Intrinsically peroxidase-mimicking RuO2–CNF nanozyme for colorimetric determination and monitoring of dopamine in PC12 cells

Abstract

This work presents a dual-functionality nanozyme with intrinsic peroxidase-like activity based on ruthenium oxide-modified carbon nanofibers (RuO₂–CNF). Electrospinning was employed as a simple and efficient method to produce modified CNF. These studies indicated that the colorimetric sensor system exhibited excellent intrinsic peroxidase-like activity in the presence of H₂O₂, leading to the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) and color change from colorless to blue. In this report, we also propose a strategy for the development of a colorimetric dopamine sensor for the selective determination of dopamine. Detailed studies demonstrate that dopamine significantly inhibits the activity of the prepared nanozyme. The color difference exhibits high sensitivity and increases linearly within the 5–35 μM dopamine concentration range. Under optimal conditions, the detection limit of the proposed sensor for dopamine was determined to be 0.36 μM. Our sensor, introduced by its simplicity and high reproducibility, provides a reliable tool for monitoring dopamine released from PC12 cells. Subsequently, upon the addition of dopamine hydrochloride, the solution's color changed from blue to colorless.