Magnetic MXene/PAMAM Composites with Flexible Dimensional Regulation for Highly Effective Enrichment of Phosphopeptides

Highly specific enrichment of phosphopeptide
is the prerequisite
for in-depth phosphoproteome research and remains a long-standing
challenge. In this work, MXenes, a new family of two-dimensional materials
which have large specific surface area, flexible functionalization,
and unique topological structure, have been applied to construct a
novel phosphopeptide enrichment platform with great convenience by
combining dimensional regulation with functional modification to prepared
multidimensional polyamidoamine (PAMAM) dendrimer functionalized magnetic
MXene composites (denoted as Ti3C2Tx@PAMAM@Fe3O4). The different
dimensions of Ti3C2Tx@PAMAM@Fe3O4 composites exhibited dimension-dependent
enrichment performance in both standard proteins and biological samples
ascribed to their different surface properties and amount of affinity
sites, indicating the effectiveness of dimension in regulating the
enrichment ability. Owing to their superior properties, the two-dimensional
Ti3C2Tx@PAMAM@Fe3O4 composites showed better enrichment performance
with high sensitivity (1 fmol μL–1), excellent
selectivity (β-casein:BSA = 1:800, molar ratio), good reusability
(five times), large enrichment capacity (200 mg g–1), and great practicability in identifying low-abundance phosphopeptides
from nonfat milk, human serum, human saliva, and rat brain lysate.
This work held great promise for future practical applications in
comprehensive phosphoproteomics analysis and extended the application
of MXene in the biological field.