A Smart Glycol-Directed Nanodevice from Rationally Designed Macroporous Materials

Plasmonic Janus hybrids for the detection of small metabolites

Janus hybrids with amphiphilic structures were used for the sensitive detection of small metabolites.

Plasmonic silver nanoshells for drug and metabolite detection

In-vitro metabolite and drug detection rely on designed materials-based analytical platforms, which are universally used in biomedical research and clinical practice. However, metabolic analysis in bio-samples needs tedious sample preparation, due to the sample complexity and low molecular abundance. A further challenge is to construct diagnostic tools. Herein, we developed a platform using silver nanoshells. We synthesized SiO2@Ag with tunable shell structures by multi-cycled silver mirror reactions. Optimized nanoshells achieved direct laser desorption/ionization mass spectrometry in 0.5 μL of bio-fluids. We applied these nanoshells for disease diagnosis and therapeutic evaluation. We identified patients with postoperative brain infection through daily monitoring and glucose quantitation in cerebrospinal fluid. We measured drug distribution in blood and cerebrospinal fluid systems and validated the function of blood-brain/cerebrospinal fluid-barriers for pharmacokinetics. Our work sheds light on the design of materials for advanced metabolic analysis and precision diagnostics.Preparation of samples for diagnosis can affect the detection of biomarkers and metabolites. Here, the authors use a silver nanoparticle plasmonics approach for the detection of biomarkers in patients as well as investigate the distribution of drugs in serum and cerebral spinal fluid.

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.

Multifunctional Magnetic Particles for Combined Circulating Tumor Cells Isolation and Cellular Metabolism Detection

We for the first time demonstrate multi-functional magnetic particles based rare cell isolation combined with the downstream laser desorption/ionization mass spectrometry (LDI-MS) to measure the metabolism of enriched circulating tumor cells (CTCs). The characterization of CTCs metabolism plays a significant role in understanding the tumor microenvironment, through exploring the diverse cellular process. However, characterizing cell metabolism is still challenging due to the low detection sensitivity, high sample complexity, and tedious preparation procedures, particularly for rare cells analysis in clinical study. Here we conjugate ferric oxide magnetic particles with anti-EpCAM on the surface for specific, efficient enrichment of CTCs from PBS and whole blood with cells concentration of 6-100 cells per mL. Moreover, these hydrophilic particles as matrix enable sensitive and selective LDI-MS detection of small metabolites (MW<500 Da) in complex bio-mixtures and can be further coupled with isotopic quantification to monitor selected molecules metabolism of ~50 CTCs. Our unique approach couples the immunomagnetic separation of CTCs and LDI-MS based metabolic analysis, which represents a key step forward for downstream metabolites analysis of rare cells to investigate the biological features of CTCs and their cellular responses in both pathological and physiological phenomena.

Polydopamine Grafted Porous Graphene as Biocompatible Nanoreactor for Efficient Identification of Membrane Proteins

Functional nanomaterials, used as nanoreactors, have shown great advantages in a variety of applications in biomedical fields. Herein, we designed a novel nanoreactor system toward the application in membrane proteomics by using polydopamine-coated nanoporous graphene foams (NGFs-PD) prepared by a facile in situ oxidative polymerization. Taking advantage of the unique 3-D structure and surface functionalization, NGFs-PD can quickly adsorb a large amount of hydrophobic membrane proteins dissolved in sodium dodecyl sulfonate (SDS)/methanol and hydrophilic trypsin in aqueous solution, and then confine the proteolysis in the nanoscale domains to fasten the reaction rate. Therefore, the current nanoreactor system combines the multifunctions of highly efficient solubilization, immobilization, and proteolysis of membrane proteins. With the nanoreactor, digestion of standard membrane proteins can be finished in 10 min. 893 membrane proteins were identified from human glioma cells (U251). All these superiorities indicate that the biocompatible NGFs-PD nanoreactor system is of great promise to facilitate high-throughput membrane proteomic analysis.

Trypsin immobilization in ordered porous polymer membranes for effective protein digestion

Fast and effective protein digestion is a vital process for mass spectrometry (MS) based protein analysis. This study introduces a porous polymer membrane enzyme reactor (PPMER) coupled to nanoflow liquid chromatography-tandem MS (nLC-ESI-MS/MS) for on-line digestion and analysis of proteins. Poly (styrene-co-maleic anhydride) (PS-co-MAn) was fabricated by the breath figure method to make a porous polymer membrane in which the MAn group was covalently bound to enzyme. Based on this strategy, microscale PPMER (μPPMER) was constructed for on-line connection with the nLC-ESI-MS/MS system. Its capability for enzymatic digestion with bovine serum albumin (BSA) was evaluated with varied digestion periods. The on-line proteolysis of BSA and subsequent analysis with μPPMER-nLC-ESI-MS/MS revealed that peptide sequence coverage increased from 10.3% (digestion time 10 min) to 89.1% (digestion time 30 min). μPPMER can efficiently digest proteins due to the microscopic confinement effect, showing its potential application in fast protein identification and protease immobilization. Applications of on-line digestion using μPPMER with human plasma and urinary proteome samples showed that the developed on-line method yielded equivalent or better performance in protein coverage and identified more membrane proteins than the in-solution method. This may be due to easy accommodation of hydrophobic membrane proteins within membrane pores.

A pH-responsive soluble polymer-based homogeneous system for fast and highly efficient N-glycoprotein/glycopeptide enrichment and identification by mass spectrometry

A homogeneous reaction system was developed for facile and highly efficient enrichment of biomolecules by exploiting the reversible self-assembly of a stimuli-responsive polymer.

Liquid phase homogeneous reactions using soluble polymer supports have found numerous applications in homogeneous catalysis and organic synthesis because of their advantages of no interface mass transfer limitation and a high conversion rate. However, their application in analytical separation is limited by the inefficient/inconvenient recovery of the target molecules from the extremely complex biological samples. Here, we report a stimuli-responsive polymer system for facile and efficient enrichment of trace amounts of biomolecules from complex biological samples. The soluble polymer supports provide a homogeneous reaction system with fast mass transfer and facilitate interactions between the supports and the target molecules. More importantly, the stimuli-responsive polymers exhibit reversible self-assembly and phase separation under pH variations, which leads to facial sample recovery with a high yield of the target biomolecules. The stimuli-responsive polymer is successfully applied to the enrichment of low abundant N-glycoproteins/glycopeptides, which play crucial roles in various key biological processes in mammals and are closely correlated with the occurrence, progression and metastasis of cancer. N-Glycoprotein is coupled to the stimuli-responsive polymer using the reported hydrazide chemistry with pre-oxidation of the oligosaccharide structure. Highly efficient enrichment of N-glycoproteins/N-glycopeptides with >95% conversion rate is achieved within 1 h, which is eight times faster than using solid/insoluble hydrazide enrichment materials. Mass spectrometry analysis achieves low femtomolar identification sensitivity and obtained 1317 N-glycopeptides corresponding to 458 N-glycoproteins in mouse brain, which is more than twice the amount obtained after enrichment using commercial solid/insoluble materials. These results demonstrate the capability of this “smart” polymer system to combine stimuli-responsive and target-enrichment moieties to achieve improved identification of key biological and disease related biomolecules.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010

This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.

High-efficiency nano/micro-reactors for protein analysis

This article reviews the recent advances regarding the development of nanomaterial-based nanoreactors and microfluidic droplet reactors and their applications in protein analysis.

A combo-pore approach for the programmable extraction of peptides/proteins

A novel combo-pore approach has been designed for the programmable purification, minimisation of sample complexity, enrichment and sensitive detection of peptides in biosamples. This approach has a superior performance to conventional protocols and commercial products.

Applications of nanomaterials in mass spectrometry analysis

Mass spectrometry (MS) based analyses have received intense research interest in a series of rapidly developing disciplines. Although current MS techniques have enjoyed great successes, several key challenges still remain in practical applications, especially for the detection of biomolecules in biological systems. The use of nanomaterials in MS based analysis provides a promising approach due to their unique physical and chemical properties. In this review, nanomaterials with different compositions and nanostructures employed in MS applications are summarised and classified by their functions. Such an integrated and wide reaching review will provide a comprehensive handbook to researchers with various backgrounds working in this exciting interdisciplinary area.

Catalytic activity and stability of glucose oxidase/horseradish peroxidase co-confined in macroporous silica foam

Investigation of the catalytic activity and stability of enzymes in confined nano/microspace provides valuable contributions to the fundamental understanding of biological reactions taking place on a mesoscopic scale within confined spaces. In this paper, macroporous silica foam (MSF) is used as a nanoreactor to co-confine glucose oxidase (GOD) and horseradish peroxidase (HRP). Then, the enzymatic cascade reactions, which act in tandem inside nanoreactors, for oxidation of glucose and 3,3',5,5'-tetramethylbenzidine (TMB) were studied. The catalytic kinetic parameters of apparent Michaelis constant (K(m)(app)) and maximum rate (V(max)) were obtained from Lineweaver-Burk plot by UV-vis spectrometry. Results showed that the catalytic activity of the co-confined enzymes is reduced compared to that of free enzymes in solution at room temperature. The stabilities of co-confined enzymes in denaturing agents, such as guanidinium chloride (GdmCl) and urea, were higher than those of free enzymes in solution. When employing a co-confined bienzyme system as a biosensor for the detection of glucose, a wider linear range of glucose was obtained for the co-confined bienzyme system than for free enzymes in solution.

Binding of HIV-1 gp120 glycoprotein to silica nanoparticles modified with CD4 glycoprotein and CD4 peptide fragments

An important step in human immunodeficiency virus infection involves the interaction between the viral envelope glycoprotein gp120 and the human host cell surface receptor CD4. Herein, we describe a CD4-functionalized mesoporous silica-based system to selectively capture HIV-gp120 with high binding efficiency. Using a protection-deprotection strategy developed recently by our group, the external surface of the mesoporous particles was selectively functionalized with soluble CD4 ("sCD4") or an 18-peptide fragment mimicking the gp120 binding region. Confocal microscopy confirmed the CD4 locations and showed that the internal pores can be made accessible after external modification in a controlled manner. An evaluation of the ability of an 18-peptide CD4 fragment versus amide-immobilized sCD4 and sCD4 immobilized through its glycosidic group indicated that while all peptides were selective, the latter method was clearly best, with nearly complete removal of whole gp120 from solution. This study shows, for the first time, that sCD4 bound to mesoporous silica particles actively recognizes and retains high binding affinity for HIV-gp120. It is anticipated that, by proper modification of the accessible internal pores, our methodology can be adopted to develop porous platforms for HIV diagnosis, imaging, drug delivery, and vaccine development.

In mesopore protein digestion: a new forthcoming strategy in proteomics

The conventional protocols for in solution or in gel protein digestion require many steps and long reaction times. The use of trypsin immobilized onto solid supports has recently captured the attention of many research groups, because these systems can speed-up protein digestion significantly. The utilization of new materials such as mesoporous silica as supports, in which enzyme and substrate are dramatically concentrated and confined in the nanospace, offers new opportunities to reduce the complexity of proteomics workflows. An overview of the procedures for in situ proteolysis of single proteins or complex protein mixtures is reported, with a special focus on porous materials used as catalysts. The challenging efforts for designing such systems aimed at mimicking the biochemistry of living cells are reviewed. Potentials, limitations and challenges of this branch of enzyme catalysis, which we indicate as in mesopore digestion, are discussed, in relation to its suitability for high-speed and high-throughput proteomics.

Reversed-phase depletion coupled with hydrophilic affinity enrichment for the selective isolation of N-linked glycopeptides by using Click OEG-CD matrix

Selective enrichment of glycopeptides is of great importance for protein glycosylation analysis using mass spectrometry since the signals of glycopeptides could be severely suppressed by the coexisting non-glycosylated peptides in the protein digest. In the present work, a strategy for N-linked glycopeptide enrichment through reversed-phase depletion coupled with hydrophilic affinity enrichment by applying the customized matrix named Click OEG-CD is developed. Compared with single hydrophilic interaction liquid chromatography (HILIC) mode, the strategy exhibited remarkably higher selectivity for N-linked glycopeptides. As many as 22, 18, and eight glycopeptides were detected in the glycopeptide fraction enriched with the strategy from the digests of human immunoglobulin G, horseradish peroxidase and bovine ribonuclease B, respectively. In addition, the strategy also showed high glycosylation microheterogeneity coverage for the enrichment of human α(1)-acid glycoprotein glycopeptides. More than 170 glycopeptides covering all the glycosylation sites were detected in the enriched fraction. The revered-phase liquid chromatography depletion coupled with HILIC enrichment strategy by using Click OEG-CD matrix is expected to show more potential in further applications in glycosylation analysis.

Functionalized periodic mesoporous organosilicas for enhanced and selective peptide enrichment

The analysis of peptides by the mass spectrometry (MS) technique is important in modern life science. The enrichment of peptides can increase the detection efficiency and is sometimes indispensable for collecting the information on proteins with low-abundance. Herein, we first report that functionalized periodic mesoporous organosilica (PMO) materials have a superior peptide enrichment property. It is demonstrated that the PMO materials with an organo-bridged (-CH(2)-) hybrid wall composition display a highly enhanced peptide enrichment ability compared to the pure silica material (SBA-15) with similar mesostructured parameters and morphology. More importantly, by surface modification of PMO with amino groups (denoted NH(2)-PMO), PMO and NH(2)-PMO with opposite charged surfaces (-25.2 and +39.0 mV, respectively) show selective affinities for positively and negatively charged peptides, respectively. By directly adding PMO, NH(2)-PMO as well as pure silica materials to the peptides solution with a low concentration (1-2 fmol/microL), 36 and 28 peptides can be detected from the BSA digestion in the presence of PMO and NH(2)-PMO, respectively, while only 6 and 4 are monitored in the case of SBA-15 enrichment and from solution without enrichment, respectively. Moreover, 69.4% (25 of 36) of enriched peptides by PMO have pI > or = 6 and 80% (21 of 28) of enriched peptides by NH(2)-PMO possess pI < or = 6. Combining the results from the NH(2)-PMO and PMO enrichment together, 51 peptides can be identified with a MOWSE score of 333. It is also noted that similar conclusions can also be obtained from the peptides solution originated from other proteins. This might be an important contribution to the understanding of the interaction between peptides and porous hosts, and the proposed method is promising for the development of both material science and biotechnology.