Ni(2+)-modified gold nanoclusters for fluorescence turn-on detection of histidine in biological fluids

In this work, Ni(2+)-modified gold nanoclusters were fabricated for fluorescence turn-on detection of histidine. The fluorescence of Au NCs was first quenched by Ni(2+). Then, the addition of histidine can restore the fluorescence of Au NCs by binding with Ni(2+) and removing it from the surface of the Au NCs. This architecture ensured non-toxic, cost-effective, label-free and sensitive detection of histidine. The developed Au NCs-based fluorescent sensor offered high selectivity for histidine over other amino acids. The relative standard deviation (RSD) for eleven replicate detections was 2.7%. The detection limit for histidine is 30 nM. The recovery of spiked histidine in human urine samples ranges from 95 to 104%.