Metal-organic framework-sealed heterogeneous nanoenzyme: A dual-mode core–shell sensor for sensitive determination of the chlorpyrifos residue in environment and bioaccumulation in food

A metal–organic framework hybrid-based nanoenzyme is developed for dual-mode sensitive detection of pesticide chlorpyrifos and its bioaccumulation . • A MOF-sealed hybrid nanoenzyme system is designed for sensing pesticide chlorpyrifos. • A dual-mode sensing strategy is realized sensitively and selectively. • The sensor showed a detection limit of chlorpyrifos with 0.2 ng mL −1 by fluorescence. • The bioaccumulation of chlorpyrifos in vegetables is determined. • The strategy can be extended as a general analysis platform against pesticide. Developing efficient and intelligent method for analyzing harmful agrochemicals like organophosphorus pesticides plays a crucial role in food and environmental safety surveillance. Herein, a metal–organic framework (MOF)-sealed heterogeneous nanoenzyme was designed for monitoring the bioaccumulation of chlorpyrifos in vegetables. The hybrid named CeO x @fZIF was sequentially prepared through cerium oxide (CeO x ) as the core, and Cu(II)-centered zeolitic imidazolate framework (ZIF) as shell, which encapsulated fluorescence dye. The fluorescence from the encapsulated dye and the colorimetric signal from the catalytic product by the inner nanoenzyme CeO x were synchronously blocked by the outer ZIF shell of CeO x @fZIF. Under the alkaline phosphatase (ALP) enzyme-mediated reduction of Cu(II) in the ZIF shell, the obstruction of shell was relieved with the shell collapse. The enzymatic capability of inner CeO x for colorimetric catalysis and the dye fluorescence were synergistically recovered in a controllable way. Accompanied with the chlorpyrifos-inhibited capability for ALP, a fluorescence/colorimetric dual-signal sensor was fabricated. The dual-mode signal of CeO x @fZIF-based nanosystem exhibited a strong linear correlation with chlorpyrifos concentrations, achieving the detection limit of 0.2 ng/mL in fluorescence and 15 ng/mL in colorimetric. This strategy was assessed across various food matrices and had an outstanding reaction with a high percentage of recovery. Furthermore, the nanoenzyme system was employed to determine chlorpyrifos accumulation in pakchoi. The presented nanosystem exploited the feasibility of MOF-controlled nanoenzyme sensor and lighted up a facile pathway to prepare dual-mode sensor of pesticide monitoring for food and ecological environment safety.