Engineering an amino-modified MOF@COF interface to construct a light-responsive oxidase-like nanozyme for rapid total antioxidant capacity assay in foods

A light-responsive oxidase-mimicking nanozyme was constructed based on a MOF@COF heterojunction. • The nanozyme-based colorimetric sensor enables rapid, smartphone-compatible TAC detection. • Light-driven, O₂-dependent ROS pathway enables photoregulated nanozyme design for food analysis. A rapid and accurate assay for total antioxidant capacity (TAC) is essential in food quality control and nutritional evaluation. In this study, a light-responsive oxidase-like nanozyme, UiO-66-NH 2 @TpPa-COF, was constructed by in-situ growth of TpPa-COF on amino-functionalized UiO-66-NH 2 . Comprehensive characterization confirmed a tightly coupled, crystalline, and hierarchically porous heterostructure with a narrowed band gap and enhanced charge transfer. Under 365 nm light, the composite exhibited efficient photoelectrochemical performance and oxidase-like activity via a light-driven, oxygen-dependent reactive oxygen species pathway. As a colorimetric TAC (μM AA Eq.) sensor, it achieved a wide linear range (0.02–60 μM for AA), a low detection limit (5.988 nM), and reliable performance in real samples (fruits, vegetables, beverages) with recoveries of 96–107%. This work provides both a sensitive nanozyme-based sensing platform and insights into the rational design of MOF/COF hybrids for advanced food analysis. A light-responsive oxidase-mimicking UiO-66-NH₂@TpPa-COF nanozyme was constructed via in-situ interfacial growth. Amino groups act as molecular bridges, forming a coupled heterojunction with narrowed bandgap, hierarchical porosity, and efficient charge separation. Under 365 nm UV, it shows reversible, O₂-dependent ROS-mediated oxidase activity. Integrated with a smartphone-based colorimetric platform, it enables rapid on-site TAC quantification in foods. This work offers both a practical food quality tool and a blueprint for MOF/COF heterojunctions in sensing. Download: Download high-res image (122KB) Download: Download full-size image