Jianxi Liu

Boronic Acid Functionalized Core-Shell Polymer Nanoparticles Prepared by Distillation Precipitation Polymerization for Glycopeptide Enrichment

The boronic acid-functionalized core-shell polymer nanoparticles, poly(N,N-methylenebisacrylamide-co-methacrylic acid)@4-vinylphenylboronic acid (poly(MBA-co-MAA)@VPBA), were successfully synthesized for enriching glycosylated peptides. Such nanoparticles were composed of a hydrophilic polymer core prepared by distillation precipitation polymerization (DPP) and a boronic acid-functionalized shell designed for capturing glycopeptides. Owing to the relatively large amount of residual vinyl groups introduced by DPP on the core surface, the VPBA monomer was coated with high efficiency, working as the shell. Moreover, the overall polymerization route, especially the use of DPP, made the synthesis of nanoparticles facile and time-saving. With the poly(MBA-co-MAA)@VPBA nanoparticles, 18 glycopeptides from horseradish peroxidase (HRP) digest were captured and identified by MALDI-TOF mass spectrometric analysis, relative to eight glycopeptides enriched by using commercially available meta-aminophenylboronic acid agarose under the same conditions. When the concentration of the HRP digest was decreased to as low as 5 nmol, glycopeptides could still be selectively isolated by the prepared nanoparticles. Our results demonstrated that the synthetic poly(MBA-co-MAA)@VPBA nanoparticles might be a promising selective enrichment material for glycoproteome analysis.

Surface-Imprinted Nanoparticles Prepared with a His-Tag-Anchored Epitope as the Template

The specific recognition of biomolecules by artificial antibodies has inspired fascination among chemists and biologists. Herein, we propose a new method to prepare epitope-oriented surface-imprinted nanoparticles with high template utilization efficiency. Using a His-tag as the anchor to facilitate the epitope immobilization/removal and the self-polymerization of dopamine to control the imprinted shell thickness, the prepared epitope-imprinted nanoparticles show specific recognition of the target protein. Moreover, with improved hydrophilicity of the His-tag-anchored epitope, this method opens up a universal route for imprinting epitopes with various polarities.

Boronic Acid-Functionalized Particles with Flexible Three-Dimensional Polymer Branch for Highly Specific Recognition of Glycoproteins

A novel organic-inorganic hybrid particle with high hydrophilicity three-dimensional boronic acid functional polymer branches was facilely synthesized through thiol-ene surface-initiated click reaction, by which the target glycoprotein could be captured selectively in the 5000-fold disrupting protein. This highest selectivity ever reported demonstrated that this boronic acid functionalized particle exhibited great potential in the recognition of cis-diol-containing biomolecules, including the glycoproteins.

Multiepitope Templates Imprinted Particles for the Simultaneous Capture of Various Target Proteins

To achieve the simultaneous capture of various target proteins, the multiepitope templates imprinted particles were developed by phase inversion-based poly(ether sulfone) (PES) self-assembly. Herein, with the top three high-abundance proteins in the human plasma, serum albumin, immunoglobulin G, and transferrin, as the target proteins, their N-terminal peptides were synthesized as the epitope templates. After the preorganization of three epitopes and PES in dimethylacetamide, the multiepitope templates imprinted particles were formed in water through self-assembly, by which the simultaneous recognition of three target proteins in human plasma was achieved with high selectivity. Furthermore, the binding kinetics study proved that the adsorption mechanism in this imprinting system toward three epitope templates was the same as that on the single-epitope imprinting polymer. These results demonstrate that our proposed multiepitope templates imprinting strategy might open a new era of artificial antibodies to achieve the recognition of various targets simultaneously.

3-Carboxybenzoboroxole Functionalized Polyethylenimine Modified Magnetic Graphene Oxide Nanocomposites for Human Plasma Glycoproteins Enrichment under Physiological Conditions

Boronate affinity materials have been successfully used for the selective recognition of glycoproteins. However, by such materials, the large-scale glycoproteins enrichment from human plasma under physiological conditions is rarely reported. In this work, 3-carboxybenzoboroxole (CBX) functionalized polyethylenimine (PEI) modified magnetic graphene oxide nanocomposites were synthesized. Benefitting from the low pKa value of CBX (∼6.9) and PEI dendrimer-assisted multivalent binding, the Freundlich constant (KF) for the adsorption of horseradish peroxidase (HRP) was 3.0-7.3 times higher than that obtained by previous work, displaying the high enrichment capacity. Moreover, PEI could improve the hydrophilicity of nanocomposites and reduce nonglycoprotein adsorption. Therefore, such nanocomposites were successfully applied to the analysis of human plasma glycoproteome under physiological conditions, and the identified glycoproteins number and recognition selectivity was increased when compared to the results obtained by previous boronic acid-functionalized particles (Sil@Poly(APBA-co-MBAAm)) under common alkaline condition (137 vs 78 and 67.8% vs 57.8%, respectively). In addition, thrombin (F2), an important plasma glycoprotein, labile under alkaline conditions, was specifically identified by our method, demonstrating the great promise of such nanocomposites in the deep-coverage glycoproteome analysis.

Glycoprotein recognition by water-compatible core–shell polymeric submicron particles

Biocompatible boronate core-shell polymeric particles were grown in a unique polymerization system via a one-pot strategy making full use of the residual soluble boronate oligomer to in situ build the core-shell structure. The obtained submicron particles were shown to exhibit excellent recognition affinity toward glycoproteins with high binding capacity and specificity.

“Thiol-ene” grafting of silica particles with three-dimensional branched copolymer for HILIC/cation-exchange chromatographic separation and N-glycopeptide enrichment

AbstractThree-dimensional branched copolymer, with N,N′-methylene bisacrylamide as the crosslinker and 3-allyloxy-2-hydroxy-1-propane sulfonic acid sodium salt as the monomer, was grafted from silica particles by thiol-ene click reaction. The obtained hydrophilic material with sulfonic acid groups was successfully applied for chromatography separation and glycopeptide enrichment. The separation mechanism was proven as the mixed mode of hydrophilic interaction and cation-exchange by investigating the effect of various chromatographic factors on the retention of polar analytes. By such mixed-mode chromatography, nucleosides, nucleobases, and acidic compounds were successfully separated. The column efficiency was up to 136,000 theoretical plates m−1 for cytidine, which was much higher than those of previous reports. Furthermore, benefitting from the large amount of hydrophilic groups provided by the branched copolymer, the material was used for the selective enrichment of glycopeptides. Results demonstrated the great potential of such material for chromatography separation and glycoproteome analysis. Graphical abstractThe branched copolymer modified HILIC/cation-exchange particles Sil@Poly(AHPS-co-MBAAm) were prepared via thiol-ene click copolymerization reaction. Such Sil@Poly(AHPS-co-MBAAm) particles showed great performance in the separation of polar compounds and the enrichment of glycopeptides.