Solvothermal Synthesis of Novel Magnetic Nickel Based Iron Oxide Nanocomposites for Selective Capture of Global- and Mono-Phosphopeptides

A facile solvothermal method was developed for synthesis
of magnetic
nickel-based iron oxide nanocomposites (MNFOs) with different ratios
of Ni2+ to Fe3+ for different reaction time.
Two factors including dosage of Ni source and length of reaction were
investigated for influence on the morphology and composition of MNFOs,
as well as their distinct selectivity for different phosphopeptides.
After thorough characterization, the possible formation mechanism
of MNFOs was proposed. Very interestingly, MNFOs with Ni2+/Fe3+ ratios of 4:5 prepared for 8 h (MNFO-S) and for
24 h (MNFO-L) can selectively capture global- and monophosphopeptides
at the fmol level with excellent enrichment performance. These two
affinity probes have been exploited to isolate and enrich the phosphopeptides
from human normal hepatic cells HL 7702 after exposure to atmospheric
fine particulates (PM2.1), which revealed that the protein
phosphorylation level was increased significantly in cells after stimulation
by fine particulate matters. The findings could provide a new insight
for the nickel-based affinity protocol to analyze the mutation of
phosphopeptides during cellular signaling pathways in response to
exogenous environment stimulation. Consequently, this present work
proposed a promising strategy to isolate monophosphopeptides from
global phosphopeptides for phosphoproteome research.