fruit peel extract as a viable alternative for AuNP synthesis. This study could possibly boost the utilization of gold nanoparticles towards applications in biology and medicine as well as environmental remediation.