Acid phosphatase biosensing via Prussian Blue-Functionalized heterometallic covalent organic framework nanozymes

The assessment of acid phosphatase (ACP) levels is of significant importance for evaluating a variety of physiological and pathological conditions, monitoring disease progression and guiding clinical therapy. We engineered a platform for ACP sensitive detection utilizing Prussian blue (PB)-incorporated heterometallic covalent organic framework (COF) nanozyme. The synthesized COF@PB/AuPt NPs demonstrate a synergistic enhancement in peroxidase-like catalytic activity originating from the combined action of PB and AuPt NPs. The introduction of COF as a support matrix endows the nanozyme with remarkable dispersity and stability, maintaining functionality even after prolonged storage for six months. The COF@PB/AuPt nanozyme can facilitate the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to oxidized TMB (oxTMB) under H₂O₂-rich conditions, which can be inhibited by reductive ascorbic acid (AA). Concurrently, ACP catalyzes the hydrolysis of L-ascorbic acid-2-phosphate into AA, which can effectively inhibit the oxidation reaction of TMB. The sensitive assay for ACP has been successfully executed, achieving a remarkably low detection limit of 2.2 mU/L. The platform demonstrates exceptional selectivity against enzymatic interferents and robust analytical performance in complex biological matrices, as evidenced by recoveries of 95-107 % and RSD below 5 % in fetal bovine serum, underscoring its potential for clinical diagnostics and biomedical research.