Preparation and application of silver nanoparticle-functionalized magnetic graphene oxide nanocomposites

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.

Terpolymeric platform with enhanced hydrophilicity via cysteic acid for serum intact glycopeptide analysis

A new polymeric (methyl methacrylate/ethylene glycol dimethacrylate/1,2-epoxy-5-hexene) base/matrix has been fabricated and decorated with zwitterionic hydrophilic cysteic acid (Cya) for the enrichment of intact N-glycopeptides from standards and biological samples. Terpolymer-Cya provides good enrichment efficiency, improved hydrophilicity, and selectivity by virtue of better surface area (2.09 × 10² m²/g) provided by terpolymer and the zwitterionic property offered by cysteic acid. Cysteic acid-functionalized polymeric hydrophilic interaction liquid chromatography (HILIC) sorbent enriches 35 and 24 N-linked glycopeptides via SPE (solid phase extraction) mode from tryptic digests of model glycoproteins, i.e., immunoglobulin G (IgG) and horseradish peroxidase (HRP), respectively. Zwitterionic chemistry of cysteine helps in achieving higher selectivity with BSA digest (1:200), and lower detection limit down to 100 attomoles with a complete glycosylation profile of each standard digest. The recovery of 81% and good reproducibility define the application of terpolymer-Cya for complex samples like a serum. Analysis of human serum provides a profile of 807 intact N-linked glycopeptides via nano-liquid chromatography-tandem mass spectrometry (nLC-MS/MS). To the best of our knowledge, this is the highest number of glycopeptides enriched by any HILIC sorbent. Selected glycoproteins are evaluated in link to various cancers including the breast, lung, uterine, and melanoma using single-nucleotide variances (BioMuta). This study represents the complete idea of using an in-house developed strategy as a successful tool to help analyze, relate, and answer glycoprotein-based clinical issues regarding cancers.

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

Protein glycosylation is among the most common and important post-translational modifications, and plays an important regulatory role in many biological processes, including signal transduction, protein translation, and immune response. Abnormal protein glycosylation is also associated with numerous diseases, suggesting that glycoproteins may offer an array of useful disease biomarkers. Mass spectrometry (MS) has become an important analytical tool in glycoproteomics. However, the low abundance and weak ionization efficiency of glycopeptides have hindered direct mass spectrometric analyses, which remain considerably challenging. Glycoprotein and glycopeptide enrichment from complex biological samples is an important step in glycoproteomics. Diverse methods have recently been developed for specific glycoprotein and glycopeptide enrichment, including hydrophilic interaction liquid chromatography (HILIC), lectin affinity chromatography, boronate affinity chromatography, and hydrazide functional affinity chromatography. A variety of enrichment materials designed for the above strategies have been developed to meet the requirement of enriching low abundance glycoproteins and glycopeptides in complex samples. Magnetic solid phase extraction (MSPE) is an efficient sample pretreatment technology that offers advantages of simple operation, low cost, and high extraction efficiency. Functionalized magnetic nanomaterials have been widely used as adsorbents in glycoproteome studies. Since magnetic adsorbent is a key factor in MSPE, in this review, the preparation of magnetic nanomaterials functionalized with sugars, ionic liquids, lectins, boronate affinity ligands, metal organic frameworks, and covalent organic frameworks, and their applications in glycoprotein and glycopeptide enrichment are summarized. These functional magnetic nanomaterials possess high specific surface area and a large number of active adsorption sites, allowing different enrichment mechanisms, including HILIC, lectin affinity chromatography, and boronate and hydrazide functional affinity chromatography. These functional magnetic nanomaterials are mainly used to enrich glycoproteins and glycopeptides in serum, plasma, cells, tissues, saliva and other biological samples. Nearly 90 papers published in the last decade from the Science Citation Index (SCI) and Chinese core journals have been cited in this paper. Finally, the development and prospects of magnetic nanomaterials in glycoprotein and glycopeptide enrichment are also discussed.

Photo-induced electrodeposition of metallic nanostructures on graphene

Graphene, a single atomic layer of sp2 hybridized carbon, is a promising material for future devices due to its excellent optical and electrical properties. Nevertheless, for practical applications, it is essential to deposit patterned metals on graphene in the micro and nano-meter scale in order to inject electrodes or modify the 2D film electrical properties. However, conventional methods for depositing patterned metals such as lift-off or etching leave behind contamination. This contamination has been demonstrated to deteriorate the interesting properties of graphene such as its carrier mobility. Therefore, to fully exploit the unique properties of graphene, the controlled and nano-patterned deposition of metals on graphene films without the use of a sacrificial resist is of significant importance for graphene film functionalization and contact deposition. In this work, we demonstrate a practical and low-cost optical technique of direct deposition of metal nano-patterned structures without the need for a sacrificial lift-off resist. The technique relies on the laser induced reduction of metal ions on a graphene film. We demonstrate that this deposition is optically driven, and the resolution is limited only by the diffraction limit of the light source being used. Patterned metal features as small as 270 nm in diameter are deposited using light with a wavelength of 532 nm and a numerical aperture of 1.25. Deposition of different metals such as Au, Ag, Pd, Pb and Pt is shown. Additionally, change in the Fermi level of the graphene film through the nano-patterned metal is demonstrated through the electrical characterization of four probe field effect transistors.

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.

Catalytic Reclamation of Silver Present in Photographic Waste Using Magnetically Separable TiO2@CuFe2O4 Nanocomposites and Thereof Its Use in Antibacterial Activity

In the present investigation, the silver present in photographic waste is reclaimed catalytically using magnetically separable TiO₂@CuFe₂O₄ nanocomposites (NCs), and further, the recovered silver nanoparticles [Ag(0) NPs] are tested against the representative bacteria for the antibacterial activity. Initially, a series of the different composites between TiO₂ nanoparticles and CuFe₂O₄ nanoparticles are synthesized by a sol-gel "ex situ" method to enhance the catalytic activity of bare nanomaterials toward the visible region of the electromagnetic spectrum. X-ray diffraction reveals the presence of characteristic patterns for the tetragonal structure in the bare materials or TiO₂@CuFe₂O₄ NCs; however, the dominance in the phase as well as intensity of the respective XRD reflections in the NCs is observed according to the content of TiO₂ or CuFe₂O₄ in the NCs. Field-emission electron microscopic images show the uniform spherical particles for the representative TiO₂@CuFe₂O₄ NCs, which is also confirmed through the HRTEM images. The magnetically separable behavior of the representative TiO₂@CuFe₂O₄ NCs is confirmed through the VSM measurements, which also shows the superparamagnetic properties due to the S-shaped nature of the hysteresis loop. Thereafter, a photoconversion reaction of Ag(I) ions to Ag(0) NPs as a model reaction is carried out using the different TiO₂@CuFe₂O₄ NCs under visible light irradiation, and hence, the higher catalytic recovery of Ag(0) NPs is observed for a composite containing 10 wt % TiO₂ and 90 wt % CuFe₂O₄ than that of other NCs or the bare one alone. The optimized protocol of the model reaction is adopted for reclaiming Ag(0) NPs from photographic waste. The progress of the catalytic reclamation reaction is monitored using UV-visible, and then sizes of the recovered Ag(0) NPs are confirmed through the HRTEM images. Thereafter, the recovered Ag(0) NPs are tested for complete photoinactivation of Escherichia coli bacteria within 120 min.

Facile synthesis of hydrophilic magnetic graphene nanocomposites via dopamine self-polymerization and Michael addition for selective enrichment of N-linked glycopeptides

The development of methods to effectively capture N-glycopeptides from the complex biological samples is crucial to N-glycoproteome profiling. Herein, the hydrophilic chitosan–functionalized magnetic graphene nanocomposites (denoted as Fe₃O₄-GO@PDA-Chitosan) were designed and synthesized via a simple two-step modification (dopamine self-polymerization and Michael addition). The Fe₃O₄-GO@PDA-Chitosan nanocomposites exhibited good performances with low detection limit (0.4 fmol·μL⁻¹), good selectivity (mixture of bovine serum albumin and horseradish peroxidase tryptic digests at a molar ration of 10:1), good repeatability (4 times), high binding capacity (75 mg·g⁻¹). Moreover, Fe₃O₄-GO@PDA-Chitosan nanocomposites were further utilized to selectively enrich glycopeptides from human renal mesangial cell (HRMC, 200 μg) tryptic digest, and 393 N-linked glycopeptides, representing 195 different glycoproteins and 458 glycosylation sites were identified. This study provides a feasible strategy for the surface functionalized novel materials for isolation and enrichment of N-glycopeptides.

Silver-decorated, light-activatable polymeric antimicrobials for combined chemo-photodynamic therapy of drug-resistant bacterial infection

In this article, we describe a silver-decorated, light-activatable polymeric antimicrobial with strong synergistic chemo-photodynamic effect to combat bacterial infections.

Recent advancements in polyethyleneimine-based materials and their biomedical, biotechnology, and biomaterial applications

Precise-synthesis strategies and integration approaches of bioinspired PEI-based systems, and their biomedical, biotechnology and biomaterial applications.

Isolation and characterization of glycosylated neuropeptides

Glycosylation is one of the most ubiquitous and complex post-translational modifications (PTMs). It plays pivotal roles in various biological processes. Studies at the glycopeptide level are typically considered as a downstream work resulting from enzymatic digested glycoproteins. Less attention has been focused on glycosylated endogenous signaling peptides due to their low abundance, structural heterogeneity and the lack of enabling analytical tools. Here, protocols are presented to isolate and characterize glycosylated neuropeptides utilizing nanoflow liquid chromatography coupled with mass spectrometry (LC-MS). We first demonstrate how to extract neuropeptides from raw tissues and perform further separation/cleanup before MS analysis. Then we describe hybrid MS methods for glycosylated neuropeptide profiling and site-specific analysis. We also include recommendations for data analysis to identify glycosylated neuropeptides in crustaceans where a complete neuropeptide database is still lacking. Other strategies and future directions are discussed to provide readers with alternative approaches and further unravel biological complexity rendered by glycosylation.

Plasmonic Ti3C2Tx MXene Enables Highly Efficient Photothermal Conversion for Healable and Transparent Wearable Device

Skin-mountable and transparent devices are highly desired for next-generation electronic applications but are susceptible to unexpected ruptures or undesired scratches, which can drastically reduce the device lifetime. Developing wearable and transparent materials with healable function that can recover their original functionality after mechanical damage under mild and noninvasive repairing operation is thus imperative. Herein, we demonstrate that the incorporation of ultrasmall quantities of plasmonic silver nanoparticle (AgNP)@MXene nanosheet hybrids to serve as photothermal fillers in waterborne elastic polyurethane enables high transparency as well as effective light-triggered healing capabilities for wearable composite coatings. The AgNP@MXene hybrid functions as a highly effective photon captor, energy transformer, and molecular heater due to the amalgamation of (1) ultrahigh photothermal conversion efficiency, high thermal conductivity, and structural properties of MXene, (2) the outstanding plasmonic effect of AgNPs, and (3) the synergistic effects from their hybrids. The resulting wearable composite coating with ultralow loading of plasmonic AgNP@MXene hybrids (0.08 wt % or 0.024 vol %) can produce a significant temperature increase of ∼111 ± 2.6 °C after the application of 600 mW cm^-2 light irradiation for 5 min, while maintaining a high optical transmittance of ∼83% at a thickness of ∼60 μm. This local temperature increase can rapidly heal the mechanical damage to the composite coating, with a healing efficiency above 97%.

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.

Self-Assembling Glutamate-Functionalized Cyclodextrin Molecular Tube for Specific Enrichment of N-Linked Glycopeptides

Cyclodextrin molecular tube (CDMT), a new comer of cyclodextrin family, possesses large and hydrophilic outer area and stable structure. Its development and applications remain highly desired, especially in the field of separation and enrichment. Herein, we developed a CDMT-based enrichment platform focusing on the specific capture of glycopeptides. To enhance the hydrophilicity of CDMT, it was functionalized with glutamate (glu). The prepared gluCDMT exhibited large hydrophilic surface, high stability, and good acidic/alkalic resistance. A solid monolithic support was employed to immobilize gluCDMT by a host-guest self-assembly synthetic strategy, which did not occupy the surface hydrophilic sites. The gluCDMT-based monolith exhibited high binding capacity (∼50 mg g^-1), good ability to capture glycopeptides (23 HRP glycopeptides and 28 IgG glycopeptides), and high selectivity (horseradish peroxidase/bovine serum albumin = 1:10 000). Moreover, the developed platform was successfully applied to analyze glycopetides in acute myelogenous leukemia cell lysate and human serum samples.

Self-assembling covalent organic framework functionalized magnetic graphene hydrophilic biocomposites as an ultrasensitive matrix for N-linked glycopeptide recognition

The development of additional functions and applications of covalent organic framework (COF)-derived materials still remains highly desired. In our work, a novel COF-functionalized magnetic graphene biocomposite (MagG@COF-5) was first developed as an ultrasensitive hydrophilic matrix via a facile self-assembly method for efficiently recognizing N-linked glycopeptides. By integrating the characteristics of the magnetic graphene and COF-5 layer, the MagG@COF-5 owns features of an outstanding magnetic response, a high specific area, strong hydrophilic properties and a unique size-exclusion effect. Accordingly, the MagG@COF-5 biocomposite showed excellent performance in N-linked glycopeptide analysis with a low detection limit (0.5 fmol μL^-1), an excellent size-exclusion effect (HRP digests/BSA, 1 : 600), good recyclability and reusability. More excitingly, the practical applicability of the biocomposite was evaluated by treatment with human serum (1 μL), in which 232 N-linked glycopeptides from 85 glycoproteins were detected. All the results demonstrate that the as-synthesized MagG@COF-5 biocomposite has huge potential for use in glycoproteome and clinical diagnosis fields. It will also open up new phases for application of COF-based materials.

Metal-organic framework preparation using magnetic graphene oxide-β-cyclodextrin for neonicotinoid pesticide adsorption and removal

A novel magnetic copper-based metal-organic framework (M-MOF) was prepared using a Fe₄O₃-graphene oxide (GO)-β-cyclodextrin (β-CD) nanocomposite as the magnetic core and support, and used for adsorption and removal of neonicotinoid insecticide pollutants from aqueous solution. M-MOF characterization suggested that ¹Fe₄O₃-GO-β-CD consisted of a thin single layer with anchored Fe₃O₄. The M-MOF was coated on the Fe₄O₃-GO-β-CD surface. The M-MOF had a large Brunauer-Emmett-Teller surface area (250.33m²g^-1) and high super-paramagnetism with saturation magnetization of 10.47emug^-1. Adsorption model analysis showed that the equilibrium data for thiacloprid fitted Langmuir monolayer adsorption and the other insecticides tested showed Freundlich bimolecular layer adsorption. The results show that M-MOF is a promising hybrid adsorbent for rapid removal of neonicotinoid insecticide pollutants from environmental waters.

Highly efficient enrichment of N-linked glycopeptides using a hydrophilic covalent-organic framework

A highly specific enrichment method for N-linked glycopeptides was successfully developed using a hydrophilic covalent-organic framework with excellent binding capacity, stability and reusability.