Boronic acid functionalized core-satellite composite nanoparticles for advanced enrichment of glycopeptides and glycoproteins.

A core-satellite-structured composite material has been successfully synthesized for capturing glycosylated peptides or proteins. This novel hybrid material is composed of a silica-coated ferrite "core" and numerous "satellites" of gold nanoparticles with lots of "anchors". The anchor, 3-aminophenylboronic acid, designed for capturing target molecules, is highly specific toward glycosylated species. The long organic chains bridging the gold surface and the anchors could reduce the steric hindrance among the bound molecules and suppress nonspecific bindings. Due to the excellent structure of the current material, the trap-and-release enrichment of glycosylated samples is quite simple, specific, and effective. Indeed, the composite nanoparticles could be used for enriching glycosylated peptides and proteins with very low concentrations, and the enriched samples can be easily separated from bulk solution by a magnet. By using this strategy, the recovery of glycopeptides and glycoproteins after enrichment were found to be 85.9 and 71.6% separately, whereas the adsorption capacity of the composite nanoparticles was proven to be more than 79 mg of glycoproteins per gram of the material. Moreover, the new composite nanoparticles were applied to enrich glycosylated proteins from human colorectal cancer tissues for identification of N-glycosylation sites. In all, 194 unique glycosylation sites mapped to 155 different glycoproteins have been identified, of which 165 sites (85.1%) were newly identified.