Catechol oxidase nanozyme based colorimetric sensors array for highly selective distinction among multiple catecholamines

In order to effectively monitor multiple catecholamine (CA) neurotransmitters with extreme similar structures, a rapid, sensitive and selective detection strategy has become an urgent problem to be solved. In this paper, a novel colorimetric sensors array based on CuNCs protected by various ligands such as tannic acid, ascorbic acid and polymethylacrylic acid (CuNCs@TA, CuNCs@AA and CuNCs@PMAA) was constructed. All of these CuNCs could mimic catechol oxidase to selective catalyze catechol-type analogues (such as CAs) to corresponding quinones along with color changes. Furthermore, experiments and theory calculations demonstrated that Cr6+-modification on the surface of CuNCs facilitated the steady-state kinetics of enzymatic activity. Based on these CuNCs as sensing probes, this sensors array can quickly detect different CAs (such as epinephrine (EP), including dopamine (DA), norepinephrine (NE) and l-dopa) with similar structures. When those analogues were added to the CuNC-based colorimetric array sensors, different absorbance changes were produced at 485 nm. Linear discriminant analysis (LDA) showed that the tri-probe colorimetric array sensors could recognize and distinguish these analogues, and corresponding binary and ternary mixtures could be well categorized. The value of Factor 1 of an array with varied CA concentrations had a good linear correlation, and the detection limit (LOD) was as low as 10−8∼10−9 mol/L. Four CA analogues in real samples were identified by CuNCs-based colorimetric array sensors. This work provides a fast and convenient experimental basis for monitoring the complex structure CAs neurotransmitters. CuNCs-based catechol oxidase nanozymes to build tri-probe colorimetric sensor array for determination of multiple catecholamines. [Display omitted] •A novel colorimetric sensors array was designed for sensitive and selective detection of multiple CAs.•The CuNCs stabilized by TA, AA and PMAA ligands were capable to imitate enzyme of catechol oxidase.•Modification of Cr6+ on the surface of CuNCs was in favor of enhancing the catalytic activity.