Fe3O4@COF(TAPT-DHTA) Nanocomposites as Magnetic Solid-Phase Extraction Adsorbents for Simultaneous Determination of 9 Mycotoxins in Fruits by UHPLC-MS/MS.

In this study, a simple and efficient magnetic solid-phase extraction (MSPE) strategy was developed to simultaneously purify and enrich nine mycotoxins in fruits, with the magnetic covalent organic framework nanomaterial Fe3O4@COF(TAPT-DHTA) as an adsorbent. The Fe3O4@COF(TAPT-DHTA) was prepared by a simple template precipitation polymerization method, using Fe3O4 as magnetic core, and 1,3,5-tris-(4-aminophenyl) triazine (TAPT) and 2,5-dihydroxy terephthalaldehyde (DHTA) as two building units. Fe3O4@COF(TAPT-DHTA) could effectively capture the targeted mycotoxins by virtue of its abundant hydroxyl groups and aromatic rings. Several key parameters affecting the performance of the MSPE method were studied, including the adsorption solution, adsorption time, elution solvent, volume and time, and the amount of Fe3O4@COF(TAPT-DHTA) nanomaterial. Under optimized MSPE conditions, followed by analysis with UHPLC-MS/MS, a wide linear range (0.05-200 µg kg-1), low limits of detection (0.01-0.5 µg kg-1) and satisfactory recovery (74.25-111.75%) were achieved for the nine targeted mycotoxins. The established method was further successfully validated in different kinds of fruit samples.

A flexible assay strategy for non-glucose targets based on sulfhydryl-terminated liposomes combined with personal glucometer.

The personal glucose meter (PGM) is one of the most successful point-of-care (POC) testing devices. It is simple, robust and inexpensive, but cannot be easily adapted to analytes other than glucose. We report a novel chemical conjugation-based assay strategy, using rational design of chemically-derivatized glucose-encapsulating liposomes, to repurpose a PGM, taking an important mycotoxin patulin as the model analyte. Sulfhydryl (-SH) was proposed for the first time as a specific functional group for efficient recognition of patulin. Multifunctional sulfhydryl-terminated glucose-encapsulating liposomes (G-LIP-SH) were synthesized in a simple, single step, which efficiently captured patulin by covalent bonding, and interacted strongly with NH2-Au@Fe3O4 nanoparticles. Magnetic removal of nanoparticles efficiently and selectively separated patulin-derivatized from un-derivatized G-LIP-SH, permitting the latter to be lysed and the released glucose measured by PGM. The PGM signal was inversely proportional to the patulin concentration, over the range of 0.1-50 ng mL-1 (R2 = 0.995) with a detection limit of 0.05 ng mL-1 (S/N = 3). This approach overcame interference from endogenous glucose, other mycotoxins and metal ions, allowing the analysis of a wide range of sample matrices and showed high specificity, acceptable reproducibility, good accuracy and optimal applicability. Other derivatization chemistries will enable this approach to be adapted to analytes with a wide range of chemical structures, to facilitate development of rapid, portable, user-friendly and cost-effective assays applicable to diverse analytes and sample matrices.