Development a hydrazide-functionalized thermosensitive polymer based homogeneous system for highly efficient N-glycoprotein/glycopeptide enrichment from human plasma exosome

Exosomes encapsulated in hydrogels for effective central nervous system drug delivery

The targeted delivery of pharmacologically active molecules, metabolites, and growth factors to the brain parenchyma has become one of the major challenges following the onset of neurodegeneration and pathological conditions. The therapeutic effect of active biomolecules is significantly impaired after systemic administration in the central nervous system (CNS) because of the blood-brain barrier (BBB). Therefore, the development of novel therapeutic approaches capable of overcoming these limitations is under discussion. Exosomes (Exo) are nano-sized vesicles of endosomal origin that have a high distribution rate in biofluids. Recent advances have introduced Exo as naturally suitable bio-shuttles for the delivery of neurotrophic factors to the brain parenchyma. In recent years, many researchers have attempted to regulate the delivery of Exo to target sites while reducing their removal from circulation. The encapsulation of Exo in natural and synthetic hydrogels offers a valuable strategy to address the limitations of Exo, maintaining their integrity and controlling their release at a desired site. Herein, we highlight the current and novel approaches related to the application of hydrogels for the encapsulation of Exo in the field of CNS tissue engineering.

Facial on-line enrichment of glycoproteins by capillary electrophoresis with boronate-functionalized poly(glycidyl methacrylate) microparticles coated column

A facial and rapid method for glycoproteins enrichment by capillary electrophoresis was developed. The 3-aminophenylboronic acid-functionalized poly(glycidyl methacrylate) microparticles (PGMA@APBA) were attached to the capillary inlet (length of ∼1.5 cm) by electrostatic self-assemble action to prepare a partially coated capillary column. The process is simple and reversible, allowing for easy renewal of the PGMA@APBA coating when its enrichment efficiency decreases. By utilizing the coated column, glycoproteins can be enriched within 2 min. The column exhibits a specific enrichment for glycoproteins and can be consecutively used for approximately 60 runs. The relative standard deviations (RSDs) of peak area of run-to-run (n = 5) and batch-to-batch (n = 3) were 1.5 % and 1.0%, respectively. The method was successfully applied to enrich glycoproteins from 1 × 1012-fold diluted real egg white sample, indicating its practical applicability.

Dual-functionalized two-dimensional metal-organic framework composite with highly hydrophilicity for effective enrichment of glycopeptides

Protein glycosylation research is currently focused on the development of various functionalized materials that can effectively enrich the levels of glycopeptides in samples. However, most of these materials possess limited glycopeptide-specific recognition sites because of large steric hindrance, unsuitable mass transfer kinetics, and relatively low surface areas. Herein, a highly hydrophilic two-dimensional (2-D) metal-organic framework (MOF) nanosheet modified with glutathione (GSH) and l-cysteine (l-Cys) (denoted as Zr-Fc MOF@Au@GC) has been synthesized for efficient glycopeptide enrichment. Using this composite material, 39 and 44 glycopeptides from horseradish peroxidase (HRP) and human serum immunoglobulin G (IgG) digests were detected, respectively, which represents a higher efficiency for glycopeptide enrichment from model glycoprotein digests than has been previously reported. The material Zr-Fc MOF@Au@GC exhibited ultra-high sensitivity (0.1 fmol/µL), excellent selectivity (weight ratio of HRP tryptic digest to bovine serum albumin (BSA) tryptic digest = 1:2000), good binding capacity (200 mg/g), satisfactory reusability, and long-term storage capacity. In addition, 655 glycopeptides corresponding to 366 glycoproteins were identified from human serum samples. To the best of our knowledge, this is the largest number of glycoproteins detected in human serum samples to date. These results indicated that Zr-Fc MOF@Au@GC has the potential to be used for the enrichment of glycopeptides in biological samples and the analysis of protein glycosylation.

Targeted Analysis of Permethylated N-Glycans Using MRM/PRM Approaches

Targeted mass spectrometric analysis is widely employed across various omics fields as a validation strategy due to its high sensitivity and accuracy. The approach has been successfully employed for the structural analysis of proteins, glycans, lipids, and metabolites. Multiple reaction monitoring (MRM) and parallel reaction monitoring (PRM) have been the methods of choice for targeted structural studies of biomolecules. These target analyses simplify the analytical workflow, reduce background interference, and increase selectivity/specificity, allowing for a reliable quantification of permethylated N-glycans in complex biological matrices.

Exploring the role of polymers to overcome ongoing challenges in the field of extracellular vesicles

Extracellular vesicles (EVs) are naturally occurring nanoparticles released from all eucaryotic and procaryotic cells. While their role was formerly largely underestimated, EVs are now clearly established as key mediators of intercellular communication. Therefore, these vesicles constitute an attractive topic of study for both basic and applied research with great potential, for example, as a new class of biomarkers, as cell-free therapeutics or as drug delivery systems. However, the complexity and biological origin of EVs sometimes complicate their identification and therapeutic use. Thus, this rapidly expanding research field requires new methods and tools for the production, enrichment, detection, and therapeutic application of EVs. In this review, we have sought to explain how polymer materials actively contributed to overcome some of the limitations associated to EVs. Indeed, thanks to their infinite diversity of composition and properties, polymers can act through a variety of strategies and at different stages of EVs development. Overall, we would like to emphasize the importance of multidisciplinary research involving polymers to address persistent limitations in the field of EVs.

Abnormal glycosylation in glioma: related changes in biology, biomarkers and targeted therapy

Glioma is a rapidly growing and aggressive primary malignant tumor of the central nervous system that can diffusely invade the brain tissue around, and the prognosis of patients is not significantly improved by traditional treatments. One of the most general posttranslational modifications of proteins is glycosylation, and the abnormal distribution of this modification in gliomas may shed light on how it affects biological behaviors of glioma cells, including proliferation, migration, and invasion, which may be produced by regulating protein function, cell-matrix and cell‒cell interactions, and affecting receptor downstream pathways. In this paper, from the perspective of regulating protein glycosylation changes and abnormal expression of glycosylation-related proteins (such as glycosyltransferases in gliomas), we summarize how glycosylation may play a crucial role in the discovery of novel biomarkers and new targeted treatment options for gliomas. Overall, the mechanistic basis of abnormal glycosylation affecting glioma progression remains to be more widely and deeply explored, which not only helps to inspire researchers to further explore related diagnostic and prognostic markers but also provides ideas for discovering effective treatment strategies and improving glioma patient survival and prognosis.

Galactose-functionalized methacrylate polymers as affinity sorbents for extraction of food allergen lectins

In this study, glycidyl methacrylate (GMA)-based materials functionalized with different galactose derivatives were prepared to be used as affinity sorbents for solid-phase extraction (SPE) of several food allergen lectins (such as phytohemagglutinin (PHA)). First, GMA-based polymers were synthesized and then galactose derivatives were immobilized onto the GMA surface using two different synthetic routes. In the first approach, the bare polymer was modified with ethylenediamine and glutaraldehyde, and subsequently two galactose derivatives were immobilized. In the second strategy, the starting polymer was modified with cystamine and gold nanoparticles (AuNPs), on which a thiolated galactose derivative was subsequently anchored. The resulting materials were characterized by scanning electron microscopy and used as SPE sorbents for the isolation of PHA (as probe protein) from food matrices. Different SPE parameters (sample pH, eluent solution composition, binding capacity, sample volume, selectivity and reusability) were evaluated. The material that provided the best PHA recovery (98%) was the one obtained in the second approach, being this material successfully applied to the selective extraction of PHA and other similar lectins from different foods (red and lima dried beans, fresh soybeans and biscuits containing soybean protein traces as indicated in their label). After SDS-PAGE of eluates, all samples only exhibited the characteristic PHA band around 30 kDa, suggesting the high potential of the developed material for application in food allergy field.

Glycan-selective in-situ growth of thermoresponsive polymers for thermoprecipitation and enrichment of N-glycoprotein/glycopeptides

In view of the biological significance and micro-heterogeneity of protein glycosylation for human health, specific enrichment of N-glycosylated proteins/peptides from complex biological samples is a prerequisite for the discovery of disease biomarkers and clinical diagnosis. In this work, we propose a "grafting-from" N-glycoprotein enriching method based on the in-situ growth of thermoresponsive polymer brushes from the N-glycosylated site of proteins. The initiator was first attached to the pre-oxidized glycan moieties by hydrazide chemistry, from which the thermoresponsive polymers can be grown to form giant protein-polymer conjugates (PPC). The thermosensitive PPC can be precipitated and separated by raising the temperature to above its lower critical solubility temperature (LCST). Mass spectrometry verified 210 N-glycopeptides corresponding to 136 N-glycoproteins in the rabbit serum. These results demonstrate the capability of the tandem thermoprecipitation strategy to enrich and separate N-glycoprotein/glycopeptide. Due to its simplicity and efficiency specifically, this method holds the potential for identifying biomarkers from biological samples in N-glycoproteome analysis.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018

This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.

Exosome-based strategies for diagnosis and therapy of glioma cancer

Glioblastoma belongs to the most aggressive type of cancer with a low survival rate that is characterized by the ability in forming a highly immunosuppressive tumor microenvironment. Intercellular communication are created via exosomes in the tumor microenvironment through the transport of various biomolecules. They are primarily involved in tumor growth, differentiation, metastasis, and chemotherapy or radiation resistance. Recently several studies have highlighted the critical role of tumor-derived exosomes against immune cells. According to the structural and functional properties, exosomes could be essential instruments to gain a better molecular mechanism for tumor understanding. Additionally, they are qualified as diagnostic/prognostic markers and therapeutic tools for specific targeting of invasive tumor cells such as glioblastomas. Due to the strong dependency of exosome features on the original cells and their developmental status, it is essential to review their critical modulating molecules, clinical relevance to glioma, and associated signaling pathways. This review is a non-clinical study, as the possible role of exosomes and exosomal microRNAs in glioma cancer are reported. In addition, their content to overcome cancer resistance and their potential as diagnostic biomarkers are analyzed.

Fast and specific enrichment and quantification of cancer-related exosomes by DNA-nanoweight-assisted centrifugation

Exosomes are nanoscale membrane vesicles actively released by cells and play an important role in the diagnosis of cancer-related diseases. However, it is challenging to efficiently enrich exosomes from extracellular fluids. In this work, we used DNA nanostructures as "nanoweights" during centrifugation to facilitate the enrichment of cancerous exosomes in human serum. Two different DNA tetrahedral nanostructures (DTNs), each carrying a specific aptamer for exosome biomarker recognition, were incubated with clinical samples simultaneously. One DTN triggered the cross-linking of multiple target exosomes and, therefore, enabled low-speed and fast centrifugation for enrichment. The other DTN further narrowed down the target exosome subtype and initiated a hybridization chain reaction (HCR) for sensitive signal amplification. The method enabled the detection of 1.8 × 10² MCF-7-derived exosomes per microliter and 5.6 × 10² HepG2-derived exosomes per microliter, with 1000-fold higher sensitivity than conventional ELISA and 10-fold higher sensitivity than some recently reported fluorescence assays. Besides, the dual-aptamer system simultaneously recognized multiple surface proteins, eliminating the interference risk from free proteins. Thus, this easy-to-operate method can enrich exosomes with excellent specificity and sensitivity and therefore will be appealing in biomedical research and clinical diagnosis.

Proteomics of post-translational modifications in colorectal cancer: Discovery of new biomarkers

Colorectal cancer (CRC) is one of the costliest health problems and ranks second in cancer-related mortality in developed countries. With the aid of proteomics, many protein biomarkers for the diagnosis, prognosis, and precise management of CRC have been identified. Furthermore, some protein biomarkers exhibit structural diversity after modifications. Post-translational modifications (PTMs), most of which are catalyzed by a variety of enzymes, extensively increase protein diversity and are involved in many complex and dynamic cellular processes through the regulation of protein function. Accumulating evidence suggests that abnormal PTM events are associated with a variety of human diseases, such as CRC, thus highlighting the need for studying PTMs to discover both the molecular mechanisms and therapeutic targets of CRC. In this review, we begin with a brief overview of the importance of protein PTMs, discuss the general strategies for proteomic profiling of several key PTMs (including phosphorylation, acetylation, glycosylation, ubiquitination, methylation, and citrullination), shift the emphasis to describing the specific methods used for delineating the global landscapes of each of these PTMs, and summarize the recent applications of these methods to explore the potential roles of the PTMs in CRC. Finally, we discuss the current status of PTM research on CRC and provide future perspectives on how PTM regulation can play an essential role in translational medicine for early diagnosis, prognosis stratification, and therapeutic intervention in CRC.

Synthesis of zwitterionic polymer modified graphene oxide for hydrophilic enrichment of N-glycopeptides from urine of healthy subjects and patients with lung adenocarcinoma

As one of the most common and important post-translational modifications, protein N-glycosylation plays essential roles in many biological processes and have long been considered closely correlated with the occurrence and progression of multiple diseases. Systematic characterization of these disease-related protein N-glycosylation is one of the most convenient ways for new diagnostic biomarker and therapeutic drug target discovering. However, the biological samples are extremely complex and the abundance of N-glycoproteins are especially low, which make highly efficient N-glycoprotein/glycopeptide enrichment before mass spectrometry analysis a prerequisite. In this work, a new type of hydrophilic material (GO-pDMAPS) was prepared by in situ growth of linear zwitterionic polymer chains on the surface of GO and it was successfully applied for N-glycopeptide enrichment from human urine. Due to the excellent hydrophilicity and the facilitate interactions between this GO-pDMAPS and the targets, a total of 1426 N-glycosylated sites corresponding to 766 N-glycoproteins as well as 790 N-glycosylation sites corresponding to 470 N-glycoproteins were enriched and identified from urine of healthy subjects and patients with lung adenocarcinoma, respectively. Among which, 27 N-glycoproteins were expressed exclusively and 4 N-glycoproteins were upregulated at least 3 times comparing with the healthy group, demonstrating the tremendous potential of this new hydrophilic material for large scale and in depth N-glycoproteome research.

Enrichment of IgG and HRP glycoprotein by dipeptide-based polymeric material

Separation, purification, and identification of glycoproteins are essential for understanding their vital roles in biological and pathological processes. However, glycoproteins are difficult to be captured due to their low abundance, strong interference from non-glycosylated proteins. Here, we report a promising dipeptide-based saccharide recognition platform to selectively enrich two typical glycoproteins, named immunoglobin G (IgG) and horseradish peroxidase (HRP). Different from the conventional glycoprotein enrichment method based on boronic acid affinity or hydrophilic interaction with glycans, the present method was established based on affinity between Pro-Glu (PE) dipeptide and mannose, which is a key unit in the pentasaccharide core of the IgG and HRP glycans. The prepared PE homopolymer surface was proved to selectively bind IgG and HRP superior to that of bovine serum albumin (BSA). Benefiting from this feature, selective enrichment of IgG and HRP was achieved from a protein mixture containing 200-fold BSA interference by using polyPE@SiO₂ under a dispersive solid-phase extraction (dSPE) mode. High adsorption capacity, controllable and selective adsorption behaviors, as well as satisfactory recovery demonstrated the high potential of the dipeptide-based polymeric material in IgG and HRP enrichment. This study might provide a new insight to solve the challenging problem of glycoprotein separation.

Repairing Effect of Platelet Enriched Plasma on Tendon Healing

To explore the repairing effect of platelet-rich plasma (PRP) on tendon (AT) healing, and provide evidence for PRP therapy to treat tendon-related diseases, 32 New Zealand white rabbits were selected to construct tendinopathy animal model. Leukocyte-rich Platelet-Rich Fibrin (Lr-PRP) and Leukocyte-poor Platelet-Rich Fibrin (Lp-PRP) were prepared, whose biological effects on tendon stem cells (TSCs) were explored. Rabbits were divided into control group, low, medium, and high dose groups regrading concentration of Lp-PRP. The number of fibroblasts, collagen fiber content, tubuloglomerular feedback-β1 (TGF-β1) expression, and biomechanical properties were compared at 15 and 30 days after operation. The results showed that Collagen-III (CoI-III) protein expression levels, interleukin-β (IL-β), and interleukin-6 (IL-6) levels in the Lp-PRP group were significantly higher than Lr-PRP group (P < 0.05). Fibroblasts and collagen fibers in group II and III were significantly higher versus group C 15 and 30 days after operation (P < 0.05). Fibroblasts and of collagen fibers in group III were significantly higher versus group II (P < 0.05). Expression of TGF-β1 in groups II and III was significantly higher than that in group C 15 days after operation (P < 0.05). Tensile load of AT repair site in group III was significantly higher than group C 30 days after operation (P < 0.05). Platelet plasma concentration had a certain repair effect on tendon injury and can effectively improve the quality of healing. In addition, Lp-PRP was better than Lr-PRP in tissue healing. When the concentration of Lp-PRP was 100%, the repair effect was the best.

Improving Isolation of Extracellular Vesicles by Utilizing Nanomaterials

Extracellular vesicles (EVs) as the new form of cellular communication have been demonstrated their potential use for disease diagnosis, prognosis and treatment. EVs are vesicles with a lipid bilayer and are present in various biofluids, such as blood, saliva and urine. Therefore, EVs have emerged as one of the most appealing sources for the discovery of clinical biomarkers. However, isolation of the target EVs from different biofluids is required for the use of EVs as diagnostic and therapeutic entities in clinical settings. Owing to their unique properties and versatile functionalities, nanomaterials have been widely investigated for EV isolation with the aim to provide rapid, simple, and efficient EV enrichment. Herein, this review presents the progress of nanomaterial-based isolations for EVs over the past five years (from 2017 to 2021) and discusses the use of nanomaterials for EV isolations based on the underlying mechanism in order to offer insights into the design of nanomaterials for EV isolations.

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.

Design and construction of a hydrophilic coating on macroporous adsorbent resins for enrichment of glycopeptides

Although macroporous adsorbent resins (MARs) have been commercialized and widely applied in industrial and life fields, it is still of necessity to develop simple approaches to functionalize MARs. One of the most widely used methods to realize excellent fouling resistance performance is surface modification of hydrophilic polymers on substrates to fabricate an anti-biofouling coating. Herein, three kinds of hydrophilic poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) MAR were designed and facilely prepared by coating a layer of porous organic polymers (POPs) via either an epoxy-amine ring-opening polymerization or amine-aldehyde condensation reaction using isophthalaldehyde (IPA), 1,4,7,10-tetraazacyclododecane (cyclen), melamine and 1,3,5-triglycidyl isocyanurate (TGIC) as precursors. By taking advantage of their merits, such as large surface area, excellent hydrophilicity and unbiased affinity toward all types of glycopeptide, three functionalized hydrophilic MARs were successfully applied to capture glycopeptides from complex samples as hydrophilic interaction liquid chromatography (HILIC) sorbents. A total of 694 N-glycopeptides and 372 N-glycosylation sites were identified from 2 μL of human serum digest with poly(TC)@MAR, which were not only more than those of poly(MT)@MAR (286 N-glycosylation sites and 547 N-glycopeptides) and poly(IM)@MAR (669 N-glycopeptides and 355 N-glycosylation sites), but also more than those of other reported HILIC materials. This work provided a new and simple way to synthesize enrichment materials for liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) analysis of glycoproteomes.

Advances in mass spectrometry-based glycoproteomics: An update covering the period 2017-2021

Protein glycosylation is one of the most common posttranslational modifications, and plays an essential role in a wide range of biological processes such as immune response, intercellular signaling, inflammation, host-pathogen interaction, and protein stability. Glycoproteomics is a proteomics subfield dedicated to identifying and characterizing the glycans and glycoproteins in a given cell or tissue. Aberrant glycosylation has been associated with various diseases such as Alzheimer's disease, viral infections, inflammation, immune deficiencies, congenital disorders, and cancers. However, glycoproteomic analysis remains challenging because of the low abundance, site-specific heterogeneity, and poor ionization efficiency of glycopeptides during LC-MS analyses. Therefore, the development of sensitive and accurate approaches to efficiently characterize protein glycosylation is crucial. Methods such as metabolic labeling, enrichment, and derivatization of glycopeptides, coupled with different mass spectrometry techniques and bioinformatics tools, have been developed to achieve sophisticated levels of quantitative and qualitative analyses of glycoproteins. This review attempts to update the recent developments in the field of glycoproteomics reported between 2017 and 2021.

[Preparation of multi-functional magnetic nanoparticles for harvesting low-molecular-weight glycoproteins]

低分子量糖蛋白被认为是发现疾病生物标志物的宝库。特异性的萃取吸附剂对这一类化合物的萃取和富集是必不可少的。硼亲和材料在近年来取得了很大的发展,但专门用于选择性富集低分子量糖蛋白的硼亲和材料目前鲜有报道。该文提出了具有多种功能的磁性纳米颗粒(MNPs),用于低分子量糖蛋白的选择性捕获。该多功能磁性纳米颗粒是用硼酸功能化聚合物网络包裹的磁性纳米复合物。该多功能磁性纳米材料是利用磁性的纳米颗粒内核通过在其表面修饰苯硼酸功能团的聚丙烯酸高分子网络链制备得到。该材料不仅具有常规磁性材料在磁分离方面的基本优势,还能提供三重预先设计的先进功能:1)尺寸排阻效应,去除高分子量蛋白质的干扰;2)对低分子量糖蛋白的选择性萃取;3)保护捕获到的低分子量糖蛋白不被降解和污染。该材料的选择性萃取功能来自于硼酸配基与糖蛋白的顺式二醇部分的亲和性,而尺寸限制效应和保护功能则依赖于磁性纳米颗粒表面修饰的聚合物网络,允许低分子量化合物选择性通过。通过实验验证了这些预设的功能,且通过改变聚合物链长可以调节限径效应的阈值。这种多功能磁性纳米复合物可以进一步发展成有前景的纳米探针,不仅可以选择性捕获低分子量糖蛋白,还可以选择性捕获核苷和聚糖等其他具有重要生物学意义的顺式二醇分子。因此,该文报道的材料制备策略为从复杂样品中选择性萃取靶标化合物的多功能吸附剂的设计和合成提供了新思路。

Glutathione-functionalized two-dimensional cobalt sulfide nanosheets for rapid and highly efficient enrichment of N-glycopeptides

Protein glycosylation plays pivotal role in a variety of biological processes and has association with many diseases. The highly efficient glycopeptide enrichment is essential for the mass spectrometry-based glycoproteome research to reduce interference from non-glycopeptides. In this study, novel glutathione-functionalized two-dimensional cobalt sulfide nanosheets (Co-S@Au-GSH) were synthesized for rapid and highly effective enrichment of glycopeptides. By using this nanomaterial, 34 and 21 N-glycopeptides were effectively captured from human serum immunoglobulin G (IgG) and horseradish peroxidase (HRP) digests, respectively. In addition, the Co-S@Au-GSH showed remarkable performance in N-glycopeptide extraction with high selectivity (HRP: BSA = 1:500), low limit of detection (0.5 fmol/μL), high binding capacity (150 mg/g), good reusability, and great robustness. Moreover, it was successfully applied in complex serum samples, demonstrating its excellent enrichment performance. These results indicated that this nanomaterial has great potential in complicated practice samples in glycoproteome determination.

[Synthesis of zwitterionic dual-functional metal-organic framework nanocomposite with ultra-hydrophilicity for selective enrichment of glycopeptides]

蛋白糖基化是生物体中普遍发生且重要的生物学过程,其参与多种分子生物学的功能和途径,是临床诊断重要的生物标志物。但是,糖肽因其丰度低、离子化效率低、糖链异质性等难点,使糖蛋白分析一直面临巨大的挑战。因此,研究合成了一种新型的两性离子双功能化纳米金(AuGC)修饰的超亲水性沸石咪唑骨架(ZIF-8)纳米复合材料(AuGC/ZIF-8),并建立了亲水相互作用色谱(HILIC)和基质辅助激光解吸电离-飞行时间质谱(MALDI-TOF MS)联用选择性富集糖肽的分析方法。谷胱甘肽和半胱氨酸双功能化的协同作用,使MOF具有超亲水性和低空间位阻,为糖肽选择性富集提供了更多的亲和位点。研究以辣根过氧化物酶(HRP)为模式糖蛋白,通过AuGC/ZIF-8富集后,MALDI-TOF MS分析。结果表明,AuGC/ZIF-8对HRP糖肽的富集能力高达250 μg/mg,且在与牛血清白蛋白(BSA)混合溶液中(HRP-BSA (1∶200,质量比))显示出对HRP糖肽的高选择性,以及极低含量下(0.3 ng/μL)的高灵敏度。因此,在复杂生物样品糖蛋白的富集分离中具有很大的应用潜力。

Current Methods of Post-Translational Modification Analysis and Their Applications in Blood Cancers

Post-translational modifications (PTMs) add a layer of complexity to the proteome through the addition of biochemical moieties to specific residues of proteins, altering their structure, function and/or localization. Mass spectrometry (MS)-based techniques are at the forefront of PTM analysis due to their ability to detect large numbers of modified proteins with a high level of sensitivity and specificity. The low stoichiometry of modified peptides means fractionation and enrichment techniques are often performed prior to MS to improve detection yields. Immuno-based techniques remain popular, with improvements in the quality of commercially available modification-specific antibodies facilitating the detection of modified proteins with high affinity. PTM-focused studies on blood cancers have provided information on altered cellular processes, including cell signaling, apoptosis and transcriptional regulation, that contribute to the malignant phenotype. Furthermore, the mechanism of action of many blood cancer therapies, such as kinase inhibitors, involves inhibiting or modulating protein modifications. Continued optimization of protocols and techniques for PTM analysis in blood cancer will undoubtedly lead to novel insights into mechanisms of malignant transformation, proliferation, and survival, in addition to the identification of novel biomarkers and therapeutic targets. This review discusses techniques used for PTM analysis and their applications in blood cancer research.

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.

Preparation of a boronate-affinity monolithic column for adsorption of nucleosides

Chitosan is a considerably versatile and promising biomaterial and can easily form a 3D hierarchical porous scaffold. In this work, a novel boronate-affinity monolithic column modified with a boronic acid-chitosan complex was prepared and characterized by different methods such as Fourier transform infrared spectroscopy, scanning electron microscopy, thermal gravimetric analysis, specific surface area analysis and pore size distribution analysis. The synthesized monolithic column was used for polymer monolithic microextraction combined with high performance liquid chromatography for the simultaneous determination of cytidine, uridine, inosine, and guanosine in milk powder samples. Several parameters affecting extraction efficiency, including the eluent proportion, eluent flow rate, sample flow rate, sample volume, and sample pH were investigated. The boronate-affinity monolithic column showed high enrichment ability due to the selective formation of cyclic borate esters between nucleosides and boronic acid groups at high pH and the release of cyclic borates at low pH values. Under the optimum operating conditions, the linear range was 0.1-50 μg mL^-1, and the correlation coefficients were in the range of 0.9993-0.9994. The LOD and LOQ were in the range of 0.0027-0.0034 and 0.0090-0.011 μg mL^-1, respectively. In addition, the results of recovery and relative standard deviation were satisfactory.

Sample preparation approaches for qualitative and quantitative analysis of lipid-derived electrophile modified proteomes by mass spectrometry

Lipid-derived electrophile (LDE) modifications, which are covalent modifications of proteins by endogenous LDEs, are essential types of protein posttranslational modifications. LDE modifications alter the protein structure and regulate their biological processes in cells. LDE modifications of proteins are also closely associated with several diseases and function as potential biomarkers for clinical diagnosis. The crucial step in studying the LDE modifications is to enrich the LDE modified proteins/peptides from complex biological samples with high efficiency and high selectivity and quantify modified proteins/peptides with high accuracy. In this review, we summarize the recent progress in MS-based proteomic technologies to globally identify and quantify LDE modified proteomes, mainly focusing on discussing the qualitative and quantitative technologies.

The "sugar-coated bullets" of cancer: Tumor-derived exosome surface glycosylation from basic knowledge to applications

Scientific interest in exosomes has exploded in recent decades. In 1990 only three articles were published on exosomes, while over 1,700 have already been published half-way into 2020.1 While researchers have shown much interest in exosomes since being discovered in 1981, an appreciation of the potential role of glycans in exosome structure and function has emerged only recently. Glycosylation is one of the most common post-translational modification, which functions in many physiological and pathological aspects of cellular function. Many components of exosomes are heavily glycosylated including proteins, lipids, among others. Thus, glycosylation undoubtedly has a great impact on exosome biosynthesis and function. Despite the importance of glycosylation in exosomes and the recent recognition of them as biomarkers for not only malignancies but also other system dysfunction and disease, the characterization of exosome glycans remains understudied. In this review, we discuss glycosylation patterns of exosomes derived from various tissues, their biological features, and potential for various clinical applications. We highlight state-of-the-art knowledge about the fine structure of exosomes, which will allow researchers to reconstruct them by surface modification. These efforts will likely lead to novel disease-related biomarker discovery, purification tagging, and targeted drug transfer for clinical applications in the future.

Role of exosomes in malignant glioma: microRNAs and proteins in pathogenesis and diagnosis

Malignant gliomas are the most common and deadly type of central nervous system tumors. Despite some advances in treatment, the mean survival time remains only about 1.25 years. Even after surgery, radiotherapy and chemotherapy, gliomas still have a poor prognosis. Exosomes are the most common type of extracellular vesicles with a size range of 30 to 100 nm, and can act as carriers of proteins, RNAs, and other bioactive molecules. Exosomes play a key role in tumorigenesis and resistance to chemotherapy or radiation. Recent evidence has shown that exosomal microRNAs (miRNAs) can be detected in the extracellular microenvironment, and can also be transferred from cell to cell via exosome secretion and uptake. Therefore, many recent studies have focused on exosomal miRNAs as important cellular regulators in various physiological and pathological conditions. A variety of exosomal miRNAs have been implicated in the initiation and progression of gliomas, by activating and/or inhibiting different signaling pathways. Exosomal miRNAs could be used as therapeutic agents to modulate different biological processes in gliomas. Exosomal miRNAs derived from mesenchymal stem cells could also be used for glioma treatment. The present review summarizes the exosomal miRNAs that have been implicated in the pathogenesis, diagnosis and treatment of gliomas. Moreover, exosomal proteins could also be involved in glioma pathogenesis. Exosomal miRNAs and proteins could also serve as non-invasive biomarkers for prognosis and disease monitoring. Video Abstract.

Construction of Magnetic Covalent Organic Frameworks with Inherent Hydrophilicity for Efficiently Enriching Endogenous Glycopeptides in Human Saliva

In this work, a magnetic covalent organic framework (COF) with inherent hydrophilicity (denoted mCTpBD) was synthesized through interface deposition of a hydrophilic COF shell on amino group-functionalized magnetite particles via the reaction between a carboxyl group-containing monomer and benzidine. Thanks to the superior hydrophilicity, appropriate porous structure, and easy magnetic separation, the resulting mCTpBD exhibited excellent performance in conveniently enriching glycopeptides from standard samples with a high sensitivity of 0.5 fmol μL^-1 and strong size-exclusion effect of up to 1:1000 (w/w). Furthermore, by using the mCTpBD adsorbent, endogenous glycopeptides in saliva of healthy people and patients with inflammatory bowel disease were successfully enriched and identified by the combined liquid chromatography-mass spectrometry/mass spectrometry technology, which indicates a promising prospective of core-shell magnetic composite microspheres with a hydrophilic COF shell in glycoproteomics research.

Proteomics: a powerful tool to study plant responses to biotic stress

In recent years, mass spectrometry-based proteomics has provided scientists with the tremendous capability to study plants more precisely than previously possible. Currently, proteomics has been transformed from an isolated field into a comprehensive tool for biological research that can be used to explain biological functions. Several studies have successfully used the power of proteomics as a discovery tool to uncover plant resistance mechanisms. There is growing evidence that indicates that the spatial proteome and post-translational modifications (PTMs) of proteins directly participate in the plant immune response. Therefore, understanding the subcellular localization and PTMs of proteins is crucial for a comprehensive understanding of plant responses to biotic stress. In this review, we discuss current approaches to plant proteomics that use mass spectrometry, with particular emphasis on the application of spatial proteomics and PTMs. The purpose of this paper is to investigate the current status of the field, discuss recent research challenges, and encourage the application of proteomics techniques to further research.

Enrichments of post-translational modifications in proteomic studies

More than 300 different protein post-translational modifications are currently known, but only a few have been extensively investigated because modified proteoforms are commonly present in sub-stoichiometry amount. For this reason, improvement of specific enrichment techniques is particularly useful for the proteomic characterization of post-translationally modified proteins. Enrichment proteomic strategies could help the researcher in the challenging issue to decipher the complex molecular cross-talk existing between the different factors influencing the cellular pathways. In this review the state of art of the platforms applied for the enrichment of specific and most common post-translational modifications, such as glycosylation and glycation, phosphorylation, sulfation, redox modifications (i.e. sulfydration and nitrosylation), methylation, acetylation, and ubiquitinylation, are described. Enrichments strategies applied to characterize less studied post-translational modifications are also briefly discussed.

Two-dimensional titanate-based zwitterionic hydrophilic sorbent for the selective adsorption of glycoproteins

The selective adsorption towards glycoproteins from complex biosamples is of vital importance in life science studies. A new zwitterionic hydrophilic material, i.e., a functionalized titanate nanosheet, is prepared by assembling well-dispersed gold nanoparticles (AuNPs) on the surface of ultrathin titanate nanosheets via an ion-exchange approach, followed through immobilizing l-cysteine (L-Cys) by Au-S bonding. This 2D-titanate-based zwitterionic hydrophilic material is shortly termed as L-Cys/Au/TiNSs and it exhibits transverse several hundred nanometers with an ultrathin nanosheet structure. The zwitterionic hydrophilic titanate nanosheets have strong adsorption affinity to glycoproteins, offering a large binding capacity towards immunoglobulin G (1098.9 mg g^-1), which could be readily stripped into an ammonium hydroxide (NH₄OH) solution (0.5%, m/v) with a recovery of 82.4%. The practical applications of L-Cys/Au/TiNSs are further proved by successful specific adsorption of IgG from human serum.

Boron-titanate monolayer nanosheets for highly selective adsorption of immunoglobulin G

Boron-titanate monolayer nanosheets were prepared through a scalable step by step intercalation approach for anchoring 3-mercaptopropyltriethoxysilane (MPTS) on the surface. MPTS provides clickable sites with 4-vinylphenylboronic acid (VPBA) via a thiol-ene (TE) click reaction to obtain monolayer titanate nanosheets with boronic acid ligands immobilized on the surface. The nanosheets obtained are denoted as VPBA-MPTS-TiNSs, with a lateral dimension of a few dozen nanometers and with a thickness of ca. 3.5 nm. The nanosheets exhibit a superior adsorption capacity of 1669.7 mg g-1 and favorable selectivity for the adsorption of glycoproteins by employing immunoglobulin G (IgG) as the protein model. The adsorbed IgG is thereafter readily collected by using 0.1% (m/v) cetane trimethyl ammonium bromide (CTAB) as the eluent. The practical applications of VPBA-MPTS-TiNSs are further demonstrated by the selective adsorption/purification of IgG from human serum.

A facilely synthesized glutathione-functionalized silver nanoparticle-grafted covalent organic framework for rapid and highly efficient enrichment of N-linked glycopeptides

The development of facilely synthetic materials for highly efficient enrichment of N-linked glycopeptides is essential in glycoproteome analysis. In this work, by utilizing the self-assembling of glutathione (GSH) on silver nanoparticles (Ag NPs), and the formation and dispersion of Ag NPs on a robust TpPa-1 substrate, a newly functionalized covalent organic framework (COF) called TpPa-1@Ag@GSH was synthesized via a simple two step post-synthetic modification. TpPa-1@Ag@GSH and intermediate products were confirmed and evaluated by nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, transmission electron microscopy, scanning electron microscopy-energy dispersive spectroscopy, Brunauer-Emmett-Teller and thermogravimetric analyses. Benefiting from the judicious selection of the substrate, the abundance of binding sites, relatively high affinity between GSH and N-linked glycopeptides, and the multivalent interactions between N-linked glycopeptides and unoccupied surfaces of Ag NPs, this porous material showed great performance in N-linked glycopeptide enrichment. By enriching N-linked glycopeptides in tryptic digests of human serum immunoglobulin G (human IgG) followed by mass spectrometry analysis, our method was proved to have good sensitivity (1 fmol), high selectivity (1 : 1500, human IgG to bovine serum albumin), high binding capacity (160 mg g-1, IgG/TpPa-1@Ag@GSH), ultra-fast capture ability (only 1 min incubation time), and good reusability (at least 5 times). It was also successfully applied to the enrichment of N-linked glycopeptides from complex biological samples. Our work improved the enrichment selectivity of COFs, reached the most rapid capture ability among off-column enrichment materials, and provided a very facile and easily popularized post-synthetic modification route for COFs in glycoproteome analysis.