A covalent organic framework (COF)-MnO2 based dual signal sensing platform for sensitive alkaline phosphatase activity detection via dynamic regulating the mimicking oxidase content

It is of great significance to accurately monitor the alkaline phosphatase (ALP) level as it plays an important role in living body activities. Herein, we develop a COF- MnO₂ system for ALP activity detection via the dynamic regulating the MnO₂ nanosheets content. MnO₂ nanosheets with oxidase-mimicking property can oxide the colorless 3,3′,5,5′-Tetramethylbenzidine (TMB) into blue oxidized TMB (oxTMB). The hexagonal structure and ordered mesoporous channels of DMTP-TAPB COF provide excellent space to accommodate the product oxTMB. The confinement of the dye molecules into COF structure leads to enhance color change and obvious fluorescence quench of the sensing system. The fluorescence quenching and color change dependent on the ALP level as it can dynamic regulate the MnO₂ content via the enzymatic hydrolysis of ascorbate-2-phosphate. Therefore, a COF-MnO₂ based dual signal sensing platform is successfully constructed to detect ALP activity, giving detection limit of 0.11 U L^-1 and 0.23 U L^-1 for fluorescence and colorimetric procedures, respectively. The practical application of the designed sensing platform is verified through the detection of ALP activity in serum samples, and satisfactory results are obtained.