Colorimetric detection of biothiols and Hg²⁺ based on the peroxidase-like activity of GTP

Guanosine-5'-triphosphate (GTP) not only plays a key role in a majority of cellular processes but also be proposed as a peroxidase-like mimic. Compared with nanozymes, GTP shows good tolerance under harsh conditions, which can be used to construct an easy colorimetric analysis for the detection of biomolecules. Here, on the basis of the peroxidase-like activity of GTP which can catalyze the oxidation of 3,3',5,5'-tetramethyl benzidine dihydrochloride (TMB), colorimetric sensing was established for biothiols and Hg²⁺. Biothiols reduced the oxTMB back to colorless TMB, and Hg²⁺ restored the formation of oxTMB, leading to the recovery of color. This method not only provides a platform for the detection of metal ions and biothiols, but also shows that GTP has great potential for analytical detection.