Fluorescence sensor based on layer-by-layer ligand self-assembled gold nanoclusters for on-site monitoring of...

The application of simple, sensitive, and reliable fluorescence sensors to measure trace targets still remains challenges, especially in identifying ideal fluorophores and developing innovative strategies. Herein, layer-by-layer self-assembly triple-ligand gold nanoclusters (L3-AuNCs) were developed using 6-aza-2-thiothymine, L-arginine, and trimethylphenylammonium, where the three ligands effectively suppressed the non-radiative decay of L3-AuNCs and helped achieve a high absolute quantum yield of 28.34%. More interestingly, L3-AuNCs exhibited a distinctive response to both pH and thiol compound, which can be generated through the acetylcholinesterase catalyzed hydrolysis of acetylthiocholine. Using chlorpyrifos as a model analyte, the limit of detection and linear range for the L3-AuNCs-based fluorescence sensor were 0.10 ng mL^-1 and 0.39-50 ng mL^-1, respectively. The average recoveries were 83.8%-104.4% in spiked chive, cowpea, celery, and Chinese yam samples. This research opens a new avenue for chlorpyrifos monitoring in the field of food chemistry through material technology innovation.