In Situ Synthesis of Magnetic Mesoporous Phenolic Resin for the Selective Enrichment of Glycopeptides

Two-dimensional hydrophilic imprinted resin-graphene oxide composite for selective extraction and rapid determination of gibberellin traces in licorice samples

This study presents novel methodologies and materials for selectively and sensitively determining gibberellin traces in licorice to address food safety concerns. A novel hydrophilic imprinted resin-graphene oxide composite (HMIR-GO) was developed with fast mass transfer, high adsorption capacity, and exceptional aqueous recognition performance for gibberellin. Leveraging the advantages of molecular imprinting, hydrophilic resin synthesis, and rapid mass transfer characteristics of GO, HMIR-GO was employed as an adsorbent, showing resistance to matrix interference. Coupled with HPLC, a rapid and selective method for determining gibberellin was established. Under optimal conditions, the method exhibited a wide linear range (0.02-5.00 μg g-1, r = 0.9999), low detection limits (3.3 ng g-1), and satisfactory recoveries (92.0-98.4%), enabling the accurate and rapid detection of gibberellin in licorice. This study introduces a pioneering strategy for the selective extraction and determination of trace gibberellin levels, offering insights for similar applications in functional foods.

Co-immobilization of crosslinked enzyme aggregates on lysozyme functionalized magnetic nanoparticles for enhancing stability and activity

Surface chemistry of carriers plays a key role in enzyme loading capacity, structure rigidity, and thus catalyze activity of immobilized enzymes. In this work, the two model enzymes of horseradish peroxidase (HRP) and glucose oxidase (GOx) are co-immobilized on the lysozyme functionalized magnetic core-shell nanocomposites (LYZ@MCSNCs) to enhance their stability and activity. Briefly, the HRP and GOx aggregates are firstly formed under the crosslinker of trimesic acid, in which the loading amount and the rigidity of the enzyme can be further increased. Additionally, LYZ easily forms a robust anti-biofouling nanofilm on the surface of SiO2@Fe3O4 magnetic nanoparticles with abundant functional groups, which facilitate chemical crosslinking of HRP and GOx aggregates with minimized inactivation. The immobilized enzyme of HRP-GOx@LYZ@MCSNCs exhibited excellent recovery activity (95.6 %) higher than that of the free enzyme (HRP&GOx). Specifically, 85 % of relative activity was retained after seven cycles, while 73.5 % of initial activity was also remained after storage for 33 days at 4 °C. The thermal stability and pH adaptability of HRP-GOx@LYZ@MCSNCs were better than those of free enzyme of HRP&GOx. This study provides a mild and ecofriendly strategy for multienzyme co-immobilization based on LYZ functionalized magnetic nanoparticles using HRP and GOx as model enzymes.

Facile fabrication of Ti4+-immobilized magnetic nanoparticles by phase-transitioned lysozyme nanofilms for enrichment of phosphopeptides

In this study, titanium (IV)-immobilized magnetic nanoparticles (Ti4+-PTL-MNPs) were firstly synthesized via a one-step aqueous self-assembly of lysozyme nanofilms for efficient phosphopeptide enrichment. Under physiological conditions, lysozymes readily self-organized into phase-transitioned lysozyme (PTL) nanofilms on Fe3O4@SiO2 and Fe3O4@C MNP surfaces with abundant functional groups, including -NH2, -COOH, -OH, and -SH, which can be used as multiple linkers to efficiently chelate Ti4+. The obtained Ti4+-PTL-MNPs possessed high sensitivity of 0.01 fmol μL-1 and remarkable selectivity even at a mass ratio of β-casein to BSA as low as 1:400 for phosphopeptide enrichment. Furthermore, the synthesized Ti4+-PTL-MNPs can also selectively identify low-abundance phosphopeptides from extremely complicated human serum samples and their rapid separation, good reproducibility, and excellent recovery were also proven. This one-step self-assembly of PTL nanofilms facilitated the facile and efficient surface functionalization of various nanoparticles for proteomes/peptidomes.

Multiply-mesoporous hydrophilic titanium dioxide nanohybrid for the highly-performed enrichment of N-glycopeptides from human serum

N-glycopeptide is considered as one of significant biomarkers which provide guidance for the diagnosis and drug design of diseases. However, the direct analysis of N-glycopeptides is nearly impracticable mainly owing to their extremely low abundance and grave signal suppression from other interfering substances in the bio-samples. In this research, a multiply-mesoporous hydrophilic TiO2 nanohybrid (mM-TiO2@Cys) was synthesized by immobilizing Cys on a TiO2 substrate with hierarchical mesopores to achieve the highly-performed enrichment of N-glycopeptides. With the advantages of superior hydrophilicity and multiply-mesoporous structure, the obtained material exhibited an excellent selectivity (IgG digests and BSA digests at the molar ratio of 1/500), a high sensitivity (1 fmol μL-1 for IgG digests) and a good size-exclusion ability (IgG digests, IgG and BSA at the molar ratio of 1/500/500) in the enrichment of N-glycopeptides from IgG digests. As a result, 281 N-glycopeptides corresponded with 109 glycoproteins were identified from 2 μL serum digests of the patients with nasopharyngeal carcinoma, and 181 N-glycopeptides corresponded with 78 glycoproteins were identified from 2 μL serum digests of the healthy volunteers, revealing the potential application value of mM-TiO2@Cys in glycoproteomics.

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.

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.

Construction of dual-hydrophilic metal-organic framework with hierarchical porous structure for efficient glycopeptide enrichment

As an important role in life activities, it is necessary and important to study protein glycosylation. The pre-enrichment of N-glycopeptides is a significant step in glycoproteomics research. According to the inherent size, hydrophilicity and other properties of N-glycopeptides, affinity materials designed to match them will be able to separate N-glycopeptides from complex samples. In this work, we designed and prepared dual-hydrophilic hierarchical porous metal-organic frameworks (MOFs) nanospheres by metal-organic assembly (MOA) based template method and post-synthesis modification strategy. The hierarchical porous structure significantly improved the diffusion rate and binding sites for N-glycopeptide enrichment. Furthermore, the combination of hydrophilic MOFs and small molecules endowed the as-prepared MOFs nanospheres excellent hydrophilicity, which is conducive to the enrichment of N-glycopeptides based on hydrophilic interaction liquid chromatography (HILIC). Therefore, the nanospheres showed surprising enrichment ability for N-glycopeptides such as excellent selectivity (1/500, human serum immunoglobulin G/bovine serum albumin, m/m) and extremely low detective limitation (0.5 fmol). Meanwhile, 550 N-glycopeptides were identified from rat liver samples, proving its application potential in glycoproteomics research and providing design idea for porous affinity materials.

Surface functionalization modification of ultra-hydrophilic magnetic spheres with mesoporous silica for specific identification of glycopeptides in serum exosomes

Protein glycosylation of human serum exosomes can reveal significant physiological information, and the development of large-scale identification strategies is crucial for the in-depth investigation of the serum exosome glycoproteome. In this study, using surface functionalization techniques, an ultra-hydrophilic mesoporous silica magnetic nanosphere (denoted as Fe₃O₄-CG@mSiO₂) was synthesized for the quick and accurate detection of glycopeptides from HRP digests. The Fe₃O₄-CG@mSiO₂ nanospheres demonstrated outstanding enrichment capability, high sensitivity (5 amol/μL), good size exclusion effect (HRP digests/BSA proteins, 1:10,000), stable reusability (at least 10 times), and an excellent recovery rate (108.6 ± 5.5%). Additionally, after enrichment by Fe₃O₄-CG@mSiO₂, 156 glycopeptides assigned to 64 proteins derived from human serum exosomes were successfully identified, which demonstrates that the nanospheres have great potential for the research of the large-scale serum exosome glycoproteome.

Applications of magnetic and electromagnetic forces in micro-analytical systems

Novel applications of magnetic fields in analytical chemistry have become a remarkable trend in the last two decades. Various magnetic forces have been employed for the migration, orientation, manipulation, and trapping of microparticles, and new analytical platforms for separating and detecting molecules have been proposed. Magnetic materials such as functional magnetic nanoparticles, magnetic nanocomposites, and specially designed magnetic solids and liquids have also been developed for analytical purposes. Numerous attractive applications of magnetic and electromagnetic forces on magnetic and non-magnetic materials have been studied, but fundamental studies to understand the working principles of magnetic forces have been challenging. These studies will form a new field of magneto-analytical science, which should be developed as an interdisciplinary field. In this review, essential pioneering works and recent attractive developments are presented.

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.

Adsorptive remediation of environmental pollutants using magnetic hybrid materials as platform adsorbents

Effective separation and remediation of environmentally hazardous pollutants are burning areas of research because of a constant increase in environmental pollution problems. An extensive number of emerging contaminants in the environmental matrices result in serious health consequences in animals, humans, and plants, even at trace levels. Therefore, it is of paramount significance to quantify these undesirable pollutants, even at a very low concentration, from the natural environment. Magnetic solid-phase extraction (MSPE) has recently achieved huge attention because of its strong magnetic domain and easy separation through an external magnetic field compared with simple solid-phase extraction. Therefore, MSPE appeared the most promising technique for removing and pre-concentration of emerging pollutants at trace level. Compared to the normal solid-phase extraction, MSPE as magnetic hybrid adsorbents offers the unique advantages of distinct nanomaterials and magnetic hybrid materials. It can exhibit efficient dispersion and rapid recycling when applying to a very complex matrix. This review highlights the possible environmental applications of magnetic hybrid nanoscale materials as effective MSPE sorbents to remediate a diverse range of environmentally toxic pollutants. We believe this study tends to evoke a variety of research thrust that may lead to novel remediation approaches in the forthcoming years.

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.

[Recent advances in functionalized magnetic nanomaterials for glycoprotein and glycopeptide enrichment]

蛋白质糖基化作为最重要的翻译后修饰之一,在生物体诸如细胞信号转导、蛋白质翻译调控、免疫应答等诸多生命过程中发挥重要作用。此外,蛋白质的异常糖基化还与肿瘤等疾病的发生发展密切相关,这为以糖蛋白为目标的疾病生物标志物的发现提供了可能。尽管质谱已经成为糖蛋白质组学的重要分析工具,但糖肽的低丰度和低电离效率使得其直接质谱分析仍面临挑战。在糖蛋白质组学研究中,从复杂的生物样品中富集糖蛋白和糖肽是重要的环节。磁性固相萃取(MSPE)是一种操作简单、成本低和萃取效率高的样品预处理方法。在磁性固相萃取中,磁性吸附剂是影响萃取效果的关键,将功能化磁性纳米材料作为吸附剂进行糖蛋白质组学研究已经得到广泛应用。该文综述了糖分子、离子液体、凝集素、硼酸亲和配体、金属有机框架、共价有机骨架等功能化磁性纳米材料的制备及其在糖蛋白及糖肽富集中的应用。上述功能化磁性纳米材料具有高比表面积、大量作用位点等特点,其富集机理包括亲水相互作用色谱、凝集素亲和作用色谱、硼酸化学法和肼化学法等,主要应用于血清、血浆、细胞、组织、唾液等样品的糖蛋白和糖肽的富集。该文引用了近十年来发表的约90篇源于科学引文索引(SCI)与中文核心期刊的相关论文,并于文末对磁性纳米材料在糖蛋白和糖肽富集领域的发展趋势进行了展望。

[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。

One-step fabrication of strongly hydrophilic mesoporous silica for comprehensive analysis of serum glycopeptidome

Glycopeptidome represents reliable predictors of physiological and pathological status. Obstructions mainly including low abundance of endogenous glycopeptides and varied interference necessitate glycopeptide enrichment prior to MS analysis. Inspired by the prevalence of hydrophilic interaction chromatography for glycopeptide enrichment, a novel magnetic mesoporous silica nanomaterial (Fe₃O₄@mSiO₂-TSG) with strongly hydrophilic property was developed through a one-pot method. In this work, the gluconamide-containing organosilane is innovatively proposed to directly serve as the strongly hydrophilic silica source for fabrication of hydrophilic mesoporous silica nanomaterial for glycopeptidomics research. Apart from excellent hydrophilicity, Fe₃O₄@mSiO₂-TSG also was equipped with large specific surface area, ordered mesopore channels and great magnetic responsiveness. With all the advantages, Fe₃O₄@mSiO₂-TSG displayed remarkable size-exclusion effect and considerable reusability. Moreover, combined with nano-LC-MS/MS, the glycopeptidome of serum from breast cancer patients was analyzed comprehensively, which showed noteworthy difference from healthy serum through gene ontology analysis, indicating great potential of the approach for glycopeptidomics research.

Bioinspired dandelion-like silica nanoparticles modified with L-glutathione for highly efficient enrichment of N-glycopeptides in biological samples

The pretreatment of complicated biological samples to eliminate the interference of nonglycopeptides and improve the efficiency of glycopeptides detection is crucial in glycoproteomics research. Hydrophilic interaction chromatography (HILIC) has been adopted for enrichment of glycosylated peptides following identification with mass spectrometry, but it is still urgent to develop novel hydrophilic materials to save cost and improve enrichment efficiency. Scientists are pursuing to fabricate freestanding intelligent artificial materials. One promising approach is to use biomimic material. In our case, "one-pot" strategy was developed to prepare bioinspired nano-core-shell silica microspheres (CSSMs), employing tetrapropylorthosilicate as the silicon source and phenolic resin as the soft template. The pore structure of the obtained microspheres diverged from the center to the outside with diameter ranged from 150 to 340 nm, and shell layer ranged from 25 to 83 nm by adjusting the preparation parameters. Some of them showed dandelion-like morphology. After hydrophilic modification, these CSSMs exhibited great hydrophilicity and could be used as sorbents for enriching N-glycopeptides from complicated biological samples in HILIC. Up to 594 unique N-glycopeptides and 367 N-glycosylation sites from 182 N-glycoproteins were unambiguously identified from 2 μL of human serum, which was superior to the enrichment performance of many HILIC materials in reported papers, demonstrating great potential advantages in proteomic application.

Effective Enrichment Strategy Using Boronic Acid-Functionalized Mesoporous Graphene-Silica Composites for Intact N- and O-Linked Glycopeptide Analysis in Human Serum

The heterogeneity and low abundance of protein glycosylation present challenging barriers to the analysis of intact glycopeptides, which is key to comprehensively understanding the role of glycosylation in an organism. Efficient and specific enrichment of intact glycopeptides could help greatly with this problem. Here, we propose a new enrichment strategy using a boronic acid (BA)-functionalized mesoporous graphene-silica composite (denoted as GO@mSiO₂-GLYMO-APB) for isolating intact glycopeptides from complex biological samples. The merits of this composite, including high surface area and synergistic effect from size exclusion functionality of mesoporous material, hydrophilic interaction of silica, and the reversible covalent binding with BA, enable the effective and specific enrichment of both intact N- and O-glycopeptides. The results from the enrichment performance of the strategy evaluated by standard glycoproteins and the application to global N- and O-glycosylation analyses in human serum indicate the robustness and potential of the strategy for intact glycopeptide analysis.

Hollow MnFe2O4@C@APBA Nanospheres with Size Exclusion and pH Response for Efficient Enrichment of Endogenous Glycopeptides

Enrichment and detection of glycopeptides are an important clinical measure for the diagnosis of complex diseases. Enrichment materials play a key role in this process; they must have an effective sample-screening ability to eliminate the interference of nonglycopeptides. In this work, novel hollow MnFe₂O₄@C@APBA nanospheres (HMCAs) with magnetic and pH responsiveness were prepared for glycopeptide enrichment. The as-prepared composites have a suitable hollow structure and large specific surface area, and the boron hydroxyl group in their cavities can fix or disconnect the hydrophilic groups of the glycopeptides at different pH, so the glycopeptides can be adsorbed or desorbed in a controllable way. Enrichment results showed that the HMCAs exhibited an excellent enrichment performance: ultralow limit of detection (approximately 0.5 fmol μL^-1), perfect size-exclusion effect (HRP/BSA, 1:800, w/w), favorable universality (HRP, IgG, and RNase B), and high binding capacity (150 mg/g). In order to verify the application of materials in practice, the HMCAs were used for the analysis of complex samples and it was found that 474 glycopeptides were identified from 210 glycoproteins in three replicate analyses of 2 μL of human serum. The results showed that the HMCAs could be used as a promising enrichment material for glycopeptide characterization in MS-based glycoproteomics and related fields.

A novel porous polymeric microsphere for the selective adsorption and isolation of conalbumin

Porous polymeric microspheres, poly(styrene-divinyl benzene, PSDVB)-poly(ethylene glycol monoallyl ether, PEGMAE), termed as PSDVB-PEGMAE, are prepared via double emulsion interfacial polymerization strategy. PSDVB-PEGMAE microspheres exhibit a mean diameter of 2.98 μm, and possess heterogeneous porous structure with a pore volume of 0.354 cm³ g^-1 and a pore size of 34.3 nm. PEGMAE moiety is identified on the external surface of the microspheres, while both PSDVB and PEGMAE moieties are found in the interior pores. The PSDVB-PEGMAE microspheres possess favorable selectivity towards the adsorption of conalbumin (ConA) through hydrogen-bonding and hydrophobic interactions, via surface and inter-pore adsorption. At pH 6, an adsorption capacity of 171.9 mg g^-1 is achieved for ConA. The captured ConA may be readily recovered by stripping with a cetane trimethyl ammonium bromide (CTAB) solution (0.1%, m/v). The microspheres are further used for the isolation of ConA from egg white, deriving high purity ConA as demonstrated by SDS-PAGE assay.

Microarray investigation of glycan remodeling during macrophage polarization reveals α2,6 sialic acid as an anti-inflammatory indicator

Glycosylation is a widely occurring posttranslational modification. Here, we applied a quick, convenient and high-throughput strategy (lectin array) to investigate the variation in glycans on different macrophage subtypes derived from THP-1 and RAW264.7 cells. For THP-1 cells, there were more significant differences in the glycan on M2 macrophages compared to the other two subtypes. In contrast, M1 macrophages exhibited more significant glycan remodeling than the other subtypes for the RAW264.7 cell line. The response of the lectins which recogonize the N-glycan and α2,6 sialic acid was higher during polarization into anti-inflammatory phase (THP-1 derived M2 subtypes), and lower in pro-inflammatory phase (RAW264.7 M1 subtypes). The regulation of several α2,6 sialyltransferase genes was coincident with the regulation of the α2,6 sialic acid on the two cell lines. The lectin response and glycosyltranferase gene expression confirmed that α2,6 sialic acid showed higher expression in the anti-inflammatory phase. This indicated that α2,6 sialic acid was a potential indicator for the anti-inflammatory response.

Preparation of magnetic mesoporous metal-phenolic coordination spheres for extraction of crystal violet and leuco-metabolites in fish

To address the undesirably low porosity of phenolic resin, a new material termed magnetic mesoporous metal-phenolic coordination spheres (Fe₃O₄@Co-TA) was synthesized by chelating tannic acid (TA) with metal ions. Fe₃O₄@Co-TA was characterized by transmission electron microscopy, scanning electron microscopy, hysteresis loop (B-H) analysis, Fourier-transform infrared spectroscopy, and N₂ adsorption-desorption. The results indicated that the new material comprises mesopores (2 nm and 3 nm) and exhibits a good magnetic response (44 emu/g). Combined with high-performance liquid chromatography (HPLC), a novel method for the detection of crystal violet (CV) and leucocrystal violet (LCV) by magnetic solid-phase extraction was established. Under the optimal extraction conditions, the linear ranges of CV and LCV detection were 0.2‒60 μg/L and 0.04‒40 μg/L, the detection limits were 0.04 μg/L and 0.008 μg/L, and the enrichment factors were 435 and 460, respectively. Fe₃O₄@Co-TA was reused ten times without significant reduction of the extraction ability. This method was successfully used for the detection of CV and LCV in fish samples, providing an effective technique for food safety monitoring and quality control.

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

Cis-diol compounds are class of biomolecules including nucleosides, glycoproteins, saccharides, and nucleotides, which play vital roles in various biological processes. Due to low abundances of these species in the complex biological samples, their identification and analysis is difficult. Boronate affinity materials are commonly used for the isolation and enrichment of cis-diol compounds, due to their unique, facile and selective enrichment mechanism. In this study we report a selective approach to extract nucleosides, glycopeptides and glycoproteins using boronic acid functionalized GMA-MAA-DVB polymer. This novel polymer, reported for the first time in proteomics, have high BET surface area (132.8447 m² g^-1) which contribute to efficient enrichment and average pore size (20.3449 nm) to facilitates the nano confinement effect for strong interactions. Hydrophilic character of methacrylic acid and diethylenetriamine, along with inherent affinity of boronic acid for glycosylated biomolecules result in selectivity up to 1:500 for peptides and 1:1000 for glycoprotein. Binding constant for cis-diol compounds are in the range of 10^-4 to 10^-6 M and theoretical binding capacity up to 85 mg g^-1 for HRP and 180 mg g^-1 for IgG, respectively. Furthermore, boronic acid functionalized polymer (BFP) enrich glycoproteins and glycopeptides in range of 1 pg mL^-1 and 0.04 ng mL^-1 with S/N ≥ 3. Finally, material is applied to enrich the glycoproteins from healthy human saliva sample and six glycoproteins are identified.

Porous graphene oxide/chitosan beads with honeycomb-biomimetic microchannels as hydrophilic adsorbent for the selective capture of glycopeptides

A porous hydrophilic affinity bead consisting of graphene oxide and chitosan (pGC) with the honeycomb-biomimetic microchannels has been synthesized and applied as hydrophilic adsorbent for selective capture of glycopeptides. The pGC beads have open-porous structure, honeycomb-like microchannels, large interior voids, and hydrophilic property. Based on the multivalent hydrophilic interactions between glycan moieties on glycopeptides and amino groups and hydroxyl groups on chitosan, the glycopeptides were enriched and separated by pGC beads. The pGC beads exhibit high sensitivity (detection limit, 5 fmol), binding capacity (111.1 mg/g), enrichment selectivity (molar ratio of human IgG to BSA tryptic digests of 1:200), and recovery yield (89.78%). By combing pGC beads and nano LC-MS/MS analysis, a total of 325 N-glycosylated peptides corresponding to 152 N-glycosylated proteins were identified from 2 μL human serum. These experimental results demonstrate the practical application of the method in glycoproteomics research. Graphical abstract Schematic representation of fabrication for porous hydrophilic affinity beads (pGC) with honeycomb-biomimetic microchannels based on graphene oxide (GO) and chitosan (CS). The pGC was successfully applied to capturing and identifying low-abundant glycopeptides from biological samples.

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.

Boronic acid-functionalized mesoporous magnetic particles with a hydrophilic surface for the multimodal enrichment of glycopeptides for glycoproteomics

Boronic acid-functionalized mesoporous magnetic particles with a hydrophilic surface for multimodal enrichment of glycopeptides for glycoproteomics.

A magnetic nanofiber-based zwitterionic hydrophilic material for the selective capture and identification of glycopeptides

High-performance affinity materials are highly required in the sample preparation process in mass spectrometry-based glycoproteomics studies. In this research, a novel magnetic nanofiber-based zwitterionic hydrophilic material is prepared for glycopeptide enrichment and identification. The one-dimensional hydroxyapatite nanofiber (HN) acted as the supporting substance for immobilizing both Fe3O4 nanoparticles and Au nanoparticles, following the surface modification with a zwitterionic tripeptide l-glutathione (GSH) via the affinity interactions between the thiol group in GSH and both Au and Fe3O4 to form the magHN/Au-GSH nanofiber. Owing to the unique structural features, excellent hydrophilicity, abundant zwitterionic molecules, and strong magnetic responsiveness, the as-prepared magHN/Au-GSH nanofiber possesses satisfactory specificity for glycopeptide enrichment. As a result, the magHN/Au-GSH nanofiber demonstrated great detection sensitivity (2 fmol), satisfying enrichment recovery (89.65%), large binding capacity (100 mg g-1), and high enrichment selectivity (1 : 100) toward glycopeptides. Furthermore, 246 N-glycosylated peptides corresponding to 104 N-glycosylated proteins were identified from only 1 μL human serum, revealing the great potential of this affinity nanofiber for glycopeptide enrichment and glycoproteomics research.

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.

l-cysteine-modified metal-organic frameworks as multifunctional probes for efficient identification of N-linked glycopeptides and phosphopeptides in human crystalline lens

Highly selective enrichment of N-linked glycopeptides and phosphopeptides from complex biological samples is extremely important prior to mass spectrometry analysis due to their low abundance as well as numerous extrinsic interferences. In this work, l-cysteine (L-Cys)-modified multifunctional metal-organic frameworks denoted as Fe₃O₄@PDA@MIL-125@Au@L-Cys (mMIL-125@Au@L-Cys) were prepared by modifications step by step. By combining hydrophilic interaction chromatography (HILIC) with metal oxide affinity chromatography (MOAC), the as-prepared material was firstly utilized to identify N-linked glycopeptides and phosphopeptides from tryptic digests of horseradish peroxidase (HRP) and beta-casein (β-casein), respectively, with the help of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and exhibited outstanding sensitivity (0.1 fmol μL^-1), great reusability (5 circles) and high selectivity (1: 100). Based on this, it was further applied into the enrichment of glycopeptides and phosphopeptides from tryptic digests of 100 μg human crystalline lens proteins. In the end, 81 N-linked glycopeptides corresponding to 35 glycoproteins and 175 phosphopeptides ascribed to 55 phosphorylated proteins were identified, respectively. The remarkable results were benefitted from the merits of improved hydrophilicity from L-Cys, strong affinity of TiO centers, numerous reaction sites on the large surface of MOFs and superparamagnetism from Fe₃O₄ cores. The design of mMIL-125@Au@L-Cys not only served as a multifunctional probe for efficient identification of N-linked glycopeptides and phosphopeptides in human crystalline lens, but also set a precedent for fabricating more MOFs with post-modifications for further proteomics research.

Preparation of epoxy-functionalized hierarchically porous hybrid monoliths via free radical polymerization and application in HILIC enrichment of glycopeptides

Owing to their multiscale pore size regimes and unique properties, the materials with hierarchically porous structures have become an important family of functional materials in recent years. They have been applied from energy conversion and storage, catalysis, separation to drug delivery, etc. The synthesis of them is difficult by the need to employ multiple templates and take complicated steps. Herein, we successfully prepared epoxy-functionalized hierarchically porous hybrid monoliths (HPHMs) with micro/meso/macro-structures in an easy way. Firstly, a bulk monolithic material was formed via free radical polymerization between polyhedral oligomeric vinylsilsesquioxanes (vinylPOSS) and allyl glycidyl ether (AGE) in the presence of polycaprolactone (PCL). Then PCL was degraded with hydrochloric acid solution, and the epoxy-functionalized HPHM was obtained. This approach was very simple and suitable for large-scale preparation. Hybrid monoliths with different specific surface area (from 5.4 to 636.7 m²/g) were prepared by adjusting the mole ratio of vinylPOSS to AGE and the content of PCL. The results of several characterization methods, including nitrogen adsorption/desorption measurements, scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP), showed that these materials contained not only micropores and mesopores but also macropores. The materials were further modified with penicillamine to be used as hydrophilic interaction chromatography (HILIC) adsorbents for enriching N-glycopeptides in IgG and serum protein tryptic digests. Up to 23 N-glycopeptides were identified from IgG digest, and 385 N-glycopeptides and 283 N-glycosylation sites were identified from human serum digest.

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.

Fabrication of hydrophilic multilayer magnetic probe for salivary glycopeptidome analysis

Variations in salivary components are closely associated with the predisposition and state of disease, the abnormal changes of salivary glycopeptidome are usually discovered as perilous singals of serious disease. Therefore, the monitoring and analyzing of salivary glycopeptidome are of even more overriding importance. In this work, a low-cost layer-by-layer assembly strategy was adopted to fabricate a hydrophilic multilayer magnetic probe (dubbed Mag-m-G6P) for salivary glycopeptidome analysis. The successful construction of multilayer structure not only guaranteed the good dispersal of probe by protecting magnetic core from itself aggregation tendency, but also endowed the probe with multiple advantages including the good hydrophilicity, uniform mesopore size and strong magnetic responsiveness, etc. As expected, with the optimized experimental conditions, the multifunctional probe showed high enrichemnt sensitivity, unbiased enrichment ability, excellent size-exclusion ability and reusability and so on in the process of standard sample analysis. At last, the Mag-m-G6P was successfully applied to salivary glycopeptidome analysis on further combination with LC-MS/MS analysis, a total of 53 endogenous glycopeptides were identified from human saliva.