Fabrication of bimetallic CuAg micro-flower with oxidase mimicking feature for colorimetric sensing of ascorbic acid in serum assisted by smartphone

As ascorbic acid (AA) plays a crucial role in the regulation of human redox metabolism, it is of great significance for reliable and sensitive detection AA. Considering this, heterogeneous flower-like bimetallic CuAg micro-composites (CuAg-MF) with unique oxidase-mimetic activity were fabricated to achieve the colorimetric sensing for AA. This strategy allows CuAg-MF to efficiently convert dissolved oxygen into •O 2 ¯ and catalyzes 3,3′,5,5′-tetramethylbenzidine (TMB) to generate an oxidized TMB (ox-TMB) with remarkable color changes, resulting in a colorimetric signal output. The detection of AA achieved by reducing ox-TMB in the obstruction of the chromogenic reaction, with a limit of detection (LOD) of 0.34 µM, and the performance stability, and reliability, as well as practicability were verified based on this mechanism. Notably, the integrating smartphone sensor provided portable, sensitive, rapid, and reliable detection of AA with a LOD of 0.39 µM, and excellent recoveries in environmental and food samples. This sensing platform was expected to apply as the efficient portable method and exhibit promising potential for AA monitoring in complex matrices.