Superhydrophilic Nanostructured Microparticles for Enhanced Phosphoprotein Enrichment from Alzheimer’s Disease Brain

Alzheimer’s disease (AD) is an incurable neurodegenerative
disorder and closely related to abnormal phosphoproteoforms. The analysis
of low-abundance phosphoproteoforms relies heavily on the enrichment
of phosphoproteins. However, existing phosphoprotein enrichment materials
suffer from either low selectivity or low coverage due to the unavoidable
unspecific adsorption of background proteins. Here, we propose a strategy
of nanostructure-enabled superhydrophilic surfaces and synthesize
Ti4+-functionalized superhydrophilic nanostructured microparticles
(SNMs-Ti4+) via an emulsion interfacial polymerization
process. In this process, hydrophilic and hydrophobic monomers assemble
into a stable oil-in-water emulsion, producing microparticles with
abundant hydrophilic phosphate nanoprotrusions on the surface. The
microparticles are subsequently functionalized with Ti4+. SNMs-Ti4+ exhibit enormous nanoprotrusions and abundant
Ti4+ modifications, which allow SNMs-Ti4+ to
effectively adsorb the phosphoproteins and suppress the unspecific
adsorption of background proteins. Using these SNMs-Ti4+, we identified 2256 phosphoproteins from HeLa cells, twice the number
of those enriched with commercial kits. From AD mouse brains, 2603
phosphoproteins were successfully enriched, and 10 times of AD-related
differentially regulated phosphoproteins were discovered than those
without enrichment. These microparticles show great prospects for
biomarker detection, disease diagnosis, and downstream biological
process disclosure.