Post-modified porous hollow nanospheres incorporating multiple strategies for comprehensive phosphoproteomics analysis of serum of Alzheimer's disease

Abstract

Alzheimer's disease (AD), as a neurodegenerative disease, has become a major disease threatening the physical and mental health of the elderly. In order to find potential cost-effective and valuable AD biomarkers from human serum, we developed and designed a post-modified functional nanomaterial denoted as H–CeO2@PEI-Ti with a porous hollow structure modified with polyethyleneimine (PEI) and Ti4+. This post-modified porous hollow nanomaterial integrated multiple enrichment strategies, including immobilized metal ion affinity chromatography (IMAC) and metal oxide affinity chromatography (MOAC) with electrostatic interaction synergy and hydrogen bond assistance was applied to the phosphoproteomics for the first time. The experimental results demonstrated good performance in the enrichment of standard phosphoprotein tryptic digests, such as extremely low detection limit (0.02 fmol), excellent selectivity (1:5000 M ratio of β-casein and BSA), given that the large specific surface area created by the special porous hollow structure. In serum analyses, 49 phosphopeptides corresponding to 31 phosphoproteins were identified in the serum of the normal controls, and 49 phosphopeptides corresponding to 32 phosphoproteins in AD patients. More importantly, some functional items based on Gene Ontology (GO) analysis after enrichment for human serum supported the molecular biological processes that may be related to the pathogenesis of AD, including copper ion binding, heparin binding and retinoid metabolism.