In this work, small size 4-mercaptophenylboronic acid functionalized gold nanoparticles (the particle size was about 3 nm) were synthesized by a simple, one-step sodium borohydride reduction method. Based on the formation of diesters between boric acid group and cis-diol of glycoprotein/glycopeptieds, it was successfully applied to selectively enrich glycoprotein and glycopeptide. Using this material to enrich glycopeptides in the tryptic digests of HRP, the MS signals of glycopeptides were nearly hundredfold enhanced. The boronic acid functionalized nanoparticles were used to selectively capture of glycoprotein from rat liver. 1589 unique glycosylation sites mapped to 156 different glycoproteins have been identified and the molecular functions of these identified glycoproteins were analyzed. Results showed that some glycoproteins, for example Hspa8 and Shc1, played important biological roles related to liver disease.

Key words: 4-mercaptophenylboronic acid, gold nanoparticle, small size, enrichment, glycoprotein, mass spectrometry, rat liver