One-pot synthesized CoFe-PBA nanocubes with intrinsic oxidase-like activity enabling colorimetric detection of alkaline phosphatase.

Alkaline phosphatase (ALP) is an essential biomarker for clinical diagnosis and food safety monitoring, and the development of facile, low-cost, and sensitive ALP detection strategies is of great significance. Herein, uniform cobalt-based Prussian blue analogue (CoFe-PBA) nanocubes were successfully synthesized via a simple one-pot coprecipitation method. The prepared CoFe-PBA possesses intrinsic oxidase-like catalytic activity originating from mixed-valence Co2+/Co3+ and Fe2+/Fe3+ active sites, which can activate dissolved oxygen to generate superoxide anion radicals (O2˙-) for substrate oxidation. Based on this catalytic characteristic, a straightforward colorimetric sensing platform was constructed for ALP detection. The sensing strategy relies on the ALP-triggered hydrolysis of L-ascorbic acid 2-phosphate trisodium salt (AAP) to produce ascorbic acid (AA), which inhibits the 3,3',5,5'-tetramethylbenzidine (TMB) chromogenic reaction and induces dose-dependent absorbance attenuation. Under optimized conditions, the proposed sensor exhibits good linear correlation, high sensitivity, acceptable selectivity and anti-interference capability. Furthermore, spike-and-recovery assays in 50-fold diluted fetal bovine serum demonstrate the potential of the platform for ALP analysis in complex biological matrices. This work provides a simple, low-cost and efficient colorimetric strategy for ALP bioassay, which holds promising potential for clinical biochemical analysis and food safety monitoring.