Porous polymer monolithic column with surface-bound gold nanoparticles for the capture and separation of cysteine-containing peptides

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.

Solid-phase microextraction with MIL-53(Al)-polymer monolithic column coupled to pressurized capillary electrochromatography for determination of chlorogenic acid and ferulic acid in sugarcane samples

In this paper, a polymer monolithic column based on poly (Butyl methacrylate-co-ethylene glycol dimethacrylate) (poly (BMA-co-EDGMA)) doped with MIL-53(Al) metal-organic framework (MOF) was prepared using an in situ polymerization method. The characteristics of MIL-53(Al)-polymer monolithic column were studied through scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), energy-dispersive spectroscopy (EDS), X-ray powder diffractometry (XRD), and nitrogen adsorption experiment. Due to its large surface area, the prepared MIL-53(Al)-polymer monolithic column has good permeability and high extraction efficiency. Using MIL-53(Al)-polymer monolithic column for solid-phase microextraction (SPME), coupled to pressurized capillary electrochromatography (pCEC), a method for the determination of trace chlorogenic acid and ferulic acid in sugarcane was established. Under optimized conditions, chlorogenic acid and ferulic acid have a good linear relationship (r ≥ 0.9965) within the concentration range of 50.0-500 µg/mL, the detection limit is 0.017 µg/mL, and the relative standard deviation (RSD) is less than 3.2%. The spike recoveries of chlorogenic acid and ferulic acid were 96.5% and 96.7%, respectively. The results indicate that the method is sensitive, practical, and convenient. It has been successfully applied to the separation and detection of trace organic phenolic compounds in sugarcane samples.

Proteomics as a Complementary Technique to Characterize Bladder Cancer

Simple Summary

Although immunohistochemistry is a routine technique in clinics, and genomics has been rapidly incorporated, proteomics is a step behind. This general situation is also the norm in bladder cancer research. This review shows the contributions of proteomics to the molecular classification of bladder cancer, and to the study of histopathology due to tissue insults caused by tumors. Furthermore, the importance of proteomics for understanding the cellular and molecular changes as a consequence of the therapy of bladder cancer cannot be neglected.

Abstract

Bladder cancer (BC) is the most common tumor of the urinary tract and is conventionally classified as either non-muscle invasive or muscle invasive. In addition, histological variants exist, as organized by the WHO-2016 classification. However, innovations in next-generation sequencing have led to molecular classifications of BC. These innovations have also allowed for the tracing of major tumorigenic pathways and, therefore, are positioned as strong supporters of precision medicine. In parallel, immunohistochemistry is still the clinical reference to discriminate histological layers and to stage BC. Key contributions have been made to enlarge the panel of protein immunomarkers. Moreover, the analysis of proteins in liquid biopsy has also provided potential markers. Notwithstanding, their clinical adoption is still low, with very few approved tests. In this context, mass spectrometry-based proteomics has remained a step behind; hence, we aimed to develop them in the community. Herein, the authors introduce the epidemiology and the conventional classifications to review the molecular classification of BC, highlighting the contributions of proteomics. Then, the advances in mass spectrometry techniques focusing on maintaining the integrity of the biological structures are presented, a milestone for the emergence of histoproteomics. Within this field, the review then discusses selected proteins for the comprehension of the pathophysiological mechanisms of BC. Finally, because there is still insufficient knowledge, this review considers proteomics as an important source for the development of BC therapies.

A hybrid nano-MOF/polymer material for trace analysis of fluoroquinolones in complex matrices at microscale by on-line solid-phase extraction capillary electrophoresis

A hybrid material (nano-metal organic framework@organic polymer, named as nano-MOF@polymer) was applied for the first time as sorbent for on-line solid-phase extraction capillary electrophoresis with ultraviolet detection (SPE-CE-UV). The resulting material was prepared building layer-by-layer a HKUST-1 (Hong Kong University of Science and Technology-1) nano-MOF onto the polymer surface, which allowed controlling the thickness and maximizing the active surface area. The sorbent was widely characterized at micro- and nano-scale to validate the synthesis and to establish the material properties. Then, fritless microcartridges (2 mm) were assembled by packing only a few micrograms of sorbent particles and investigated for preconcentration of fluoroquinolones (FQs) in several real samples (river water, human urine and whole cow milk). Under the optimized conditions, the sample (ca. 60 μL) was loaded in separation background electrolyte (BGE, 50 mM phosphate (pH 7)), and retained analytes were eluted using a small volume of 2% v/v formic acid in methanol (ca. 50 nL). The SPE-CE-UV method was validated in terms of linearity, limit of detection (LOD), limit of quantification (LOQ), repeatability, reproducibility and reusability. The developed method showed a LOD decreasing until 1 ng L^-1 when larger volumes of sample were loaded (ca. 180 μL), which was 500,000 times lower than by CE-UV. This undescribed sensitivity enhancement would arise from the homogenous and populated MOF nano-domains and the appropriate permeability of the hybrid material, which would promote high extraction efficiency and loading capacity. Furthermore, the sorbent showed appropriate selectivity regardless the analyzed complex environmental, biological or food matrix samples, achieving excellent detectability and recoveries (>90%).

Organic polymer monolithic columns with incorporated bare and cyano-modified fumed silica nanoparticles for use in hydrophilic interaction liquid chromatography

This research article presents the preparation and characterization of monolithic columns with incorporated bare fumed silica nanoparticles (FSNPs) and cyano-modified FNSPs (CN-FSNPs) and their subsequent use in hydrophilic interaction liquid chromatography (HILIC) of neutral, polar, and low molecular weight solutes. The monolithic support was based on the in situ polymerization of glyceryl monomethacrylate (GMM) and ethylene glycol dimethacrylate (EDMA) yielding the poly(GMM-co-EDMA) monolith for the incorporation of bare FNSPs and of CN-FSNPs. The poly(GMM-co-EDMA) functioned as a “true support” for bare FSNPs and CN-FSNPs “stationary phases” as manifested by bare FSNPs and CN-FSNPs being the major contributors to solute retention and column selectivity. Overall, the prepared bare FSNPs and CN-FSNPs stationary phases proved useful in HILIC of small polar solutes including dimethylformamide, formamide, thiourea, nucleobases, nucleosides, organic acids, food additives, vitamins, and biological amines.

3D printed fluidic platform with in-situ covalently immobilized polymer monolithic column for automatic solid-phase extraction

In this work, 3D stereolithographic printing is proposed for the first time for the fabrication of fluidic devices aimed at in-situ covalent immobilization of polymer monolithic columns. Integration in advanced flow injection systems capitalized upon programmable flow was realized for fully automatic solid-phase extraction (SPE) and clean-up procedures as a 'front-end' to on-line liquid chromatography. The as-fabricated 3D-printed extraction column devices were designed to tolerate the pressure drop of forward-flow fluidic systems when handling large sample volumes as demonstrated by the determination of anti-microbial agents, plastic additives and monomers as models of emerging contaminants (4-hydroxybenzoic acid, methylparaben, phenylparaben, bisphenol A and triclosan). Decoration of the monolithic phase with gold nanoparticles (AuNPs) was proven most appropriate for the enrichment of phenolic-type target compounds. In particular, the absolute recoveries for the tested analytes ranged from 73 to 92% both in water and saliva samples. The 3D printed composite monolith showed remarkable analytical features in terms of loading capacity (2 mg g-1), breakthrough volume (10 mL), satisfactory batch-to-batch reproducibility (<9% RSD), and easy on-line coupling of the SPE device to HPLC systems. The fully automatic 3D-printed SPE-HPLC hyphenated system was also exploited for the on-line extraction, matrix clean-up and determination of triclosan in 200 μL of real saliva samples.

Polymeric monolithic microcartridges with gold nanoparticles for the analysis of protein biomarkers by on-line solid-phase extraction capillary electrophoresis-mass spectrometry

In this study, polymeric monoliths with gold nanoparticles (AuNP@monolith) were investigated as microcartridges for the analysis of protein biomarkers by on-line solid-phase extraction capillary electrophoresis-mass spectrometry (SPE-CE-MS). "Plug-and-play" microcartridges (7 mm) were prepared from a glycidyl methacrylate (GMA)-based monolithic capillary column (5 cm x 250 µm i.d.), which was modified with ammonia and subsequently functionalized with gold nanoparticles (AuNPs). The performance of these novel microcartridges was evaluated with human transthyretin (TTR), which is a protein related to different types of familial amyloidotic polyneuropathies (FAP). Protein retention depended on the isoelectric point of the protein (TTR pI~5.4) and elution was achieved with a basic phosphate solution. Under the optimized conditions, limits of detection (LODs) for TTR by AuNP@monolith-SPE-CE-MS were 50 times lower than by CE-MS (5 vs 250 mg•L^-1, with an ion trap (IT) mass spectrometer). The sensitivity enhancement was similar compared to SPE-CE-MS using immunoaffinity (IA) microcartridges with intact antibodies against TTR. Linearity, repeatability in migration times and peak areas, reusability, reproducibility and application to serum samples were also evaluated.

Various Strategies in Post-Polymerization Functionalization of Organic Polymer-Based Monoliths Used in Liquid Phase Separation Techniques

This review article is aimed at summarizing the various strategies that have been developed so far for post-polymerization functionalization (PPF) of organic polymer-based monoliths used in liquid phase separation techniques, namely HPLC at all scales and capillary electrochromatography (CEC). The reader will find the organic reactions performed on monolithic columns for grafting the chromatographic ligands needed for solving the separation problems on hand. This process involves therefore the fabrication of template monoliths that carry reactive functional groups to which chromatographic ligands can be covalently attached in a post-polymerization kind of approach. That is, the template monolith that has been optimized in terms of pore structure and other morphology can be readily modified and tailor made on column to fit a particular separation. The review article will not only cover the various strategies developed so far but also describe their separation applications. To the best of our knowledge, this review article will be the first of its kind.

Recent Advances in Capillary Electrochromatography of Proteins and Carbohydrates in the Biopharmaceutical and Biomedical Field

Capillary electrochromatography (CEC) is a powerful hybrid separation technique that combines capillary electrophoresis and capillary chromatography, capable to address the analytical challenges of proteomics and glycomics. The focus of this paper is to review the recent developments in capillary electrochromatography of proteins and carbohydrates. The different column types applied in capillary electrochromatography such as packed bed, open tubular and monoliths are conferred in detail with respective separation examples. A comprehensive comparison is also given listing the mostly utilized coating methods, stationary phase materials and column preparation methods. The choice of porogenic solvent combinations for monolithic column fabrication is thoroughly discussed, paying close attention to the fine tuning options for the separation driving electroosmotic flow. Application examples of CEC in process analytical technology for the biopharmaceutical and biomarker discovery in the biomedical fields are also given.

Mass spectrometry combined with affinity probes for the identification of CP4 EPSPS in genetically modified soybeans

Sample preparation methods used for genetically modified organisms (GMOs) analysis are often time consuming, require extensive manual manipulation, and result in limited amounts of purified protein, which may complicate the detection of low-abundance GM protein. A robust sample pretreatment method prior to mass spectrometry (MS) detection of the transgenic protein (5-enolpyruvylshikimate-3-phosphate synthase [CP4 EPSPS]) present in Roundup Ready soya is investigated. Liquid chromatography-multiple reaction monitoring tandem MS (nano LC-MS/MS-MRM) was used for the detection and quantification of CP4 EPSPS. Gold nanoparticles (AuNPs) and concanavalin A (Con A)-immobilized Sepharose 4B were used as selective probes for the separation of the major storage proteins in soybeans. AuNPs that enable the capture of cysteine-containing proteins were used to reduce the complexity of the crude extract of GM soya. Con A-sepharose was used for the affinity capture of β-conglycinin and other glycoproteins of soya prior to enzymatic digestion. The methods enabled the detection of unique peptides of CP4 EPSPS at a level as low as 0.5% of GM soya in MRM mode. Stable-isotope dimethyl labeling was further applied to the quantification of GM soya. Both probes exhibited high selectivity and efficiency for the affinity capture of storage proteins, leading to the quantitative detection at 0.5% GM soya, which is a level below the current European Union's threshold for food labeling. The square correlation coefficients were greater than 0.99. The approach for sample preparation is very simple without the need for time-consuming protein prefractionation or separation procedures and thus presents a significant improvement over existing methods for the analysis of the GM soya protein.

Challenges and Advances in the Fabrication of Monolithic Bioseparation Materials and their Applications in Proteomics Research

High-performance liquid chromatography integrated with tandem mass spectrometry (HPLC-MS/MS) has become a powerful technique for proteomics research. Its performance heavily depends on the separation efficiency of HPLC, which in turn depends on the chromatographic material. As the "heart" of the HPLC system, the chromatographic material is required to achieve excellent column efficiency and fast analysis. Monolithic materials, fabricated as continuous supports with interconnected skeletal structure and flow-through pores, are regarded as an alternative to particle-packed columns. Such materials are featured with easy preparation, fast mass transfer, high porosity, low back pressure, and miniaturization, and are next-generation separation materials for high-throughput proteins and peptides analysis. Herein, the recent progress regarding the fabrication of various monolithic materials is reviewed. Special emphasis is placed on studies of the fabrication of monolithic capillary columns and their applications in separation of biomolecules by capillary liquid chromatography (cLC). The applications of monolithic materials in the digestion, enrichment, and separation of phosphopeptides and glycopeptides from biological samples are also considered. Finally, advances in comprehensive 2D HPLC separations using monolithic columns are also shown.

Green Silver Nanoparticles Confined in Monolithic Silica Disk-packed Spin Column for Human Serum Albumin Preconcentration

Background:

In recent times many new uses have been found for nanomaterials that have undergone homogenous immobilization within porous supports. For this paper, immobilization of SNPs on a thiol-functionalized silica monolith using a fast, easy, environmentally friendly and costeffective process was performed. This was achieved by modifying the surface of a silica-based monolith using thiol groups, and then we fabricated green SNPs in situ, reducing an inorganic precursor silver nitrate solution (AgNO3) by employing tangerine peel extract as a reducing reagent, with Ag-thiol bonds forming along the monument. Doing this allows monoliths to be prepared in such a way that, as TEM analysis demonstrated, SNPs are evenly distributed along the rod's length. Once the materials had been fabricated, they were employed as a sorbent by being placed in a centrifuge. The SNP-thiol functionalized silica monolith was then tested using a standard protein (HSA).

Methods:

The process involves creating monolithic materials by employing a two-part sol-gel technique before modifying the surface of the silica-based monolith using thiol groups for hosting purposes. Homogenous surface coverage was achieved through the use of a non-toxic "green" reducing reagent (tangerine peel extract) to reduce a silver nitrate solution in place to create SNPs joined to the pore surface of a thiol-functionalized silica monolith, employing bonds of Ag-thiol. Once these materials were synthesized, they were classified by utilizing a number of methods based on SEM coupled with EDAX, TEM, AFM and BET analysis. The silica-based monolith, embedded with constructed SNPs, was employed as a sorbent in the preconcentration of human serum albumin (HSA).

Results:

The performance of the fabricated materials was measured against a silica-based monolith with no SNPs. Also, a silica monolith with constructed SNPs embedded was employed to capture HSA within a sample of human urine mixed with a double detergent concentrate (SDS). Such a monolith containing functionalized SNPs can be a highly effective sorbent for preconcentration of proteins in complex samples.

Conclusion:

It was shown to have superior performance compared to a bare silica-based monolith. Additionally, it was shown that a monolithic column modified by SNPs could preconcentrate spiked HSA in urine samples.

Functionalized gold nanoparticles for sample preparation: A review

Sample preparation is a crucial step for the reliable and accurate analysis of both small molecule and biopolymers which often involves processes such as isolation, pre-concentration, removal of interferences (purification), and pre-processing (e.g., enzymatic digestion) of targets from a complex matrix. Gold nanoparticle (GNP)-assisted sample preparation and pre-concentration has been extensively applied in many analytical procedures in recent years due to the favorable and unique properties of GNPs such as size-controlled synthesis, large surface-to-volume ratio, surface inertness, straightforward surface modification, easy separation requiring minimal manipulation of samples. This review article primarily focuses on applications of GNPs in sample preparation, in particular for bioaffinity capture and biocatalysis. In addition, their most common synthesis, surface modification and characterization methods are briefly summarized. Proper surface modification for GNPs designed in accordance to their target application directly influence their functionalities, e.g., extraction efficiencies, and catalytic efficiencies. Characterization of GNPs after synthesis and modification is worthwhile for monitoring and controlling the fabrication process to ensure proper quality and functionality. Parameters such as morphology, colloidal stability, and physical/chemical properties can be assessed by methods such as surface plasmon resonance, dynamic light scattering, ζ-potential determinations, transmission electron microscopy, Taylor dispersion analysis, and resonant mass measurement, among others. The accurate determination of the surface coverage appears to be also mandatory for the quality control of functionality of the nanoparticles. Some promising applications of (functionalized) GNPs for bioanalysis and sample preparation are described herein.

Fabrication of a ferrocene-based monolithic column with a network structure and its application in separation of protein and small molecules

A novel ferrocene-based monolith with a network structure was fabricated via in situ free radical polymerization using vinyl ferrocene as the co-monomer within a stainless-steel column (50 × 4.6 mm i.d.) for the separation of proteins from complex bio-samples, taking merit of the specific absorption of ferrocene to protein, including human plasma, egg white, and standard proteins. The morphology and pore size distribution indicate that the optimized monolith has a relatively uniform structure with the network. The results showed that 26 fractions were separated from human plasma, and the column efficiency of the aromatic small molecule, naphthalene, was up to 30,560 plates m^-1. The homemade monolith showed excellent selectivity for intact proteins, mainly depending on the hydrophobic chromatography mechanism of ferrocene. In addition, the electrostatic interaction and hydrogen-bond interaction were the additional interactions in the chromatographic separation owing to the sandwich structure of ferrocene present in the monolithic column.

An Overview of Molecular Modeling for Drug Discovery with Specific Illustrative Examples of Applications

In this paper we review the current status of high-performance computing applications in the general area of drug discovery. We provide an introduction to the methodologies applied at atomic and molecular scales, followed by three specific examples of implementation of these tools. The first example describes in silico modeling of the adsorption of small molecules to organic and inorganic surfaces, which may be applied to drug delivery issues. The second example involves DNA translocation through nanopores with major significance to DNA sequencing efforts. The final example offers an overview of computer-aided drug design, with some illustrative examples of its usefulness.

Nanoporous block copolymer membranes immobilized with gold nanoparticles for continuous flow catalysis

Nanoporous polymers with functionalizable surfaces are desired in the preparation of reactors for continuous flow catalysis.

Multi-lumen capillary based trypsin micro-reactor for the rapid digestion of proteins

In this work we evaluated a novel microreactor prepared using a surface modified, high surface-to-volume ratio multi-lumen fused silica capillary (MLC). The MLC investigated contained 126 parallel channels, each of 4 μm internal diameter. The MLC, along with conventional fused silica capillaries of 25 μm and 50 μm internal diameter, were treated by (3-aminopropyl)triethoxysilane (APTES) and then modified with gold nanoparticles, of ∼20 nm in diameter, to ultimately provide immobilisation sites for the proteolytic enzyme, trypsin. The modified capillaries and MLCs were characterised and profiled using non-invasive scanning capacitively coupled contactless conductivity detection (sC4D). The sC4D profiles confirmed a significantly higher amount of enzyme was immobilised to the MLC when compared to the fused silica capillaries, attributable to the increased surface to volume ratio. The MLC was used for dynamic protein digestion, where peptide fragments were collected and subjected to off-line chromatographic evaluation. The digestion was achieved with the MLC reactor, using a residence time of just 1.26 min, following which the HPLC peak associated with the intact protein decreased by >70%. The MLC reactors behaved similarly to the classical in vitro or in-solution approach, but provided a reduction in digestion time, and fewer peaks associated with trypsin auto-digestion, which is common using in-solution digestion. The digestion of cytochrome C using both the MLC-IMER and the in-solution approach, resulted in a sequence coverage of ∼80%. The preparation of the MLC microreactor was reproducible with <2.5% RSD between reactors (n = 3) as determined by sC4D.

Enantiomeric separation of adrenaline, noradrenaline, and isoprenaline by capillary electrophoresis using streptomycin-modified gold nanoparticles

Enantiomeric separations of the adrenergic compounds adrenaline, noradrenaline, and isoprenaline were studied. Electromigrative separations were performed in uncoated fused silica capillaries using streptomycin-modified gold nanoparticles (ST-AuNPs) as an additive to the background electrolyte. The ST-AuNPs are shown to serve as an effective chiral selector. The modified AuNPs were characterized in terms of size and zeta potential, and by IR and UV-vis spectra. The effects of ST-AuNP concentration, pH value, temperature, and separation voltage on the separations were systematically studied. Under optimized experimental conditions, racemic mixtures of the respective adrenergic drugs were baseline-separated within 7 min with a resolution of up to 7.5. The relative standard deviations of the resolution in inter-day and intra-day studies (n = 5) were generally <5%. Graphical abstract Schematic of the method for enantiomeric separations. (A): At low concentrations of streptavidinylated gold nanoparticles (ST-AuNPs), the better matching enantiomer is preferably "transported" by the ST-AuNPs; (B) ST-AuNP concentration increased to an optimal value; (C): The ST-AuNP concentration is too high; even poorly matching enantiomers will be transported simultaneously.

Green synthesis of monolithic column incorporated with graphene oxide using room temperature ionic liquid and eutectic solvents for capillary electrochromatography

In this work, a hybrid monolith incorporated with graphene oxide (GO) was prepared in the first time with binary green porogens of deep eutectic solvents (DESs) and room temperature ionic liquids (RTILs). GO was modified with 3-(trimethoxysilyl) propylmethacrylate (γ-MPS), and the resultant GO-MPS can be incorporated into poly (methacrylic acid-co-butylmethacrylate-co-ethylene glycol dimethacrylate) monoliths covalently. A hybrid monolithic column with high permeability and homogeneity can be achieved due to good dispersion of GO-MPS in the green solvents. The GO-MPS incorporated monolith was characterized by transmission electron microscopy, scanning electron microscopy, thermogravimetric analysis and nitrogen adsorption tests. The separation of small organic molecules of alkylphenones and alkylbenzenes was used to evaluate the performance of GO-MPS grafted monolith. The GO-MPS grafted monolith displayed the maximum column efficiency of 147,000 plates/m, about twice higher than the GO-free monolith. In addition, all of the retention and selectivity of small molecules of alkylphenones and alkylbenzenes increased due to the addition of GO-MPS. The results demonstrated that the use of DESs and RTILs is a powerful approach for the preparation of GO incorporated polymer monoliths. The monolith was further applied to the separation of tryptic digests from bovine serum albumin, and the result indicated its potential in the analysis of some complex samples.

Organic polymer-based monolithic stationary phases with incorporated nanostructured materials for HPLC and CEC

This review article is concerned with the recent advances made in the field of organic polymer-based monoliths with incorporated nanostructured materials (NSMs) for use in liquid chromatography and capillary electrochromatography. It covers the pertinent literature published over the last 7-8 years with a total of 56 references. The present article has two distinct parts: one major part encompassing "traditional" organic polymer-based monoliths modified with NSMs and a minor part on cryogels modified with NSMs.

Design of five-layer gold nanoparticles self-assembled in a liquid open tubular column for ultrasensitive nano-LC-MS/MS proteomic analysis of 80 living cells

In this work, for the first time, a liquid open tubular column modified by five-layer gold nanoparticles and linked with C₁₈ (GNPs@C₁₈ ) was designed and fabricated for nano-LC-MS/MS analysis of 80 living cells. Sixty nanometer gold nanoparticles were self-assembled layer by layer on the inner wall of a 20 μm id fused-silica capillary. C₁₈ was then linked on the gold nanoparticles to make the liquid open tubular column show hydrophobic character. Enough loading capacities for analysis of 80 living cells, ∼100 fmol for pk-10 and ∼30 fmol for insulin, were obtained with the 2 m × 20 μm id five-layer GNPs@C₁₈ open tubular column. The open tubular column was used in an online pretreatment and direct nano-LC-MS/MS analysis system to analyze 80 living HepG2 cells. In total, 650 proteins were identified in triplicate runs. The subcellular localization of the identified proteins showed that our system had no bias toward different cellular compartments. Protein copy number per cell of the identified proteins showed that the detection limit could reach 50 zmol and the abundance of the identified proteins could cover a dynamic range of 6 orders.

Human Antimicrobial Peptides in Bodily Fluids: Current Knowledge and Therapeutic Perspectives in the Postantibiotic Era

Antimicrobial peptides (AMPs) are an integral part of the innate immune defense mechanism of many organisms. Due to the alarming increase of resistance to antimicrobial therapeutics, a growing interest in alternative antimicrobial agents has led to the exploitation of AMPs, both synthetic and isolated from natural sources. Thus, many peptide-based drugs have been the focus of increasing attention by many researchers not only in identifying novel AMPs, but in defining mechanisms of antimicrobial peptide activity as well. Herein, we review the available strategies for the identification of AMPs in human body fluids and their mechanism(s) of action. In addition, an overview of the distribution of AMPs across different human body fluids is provided, as well as its relation with microorganisms and infectious conditions.

Advances in organic polymer-based monolithic column technology for high-resolution liquid chromatography-mass spectrometry profiling of antibodies, intact proteins, oligonucleotides, and peptides

This review focuses on the preparation of organic polymer-based monolithic stationary phases and their application in the separation of biomolecules, including antibodies, intact proteins and protein isoforms, oligonucleotides, and protein digests. Column and material properties, and the optimization of the macropore structure towards kinetic performance are also discussed. State-of-the-art liquid chromatography-mass spectrometry biomolecule separations are reviewed and practical aspects such as ion-pairing agent selection and carryover are presented. Finally, advances in comprehensive two-dimensional LC separations using monolithic columns, in particular ion-exchange×reversed-phase and reversed-phase×reversed-phase LC separations conducted at high and low pH, are shown.

Application of Porous Materials to Carbohydrate Chemistry and Glycoscience

There is a growing interest in using a range of porous materials to meet research needs in carbohydrate chemistry and glycoscience in general. Among the applications of porous materials reviewed in this chapter, enrichment of glycans from biological samples prior to separation and analysis by mass spectrometry is a major emphasis. Porous materials offer high surface area, adjustable pore sizes, and tunable surface chemistry for interacting with glycans, by boronate affinity, hydrophilic interactions, molecular imprinting, and polar interactions. Among the materials covered in this review are mesoporous silica and related materials, porous graphitic carbon, mesoporous carbon, porous polymers, and nanoporous gold. In some applications, glycans are enzymatically or chemically released from glycoproteins or glycopeptides, and the porous materials have the advantage of size selectivity admitting only the glycans into the pores and excluding proteins. Immobilization of lectins onto porous materials of suitable pore size allows for the use of lectin-carbohydrate interactions in capture or separation of glycoproteins. Porous material surfaces modified with carbohydrates can be used for the selective capture of lectins. Controlled release of therapeutics from porous materials mediated by glycans has been reported, and so has therapeutic targeting using carbohydrate-modified porous particles. Additional applications of porous materials in glycoscience include their use in the supported synthesis of oligosaccharides and in the development of biosensors for glycans.

Solid supports for extraction and preconcentration of proteins and peptides in microfluidic devices: A review

Determination of proteins and peptides is among the main challenges of today's bioanalytical chemistry. The application of microchip technology in this field is an exhaustively developed concept that aims to create integrated and fully automated analytical devices able to quantify or detect one or several proteins from a complex matrix. Selective extraction and preconcentration of targeted proteins and peptides especially from biological fluids is of the highest importance for a successful realization of these microsystems. Incorporation of solid structures or supports is a convenient solution employed to face these demands. This review presents a critical view on the latest achievements in sample processing techniques for protein determination using solid supports in microfluidics. The study covers the period from 2006 to 2015 and focuses mainly on the strategies based on microbeads, monolithic materials and membranes. Less common approaches are also briefly discussed. The reviewed literature suggests future trends which are discussed in the concluding remarks.