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

Glycosylation: mechanisms, biological functions and clinical implications

Protein post-translational modification (PTM) is a covalent process that occurs in proteins during or after translation through the addition or removal of one or more functional groups, and has a profound effect on protein function. Glycosylation is one of the most common PTMs, in which polysaccharides are transferred to specific amino acid residues in proteins by glycosyltransferases. A growing body of evidence suggests that glycosylation is essential for the unfolding of various functional activities in organisms, such as playing a key role in the regulation of protein function, cell adhesion and immune escape. Aberrant glycosylation is also closely associated with the development of various diseases. Abnormal glycosylation patterns are closely linked to the emergence of various health conditions, including cancer, inflammation, autoimmune disorders, and several other diseases. However, the underlying composition and structure of the glycosylated residues have not been determined. It is imperative to fully understand the internal structure and differential expression of glycosylation, and to incorporate advanced detection technologies to keep the knowledge advancing. Investigations on the clinical applications of glycosylation focused on sensitive and promising biomarkers, development of more effective small molecule targeted drugs and emerging vaccines. These studies provide a new area for novel therapeutic strategies based on glycosylation.

Evaluating future strategies for sustainable growth of fiberglass composites industry in developing countries: A novel hybrid SWOT-Fuzzy extended PIPRECIA approach

The global fiberglass-composite market is expanding tremendously due to its extensive applications in the construction and automotive sector. The progress in low-medium income developing countries is slow. This study explores an exclusive hybrid model of SWOT (strengths, weaknesses, opportunities, and threats) analysis and Fuzzy extended PIPRECIA (pivot pairwise relative criteria importance assessment) to evaluate the strategies for sustainable development of fiberglass composites industry in Pakistan as a representative of low-medium developing countries. SWOT analysis is employed for examining the factors and sub-factors which have been extracted from a real-time industrial survey. While internal and external factors are also critically established to formulate a TOWS matrix comprising nine proposed strategies. Later the preferences as proposed by experts are evaluated by Fuzzy extended PIPRECIA i.e., a MCDM (multi-criteria decision making) model. Finally, SWOT factors, sub-factors and strategic choices are orderly ranked and presented. The results of the study reveal that development of a suitable environment to attract investors for the advancement and growth of the local fiber composites manufacturing industry (WO2 i.e., 0.175) is a most desirable and highly prioritized strategic choice. While maximizing environmental research to reduce environmental impact and better management of resources (WT2 i.e., 0.076) is the least favorable. The application of this exclusively developed MCDM model will provide an insight to the policy makers and assistive in strategic management and sustainable development of composite industry in developing countries. While this model can also be effective for other complex planning and decision-making processes.

Lectin-Based SP3 Technology Enables N-Glycoproteomic Analysis of Mouse Oocytes

N-glycosylation is one of the most universal and complex protein post-translational modifications (PTMs), and it is involved in many physiological and pathological activities. Owing to the low abundance of N-glycoproteins, enrichment of N-glycopeptides for mass spectrometry analysis usually requires a large amount of peptides. Additionally, oocyte protein N-glycosylation has not been systemically characterized due to the limited sample amount. Here, we developed a glycosylation enrichment method based on lectin and a single-pot, solid-phase-enhanced sample preparation (SP3) technology, termed lectin-based SP3 technology (LectinSP3). LectinSP3 immobilized lectin on the SP3 beads for N-glycopeptide enrichment. It could identify over 1100 N-glycosylation sites and 600 N-glycoproteins from 10 μg of mouse testis peptides. Furthermore, using the LectinSP3 method, we characterized the N-glycoproteome of 1000 mouse oocytes in three replicates and identified a total of 363 N-glycosylation sites from 215 N-glycoproteins. Bioinformatics analysis revealed that these oocyte N-glycoproteins were mainly enriched in cell adhesion, fertilization, and sperm-egg recognition. Overall, the LectinSP3 method has all procedures performed in one tube, using magnetic beads. It is suitable for analysis of a low amount of samples and is expected to be easily adaptable for automation. In addition, our mouse oocyte protein N-glycosylation profiling could help further characterize the regulation of oocyte functions.

Enrichment methods of N-linked glycopeptides from human serum or plasma: A mini-review

Human diseases often correlate with changes in protein glycosylation, which can be observed in serum or plasma samples. N-glycosylation, the most common form, can provide potential biomarkers for disease prognosis and diagnosis. However, glycoproteins constitute a relatively small proportion of the total proteins in human serum and plasma compared to the non-glycosylated protein albumin, which constitutes the majority. The detection of microheterogeneity and low glycan abundance presents a challenge. Mass spectrometry facilitates glycoproteomics research, yet it faces challenges due to interference from abundant plasma proteins. Therefore, methods have emerged to enrich N-glycans and N-linked glycopeptides using glycan affinity, chemical properties, stationary phase chemical coupling, bioorthogonal techniques, and other alternatives. This review focuses on N-glycans and N-glycopeptides enrichment in human serum or plasma, emphasizing methods and applications. Although not exhaustive, it aims to elucidate principles and showcase the utility and limitations of glycoproteome characterization.

Systematic characterization of extracellular glycoproteins using mass spectrometry

Surface and secreted glycoproteins are essential to cells and regulate many extracellular events. Because of the diversity of glycans, the low abundance of many glycoproteins, and the complexity of biological samples, a system-wide investigation of extracellular glycoproteins is a daunting task. With the development of modern mass spectrometry (MS)-based proteomics, comprehensive analysis of different protein modifications including glycosylation has advanced dramatically. This review focuses on the investigation of extracellular glycoproteins using MS-based proteomics. We first discuss the methods for selectively enriching surface glycoproteins and investigating protein interactions on the cell surface, followed by the application of MS-based proteomics for surface glycoprotein dynamics analysis and biomarker discovery. We then summarize the methods to comprehensively study secreted glycoproteins by integrating various enrichment approaches with MS-based proteomics and their applications for global analysis of secreted glycoproteins in different biological samples. Collectively, MS significantly expands our knowledge of extracellular glycoproteins and enables us to identify extracellular glycoproteins as potential biomarkers for disease detection and drug targets for disease treatment.

ZIC-cHILIC Functionalized Magnetic Nanoparticle for Rapid and Sensitive Glycopeptide Enrichment from <1 µL Serum

Due to their unique glycan composition and linkage, protein glycosylation plays significant roles in cellular function and is associated with various diseases. For comprehensive characterization of their extreme structural complexity occurring in >50% of human proteins, time-consuming multi-step enrichment of glycopeptides is required. Here we report zwitterionic n-dodecylphosphocholine-functionalized magnetic nanoparticles (ZIC-cHILIC@MNPs) as a highly efficient affinity nanoprobe for large-scale enrichment of glycopeptides. We demonstrate that ZIC-cHILIC@MNPs possess excellent affinity, with 80-91% specificity for glycopeptide enrichment, especially for sialylated glycopeptide (90%) from biofluid specimens. This strategy provides rapidity (~10 min) and high sensitivity (<1 μL serum) for the whole enrichment process in patient serum, likely due to the rapid separation using magnetic nanoparticles, fast reaction, and high performance of the affinity nanoprobe at nanoscale. Using this strategy, we achieved personalized profiles of patients with hepatitis B virus (HBV, n = 3) and hepatocellular carcinoma (HCC, n = 3) at the depth of >3000 glycopeptides, especially for the large-scale identification of under-explored sialylated glycopeptides. The glycoproteomics atlas also revealed the differential pattern of sialylated glycopeptides between HBV and HCC groups. The ZIC-cHILIC@MNPs could be a generic tool for advancing the glycoproteome analysis, and contribute to the screening of glycoprotein biomarkers.

A Pragmatic Guide to Enrichment Strategies for Mass Spectrometry-Based Glycoproteomics

Glycosylation is a prevalent, yet heterogeneous modification with a broad range of implications in molecular biology. This heterogeneity precludes enrichment strategies that can be universally beneficial for all glycan classes. Thus, choice of enrichment strategy has profound implications on experimental outcomes. Here we review common enrichment strategies used in modern mass spectrometry-based glycoproteomic experiments, including lectins and other affinity chromatographies, hydrophilic interaction chromatography and its derivatives, porous graphitic carbon, reversible and irreversible chemical coupling strategies, and chemical biology tools that often leverage bioorthogonal handles. Interest in glycoproteomics continues to surge as mass spectrometry instrumentation and software improve, so this review aims to help equip researchers with the necessary information to choose appropriate enrichment strategies that best complement these efforts.

Boron-Modified Defect-Rich Molybdenum Disulfide Nanosheets: Reducing Nonspecific Adsorption and Promoting a High Capacity for Isolation of Immunoglobulin G

A new type of boric acid derivative-modified molybdenum disulfide nanosheet was prepared by amination and sulfur chemical grafting, where lipoic acid, lysine, and 5-carboxybenzoboroxole were used as reactants. The two-dimensional composite, abbreviated as MoS₂-Lys-CBX, is an ultrathin nanosheet with a minimum unit of single or few layers. Compared with the original molybdenum disulfide, the nonspecific adhesion of interfering proteins on the surface was reduced, and the adsorption capacity of glycoproteins was enhanced, which was 1682.2 mg g^-1 represented by IgG. The adsorbed IgG can be easily eluted with 0.3 wt % CTAB with an elution efficiency of 94.1%. Circular dichroism spectra indicate no obvious conformation change of IgG during the purification process by the MoS₂-Lys-CBX nanosheets. The as-prepared MoS₂-Lys-CBX nanosheets were then employed for the isolation of IgG from human serum sample, obtaining high-purity light and heavy chains of IgG, as demonstrated by SDS-PAGE assays.

Signature-Ion-Triggered Mass Spectrometry Approach Enabled Discovery of N- and O-Linked Glycosylated Neuropeptides in the Crustacean Nervous System

Crustaceans are commonly used model organisms to study neuromodulation. Despite numerous reported crustacean neuropeptide families and their functions, there has been no report on neuropeptide glycosylation. This is in part due to a lack of sensitive methods that enable deciphering this intricate low-abundance post-translational modification, even though glycosylation has been shown to play an important role in neuromodulation. Here, we describe the discovery of glycosylated neuropeptides with an enrichment-free approach, taking advantage of signature oxonium ions produced in higher-energy collision dissociation (HCD) MS/MS spectra. The detection of the oxonium ions in the HCD scans suggests glycan attachment to peptides, allowing electron-transfer/higher-energy collision dissociation (EThcD) to be performed to selectively elucidate structural information of glycosylated neuropeptides that are buried in nonglycosylated peptides. Overall, 4 N-linked and 14 O-linked glycosylated neuropeptides have been identified for the first time in the crustacean nervous system. In addition, 91 novel putative neuropeptides have been discovered based on the collected HCD scans. This hybrid approach, coupling a shotgun method for neuropeptide discovery and targeted strategy for glycosylation characterization, enables the first report on glycosylated neuropeptides in crustaceans and the discovery of additional neuropeptides simultaneously. The elucidation of novel glycosylated neuropeptides sheds light on the crustacean peptidome and offers novel insights into future neuropeptide functional studies.

Boronic acid-functionalized agarose affinity chromatography for isolation of tropomyosin in fishes

BACKGROUND

Tropomyosin is now receiving increasing attention because of its significant allergenic activity in various fishery products but its simple and effective isolation still remains a challenging task.

RESULTS

An agarose-based boronate affinity chromatography was produced for the first time to isolate tropomyosin in various fishery products using 3,5-difluoro-4-formyl-phenylboronic acid as the functional monomer, tris(2-aminoethyl)amine as the multi-branched ligand, and agarose gel particles as supporting materials. The agarose concentration, binding pH, and the concentration of elution buffers demonstrated significant effects on separation performance. Under optimized conditions, the purity of the isolated tropomyosin was higher than 90%, with the column adsorption capacity over 1.85 mg mL^-1 and the enrichment efficiency over 65%. Such efficiency was also validated with different fish samples including Paralichthys olivaceus, Thunnusthynnus, Oreochromis spp., and Lophius litulon.

CONCLUSION

In comparison with conventional methods, the established affinity chromatography demonstrated excellent biocompatibility (without involving any organic solvent), better speed (from at least 1-2 days to 3-4 h), and simplicity (from at least five steps to three steps). This suggests that it is a novel and promising technique for the isolation of tropomyosin and other glycoproteins (including most allergens) in foodstuffs. © 2019 Society of Chemical Industry.

N-GlycositeAtlas: a database resource for mass spectrometry-based human N-linked glycoprotein and glycosylation site mapping

BACKGROUND

N-linked glycoprotein is a highly interesting class of proteins for clinical and biological research. The large-scale characterization of N-linked glycoproteins accomplished by mass spectrometry-based glycoproteomics has provided valuable insights into the interdependence of glycoprotein structure and protein function. However, these studies focused mainly on the analysis of specific sample type, and lack the integration of glycoproteomic data from different tissues, body fluids or cell types.

METHODS

In this study, we collected the human glycosite-containing peptides identified through their de-glycosylated forms by mass spectrometry from over 100 publications and unpublished datasets generated from our laboratory. A database resource termed N-GlycositeAtlas was created and further used for the distribution analyses of glycoproteins among different human cells, tissues and body fluids. Finally, a web interface of N-GlycositeAtlas was created to maximize the utility and value of the database.

RESULTS

The N-GlycositeAtlas database contains more than 30,000 glycosite-containing peptides (representing > 14,000 N-glycosylation sites) from more than 7200 N-glycoproteins from different biological sources including human-derived tissues, body fluids and cell lines from over 100 studies.

CONCLUSIONS

The entire human N-glycoproteome database as well as 22 sub-databases associated with individual tissues or body fluids can be downloaded from the N-GlycositeAtlas website at http://nglycositeatlas.biomarkercenter.org.

Global and site-specific analysis of protein glycosylation in complex biological systems with Mass Spectrometry

Protein glycosylation is ubiquitous in biological systems and plays essential roles in many cellular events. Global and site-specific analysis of glycoproteins in complex biological samples can advance our understanding of glycoprotein functions and cellular activities. However, it is extraordinarily challenging because of the low abundance of many glycoproteins and the heterogeneity of glycan structures. The emergence of mass spectrometry (MS)-based proteomics has provided us an excellent opportunity to comprehensively study proteins and their modifications, including glycosylation. In this review, we first summarize major methods for glycopeptide/glycoprotein enrichment, followed by the chemical and enzymatic methods to generate a mass tag for glycosylation site identification. We next discuss the systematic and quantitative analysis of glycoprotein dynamics. Reversible protein glycosylation is dynamic, and systematic study of glycoprotein dynamics helps us gain insight into glycoprotein functions. The last part of this review focuses on the applications of MS-based proteomics to study glycoproteins in different biological systems, including yeasts, plants, mice, human cells, and clinical samples. Intact glycopeptide analysis is also included in this section. Because of the importance of glycoproteins in complex biological systems, the field of glycoproteomics will continue to grow in the next decade. Innovative and effective MS-based methods will exponentially advance glycoscience, and enable us to identify glycoproteins as effective biomarkers for disease detection and drug targets for disease treatment. © 2019 Wiley Periodicals, Inc. Mass Spec Rev 9999: XX-XX, 2019.

Functionalized gold nanoparticles for sample preparation: A review

Sample preparation is a crucial step for the reliable and accurate analysis of both small molecule and biopolymers which often involves processes such as isolation, pre-concentration, removal of interferences (purification), and pre-processing (e.g., enzymatic digestion) of targets from a complex matrix. Gold nanoparticle (GNP)-assisted sample preparation and pre-concentration has been extensively applied in many analytical procedures in recent years due to the favorable and unique properties of GNPs such as size-controlled synthesis, large surface-to-volume ratio, surface inertness, straightforward surface modification, easy separation requiring minimal manipulation of samples. This review article primarily focuses on applications of GNPs in sample preparation, in particular for bioaffinity capture and biocatalysis. In addition, their most common synthesis, surface modification and characterization methods are briefly summarized. Proper surface modification for GNPs designed in accordance to their target application directly influence their functionalities, e.g., extraction efficiencies, and catalytic efficiencies. Characterization of GNPs after synthesis and modification is worthwhile for monitoring and controlling the fabrication process to ensure proper quality and functionality. Parameters such as morphology, colloidal stability, and physical/chemical properties can be assessed by methods such as surface plasmon resonance, dynamic light scattering, ζ-potential determinations, transmission electron microscopy, Taylor dispersion analysis, and resonant mass measurement, among others. The accurate determination of the surface coverage appears to be also mandatory for the quality control of functionality of the nanoparticles. Some promising applications of (functionalized) GNPs for bioanalysis and sample preparation are described herein.

Mapping human N-linked glycoproteins and glycosylation sites using mass spectrometry

N-linked glycoprotein is a highly interesting class of proteins for clinical and biological research. Over the last decade, large-scale profiling of N-linked glycoproteins and glycosylation sites from biological and clinical samples has been achieved through mass spectrometry-based glycoproteomic approaches. In this paper, we reviewed the human glycoproteomic profiles that have been reported in more than 80 individual studies, and mainly focused on the N-glycoproteins and glycosylation sites identified through their deglycosylated forms of glycosite-containing peptides. According to our analyses, more than 30,000 glycosite-containing peptides and 7,000 human glycoproteins have been identified from five different body fluids, twelve human tissues (or related cell lines), and four special cell types. As the glycoproteomic data is still missing for many organs and tissues, a systematical glycoproteomic analysis of various human tissues and body fluids using a uniform platform is still needed for an integrated map of human N-glycoproteomes.

Synthesis, characterization and properties of tropine-based ionic liquids gels

Hydrophilic ionic liquid (IL) gels based-on tropine as a potential separation material.

Mass Spectrometry-Based Chemical and Enzymatic Methods for Global Analysis of Protein Glycosylation

Glycosylation is one of the most common protein modifications, and it is essential for mammalian cell survival. It often determines protein folding and trafficking, and regulates nearly every extracellular activity, including cell-cell communication and cell-matrix interactions. Aberrant protein glycosylation events are hallmarks of human diseases such as cancer and infectious diseases. Therefore, glycoproteins can serve as effective biomarkers for disease detection and targets for drug and vaccine development. Despite the importance of glycoproteins, global analysis of protein glycosylation (either glycoproteins or glycans) in complex biological samples has been a daunting task, and here we mainly focus on glycoprotein analysis using mass spectrometry (MS)-based bottom-up proteomics. Although the emergence of MS-based proteomics has provided a great opportunity to analyze glycoproteins globally, the low abundance of many glycoproteins and the heterogeneity of glycans dramatically increase the technical difficulties. In order to overcome these obstacles, considerable progress has been made in recent years, which has contributed to comprehensive analysis of glycoproteins. In our lab, we developed effective MS-based chemical and enzymatic methods to (1) globally analyze glycoproteins in complex biological samples, (2) target glycoproteins specifically on the surface of human cells, (3) systematically quantify glycoprotein and surface glycoprotein dynamics (the abundance changes of glycoproteins as a function of time), and (4) selectively characterize glycoproteins with a particular and important glycan. In this Account, we first briefly describe the glycopeptide/protein enrichment methods in the literature and then discuss the developments of boronic acid-based methods to enrich glycopeptides for large-scale analysis of protein glycosylation. Boronic acids can form reversible covalent interactions with sugars, but the low binding affinity of normal boronic acid-based methods prevents us from capturing glycoproteins with low abundance, which often contain more valuable information. We enhanced the boronic acid-glycan interactions by using a boronic acid derivative (benzoboroxole) and conjugating it onto a dendrimer to allow synergistic interactions between the boronic acid derivative and sugars. The new method is capable of globally analyzing protein glycosylation with site and glycan structure information, especially for those with low abundance. In the next part, we discuss the combination of metabolic labeling, click chemistry and enzymatic reactions, and MS-based proteomics as a very powerful approach for surface glycoproteome analysis in human cells. The methods enable us to specifically identify surface glycoproteins and to quantify their abundance changes and dynamics together with quantitative proteomics. The last section of this Account focuses on chemical and enzymatic methods to study glycoproteins containing a particular and important glycan (the Tn antigen, i.e., O-GalNAc). Although not comprehensive, this Account provides an overview of chemical and enzymatic methods to characterize protein glycosylation in combination with MS-based proteomics. These methods will have extensive applications in the fields of biology and biomedicine, which will lead to a better understanding of glycoprotein functions and the molecular mechanisms of diseases. Eventually, glycoproteins will be identified as effective biomarkers for disease detection and drug targets for disease treatment.

Mass spectrometric analysis of the N-glycoproteome in statin-treated liver cells with two lectin-independent chemical enrichment methods

Protein N-glycosylation is essential for mammalian cell survival and is well-known to be involved in many biological processes. Aberrant glycosylation is directly related to human disease including cancer and infectious diseases. Global analysis of protein N-glycosylation will allow a better understanding of protein functions and cellular activities. Mass spectrometry (MS)-based proteomics provides a unique opportunity to site-specifically characterize protein glycosylation on a large scale. Due to the complexity of biological samples, effective enrichment methods are critical prior to MS analysis. Here, we compared two lectin-independent methods to enrich glycopeptides for the global analysis of protein N-glycosylation by MS. The first boronic acid-based enrichment (BA) method benefits from the universal and reversible interactions between boronic acid and sugars; the other method utilizes metabolic labeling and click chemistry (MC) to incorporate a chemical handle into glycoproteins for future affinity enrichment. We comprehensively compared the performance of the two methods in the identification and quantification of glycoproteins in statin-treated liver cells. Based on the current results, the BA method is more universal in enriching glycopeptides, while with the MC method, cell surface glycoproteins were highly enriched, and the quantification results appear to be more dynamic because only the newly-synthesized glycoproteins were analyzed. In addition, we normalized the glycosylation site ratios by the corresponding parent protein ratios to reflect the real modification changes. In combination with MS-based proteomics, effective enrichment methods will vertically advance protein glycosylation research.

Nanoparticle-supported polymer brushes for temperature-regulated glycoprotein separation: investigation of structure-function relationship

In this work, we synthesized a series of nanoparticle-supported boronic acid polymer brushes for affinity separation of glycoproteins. Polymer brushes were prepared by surface-initiated atom transfer radical polymerization of glycidyl methacrylate and N-isopropylacrylamide, followed by stepwise modification of the pendant as well as the end functional groups to introduce boronic acid moieties through a Cu(i)-catalyzed alkyne-azide cycloaddition reaction. We investigated the impact of the polymer structure on glycoprotein binding under different pH and temperature conditions, and established new methods that allow glycoproteins to be more easily isolated and recovered with minimal alteration in solvent composition. Our experimental results suggest that for the separation of glycoproteins, terminal boronic acids located at the end of polymer chains play the most important role. The thermo-responsibility of the new affinity adsorbents, in addition to the high capacity for glycoprotein binding (120 mg ovalbumin per g adsorbent), provides a convenient means to realize simplified bioseparation not only for glycoproteins, but also for other carbohydrate-containing biological molecules.

An enrichment method based on synergistic and reversible covalent interactions for large-scale analysis of glycoproteins

Protein glycosylation is ubiquitous in biological systems and essential for cell survival. However, the heterogeneity of glycans and the low abundance of many glycoproteins complicate their global analysis. Chemical methods based on reversible covalent interactions between boronic acid and glycans have great potential to enrich glycopeptides, but the binding affinity is typically not strong enough to capture low-abundance species. Here, we develop a strategy using dendrimer-conjugated benzoboroxole to enhance the glycopeptide enrichment. We test the performance of several boronic acid derivatives, showing that benzoboroxole markedly increases glycopeptide coverage from human cell lysates. The enrichment is further improved by conjugating benzoboroxole to a dendrimer, which enables synergistic benzoboroxole–glycan interactions. This robust and simple method is highly effective for sensitive glycoproteomics analysis, especially capturing low-abundance glycopeptides. Importantly, the enriched glycopeptides remain intact, making the current method compatible with mass-spectrometry-based approaches to identify glycosylation sites and glycan structures.

Understanding the functions of protein glycosylation critically depends on methods to efficiently enrich glycoproteins from complex samples. Here, the authors develop a strategy using dendrimer-conjugated benzoboroxole to enhance glycopeptide enrichment, providing the basis for more comprehensive glycoprotein analyses.

Glucose-sensitive polymer nanoparticles for self-regulated drug delivery

Glucose-sensitive drug delivery systems, which can continuously and automatically regulate drug release based on the concentration of glucose, have attracted much interest in recent years. Self-regulated drug delivery platforms have potential application in diabetes treatment to reduce the intervention and improve the quality of life for patients. At present, there are three types of glucose-sensitive drug delivery systems based on glucose oxidase (GOD), concanavalin A (Con A), and phenylboronic acid (PBA) respectively. This review covers the recent advances in GOD-, Con A-, or PBA-mediated glucose-sensitive nanoscale drug delivery systems, and provides their major challenges and opportunities.

Boronic Acid-Modified Magnetic Fe3O4@mTiO2 Microspheres for Highly Sensitive and Selective Enrichment of N-Glycopeptides in Amniotic Fluid

Although mesoporous materials and magnetic materials are used to enrich glycopeptides, materials sharing both mesoporous structures and magnetic properties have not been reported for glycopeptide analyses. Here we prepared boronic acid-modified magnetic Fe₃O₄@mTiO₂ microspheres by covalent binding of boronic acid molecules onto the surfaces of silanized Fe₃O₄@mTiO₂ microspheres. The final particles (denoted as B-Fe₃O₄@mTiO₂) showed a typical magnetic hysteresis curve, indicating superparamagnetic behavior; meanwhile, their mesoporous sizes did not change in spite of the reduction in surface area and pore volume. By using these particles together with conventional poly(methyl methacrylate) (PMMA) nanobeads, we then developed a synergistic approach for highly specific and efficient enrichment of N-glycopeptides/glycoproteins. Owing to the introduction of PMMA nanobeads that have strong adsorption towards nonglycopeptides, the number of N-glycopeptides detected and the signal-to-noise ratio in analyzing standard proteins mixture both increased appreciably. The recovery of N-glycopeptides by the synergistic method reached 92.1%, much improved than from B-Fe₃O₄@mTiO₂ alone that was 75.3%. Finally, we tested this approach in the analysis of amniotic fluid, obtaining the maximum number and ratio of N-glycopeptides compared to the use of B-Fe₃O₄@mTiO₂ alone and commercial SiMAG-boronic acid particles. This ensemble provides an interesting and efficient enrichment platform for glycoproteomics research.

Designed synthesis of ultra-hydrophilic sulfo-functionalized metal-organic frameworks with a magnetic core for highly efficient enrichment of the N-linked glycopeptides

Highly efficient extraction and enrichment of the N-linked glycopeptides from complex biological samples before mass spectrometry analysis remains important but challenging, due to the low abundance and suppression by proteins and salts. Herein, a facile route to an ultra-hydrophilic metal-organic frameworks (MOFs)-functionalized magnetic nanoparticle (Fe₃O₄@PDA@Zr-SO₃H) was proposed. The as-prepared MOFs was endowed with excellent and unique properties, such as excellent hydrophilicity, ultrahigh surface area, and strong magnetic responsiveness. By virtue of these properties and based on hydrophilic interaction, Fe₃O₄@PDA@Zr-SO₃H exhibited outstanding sensitivity and selectivity, remarkable recyclability and stability towards N-linked glycopeptide enrichment. In deep, a total of 177 N-linked glycopeptides, assigned to 85 different glycoproteins, were identified from the healthy human serum after treated with the Fe₃O₄@PDA@Zr-SO₃H. These results confirmed that our strategy offered a promising platform for preparing hydrophilic metal-organic framework-functionalized magnetic nanoparticles for glycosylation analysis by mass spectrometry analysis.

Designed synthesis of a "One for Two" hydrophilic magnetic amino-functionalized metal-organic framework for highly efficient enrichment of glycopeptides and phosphopeptides

Highly efficient enrichment of glycopeptides or phosphopeptides from complex biological samples is indispensable for high-throughput mass spectrometry analysis. In this study, for the first time, a "one for two" hydrophilic magnetic amino-functionalized metal-organic framework (MOF) was designed and synthesized for selective enrichment of both glycopeptides and phosphopeptides. A well-known solvo-thermal reaction was adopted to prepare a magnetic core Fe₃O₄, followed by self- polymerization of dopamine, creating a polydopamine (PDA) onto Fe₃O₄. Thanks to the hydroxyl and amino group of PDA, Zr³⁺ was easily adhered to the surface, inducing the following one-pot MOF reaction with amino ligand. After characterization of the as-prepared MOFs (denoted as Fe₃O₄@PDA@UiO-66-NH₂), its ultrahigh surface area, excellent hydrophilicity and strong magnetic responsiveness were highly confirmed. Based on hydrophilic interaction, it was applied to glycopeptide enrichment, while based on strong binding between Zr and phosphopeptides, it was applied to phosphopeptide enrichment, both exhibiting excellent performance in standard proteins and human serum with high sensitivity and selectivity. These results showed the as-prepared MOFs had great potential in proteomics research.

Temperature and pH Dual-Responsive Core-Brush Nanocomposite for Enrichment of Glycoproteins

In this report, we present a novel modular approach to the immobilization of a high density of boronic acid ligands on thermoresponsive block copolymer brushes for effective enrichment of glycoproteins via their synergistic multiple covalent binding with the immobilized boronic acids. Specifically, a two-step, consecutive surface-initiated atom transfer radical polymerization (SI-ATRP) was employed to graft a flexible block copolymer brush, pNIPAm-b-pGMA, from an initiator-functionalized nanosilica surface, followed by postpolymerization modification of the pGMA moiety with sodium azide. Subsequently, an alkyne-tagged boronic acid (PCAPBA) was conjugated to the polymer brush via a Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) click reaction, leading to a silica-supported polymeric hybrid material, Si@pNIPAm-b-pBA, with a potent glycol binding affinity. The obtained core-brush nanocomposite was systematically characterized with regard to particle size, morphology, organic content, brush density, and number of immobilized boronic acids. We also studied the characteristics of glycoprotein binding of the nanocomposite under different conditions. The nanocomposite showed high binding capacities for ovalbumin (OVA) (98.0 mg g^-1) and horseradish peroxidase (HRP) (26.8 mg g^-1) in a basic buffer (pH 9.0) at 20 °C. More importantly, by adjusting the pH and temperature, the binding capacities of the nanocomposite can be tuned, which is meaningful for the separation of biological molecules. In general, the synthetic approach developed for the fabrication of block copolymer brushes in the nanocomposite opened new opportunities for the design of more functional hybrid materials that will be useful in bioseparation and biomedical applications.

Phenylboronic acid-functionalized core–shell magnetic composite nanoparticles as a novel protocol for selective enrichment of fructose from a fructose–glucose aqueous solution

We developed an efficient and mild method for the preparation of boronic acid-functionalized magnetic nanoparticles (MNPs), and the selective separation of fructose from a sample solution was demonstrated for the first time.

pH-Responsive magnetic nanospheres for the reversibly selective capture and release of glycoproteins

We present a pH-stimuli-responsive strategy to reversibly capture and release glycoproteins with high selectivity from a pure protein, model protein mixture and even a real biological sample.

Preparation of novel anionic polymeric ionic liquid materials and their potential application to protein adsorption

A series of novel anionic polymeric ionic liquid materials were prepared and used to adsorb bovine hemoglobin from bovine blood.

Functionalization of Planet-Satellite Nanostructures Revealed by Nanoscopic Localization of Distinct Macromolecular Species

The development of a straightforward method is reported to form hybrid polymer/gold planet-satellite nanostructures (PlSNs) with functional polymer. Polyacrylate type polymer with benzyl chloride in its backbone as a macromolecular tracer is synthesized to study its localization within PlSNs by analyzing the elemental distribution of chlorine. The functionalized nanohybrid structures are analyzed by scanning transmission electron microscopy, electron energy loss spectroscopy, and spectrum imaging. The results show that the RAFT (reversible addition-fragmentation chain transfer) polymers' sulfur containing end groups are colocalized at the gold cores, both within nanohybrids of simple core-shell morphology and within higher order PlSNs, providing microscopic evidence for the affinity of the RAFT group toward gold surfaces.

Hybrid Approach Combining Boronate Affinity Magnetic Nanoparticles and Capillary Electrophoresis for Efficient Selection of Glycoprotein-Binding Aptamers

Capillary electrophoresis (CE) and magnetic beads have been widely used for the selection of aptamers owing to their efficient separation ability. However, these methods alone are associated with some apparent drawbacks. CE suffers from small injection volumes and thereby only a limited amount of aptamer can be collected at each round. While the magnetic beads approach is often associated with tedious procedure and nonspecific binding. Herein we present a hybrid approach that combines the above two classical aptamer selection methods to overcome the drawbacks associated with these methods alone. In this hybrid method, one single round selection by boronate affinity magnetic nanoparticles (BA-MNPs) was first performed and then followed by a CE selection of a few rounds. The BA-MNPs-based selection eliminated nonbinding sequences, enriching effective sequences in the nucleic acid library. While the CE selection, which was carried out in free solutions, eliminated steric hindrance effects in subsequent selection. Two typical glycoproteins, Ribonuclease B (RNase B) and alkaline phosphatase (ALP), were used as targets. This hybrid method allowed for efficient selection of glycoprotein-binding aptamers within 4 rounds (1 round of BA-MNPs-based selection and 3 rounds of CE selection) and the dissociation constants reached 10^-8 M level. The hybrid selection approach exhibited several significant advantages, including speed, affinity, specificity, and avoiding negative selection. Using one of the selected ALP-binding aptamers as an affinity ligand, feasibility for real application of the selected aptamers was demonstrated through constructing an improved enzyme activity assay.

Mapping and analyzing the human liver proteome: progress and potential

INTRODUCTION

The liver is an important organ in humans. Hepatocellular carcinoma (HCC) is one of the deadliest cancers in the world. Progress in the Human Liver Proteome Project (HLPP) has improved understanding of the liver and the liver cancer proteome.

AREAS COVERED

Here, we summarize the recent progress in liver proteome modification profiles, proteomic studies in liver cancer, proteomic study in the search for novel liver cancer biomarkers and drug targets, and progress of the Chromosome Centric Human Proteome Project (CHPP) in the past five years in the Institutes of Biomedical Sciences (IBS) of Fudan University. Expert commentary: Recent advances and findings discussed here provide great promise of improving the outcome of patients with liver cancer.

Zirconium-doped magnetic microspheres for the selective enrichment of cis-diol-containing ribonucleosides

Zirconium-doped magnetic microspheres (Zr-Fe3O4) for the selective enrichment of cis-diol-containing biomolecules were easily synthesized via a one-step hydrothermal method. Characterization of the microspheres revealed that zirconium was successfully doped into the lattice of Fe3O4 at a doping level of 4.0 at%. Zr-Fe3O4 possessed good magnetic properties and high specificity towards cis-diol molecules, as shown using 28 compounds. For ribonucleosides, the adsorbent not only has favorable anti-interferential abilities but also has a high adsorption capacity up to 159.4μmol/g. As an example of a real application, four ribonucleosides in urine were efficiently enriched and detected via magnetic solid-phase extraction coupled with high-performance liquid chromatography. Under the optimized extraction conditions, the detection limits were determined to be between 0.005 and 0.017μg/mL, and the linearities ranged from 0.02 to 5.00μg/mL (R≥0.996) for these analytes. The accuracy of the analytical method was examined by studying the relative recoveries of the analytes in real urine samples, with recoveries varying from 77.8% to 119.6% (RSDs<10.6%, n=6). The results indicate that Zr-Fe3O4 is a suitable adsorbent for the analysis of cis-diol-containing biomolecules in practical applications.