“Green” Synthesis and Antioxidant Activity of Thermally Stable Gold Nanoparticles Encapsulated in Carbon Nanosheets

Vincent K S Hsiao,Jia-Yi Wang,Hui-Wen Lin,Chih-Chien Chu

doi:10.3390/app10072272

Abstract

We have developed a “green” method for fabricating gold nanoparticles (AuNPs) through biogenic approaches. The proposed method has the advantages of facile preparation under ecofriendly conditions. AuNPs encapsulated in carbon nanosheets, and exhibiting high thermal stability, were fabricated by autoclaving pectin-capped AuNPs, which were subsequently collected through high-speed centrifugation and redispersed in aqueous solution. The 1,1-diphenyl-2-picrylhydrazy (DPPH) radical scavenging assay indicated that our prepared AuNPs exhibited more prolonged antioxidant capacity than pristine apple extracts. Electron paramagnetic resonance (EPR) spectra showed that approximately 80% of DPPH radicals were scavenged by the pectin-capped AuNPs at a concentration of 3 mg/mL. According to our results, AuNPs prepared through biogenic approaches have potential use in the food industry.

Highlights

Biogenic approaches for synthesizing gold nanostructures with unique chemophysical and biological properties have received considerable attention in the last decade [1]
AuNPs were first fabricated through a standard one-pot single-step synthesis process in the presence of sodium citrate, apple extracts, and with the precursor, a HAuCl4 water solution
The sodium-citrate-stabilized AuNPs could not recover their redispersion ability; this indicates the instability of sodium-citrate-capped AuNPs in water solution and demonstrate that such AuNPs cannot be applied in the food industry

Summary

Introduction

Biogenic approaches for synthesizing gold nanostructures with unique chemophysical and biological properties have received considerable attention in the last decade [1]. “Green” synthesis methods typically entail adopting environmentally friendly protocols based on natural or biological agents such as nature gums [2], fruit extracts [3,4,5,6,7,8], plant tissues (including leaf, fruit, peel, flower, and root) [9,10,11,12,13,14,15] for synthesis. In one-pot single-step synthesis methods, biological extracts are mixed with an auric salt (HAuCl4 ) solution at either room or elevated temperature and conversion occurs within a few minutes in the absence of external additives used as reducing, stabilizing, or capping agents.

Methods

Results

Conclusion