Green synthesis of gold nanoparticles using plant extracts as reducing agents

TLDR

The study proposes that specific antioxidants in plant extracts are responsible for reducing gold ions to form nanoparticles. Gold nanoparticles were synthesized by reducing gold salts with extracts from Salvia officinalis, Lippia citriodora, Pelargonium graveolens, and Punica granatum, and characterized by DLS, NTA, SEM, TEM, and IR spectroscopy, with biocompatibility assessed via L‑cell growth assays. The nanoparticles exhibited consistent size distributions across all three measurement methods, remained biocompatible and stable for over three weeks, and are suitable for imaging and drug‑delivery applications.

Abstract

Gold nanoparticles (GNPs) were prepared using four different plant extracts as reducing and stabilizing agents. The extracts were obtained from the following plants: Salvia officinalis, Lippia citriodora, Pelargonium graveolens and Punica granatum. The size distributions of the GNPs were measured using three different methods: dynamic light scattering, nanoparticle-tracking analysis and analysis of scanning electron microscopy images. The three methods yielded similar size distributions. Biocompatibility was examined by correlation of L-cell growth in the presence of different amounts of GNPs. All GNPs showed good biocompatibility and good stability for over 3 weeks. Therefore, they can be used for imaging and drug-delivery applications in the human body. High-resolution transmission electron microscopy was used to view the shapes of the larger GNPs, while infrared spectroscopy was employed to characterize the various functional groups in the organic layer that stabilize the particles. Finally, active ingredients in the plant extract that might be involved in the formation of GNPs are proposed, based on experiments with pure antioxidants that are known to exist in that plant.