Designing versatile sandwich-like magnetic Nb2O5 nanocomposites derived from Nb2C MXene for phosphopeptide enrichment.

BACKGROUND

The enrichment of phosphopeptides prior to their detection is essential for the identification of protein phosphorylation followed by matrix assisted laser desorption/ionization time-of-flight mass spectrometry because of their low concentration, low deionization efficiency and suppression from the interference derived from high-abundance counterparts. Niobium-based affinity materials have great potential in the enrichment of phosphopeptide enrichment, yet have not been extensively studied. To date, there are no reports on the application of Nb2CTx-based materials in separation science, especially in the application in phosphopeptide enrichment.

RESULTS

In this work, Nb2C MXene derived sandwich-like magnetic Nb2O5 nanocomposites (denoted as m-Nb2O5-Fe2O3) were designed and synthesized for the first time by HF-etching of Nb2AlC MAX phase, in situ growth of Fe3O4 nanoparticles and calcination in air. The nanocomposites were then applied as magnetic solid-phase extraction (MSPE) adsorbents in the enrichment of phosphopeptides through the synergistic metal oxide affinity chromatography mechanism by Nb-O and Fe-O. The MSPE method exhibited extremely low detection limit (0.1 nmol L-1 of β-casein), great anti-interference ability (1:2000 of the molar ratio of β-casein to bovine serum albumin), good reusability (3 cycles) and satisfactory recovery (87.6%). The universality of m-Nb2O5-Fe2O3 was further verified by the successful application in non-fat milk, human saliva and a traditional Chinese medicine injection.

SIGNIFICANCE: The m-Nb2O5-Fe2O3 nanocomposites are able to enrich phosphopeptides with high efficiency from diverse samples, thanks to the layered structure which provides abundant specific binding sites of Nb-O and Fe-O towards phosphate groups in phosphopeptides. The composites show great potential as a promising material for phosphopeptide enrichment from complex biological and biomedical samples.