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
Jintong Liu, Jie Tang, Yanyang Mo, Lin Zhou, Tingting Cai, Hong Yang
Abstract
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.