Diethylenetriamine assisted functionalization of boronic acid on poly GMA-MAA-DVB for selective enrichment of glycoproteins and glycopeptides

Electrospun Fiber Membrane with the Dual Affinity of Chelation and Covalent Interactions for the Efficient Enrichment of Glycoproteins

As important biomarkers of many diseases, glycoproteins are of great significance to biomedical science. It is essential to develop efficient glycoprotein enrichment platforms and investigate their adsorption mechanism. In this work, a conspicuous enrichment strategy for glycoproteins was developed by using an electrospun fiber membrane wrapped with polydopamine (PDA) and modified with 3-aminophenylboronic acid and nickel ions, named PAN/DA@PDA@APBA/Ni. The enrichment characteristics of PAN/DA@PDA@APBA/Ni toward glycoproteins were explored through adsorption behavior. Thanks to the existence of two sites of interaction (metal ion chelation and boronate affinity), PAN/DA@PDA@APBA/Ni exhibited significant enrichment capacity for glycoproteins, ovalbumin (604.6 mg/g), and human immunoglobulin G (331.0 mg/g). The adsorption kinetic results of glycoprotein ovalbumin on PAN/DA@PDA@APBA/Ni conform to the pseudo-first-order kinetic model in the first adsorption stage, while the second half adsorption stage is more in line with the pseudo-second-order kinetic model. Moreover, the physical characteristics of PAN/DA@PDA@APBA/Ni and subsequent adsorption experiments on electrospun fiber modified with only phenylboronic acid or nickel ions both confirmed two sites of interaction (metal ion chelation and boronate affinity, respectively). Furthermore, a stepwise elution method with dual-affinity interaction was designed and successfully applied to enrich glycoproteins in real biological samples. This work provides an idea for sample pretreatment, especially for the design of dual-affinity materials in glycoproteins enrichment.

Biosensors with Boronic Acid-Based Materials as the Recognition Elements and Signal Labels

It is of great importance to have sensitive and accurate detection of cis-diol-containing biologically related substances because of their important functions in the research fields of metabolomics, glycomics, and proteomics. Boronic acids can specifically and reversibly interact with 1,2- or 1,3-diols to form five or six cyclic esters. Based on this unique property, boronic acid-based materials have been used as synthetic receptors for the specific recognition and detection of cis-diol-containing species. This review critically summarizes the recent advances with boronic acid-based materials as recognition elements and signal labels for the detection of cis-diol-containing biological species, including ribonucleic acids, glycans, glycoproteins, bacteria, exosomes, and tumor cells. We also address the challenges and future perspectives for developing versatile boronic acid-based materials with various promising applications.

Hydrophilic, dual amino acid-functionalized zinc sulfide quantum dot for specific identification of N-glycopeptides from biological samples

RATIONALE

Glycosylation of proteins is one of the most significant and complex post-translational modifications, and N-glycosylation plays a crucial role in life activities. Mass spectrometry (MS) has been a powerful technique in the analysis of protein glycosylation. However, the direct detection of glycoproteins in biological samples based on MS still suffers from huge challenges. Therefore, enrichment and purification of samples before MS analysis is an essential prerequisite.

METHODS

Hydrophilic interaction liquid chromatography (HILIC) has significantly developed for selective enrichment of glycopeptides due to its simple operation process and unbiased enrichment. Herein, hydrophilic, dual amino acid-functionalized zinc sulfide quantum dots (ZnS QDs) were prepared to enrich glycopeptides using an easy procedure. The enriched glycopeptides were detected using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS).

RESULTS

The obtained material exhibited high selectivity (1:2000), low detection limit (0.1 fmol/μl), good repeatability (10 times), and excellent recovery (89.8%) in glycopeptide enrichment. In the actual application in biological samples, 71 N-glycopeptides and 161 N-glycopeptides were detected from human saliva and serum, respectively.

CONCLUSIONS

ZnS-Au-GC was successfully prepared using an easy method. The results showed that the obtained material exhibited excellent performance in glycopeptide enrichment. Furthermore, it had showed great potential for glycopeptide enrichment in complex biological samples.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2019-2020

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2020. Also included are papers that describe methods appropriate to analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. The review is basically divided into three sections: (1) general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, quantification and the use of arrays. (2) Applications to various structural types such as oligo- and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals, and (3) other areas such as medicine, industrial processes and glycan synthesis where MALDI is extensively used. Much of the material relating to applications is presented in tabular form. The reported work shows increasing use of incorporation of new techniques such as ion mobility and the enormous impact that MALDI imaging is having. MALDI, although invented nearly 40 years ago is still an ideal technique for carbohydrate analysis and advancements in the technique and range of applications show little sign of diminishing.

Nanopore-Based Single-Entity Electrochemistry for the Label-Free Monitoring of Single-Molecule Glycoprotein-Boronate Affinity Interaction and Its Sensing Application

Nanopipettes provide a promising confined space that enables advances in single-molecule analysis, and their unique conical tubular structure is also suitable for single-cell analysis. In this work, functionalized-nanopore-based single-entity electrochemistry (SEE) analysis tools were developed for the label-free monitoring of single-molecule glycoprotein-boronate affinity interaction for the first time, and immunoglobulin G (IgG, one of the important biomarkers for many diseases such as COVID-19 and cancers) was employed as the model glycoprotein. The principle of this method is based on a single glycoprotein molecule passing through 4-mercaptophenylboronic acid (4-MPBA)-modified nanopipettes under a bias voltage and in the meantime interacting with the boronate group from modified 4-MPBA. This translocation and affinity interaction process can generate distinguishable current blockade signals. Based on the statistical analysis of these signals, the equilibrium association constant (κ_a) of single-molecule glycoprotein-boronate affinity interaction was obtained. The results show that the κ_a of IgG in the confined nanopore at the single-molecule level is much larger than that measured in the open system at the ensemble level, which is possibly due to the enhanced multivalent synergistic binding in the restricted space. Moreover, the functionalized-nanopore-based SEE analysis tools were further applied for the label-free detection of IgG, and the results indicate that our method has potential application value for the detection of glycoproteins in real samples, which also paves way for the single-cell analysis of glycoproteins.

A novel hydrophilic hydrogel with a 3D network structure for the highly efficient enrichment of N-glycopeptides

A novel super-hydrophilic hydrogel (ZIF-8/SAP) was first proposed and facilely fabricated to capture N-glycopeptides from complex biological samples with excellent selectivity and sensitivity.

A review on recent advances in the enrichment of glycopeptides and glycoproteins by liquid chromatographic methods: 2016-Present

Among various protein post-translational modifications (PTMs), glycosylation has received special attention due to its immense role in molecular interactions, cellular signal transduction, immune response, etc. Aberration in glycan moieties of a glycoprotein is associated with cancer, diabetes, and bacterial and viral infections. In biofluids (plasma, saliva, urine, milk, etc.), glycoproteins are low in abundance and are masked by the presence of high abundant proteins. Hence, prior to their identification using mass spectrometry methods, liquid chromatography (LC)-based approaches were widely used. A general enrichment strategy involves a protein digestion step, followed by LC-based enrichment and desorption of glycopeptides, and enzymatic excision of the glycans. The focus of this review article is to highlight the articles published since 2016 that dealt with different LC-based approaches for glycopeptide and glycoprotein enrichment. The preparation of stationary phases, their surface activation, and ligand immobilization strategies have been discussed in detail. Finally, the major developments and future trends in the field have been summarized.

ZIF-based boronic acid functionalized metal-organic frameworks for the enrichment of cis-diol-containing luteolin from food samples prior to HPLC

Zeolite imidazole framework-based boronic acid-functionalized metal-organic frameworks (ZIF-67@PDA@BA-Zr-MOFs) were developed as an adsorbent for solid phase extraction (SPE) of luteolin (LTL) from peanut shell samples. Herein, ZIF-67 as a support matrix, polydopamine (PDA) as a coating to introduce amino and hydroxyl groups on the matrix surface to fix metal-organic frameworks (MOFs), zirconium tetrachloride (ZrCl₄) as a precursor, terephthalic acid (TPA), and 3-carboxyphenylboronic acid (3-CPBA) as the mutual organic building blocks, and 3-CPBA was also a boronate affinity functional monomer. The effects of synthesis conditions, SPE conditions, selectivity, competitivity, reproducibility, and reusability were evaluated in detail. Under the optimal conditions, the maximum adsorption capacity is 71.4 mg g^-1. The utility of ZIF-67@PDA@BA-Zr-MOFs as an adsorbent for SPE of LTL is supported by the presence of the abundant pore structure, as well as the boronate affinity sites facilitated the rapid binding of the adsorbent to the template. The concentration of the extracted LTL was determined by the high-performance liquid chromatography-ultraviolet (HPLC-UV), with calibration plots being linear in the concentration range 0.05-100 mg L^-1 and a limit of detection (LOD) of 0.035 mg L^-1. The method was applied to determine the LTL in peanut shell samples and recovered the target analyte in the range 85.6% to 99.2% (the standard deviations are less than 3.3%, n = 3). In addition, we incorporated boronate affinity and MOFs material into an SPE system to provide a promising strategy to detect other cis-diol-containing analytes in the complex matrix.

Flexible and hierarchical metal-organic framework composite as solid-phase media for facile affinity-tip fabrication to selectively enrich glycopeptides and phosphopeptides

Micro-tip-based solid-phase microextraction is considered as one of the green and powerful analytical sample preparation techniques, but its efficiency is severely hampered by some basic issues such as tedious fabrication, instability of sorbent bed, and blocking of the tip, especially for biological samples due to low permeability. These issues are tackled by introducing a flexible and hierarchical substrate in the microtip, having good mechanical strength and specific functionality to capture the desired biomolecules. Considering the well-ordered and flexible structure of melamine foam, it was used as a substrate and for hydrophilic interaction chromatography (HILIC). Metal-organic framework, due to its excellent characteristics, was grafted on its surface anchored by self-assembling polydopamine. The resulting material was characterized and packed in the tip by just pressing the material in the conical structure of the tip. This affinity tip established good and tunable permeability and was used to selectively enrich glycopeptides as well as phosphopeptides. The affinity tip demonstrated excellent performance to enrich glycopeptides and phosphopeptides with a low limit of detection up to 0.5 fmol μL^-1 from tryptic digests of horseradish peroxidase and β-Casein, respectively, and was stable up to 5 rounds of enrichment. Moreover, this affinity-tip also exhibited high selectivity up to up to 1:1000 (HRP digest to BSA digest) for glycopeptides and 1:200 (β-Casein digest to BSA digest) for phosphopeptides and demonstrated several other fascinating characteristics such as; excellent size exclusion effect for the omission of large-sized proteins, modest backpressure, reproducibility, reusability, smooth enrichment, and successfully applied to a human saliva sample.

Boronic Acid-Functionalized Scholl-Coupling Mesoporous Polymers for Online Solid-Phase Extraction of Brassinosteroids from Plant-Derived Foodstuffs

Brassinosteroids (BRs) are natural, nontoxic, non-hazardous, biosafe, and eco-friendly plant hormones, possessing diverse pharmacological activities. However, little is known about the type and content of BRs in frequently consumed plant-derived foodstuffs because of their low abundance and high abundance of interference. In this study, a selective, accurate, and sensitive method based on the online solid-phase extraction using the boronic acid-functionalized Scholl-coupling microporous polymer was developed for the analysis of BRs in plant-derived foodstuffs. Under optimum conditions, an excellent linearity (R² ≥ 0.9970) and lower limits of detection (0.010-0.070 pg mL^-1) were obtained. The high relative recoveries were in the range of 90.33-109.34% with relative standard deviations less than 9.73%. The method was successfully used for the determination of BRs in fifteen plant-derived foodstuffs. The present work offers a valuable tool for exploring BRs from the plant-derived foodstuffs and can provide useful information for developing functional foods.

Gold nanoparticle-glutathione functionalized MOFs as hydrophilic materials for the selective enrichment of glycopeptides

Herein, a novel zwitterionic hydrophilic metal-organic framework (MOF)-functionalized material was synthesized through grafting l-glutathione (GSH) onto the Au which acts as the intermediate layer to modify the base material (PEI-ZIF-8) by the sulfhydryl group provided by GSH and the affinity provided by Au (denoted as PEI-ZIF-8@Au@GSH). The obtained product was employed to capture glycopeptides. Benefit from its excellent hydrophilic properties, abundant amphoteric ions, and unique large specific surface area, this material demonstrated amazing ability in the enrichment and identification of glycopeptides. As a result, the PEI-ZIF-8@Au@GSH displayed high sensitivity (as low as 2 fmol), excellent binding capacity (500 mg/g), outstanding enrichment selectivity (maximum mass ratio HRP to BSA is 1:1000) toward glycopeptides, and the ability to recycle at least five times. Furthermore, 35 and 51 glycopeptides were successfully detected from 5 μL human saliva and human serum respectively in the examination of the actual sample by MALDI-TOF MS. The above results indicated that the PEI-ZIF-8@Au@GSH had a satisfactory potential in the field of glycoproteomics.