Zinc pyrovanadate nanorods with excellent peroxidase-like activity at physiological pH for the colorimetric assay of H2O2 and epinephrine

Abstract

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 (Zn₃V₂O₇(OH)₂·2H₂O) 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 H₂O₂ at physiological pH (pH = 7) in 2 min. In addition, the catalytic behaviors of Zn₃V₂O₇(OH)₂·2H₂O as a peroxidase-like nanozyme conform to the Michaelis–Menten equation. Scavenger experiments prove that the catalytic activity of Zn₃V₂O₇(OH)₂·2H₂O is ascribed to ˙O₂⁻ radicals generated in the process of catalysis. Based on the peroxidase-like activity of the Zn₃V₂O₇(OH)₂·2H₂O nanozyme, a fast and convenient colorimetric sensor has been constructed to detect H₂O₂ 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 H₂O₂ in milk and EP in serum.