Synthesis of multi-spiny gold nanoparticles of controlled shape and their use as a SERS substrate for the detection of pesticide residues

Plasmonic gold nanoparticles of different shape attract much interest due to their unique physicochemical properties. Compared to gold nanorods and gold nanospheres, multi-spiny gold nanoparticles (AuNPs) with rough surfaces have higher adsorptivity and SERS activity. However, at present, one of the greatest challenges is effective tuning the density of spines of AuNPs. In this work, we describe a synthesis of AuNPs with a tunable number of spines. Furthermore, we propose a new mechanism to explain the causes of morphological evolution of AuNPs. The synthesized AuNPs with optimum number of spines exhibit extremely high sensitivity to 4-aminothiophenol, its lower limit of detection (LOD) is almost 1 nmol L−1. The SERS spectroscopy with prepared AuNPs was used to detect thiram residues in grapes, and LOD was lower than 1 µmol L−1. These results demonstrate that AuNPs are excellent SERS substrates for detection of chemical contaminants in food.