Self-Powered CaO2/Heme@Zn-MOF Enabled Fluorescence Immunosensing Strategy for Accurate and Selective Isoprocarb Monitoring.

Accurate and sensitive detection of pesticide residues is crucial for environmental safety and human health. Herein, a self-powered metal-organic framework nanozyme-based immunoassay was developed for selective and sensitive detection of isoprocarb by encapsulating calcium peroxide and heme into a Zn-MOF to construct the CaO2/heme@Zn-MOF composite. The prepared nanozyme exhibits intrinsic peroxidase-like activity and enables in situ H2O2 generation under acidic conditions, effectively eliminating the need for external oxidants. By coupling antibody-antigen specific recognition with catalytic signal amplification of CaO2/heme@Zn-MOF, a competitive nanozyme-linked immunosorbent assay was established for selective detection of isoprocarb. The fluorescence signal originating from o-phenylenediamine oxidation gradually decreases with an increase in isoprocarb concentration, allowing quantitative analysis with a detection limit of 0.017 μM. The entire competitive immunoassay can be completed within an optimal detection time of 90 min. Furthermore, the proposed method demonstrates excellent practical reliability and anti-interference capability in real water and agricultural products, achieving quantitative recovery rates ranging from 92.85% to 107.14% with relative standard deviations of less than 5.91%. Furthermore, a portable immunomagnetic bead with paper devices was fabricated for on-site analysis. This work provides a general strategy for integrating self-powered nanozymes with immunoassays, thereby expanding their potential for portable environmental monitoring.