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

A protocol of carbonized on-column enrichment for urinary exosomal N-glycans profiling

As a widely present vesicle, exosome plays an important role in lots of biological processes due to its inclusive cargos. In particular, exosome glycan cargo is attracting attentions since its aberrant alteration is closely related to many progressions in diseases. In this work, a novel carbonized packing capillary trap column for urinary exosomal N-glycan enrichment was proposed. The carbonized packing exhibited large specific surface area, mesoporous structure with narrow pore size distribution and abundant carbon for specially interacting with oligosaccharides. Benefitting from all these advantages, the N-glycans deriving from standard glycoproteins or complex human urine exosomes could be identified with high sensitivity and selectivity. Finally, from the glycans identified in healthy volunteers and patients with bladder carcinoma, we observed that 10 of glycans shared by two groups were obvious downregulation and the 18 were upregulation. These results show great potential of capillary trap column as a tool for the enrichment and detection of glycans in exosomal, attracting more attention on disease progression monitoring and biomarker discovery.

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.

Graphene functionalized with structurally complementary amino acids for sensitive recognition of N-linked glycopeptides

Herein, a hydrophilic graphene composite functionalized with glutathione (GSH) and L(+)-Cysteine (Cys) was prepared via a simple and fast synthesis route, which was named G@S@Au@GC. The combination attack with two different zwitterionic polymers resulted in enhanced adsorption sites for glycopeptides. The obtained G@S@Au@GC exhibited excellent performance on a low limit of detection (0.2 fmol), a high selectivity (HRP: bovine serum albumin = 1:1500), a good load capacity (250 μg•mg^-1) and recovery rate (93%), which was also evaluated with IgG. Subsequently, 60 glycopeptides from complex biological sample (human saliva) were identified by Nano-LC-MS/MS. The advantages of combination attack, low-cost, simple and fast synthesis, and superior enrichment performance make G@S@Au@GC composite a bright future on glycoproteomics analysis and related diseases.

Hydrophilic carrageenan functionalized magnetic carbon-based framework linked by silane coupling agent for the enrichment of N-glycopeptides from human saliva

In this work, a magnetic graphene material coated with mesoporous silica was selected as the substrate, 3-glycidoxypropyltrimethoxysilane and polyethyleneimine were sequentially bonded through chemical reactions, and then carrageenan was successfully introduced by electrostatic interaction; finally, hydrophilic nanocomposite material was prepared. Due to the large number of hydrophilic groups, and polyethyleneimine was connected by means of chemical bonds, this material exhibits good hydrophilicity and stability for glycopeptide enrichment. In the actual enrichment process, nanomaterial exhibits high selectivity (1:500), high sensitivity (2 fmol), and good repeatability (five cycles). In addition, the synthesized material also shows a good enrichment effect in the face of actual complex biological samples, which captured 40 N-glycopeptides from human saliva, indicating the application potential for enrichment of N-glycopeptides.

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.