Elution-free ultra-sensitive enrichment for glycopeptides analyses: Using a degradable, post-modified Ce-metal-organic framework

Oriented assembly of hydrophilic nanochains modified by porous zirconium-based coordination polymers for glycopeptides analysis

Mass spectrometry (MS)-based glycoproteomics research requires additional sample pretreatment to improve the effective identification of low-abundance glycopeptides without interference from non-glycoproteins. Herein, an attractive strategy using resorcinol-formaldehyde (RF) resin and zirconium-based coordination polymer (Zr-BCP) was established to prepare one-dimensional porous coordination polymer composites for glycopeptide enrichment before MS analysis. The obtained Fe3O4@RF@Zr-BCP nanochains feature excellent magnetic response (42.26 emu/g), high hydrophilicity (16.0°), and large specific surface area (140.84 m2/g), which provides abundant affinity sites for specific capture of glycopeptides. The materials exhibit outstanding performance in the enrichment of glycopeptides in terms of sensitivity (15 fmol/μL IgG), selectivity (1:200, molar ratio of IgG/BSA), loading capacity (200 mg/g) and recovery (106.4 ± 3.5%). In addition, the developed method based on Fe3O4@RF@Zr-BCP has been successfully applied to capture glycopeptides in tryptic digest of mouse teratoma cell extracts. It is worth emphasizing that compared with dispersed nanoparticles, the one-dimensional chain structure brings extraordinary reusability to Fe3O4@RF@Zr-BCP nanochains, which is conducive to the rapid cyclic enrichment of glycopeptides. This present work provides a potential enrichment platform for comprehensive glycoprotein analysis, and opens a new avenue for the application of oriented-assembly nanochains.

Development of a MOF-based SPE method combined with GC-MS for simultaneous determination of alachlor, acetochlor and pretilachlor in field soil

In this work, a rapid, highly selective, reusable and effective method was developed for simultaneous determination of alachlor, acetochlor and pretilachlor in field soil by GC-MS coupled with MIL-101 based SPE. Main factors affecting the SPE by using MIL-101 were optimized. Moreover, by comparing with the other commercial materials such as C₁₈, PSA and Florisil, the MIL-101(Cr) exhibited excellent adsorption performance, which aimed at amide herbicides. On the other hand, method validation displayed excellent method performance, achieving good linearities with r² ≥ 0.9921, limits of detection between 0.25-0.45 μg kg^-1, enrichment factors ≥ 89, matrix effect in the range of ± 20%, recoveries between 86.3% and 102.4%, and RSD lower than 4.38%. The developed method was successfully applied to the determination of amide herbicides in soil taken from the wheat, corn and soybean field at different depths, where the concentration of alachlor, acetochlor and pretilachlor were in the range of 0.62-8.04 μg kg^-1. It was demonstrated that the more depth of soil, the lower of three amide herbicides. This finding could be proposed a novel method to detect the amide herbicides in the agriculture and food industry.

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.

Advances in hydrophilic metal-organic frameworks for N-linked glycopeptide enrichment

The comprehensive profiling of glycoproteins is of great significance for the timely clinical diagnosis and therapy. However, inherent obstacles hamper their direct analysis from biological samples, and specific enrichment prior to analysis is indispensable. Among the various approaches for glycopeptide enrichment, hydrophilic interaction liquid chromatography (HILIC) has attracted special focus, especially for the development of novel hydrophilic materials, which is the key of HILIC. Metal-organic frameworks (MOFs) are a type of porous materials constructed from the self-assembly of metal and organic linkers. Advantages such as high surface area, flexible pore size, and easy modification render hydrophilic MOFs as ideal candidates for HILIC, which has inspired many studies over the past years. In this review, advances in hydrophilic MOFs for N-linked glycopeptide enrichment are summarized. According to the synthesis strategies, those materials are categorized into three classes, namely pristine MOFs, MOFs with chemical modifications, and MOFs-derived composite. In each categorization, the preparation and the function of different moieties are covered, as well as the enrichment performances of sensitivity, selectivity, and practical application. Finally, a summary and future perspective on the applications of hydrophilic MOFs for N-linked glycopeptide enrichment are briefly discussed. This review is expected to raise awareness of the properties of hydrophilic MOFs and offer some valuable information to further research in glycoproteomics.

Nanostructure stable hydrophilic hierarchical porous metal-organic frameworks for highly efficient enrichment of glycopeptides

Protein glycosylation plays a vital role in many physiological activities in organisms. Due to the low abundance of glycopeptides and the interference of numerous non-glycopeptides in biological samples, selective enrichment of glycopeptides is of great significance for their successful identification. Metal organic frameworks (MOFs) materials are appropriate for glycopeptides enrichment by virtue of their large specific surface area and outstanding hydrophilic properties. However, the instability of hydrophilic MOFs in acidic solutions have severely limited their applications. In this work, a rational facile strategy was established to synthesize a stable hydrophilic hierarchical porous MOF (denoted as HP-MOF-Arg@mSiO₂). This new material improved the selectivity and sensitivity of enrichment for glycopeptides via modification of arginine groups. More importantly, the mesoporous silica layer was introduced to enhance the stability of MOFs in aqueous solution and achieve the size exclusion effect of large-size proteins in complex samples. Overall, owing to the unique hierarchical porous and the hydrophilic modification, the synthesized HP-MOF-Arg@mSiO₂ materials showed excellent hydrophilicity and hydrolytic stability, resulting in outstanding specific separation capacity in glycopeptides enrichment. A total of 521 and 342 glycopeptides were respectively captured from 2 μL human serum digests and mouse testis tissue digests, revealing the potential of the materials in the study of glycoproteomics in complex biological samples.

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.

Facile preparation of polymer-grafted ZIF-8-modified magnetic nanospheres for effective identification and capture of phosphorylated and glycosylated peptides

As a member of MOFs, Zn-MOFs (ZIF-8) are seldom used in phosphopeptide enrichment because ZIF-8 is soluble in acid solutions. Therefore, properly designing a novel strategy to overcome the defect of ZIF-8 is necessary. In this study, a novel multifunctional nanoprobe was designed by uniting magnetic core, titania shell and hydrophilic metal-organic frameworks (named as Fe3O4@PDA@mTiO2@PEI-g-ZIF-8). Integrating the strategies of hydrophilic interaction affinity chromatography (HILIC), immobilized metal ion affinity chromatography (IMAC) and metal oxide affinity chromatography (MOAC), the Fe3O4@PDA@mTiO2@PEI-g-ZIF-8 mesoporous microspheres can enrich phosphorylated peptides and glycosylated peptides simultaneously. Fe3O4@PDA@mTiO2@PEI-g-ZIF-8 has high selectivity (maximum molar ratio β-casein/HRP : BSA = 1 : 1000), low detection limit (2 fmol) towards phosphopeptides and glycopeptides. Besides, the Fe3O4@PDA@mTiO2@PEI-g-ZIF-8 also exhibited a fine performance in the actual sample detection. In the experiment, taking saliva as a sample, 16 phosphorylated peptides were identified, and from a human serum sample, 4 phosphorylated peptides were selectively identified. All in all, the materials show great potential in the future study of phosphoproteomics and glycoproteomics.

Sensitive detection of carcinoembryonic antigen (CEA) by a sandwich-type electrochemical immunosensor using MOF-Ce@HA/Ag-HRP-Ab2 as a nanoprobe

Sandwich-type electrochemical immunosensor was one of the main methods for detecting carcinoembryonic antigen (CEA). In this work, using Ce-MoF as the skeleton precursor, hyaluronic acid (HA) was coated on the surface of Ce-metal organic framework (Ce-MoF), which loaded with silver nanoparticles (Ag NPs) and horseradish peroxidase (HRP) to catalyze H₂O₂ and double amplified the current signal. Thus, a sensitive sandwich-type electrochemical immunosensor (Ce-MoF@ HA/Ag-HRP) was designed to detect carcinoembryonic antigen (CEA). The designed immunosensor used Au NPs to enhance the ability of attach more the first antibody (Ab₁). This was due to Au NPs had good electrical conductivity and biocompatibility to accelerate electron transfer on the surface of the electrode. HA was riched in -COOH, -OH and had excellent biocompatibility, which can carry more Ag NPs to catalyze H₂O₂. Finally, the prepared sandwich-type electrochemical immunosensor had excellent biocompatibility and great catalytic performance. The immunosensor can be tested within 30 min and the logarithm of the current signal and CEA concentration showed a broad linear response range of 1 pg ml^-1-80 ng ml^-1, and the detection limit of CEA was 0.2 pg ml^-1. More importantly, the proposed immunosensor had good reproducibility, selectivity, stability and without matrix effect. This confirmed that the proposed immunosensor had broad prospects in early clinical trials.

Postsynthesis of zwitterionic hydrophilic composites for enhanced enrichment of N-linked glycopeptides from human serum

RATIONALE

Glycosylation of proteins plays an important role in life activities, but the concentration of naturally occurring glycopeptides is usually relatively low, and glycosylation has microfacies heterogeneity, so direct mass spectrometry is not feasible. Therefore, selective enrichment of glycopeptides before mass spectrometry has turned into an urgent problem to be resolved.

METHODS

Herein, the zwitterionic L-cysteine functionalized hydrophilic graphene oxide composite (GO@PDA@MIL-125-NH₂ @Au@L-Cys) was prepared via a postsynthetic method. The obtained material was used for glycopeptide enrichment. The enriched peptides were then detected using matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) to demonstrate the enrichment performance of the material.

RESULTS

In the actual enrichment process, GO@PDA@MIL-125-NH₂ @Au@L-Cys nanomaterials exhibited high selectivity (1:1000), outstanding sensitivity (0.5 fmol), and excellent repeatability for the enrichment of glycopeptides. In addition, the proposed material showed good performance in the enrichment of glycopeptides from complex biosamples; 56 glycopeptides were detected from 2 μL of human serum using MALDI-TOFMS.

CONCLUSIONS

The experimental results showed that GO@PDA@MIL-125-NH₂ @Au@L-Cys exhibited excellent performance on glycopeptide analysis. It has great potential in the enrichment of glycopeptides and provides new ideas for synthetic materials with better enrichment properties in the future.

A dual-zwitterion functionalized ultra-hydrophilic metal–organic framework with ingenious synergy for enhanced enrichment of glycopeptides

A rational strategy was introduced for the synthesis of a novel dual functionalized metal–organic framework nanocomposite (AuGC/ZIF-8) with ultra-hydrophilicity to enhance glycopeptide enrichment.

Advances in hydrophilic nanomaterials for glycoproteomics

Owing to the formidable challenge posed by microheterogeneities in glycosylation sites, macroheterogeneity of the modification number of glycans, and low abundance and ionization efficiency of glycosylation, the crucial premise for conducting in-depth profiling of the glycoproteome is to develop highly efficient technology for separation and enrichment. The appearance of hydrophilic interaction chromatography (HILIC) has considerably accelerated the progress in glycoproteomics. In particular, additional hydrophilic nanomaterials have been developed for glycoproteomics research in the recent years. In this review, we mainly summarize the recent progresses made in the design and synthesis of different hydrophilic nanomaterials, as well as their applications in glycoproteomics, according to the classification of the main hydrophilic functional molecules on the surface. Further, we briefly illustrate the potential retention mechanism of the HILIC mode and discuss the limits and barriers of hydrophilic nanomaterials in glycoproteomics, as well as propose their possible development trends in the future.