Facile Removal of Phytochromes and Efficient Recovery of Pesticides Using Heteropore Covalent Organic Framework-Based Magnetic Nanospheres and Electrospun Films

Abstract

Nontargeted analysis of food safety requires selective removal of interference matrices and highly efficient recovery of chemical hazards. Porous materials such as covalent organic frameworks (COFs) show great promise in selective adsorption of matrix molecules via size selectivity. Considering the complexity of interference matrices, we prepared crystalline heteropore COFs whose two kinds of pores have comparable sizes to those of several common phytochromes, main interference matrices in vegetable sample analysis. By controlling the growth of COFs on the surface of Fe 3 O 4 nanoparticles or by utilizing a facile co-electrospinning method, heteropore COF-based magnetic nanospheres or electrospun nanofiber films were prepared, respectively. Both the nanospheres and the films maintain the dual-pore structures of COFs and show good stability and excellent reusability. Via simple magnetic separation or immersion operation, respectively, they were successfully used for the complete removal of phytochromes and highly efficient recovery of 15 pesticides from the extracts of four vegetable samples, and the recoveries are in the range of 83.10−114.00 and 60.52−107.35%, respectively. Film-based immersion operation gives better sample pretreatment performance than the film-based filtration one. This work highlights the great application potentials of heteropore COFs in sample pretreatment for nontargeted analysis, thus opening up a new way to achieve high-performance sample preparation in many fields such as food safety analysis, environment monitoring, and so on.

Current Applications of Magnetic Nanomaterials for Extraction of Mycotoxins, Pesticides, and Pharmaceuticals in Food Commodities

“…In another study, a non-target analysis of over 204 pesticides was carried out by developing a magnetic blade-spray tandem mass spectrometry assay (MBS-MS/MS) [ 196 ]. In addition, the identification of pesticides and phytochromes from vegetables using heteropore covalent organic framework coated with magnetic nanosphere was reported [ 197 ]. The studies highlight the potential application of MNMs for sample pretreatment for non-target analytes.…”

Covalent Organic Framework Composites: Synthesis and Analytical Applications

“…Furthermore, the COF particles were firmly bound within the PBI-BuI backbone, not allowing the COF to leach out from the polymer matrix. Electrospinning has been used to gain access to COF-based films [74]. Dual-pore COF was first synthesized using 4,4′,4′′,4′′′-(ethane-1,1,2,2-tetrayl)tetraaniline (ETTA) and [1,1′-biphenyl]-4,4′-dicarbaldehyde (BPDA) as monomers, and dispersed homogeneously in DMF with polyacrylonitrile (PAN) to obtain the spinning solution.…”

“…Furthermore, the films maintained the dual-pore structure of the COF and showed good stability and excellent reusability in removing phytochromes from vegetable extracts by filtration or immersion. Electrospinning has been used to gain access to COF-based films [74]. Dual-pore COF was first synthesized using 4,4 ,4",4 -(ethane-1,1,2,2-tetrayl)tetraaniline (ETTA) and [1,1 -biphenyl]-4,4dicarbaldehyde (BPDA) as monomers, and dispersed homogeneously in DMF with polyacrylonitrile (PAN) to obtain the spinning solution.…”

“…A dual-pore COF based on the combination of ETTA and BPDA building blocks was successfully embedded in PAN matrix by electrospinning (for synthesis, see Section 2.8) [74]. The resulting PAN/COF nanofiber films were applied for TFME of phytochromes and pesticides in food extracts.…”

“…(c) Digital photo and (d) SEM image of the PAN@COF film. Reprinted with permission from[74]. Copyright (2020) American Chemical Society.…”