Boosting the phosphatase-like activity of UiO-66 nanozyme by introducing open metal sites for enhanced immunoassay

The phosphatase-like activity of UiO-66 was improved by introducing OMS. • UiO-66-OMS exhibited twice the catalytic activity of pristine UiO-66. • This enhanced activity results from enlarged pores and boosted Lewis acidity. • A sensitive colorimetric immunoassay was developed for the detection of CEA. UiO-66 with open metal sites (UiO-66-OMS) nanozymes were synthesized via defect engineering through the introduction of benzoic acid as a modulator during UiO-66 synthesis. As a monocarboxylic acid analogous to the organic ligand 1,4-benzenedicarboxylic acid (BDC), benzoic acid competes with BDC for coordination to Zr O clusters, thereby creating abundant coordinatively unsaturated open metal sites while preserving the crystal structure of UiO-66. Using 4-nitrophenyl phosphate ( p -NPP) as the model colorimetric substrate, UiO-66-OMS exhibited enhanced phosphatase-like catalytic activity, which was twice that of pristine UiO-66. Mechanistic investigations revealed that the increased activity stems from the enlarged pore size and specific surface area of the nanozyme, as well as its enhanced Lewis acidity. By employing UiO-66-OMS as an antibody label, a sensitive colorimetric immunoassay was developed for the detection of carcinoembryonic antigen (CEA), with a linear range of 10–400 ng/mL and a limit of detection of 1.17 ng/mL. This study offers a new strategy for the development of highly active MOF-based nanozymes. Download: Download high-res image (111KB) Download: Download full-size image