A facile photothermometric sensor of acid phosphatase based on CoOOH nanozymes-mediated 3,3′,5,5′-tetramethylbenzidine photothermal system

Nanozymes-catalyzed 3,3′,5,5′-tetramethylbenzidine (TMB) reaction systems have been extensively used for fabricating colorimetric sensors, but they still require advanced instruments like color analysis software or ultraviolet spectrophotometers to achieve accurate quantitative analysis. Herein, we explored an alternative strategy to convert a color readout to a temperature readout of a CoOOH nanoflakes-TMB colorimetric reaction system, and successfully fabricated a simple and facile photothermometric sensor of acid phosphatase (ACP) by using a common thermometer as the reader. It mainly performed based on the strong photothermal effect of the oxidation product (TMBox) of TMB upon an 808 nm near-infrared (NIR) laser irradiation, which showed a close relationship with the ACP content with a lower limit of detection (LOD) of 0.037 mU/mL for photothermometric ACP determination. This photothermometric method was proved to be suitable for not only sensing ACP but also screening its inhibitor in human serum, and providing a simple, rapid, convenient, low cost, and portable organic chromogenic substrate-based sensing platform.