Zinc pyrovanadate nanorods with excellent peroxidase-like activity at physiological pH for the colorimetric assay of H 2 O 2 and epinephrine.

Exploring highly active peroxidase mimics at physiological pH is important for the construction of efficient and convenient colorimetric sensing platforms for detecting small biomolecules. In this work, prepared zinc pyrovanadate (Zn 3 V 2 O 7 (OH) 2 ·2H 2 O) nanorods exhibit excellent peroxidase-like activity, which is verified by the fast oxidation of colorless 3,3',5,5'-tetramethylbenzidine (TMB) into a blue product (oxTMB) by H 2 O 2 at physiological pH (pH = 7) in 2 min. In addition, the catalytic behaviors of Zn 3 V 2 O 7 (OH) 2 ·2H 2 O as a peroxidase-like nanozyme conform to the Michaelis-Menten equation. Scavenger experiments prove that the catalytic activity of Zn 3 V 2 O 7 (OH) 2 ·2H 2 O is ascribed to ˙O 2 - radicals generated in the process of catalysis. Based on the peroxidase-like activity of the Zn 3 V 2 O 7 (OH) 2 ·2H 2 O nanozyme, a fast and convenient colorimetric sensor has been constructed to detect H 2 O 2 and epinephrine (EP) under physiological pH. The detection limit of EP is as low as 0.26 μM. In addition, the feasibility of the proposed sensor has been validated to detect H 2 O 2 in milk and EP in serum.