Herein, we develop a rapid, sensitive and selective approach for the colorimetric detection of DA using AuNPs, with theoretical simplicity
and low technical demands. In alkaline solution, DA capps and aggregates AuNPs (DA-AuNPs) due to the covalent and noncovalent
interactions between DA and AuNPs The DA-AuNPs are modified by the hydrolysate of thioglycolic acid (TGA2) through Au–S bonds Due to the strong hydrogen-bonds (NH⋯OC and OH⋯OC) formed between TGA2 and DA, the AuNPs are further aggregated With the increase of DA concentrations, the color of AuNPs gradually changes from an initial red to purple, then gray and finally yellow
shows the probable mechanism for the detection of DA. Due to the strong covalent and noncovalent interactions between DA and AuNPs DA caps and aggregates AuNPs (DA-AuNPs) in alkaline solution