Balancing "on" and "off" response of hydroxyl groups to a nanozyme-catalyzing system for the construction of an ultra-sensitive and selective "signal-on" detection platform for dopamine

• Published in: RSC advances Vol. 13; no. 27; pp. 18443 - 18449
• Main Authors: Lan, Hongmei, Li, Gaoya, Chen, Guo, Ding, Mengyao, Xiao, Shuangling, Xiang, Jianglin, Duan, Xingwu, Cao, Haiyan, Shi, Wenbing, Dong, Wenfei
• Format: Journal Article
• Language: English
• Published: England Royal Society of Chemistry 15.06.2023; The Royal Society of Chemistry
• Subjects: Absorbance; Balancing; Benzene; Catalytic activity; Catechol; Chemistry; Dopamine; Functional groups; Hydrogen peroxide; Hydroxyl groups; Molybdenum disulfide; Oxidation; Oxidizing agents; Peroxidase; Selectivity; Sensitivity; Substrates; Valence
• ISSN: 2046-2069; 2046-2069
• DOI: 10.1039/d3ra02946h

Targeting the functional groups present in analytes by nanozyme-catalyzed systems is a promising strategy to construct sensitive and selective platforms for the sensing of specific analytes. Herein, various groups (-COOH, -CHO, -OH, and -NH 2 ) on benzene were introduced in an Fe-based nanozyme system with MoS 2 -MIL-101(Fe) as the model peroxidase nanozyme, H 2 O 2 as the oxidizing agent, and TMB as the chromogenic substrate, and the effects of these groups at both a low concentration and high concentration were further investigated. It was found that the hydroxyl group-based substance catechol showed an "on" effect at a low concentration to increase the catalytic rate and enhance the absorbance signal, whereas an "off" effect at a high concentration with a decreased absorbance signal. Based on these results, the "on" mode and "off" mode for the biological molecule dopamine, a type of catechol derivative, were proposed. In the control system, MoS 2 -MIL-101(Fe) catalyzed the decomposition of H 2 O 2 to produce ROS, which further oxidized TMB. In the "on" mode, the hydroxyl groups of dopamine could combine with the Fe( iii ) site of the nanozyme to lower its oxidation state, resulting in higher catalytic activity. In the "off" mode, the excess dopamine could consume ROS, which inhibited the catalytic process. Under the optimal conditions, by balancing the "on" and "off" modes, the "on" mode for the detection of dopamine was found to have better sensitivity and selectivity. The LOD was as low as 0.5 nM. This detection platform was successfully applied for the detection of dopamine in human serum with satisfactory recovery. Our results can pave the way for the design of nanozyme sensing systems with sensitivity and selectivity. By balancing the "signal-on" effect in less DA and "signal-off" effect in excess DA, the "signal-on" mode for the detection of DA was proposed with higher sensitivity and selectivity.