Atomically-precise Au24Ag1 Clusterzymes with Enhanced Peroxidase-like Activity for Bioanalysis

Atomically-precise clusterzymes have been widely studied for their special physicochemical properties, but it is still a challenge to enhance their peroxidase-like activity. Herein, we demonstrated that by substituting a single Ag atom into Au(25 )nanoclusters to form Au24Ag1 nanoclusters, the peroxidase-like activity was enhanced greatly. In the presence of H2O2, Au24Ag1 could produce reactive oxygen species(ROS) to oxidize colorless 3,3'5,5'-tetramethylbenzidine(TMB) to the blue oxidized TMB (oxTMB). It is worth mentioning that pyrophosphate compounds inhibit the activity of Au 24 Ag i . Since alkaline phosphatase(ALP) can dephosphorylate the substrate phosphate compound, that is, remove the phosphate group on the substrate by hydrolysis, the enzymatic activity of the clusterzyme is restored. Based on this, we have developed a sensitive and reliable colorimetric sensing system for the detection of pyrophosphate ion(PPi), adenosine triphosphate(ATP), adenosine diphosphate(ADP) and ALP, respectively. Importantly, the detection limit of the assay system is lower than those of most of the assays that have been reported. In addition, we also built a simple optical logic gate on this basis, further extending the application of metal nanoclusters as peroxidase mimics in bioanalysis. This work could help to shed light on the structure-activity relationship of nanozyme.