Potato-chip-like two-dimensional magnetic trimetallic oxides derived from MXene-MOF nanocomposites for fast enrichment of phosphopeptides

Both MXenes and metal-organic frameworks (MOFs) have been attracting lots of attention since being found and have been applied in various fields. Furthermore, MXene-MOF composites have been recently studied to combine the advantages of MXenes and MOFs. However, the synthesis of MXene-MOF composites still suffers from questions such as low-efficiency of exfoliation of MXenes to layered nanosheets, uneven distribution of MOF nanoparticles on MXene nanosheets and extra modification process before the growth of MOF nanoparticles. To resolve these problems, herein, a sonication-assisted minimally intensive layer delamination (SA-MILD) method was proposed to achieve high yield of thin-layer Ti 3 C 2 T x MXene nanosheets. Then, a stirring in-situ growth method (SISG) was carried out to uniformly grow UiO-66–NH 2 nanoparticles on Ti 3 C 2 T x nanosheets to form two-dimensional potato-chip-like Ti 3 C 2 –UiO-66–NH 2 nanocomposites instead of conventional solvothermal method for the first time. Finally, MXene-MOF composites were calcined to increase the chemical stability and endowed with magnetism by the in-situ oxidation growth of Fe 3 O 4 nanoparticles. Thanks to the massively exposed Ti O, Zr O and Fe O sites, the well-characterized magnetic trimetallic oxides (MTMOs) could enrich phosphopeptides by easy magnetic separation through metal oxide affinity chromatography mechanism in a short time. High sensitivity (0.5 nmol∙L −1 of α −/ β -casein) and great anti-interference ability (1:1:2000 of the molar ratio of α −/ β -casein to bovine serum albumin) were realized for the efficient enrichment of phosphopeptides with MTMOs. Non-fat milk and traditional Chinese medicine injections were used as the examples to explore the biomedical applicability of the as-prepared MTMOs with excellent results.