Fig. 1.

UV–visible spectroscopic analysis of 1 GAuNPs, 2 GSH, and 3 lipoic acid-stabilized GAuNPs 1 the blue line indicates the peak at a wave length of 500–550 nm fir GAuNPs, 2 the dashed line indicates the peak at a wave length of 550–600 nm for GSH-GAuNPs, 3 the green dotted line indicates the peak at a wave length of 600–650 nm for LA-GAuNPs. The beakers a, b, and c imply the color change after the addition of auro chloric acid to grape extract, GSH, and lipoic acid a AUNPs synthesized from grape extract, b GAuNPs stabilized and capped with glutathione, c GAuNPs stabilized and capped with lipoic acid