A colorimetric sensor for acid phosphatase activity detection based on acridone derivative as visible-light-stimulated oxidase mimic.

Currently, organic artificial enzymes as biocatalysts have been extensively used to construct various colorimetric sensors. However, exploiting a potential organic artificial enzyme with high catalytic efficiency still remains a challenge. To address this issue, herein, we synthesize an acridone derivative 10-benzyl-2-amino-acridone (BAA). The synthesized BAA exhibits an intrinsic visible-light-stimulated oxidase-like activity, which is capable of oxidizing various chromogenic substrates without destructive hydrogen peroxide (H2O2) under visible light stimulation, resulting in colored products. The reaction system can be regulated by switching light on and off, which is milder and more reliable means than others H2O2-dependent. The photocatalytic mechanism of BAA is investigated in detail. However, l-ascorbic acid (AA), an antioxidant generating from the acid phosphatase (ACP)-mediated hydrolysis of 2-phospho-l-ascorbic acid (AAP), is able to inhibit the catalytic activity of BAA. Based on the above properties, a facile, photo-switchable and low-cost colorimetric sensing strategy is developed for ACP detection. The linear range is 0.05-2.5 U/L (r = 0.9994), and the limit of detection (LOD) is 0.0415 U/L. Moreover, the proposed sensing system can be applied for monitoring ACP activity in practical samples, demonstrating promising applications in clinical analysis and biosensor platform.