Dynamic light scattering as an efficient tool to study glyconanoparticle-lectin interactions

Immune cell receptor-specific nanoparticles as a potent adjuvant for nasal split influenza vaccine delivery

Mucosal delivery systems have gained much attention as effective way for antigen delivery that induces both systemic and mucosal immunity. However, mucosal vaccination faces the challenges of mucus barrier and effective antigen uptake and presentation. In particular, split, subunit and recombinant protein vaccines that do not have an intact pathogen structure lack the efficiency to stimulate mucosal immunity. In this study, poly (lactic acid-co-glycolic acid-polyethylene glycol) (PLGA-PEG) block copolymers were modified by mannose to form a PLGA-PEG-Man conjugate (mannose modified PLGA-PEG), which were characterized. The novel nanoparticles (NPs) prepared with this material had a particle size of about 150 nm and a zeta potential of -15 mV, and possessed ideal mucus permeability, immune cell targeting, stability and low toxicity. Finally, PLGA-PEG-Man nanoparticles (PLGA-PEG-Man NPs) were successfully applied for intranasal delivery of split influenza vaccine in rat for the first time, which triggered strong systemic and mucosal immune responses. These studies suggest that PLGA-PEG-Man NPs could function as competitive potential nano-adjuvants to address the challenge of inefficient mucosal delivery of non-allopathogenic antigens.

A brief insight to the role of glyconanotechnology in modern day diagnostics and therapeutics

Carbohydrate-protein and carbohydrate-carbohydrate interactions are very important for various biological processes. Although the magnitude of these interactions is low compared to that of protein-protein interaction, the magnitude can be boosted by multivalent approach known as glycocluster effect. Nanoparticle platform is one of the best ways to present diverse glycoforms in multivalent manner and thus, the field of glyconanotechnology has emerged as an important field of research considering their potential applications in diagnostics and therapeutics. Considerable advances in the field have been achieved through development of novel techniques, use of diverse metallic and non-metallic cores for better efficacy and application of ever-increasing number of carbohydrate ligands for site-specific interaction. The present review encompasses the recent developments in the area of glyconanotechnology and their future promise as diagnostic and therapeutic tools.

Maltoheptaose-Presenting Nanoscale Glycoliposomes for the Delivery of Rifampicin to E. coli

Liposomes, a nanoscale drug delivery system, are well known for their ability to improve pharmacokinetics and reduce drug toxicity. In this work, maltoheptaose (G7)-presenting glycoliposomes were synthesized and evaluated in the delivery of the antibiotic rifampicin. Two types of liposomes were prepared: nonfluid liposomes from l-α-phosphatidylcholine (PC) and cholesterol, and fluid liposomes from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and 1,2-dimyristoyl-sn-glycero-3-phospho-(1'-rac-glycerol). G7-derivatized glycolipid, G7-DPPE (DPPE: 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine), was incorporated into the liposomes at 21 and 14 μmol/mg to form nanoparticles of 75 ± 12 and 146 ± 14 nm for the nonfluid and fluid G7-glycoliposomes, respectively. The multivalent G7-glycoliposomes were characterized by lectin binding with concanavalin A (Con A). The dissociation constant K _d between Con A and the nonfluid or fluid G7-glycoliposomes was 0.93 or 0.51 μM, which represented ~900- or 1600-fold stronger affinity than the binding between Con A and G7. The G7-glycoliposomes were loaded with rifampicin at 6.6 and 16 wt % encapsulation for the nonfluid and fluid G7-glycoliposomes, respectively. Introducing a carbohydrate in the liposomes slowed down the release of rifampicin, with the G7-glycoliposomes having the slowest release rate and the lowest permeability coefficient among the liposome formulations. The fluid G7-glycoliposomes lowered the minimal inhibitory concentration (MIC) of rifampicin against E. coli ORN208 by about 3 times, whereas liposomes without G7 or Man (d-mannose)-glycoliposomes showed no improvement in MIC. The rifampicin-loaded fluid G7-glycoliposomes demonstrated the best sustained antibacterial activity against E. coli, with up to 2 log reduction in the colony forming units at 4 × MIC after 24 h. Fluorescence resonance energy transfer and confocal fluorescence microscopy revealed stronger interactions of the bacterium with the fluid G7-glycoliposomes than other liposome formulations.

Effective ACE2 peptide-nanoparticle conjugation and its binding with the SARS-Cov-2 RBD quantified by dynamic light scattering

The infection of coronavirus initiates with the binding between its spike protein receptor binding domain (RBD) and a human cellular receptor called angiotensin-converting enzyme 2 (ACE2). Here, we construct truncated ACE2 peptide-conjugated gold nanoparticles as antiviral scaffolds and study their binding with the SARS-CoV-2 RBD using dynamic light scattering (DLS). Systematic DLS analysis identifies the effective peptide-nanoparticle conjugation and its efficient, specific, and long-lasting multivalent binding towards the RBD with a binding affinity of 41 nM, indicating the potential of this antiviral platform to compete with natural ACE2-RBD interactions for viral blocking and showcasing an accessible approach to measure the binding constants and kinetics.

Gold nanoparticles-based assays for biodetection in urine

Urine is a biofluid easy to collect through a non-invasive technique that allows collecting a large volume of sample. The use of urine for disease diagnosis is not yet well explored. However, it has gained attention over the last three years. It has been applied in the diagnosis of several illnesses such as kidney disease, bladder cancer, prostate cancer and cardiovascular diseases. In the last decade, gold nanoparticles (Au NPs) have attracted attention in biosensors' development for the diagnosis of diseases due to their electrical and optical properties, ability to conjugate with biomolecules, high sensitivity, and selectivity. Therefore, this article aims to present a comprehensive view of state of the art on the advances made in the quantification of analytes in urinary samples using AuNPs based assays, with a focus on protein analysis. The type of diagnosis methods, the Au NPs synthesis approaches and the strategies for surface modification aiming at selectivity towards the different targets are highlighted.

Quantification of binding affinity of glyconanomaterials with lectins

Carbohydrate-mediated interactions are involved in many cellular activities including immune responses and infections. These interactions are relatively weak, and as such, cells employ multivalency, i.e., the presentation of multiple monovalent carbohydrate ligands within a close proximity, for cooperative binding thus drastically enhanced binding affinity. In the past two decades, the field of glyconanomaterials has emerged where nanomaterials are used as multivalent scaffolds to present multiple copies of carbohydrate ligands on the nanomaterial surface. At the core of glyconanomaterial research is the ability to control and modulate multivalency through ligand display. For the quantitative evaluation of multivalency, the binding affinity must be determined. Quantification of the binding parameters provides insights for not only the fundamental glyconanomaterial-lectin interactions, but also the rational design of effective diagnostics and therapeutics. Several methods have been developed to determine the binding affinity of glyconanomaterials with lectins, including fluorescence competitive assays in solution or on microarrays, Förster resonance energy transfer, fluorescence quenching, isothermal titration calorimetry, surface plasmon resonance spectroscopy, quartz crystal microbalance and dynamic light scattering. This Feature Article discusses each of these techniques, as well as how each technique is applied to determine the binding affinity of glyconanomaterials with lectins, and the data analysis. Although the results differed depending on the specific method used, collectively, they showed that nanomaterials as multivalent scaffolds could amplify the binding affinity of carbohydrate-lectin interactions by several orders of magnitude, the extent of which depending on the structure of the carbohydrate ligand, the ligand density, the linker length and the particle size.

Targeted Delivery of Adamantylated Peptidoglycan Immunomodulators in Lipid Nanocarriers: NMR Shows That Cargo Fragments Are Available on the Surface

We present an in-depth investigation of the membrane interactions of peptidoglycan (PGN)-based immune adjuvants designed for lipid-based delivery systems using NMR spectroscopy. The derivatives contain a cargo peptidoglycan (PGN) dipeptide fragment and an adamantyl group, which serves as an anchor to the lipid bilayer. Furthermore, derivatives with a mannose group that can actively target cell surface receptors on immune cells are also studied. We showed that the targeting mannose group and the cargo PGN fragment are both available on the lipid bilayer surface, thereby enabling interactions with cognate receptors. We found that the nonmannosylated compounds are incorporated stronger into the lipid assemblies than the mannosylated ones, but the latter compounds penetrate deeper in the bilayer. This might be explained by stronger electrostatic interactions available for zwitterionic nonmannosylated derivatives as opposed to the compounds in which the charged N-terminus is capped by mannose groups. The higher incorporation efficiency of the nonmannosylated compounds correlated with a larger relative enhancement in immune stimulation activities upon lipid incorporation compared to that of the derivatives with the mannose group. The chirality of the adamantyl group also influenced the incorporation efficiency, which in turn correlated with membrane-associated conformations that affect possible intermolecular interactions with lipid molecules. These findings will help in improving the development of PGN-based immune adjuvants suitable for delivery in lipid nanoparticles.

Immunization with mannosylated nanovaccines and inhibition of the immune-suppressing microenvironment sensitizes melanoma to immune checkpoint modulators

A low response rate, acquired resistance and severe side effects have limited the clinical outcomes of immune checkpoint therapy. Here, we show that combining cancer nanovaccines with an anti-PD-1 antibody (αPD-1) for immunosuppression blockade and an anti-OX40 antibody (αOX40) for effector T-cell stimulation, expansion and survival can potentiate the efficacy of melanoma therapy. Prophylactic and therapeutic combination regimens of dendritic cell-targeted mannosylated nanovaccines with αPD-1/αOX40 demonstrate a synergism that stimulates T-cell infiltration into tumours at early treatment stages. However, this treatment at the therapeutic regimen does not result in an enhanced inhibition of tumour growth compared to αPD-1/αOX40 alone and is accompanied by an increased infiltration of myeloid-derived suppressor cells in tumours. Combining the double therapy with ibrutinib, a myeloid-derived suppressor cell inhibitor, leads to a remarkable tumour remission and prolonged survival in melanoma-bearing mice. The synergy between the mannosylated nanovaccines, ibrutinib and αPD-1/αOX40 provides essential insights to devise alternative regimens to improve the efficacy of immune checkpoint modulators in solid tumours by regulating the endogenous immune response.

The Sialic Acid-Dependent Nematocyst Discharge Process in Relation to Its Physical-Chemical Properties Is A Role Model for Nanomedical Diagnostic and Therapeutic Tools

Formulas derived from theoretical physics provide important insights about the nematocyst discharge process of Cnidaria (Hydra, jellyfishes, box-jellyfishes and sea-anemones). Our model description of the fastest process in living nature raises and answers questions related to the material properties of the cell- and tubule-walls of nematocysts including their polysialic acid (polySia) dependent target function. Since a number of tumor-cells, especially brain-tumor cells such as neuroblastoma tissues carry the polysaccharide chain polySia in similar concentration as fish eggs or fish skin, it makes sense to use these findings for new diagnostic and therapeutic approaches in the field of nanomedicine. Therefore, the nematocyst discharge process can be considered as a bionic blue-print for future nanomedical devices in cancer diagnostics and therapies. This approach is promising because the physical background of this process can be described in a sufficient way with formulas presented here. Additionally, we discuss biophysical and biochemical experiments which will allow us to define proper boundary conditions in order to support our theoretical model approach. PolySia glycans occur in a similar density on malignant tumor cells than on the cell surfaces of Cnidarian predators and preys. The knowledge of the polySia-dependent initiation of the nematocyst discharge process in an intact nematocyte is an essential prerequisite regarding the further development of target-directed nanomedical devices for diagnostic and therapeutic purposes. The theoretical description as well as the computationally and experimentally derived results about the biophysical and biochemical parameters can contribute to a proper design of anti-tumor drug ejecting vessels which use a stylet-tubule system. Especially, the role of nematogalectins is of interest because these bridging proteins contribute as well as special collagen fibers to the elastic band properties. The basic concepts of the nematocyst discharge process inside the tubule cell walls of nematocysts were studied in jellyfishes and in Hydra which are ideal model organisms. Hydra has already been chosen by Alan Turing in order to figure out how the chemical basis of morphogenesis can be described in a fundamental way. This encouraged us to discuss the action of nematocysts in relation to morphological aspects and material requirements. Using these insights, it is now possible to discuss natural and artificial nematocyst-like vessels with optimized properties for a diagnostic and therapeutic use, e.g., in neurooncology. We show here that crucial physical parameters such as pressure thresholds and elasticity properties during the nematocyst discharge process can be described in a consistent and satisfactory way with an impact on the construction of new nanomedical devices.

Synthesis of Carbohydrate-Grafted Glycopolymers Using a Catalyst-Free, Perfluoroarylazide-Mediated Fast Staudinger Reaction

Glycopolymers have gained increasing importance in investigating glycan-lectin interactions, as drug delivery vehicles and in modulating interactions with proteins. The synthesis of these glycopolymers is still a challenging and rigorous exercise. In this regard, the highly efficient click reaction, copper (I)-catalyzed alkyne-azide cycloaddition, has been widely applied not only for its efficiency but also for its tolerance of the appended carbohydrate groups. However, a significant drawback of this method is the use of the heavy metal catalyst which is difficult to remove completely, and ultimately toxic to biological systems. In this work, we present the synthesis of carbohydrate-grafted glycopolymers utilizing a mild and catalyst-free perfluorophenyl azide (PFPA)-mediated Staudinger reaction. Using this strategy, mannose (Man) and maltoheptaose (MH) were grafted onto the biodegradable poly(lactic acid) (PLA) by stirring a PFAA-functionalized PLA with a phosphine-derivatized Man or MH in DMSO at room temperature within an hour. The glycopolymers were characterized by ¹H-NMR, 19F-NMR, 31P-NMR and FTIR.

Catalyst-Free Cycloaddition Reaction for the Synthesis of Glyconanoparticles

A new conjugation method for the immobilization of carbohydrates on nanomaterials was demonstrated simply by mixing perfluorophenyl azide-functionalized silica nanoparticles (SNPs), an amine-derivatized carbohydrate, and phenylacetaldehyde under ambient conditions without any catalyst. The density of carbohydrates on the glyconanoparticles was determined using the quantitative ¹⁹F NMR (¹⁹F qNMR) technique; for example, the density of d-mannose (Man) on Man-SNPs was 2.5 ± 0.2 × 10^-16 nmol/nm². The glyconanoparticles retained their binding affinity and selectivity toward cognate lectins. The apparent dissociation constant of the glyconanoparticles was measured by a fluorescence competition assay, where the binding affinity of Man-SNPs was almost 4 orders of magnitude higher than that of Man with concanavalin A. Moreover, even with a ligand density of 2.6 times lower than Man-SNPs synthesized by the copper-catalyzed azide-alkyne cycloaddition, the binding affinity of Man-SNPs prepared by the current method was more than 4 times higher.

Electrochemical Impedance Spectroscopy Study of Concanavalin A Binding to Self-Assembled Monolayers of Mannosides on Gold Wire Electrodes

The interactions of the lectin Concanavalin A (Con A) with self-assembled monolayers (SAMs) of thiolated mono-, di-, and tri-mannosides were studied on the surface of gold wires using electrochemical impedance spectroscopy (EIS). The SAMs of mannosides were prepared either pure or along with thiolated triethylene glycol (TEG) at different molar ratios (1:1, 1:2, 1:4, 1:9, and 1:19) to better understand and optimize the interaction conditions. The charge-transfer resistance of the [Fe(CN)₆]^3-/^4- redox probe was compared before and after the interaction at different concentrations of Con A to determine the equilibrium dissociation constant (K_d) and limit of detection (LOD). Values of K_d were found in the nanomolar range showing multivalent interactions between mannosides and Con A, and LOD was found ranging from 4-13 nM depending on the type of mannoside SAM used. Analysis using the Hill equation suggests negative cooperativity in the binding behavior. Peanut agglutinin was used as a negative control, and cyclic voltammetry was used to further support the experiments. We have found that neither the pure nor the widely dispersed monolayers of mannosides provide the conditions for optimal binding of Con A. The binding of Con A to these SAMs is sensitive to the molar ratio of the mannoside used to prepare the SAM and to the structure of the mannoside. A simple cleaning method has also been shown to regenerate the used gold wire electrodes. The results from these experiments contribute to the development of simple, cheap, selective, and sensitive EIS-based bioassays, especially for lectin-carbohydrate interactions.

Magnetic Multivalent Trehalose Glycopolymer Nanoparticles for the Detection of Mycobacteria

A multivalent trehalose-grafted poly(lactic acid) is synthesized and encapsulated with iron oxide magnetic nanoparticles. The magnetic micelles interact with Mycobacterium smegmatis to form orange clusters. Very little particle interaction is found on Staphylococcus epidermidis 35984 or Escherichia coli ORN 208. The presented new approach to the detection of mycobacteria does not require molecular biology reagents or sophisticated instruments.

Selective targeting of Mycobacterium smegmatis with trehalose-functionalized nanoparticles

Silica and iron oxide nanoparticles with sizes ranging from 6 to 40 nm were functionalized with trehalose. The trehalose-conjugated nanoparticles showed strong interactions with Mycobacterium smegmatis (M. smegmatis) and minimal interactions with macrophage (RAW 264.7) or A549 cells. In addition, trehalose-conjugated silica nanoparticles selectively interacted with M. smegmatis on M. smegmatis-treated A549 cells, demonstrating high potential of trehalose in developing targeted therapy for treating mycobacterial infection.

Glyconanomaterials for biosensing applications

Nanomaterials constitute a class of structures that have unique physiochemical properties and are excellent scaffolds for presenting carbohydrates, important biomolecules that mediate a wide variety of important biological events. The fabrication of carbohydrate-presenting nanomaterials, glyconanomaterials, is of high interest and utility, combining the features of nanoscale objects with biomolecular recognition. The structures can also produce strong multivalent effects, where the nanomaterial scaffold greatly enhances the relatively weak affinities of single carbohydrate ligands to the corresponding receptors, and effectively amplifies the carbohydrate-mediated interactions. Glyconanomaterials are thus an appealing platform for biosensing applications. In this review, we discuss the chemistry for conjugation of carbohydrates to nanomaterials, summarize strategies, and tabulate examples of applying glyconanomaterials in in vitro and in vivo sensing applications of proteins, microbes, and cells. The limitations and future perspectives of these emerging glyconanomaterials sensing systems are furthermore discussed.

Glyco-nano-oncology: Novel therapeutic opportunities by combining small and sweet

Recent efforts toward defining the molecular features of the tumor microenvironment have revealed dramatic changes in the expression of glycan-related genes including glycosyltransferases and glycosidases. These changes affect glycosylation of proteins and lipids not only in cancer cells themselves, but also in cancer associated-stromal, endothelial and immune cells. These glycan alterations including increased frequency of β1,6-branched N-glycans and bisecting N-glycans, overexpression of tumor-associated mucins, preferred expression of T, Tn and sialyl-Tn antigen and altered surface sialylation, may contribute to tumor progression by masking or unmasking specific ligands for endogenous lectins, including members of the C-type lectin, siglec and galectin families. Differential expression of glycans or glycan-binding proteins could be capitalized for the identification of novel biomarkers and might provide novel opportunities for therapeutic intervention. This review focuses on the biological relevance of lectin-glycan interactions in the tumor microenvironment (mainly illustrated by the immunosuppressive and pro-angiogenic activities of galectin-1) and the design of functionalized nanoparticles for pharmacological delivery of multimeric glycans, lectins or selective inhibitors of lectin-glycan interactions with antitumor activity.

Facile fabrication of glycopolymer-based iron oxide nanoparticles and their applications in the carbohydrate–lectin interaction and targeted cell imaging

A novel method for facile fabrication of glycopolymer-based iron oxide nanoparticles (GIONs) is developed.

Gold Nanoparticles Decorated with Sialic Acid Terminated Bi-antennary N-Glycans for the Detection of Influenza Virus at Nanomolar Concentrations

Gold nanoparticles decorated with full-length sialic acid terminated complex bi-antennary N-glycans, synthesized with glycans isolated from egg yolk, were used as a sensor for the detection of both recombinant hemagglutinin (HA) and whole influenza A virus particles of the H1N1 subtype. Nanoparticle aggregation was induced by interaction between the sialic acid termini of the glycans attached to gold and the multivalent sialic acid binding sites of HA. Both dynamic light scattering (DLS) and UV/Vis spectroscopy demonstrated the efficiency of the sensor, which could detect viral HA at nanomolar concentrations and revealed a linear relationship between the extent of nanoparticle aggregation and the concentration of HA. UV/Vis studies also showed that these nanoparticles can selectively detect an influenza A virus strain that preferentially binds sialic acid terminated glycans with α(2→6) linkages over a strain that prefers glycans with terminal α(2→3)-linked sialic acids.

Glyconanomaterials for Combating Bacterial Infections

Bacterial infections constitute an increasing problem to human health in response to build-up of resistance to present antibiotics and sluggish development of new pharmaceuticals. However, a means to address this problem is to pinpoint the drug delivery to-and into-the bacteria. This results in a high local concentration of the drug, circumventing the increasingly high doses otherwise necessary. Combined with other effectors, such as covalent attachment to carriers, rendering the drugs less degradable, and the combination with efflux inhibitors, old drugs can be revived. In this context, glyconanomaterials offer exceptional potential, since these materials can be tailored to accommodate different effectors. In this Concept article, we describe the different advantages of glyconanomaterials, and point to their potential in antibiotic "revitalization".

Development of functionalized nanoparticles for vaccine delivery to dendritic cells: a mechanistic approach

AIM

Produce biodegradable nanoparticles to target antigen-presenting cells (APCs) and evaluate their potential to be used as a vaccine delivery system.

MATERIALS & METHODS

Untargeted PEGylated poly(d,l-lactic-co-glycolide)-based nanoparticles and mannose-grafted nanoparticles were formulated and physicochemically characterized. Immortalized and primary APCs were used to study nanoparticle internalization patterns. The endocytic pathways and intracellular trafficking followed by nanoparticles were also investigated.

RESULTS & DISCUSSION

Nanoparticles displayed mannose residues available for binding at the nanoparticle surface. Different nanoparticle internalization patterns by immortalized and primary APCs were verified. Macropinocytosis, clathrin-mediated endocytosis, caveolin- and lipid raft-dependent endocytosis are involved in nanoparticles internalization. Nanoparticles demonstrate both endolysosomal and cytosolic localizations and a tendency to accumulate nearby the endoplasmic reticulum.

CONCLUSION

The developed nanoparticles might drive antigens to be presented through MHC class I and II molecules to both CD8(+) and CD4(+) T cells, favoring a complete and coordinated immune response.

Glycodendrimers and Modified ELISAs: Tools to Elucidate Multivalent Interactions of Galectins 1 and 3

Multivalent protein-carbohydrate interactions that are mediated by sugar-binding proteins, i.e., lectins, have been implicated in a myriad of intercellular recognition processes associated with tumor progression such as galectin-mediated cancer cellular migration/metastatic processes. Here, using a modified ELISA, we show that glycodendrimers bearing mixtures of galactosides, lactosides, and N-acetylgalactosaminosides, galectin-3 ligands, multivalently affect galectin-3 functions. We further demonstrate that lactose functionalized glycodendrimers multivalently bind a different member of the galectin family, i.e., galectin-1. In a modified ELISA, galectin-3 recruitment by glycodendrimers was shown to directly depend on the ratio of low to high affinity ligands on the dendrimers, with lactose-functionalized dendrimers having the highest activity and also binding well to galectin-1. The results depicted here indicate that synthetic multivalent systems and upfront assay formats will improve the understanding of the multivalent function of galectins during multivalent protein carbohydrate recognition/interaction.

Anilide formation from thioacids and perfluoroaryl azides

A metal-free method for fast and clean anilide formation from perfluoroaryl azide and thioacid is presented. The reaction proved highly efficient, displaying fast kinetics, high yield, and good chemoselectivity. The transformation was compatible with various solvents and tolerant to a wide variety of functional groups, and it showed high performance in polar protic/aprotic media, including aqueous buffer systems.

Gold nanoparticle-enabled blood test for early stage cancer detection and risk assessment

When citrate ligands-capped gold nanoparticles are mixed with blood sera, a protein corona is formed on the nanoparticle surface due to the adsorption of various proteins in the blood to the nanoparticles. Using a two-step gold nanoparticle-enabled dynamic light scattering assay, we discovered that the amount of human immunoglobulin G (IgG) in the gold nanoparticle protein corona is increased in prostate cancer patients compared to noncancer controls. Two pilot studies conducted on blood serum samples collected at Florida Hospital and obtained from Prostate Cancer Biorespository Network (PCBN) revealed that the test has a 90-95% specificity and 50% sensitivity in detecting early stage prostate cancer, representing a significant improvement over the current PSA test. The increased amount of human IgG found in the protein corona is believed to be associated with the autoantibodies produced in cancer patients as part of the immunodefense against tumor. Proteomic analysis of the nanoparticle protein corona revealed molecular profile differences between cancer and noncancer serum samples. Autoantibodies and natural antibodies produced in cancer patients in response to tumorigenesis have been found and detected in the blood of many cancer types. The test may be applicable for early detection and risk assessment of a broad spectrum of cancer. This new blood test is simple, low cost, requires only a few drops of blood sample, and the results are obtained within minutes. The test is well suited for screening purpose. More extensive studies are being conducted to further evaluate and validate the clinical potential of the new test.

Synthesis of multifunctional cellulose nanocrystals for lectin recognition and bacterial imaging

Multifunctional cellulose nanocrystals have been synthesized and applied as a new type of glyconanomaterial in lectin binding and bacterial imaging. The cellulose nanocrystals were prepared by TEMPO-mediated oxidation and acidic hydrolysis, followed by functionalization with a quinolone fluorophore and carbohydrate ligands. The cellulose nanocrystals were subsequently applied in interaction studies with carbohydrate-binding proteins and in bacterial imaging. The results show that the functional cellulose nanocrystals could selectively recognize the corresponding cognate lectins. In addition, mannosylated nanocrystals were shown to selectively interact with FimH-presenting E. coli, as detected by TEM and confocal fluorescence microscopy. These glyconanomaterials provide a new application of cellulose nanocrystals in biorecognition and imaging.

Glyconanomaterials: Emerging applications in biomedical research

Carbohydrates constitute the most abundant organic matter in nature, serving as structural components and energy sources, and mediating a wide range of cellular activities. The emergence of nanomaterials with distinct optical, magnetic, and electronic properties has witnessed a rapid adoption of these materials for biomedical research and applications. Nanomaterials of various shapes and sizes having large specific surface areas can be used as multivalent scaffolds to present carbohydrate ligands. The resulting glyconanomaterials effectively amplify the glycan-mediated interactions, making it possible to use these materials for sensing, imaging, diagnosis, and therapy. In this review, we summarize the synthetic strategies for the preparation of various glyconanomaterials. Examples are given where these glyconanomaterials have been used in sensing and differentiation of proteins and cells, as well as in imaging glycan-medicated cellular responses.

Next generation ligand binding assays-review of emerging real-time measurement technologies

Over the last few years, numerous ligand binding assay technologies that utilize real-time measurement have been introduced; however, an assemblage and evaluation of these technologies has not previously been published. Herein, we describe six emerging real-time measurement technologies: Maverick™, MX96 SPR™, NanoDLSay™, AMMP®/ViBE®, SoPrano™, and two Lab-on-a-Chip (LoC) microfluidic devices. The development stage gate of these technologies ranges from pre-commercial to commercially available. Due to the novelty, the application and utility of some of the technologies regarding bioanalysis are likely to evolve but it is our hope that this review will provide insight into the direction the development of real-time measurement technologies is moving and the vision of those that are taking us there. Following the technology discussions, a comprehensive summary table is presented.

β-Cyclodextrin-bearing gold glyconanoparticles for the development of site specific drug delivery systems

Three novel gold nanoparticles containing multiple long, flexible linkers decorated with lactose, β-cyclodextrin, and both simultaneously have been prepared. The interaction of such nanoparticles with β-d-galactose-recognizing lectins peanut agglutinin (PNA) and human galectin-3 (Gal-3) was demonstrated by UV-vis studies. Gal-3 is well-known to be overexpressed in several human tumors and can act as a biorecognizable target. This technique also allowed us to estimate their loading capability toward the anticancer drug methotrexate (MTX). Both results make these glyconanoparticles potential site-specific delivery systems for anticancer drugs.

Multivalent glycosylated nanoparticles for studying carbohydrate–protein interactions

Glyconanoparticles decorated with multiple copies of various biologically relevant carbohydrates serve as scaffolds for protein binding assay, molecular imaging, targeted therapy, and bacterium detection.

Study of wild-type α-synuclein binding and orientation on gold nanoparticles

The disruption of α-synuclein (α-syn) homeostasis in neurons is a potential cause of Parkinson's disease, which is manifested pathologically by the appearance of α-syn aggregates, or Lewy bodies. Treatments for neurological diseases are extremely limited. To study the potential use of gold nanoparticles (Au NPs) to limit α-syn misfolding, the binding and orientation of α-syn on Au NPs were investigated. α-Syn was determined to interact with 20 and 90 nm Au NPs via multilayered adsorption: a strong electrostatic interaction between α-syn and Au NPs in the hard corona and a weaker noncovalent protein-protein interaction in the soft corona. Spectroscopic and light-scattering titrations led to the determinations of binding constants for the Au NP α-syn coronas: for the hard corona on 20 nm Au NPs, the equilibrium association constant was 2.9 ± 1.1 × 10(9) M(-1) (for 360 ± 70 α-syn/NP), and on 90 nm Au NPs, the hard corona association constant was 9.5 ± 0.8 × 10(10) M(-1) (for 5300 ± 700 α-syn/NP). The binding of the soft corona was thermodynamically unfavorable and kinetically driven and was in constant exchange with "free" α-syn in solution. A protease digestion method was used to deduce the α-syn orientation and structure on Au NPs, revealing that α-syn absorbs onto negatively charged Au NPs via its N-terminus while apparently retaining its natively unstructured conformation. These results suggest that Au NPs could be used to sequester and regulate α-syn homeostasis.

Sensing lectin-glycan interactions using lectin super-microarrays and glycans labeled with dye-doped silica nanoparticles

A new microarray platform, based on lectin super-microarrays and glycans labeled with dye-doped nanoparticles, has been developed to study glycan-lectin interactions. Glycan ligands were conjugated onto fluorescein-doped silica nanoparticles (FSNPs) using a general photocoupling chemistry to afford FSNP-labeled glycan probes. Lectins were printed on epoxy slides in duplicate sets to generate lectin super-microarrays where multiple assays could be carried out simultaneously in each lectin microarray. Thus, the lectin super-microarray was treated with FSNP-labeled glycans to screen for specific binding pairs. Furthermore, a series of ligand competition assays were carried out on a single lectin super-microarray to generate the dose-response curve for each glycan-lectin pair, from which the apparent affinity constants were obtained. Results showed 4-7 orders of magnitude increase in affinity over the free glycans with the corresponding lectins. Thus, the glycan epitope structures having weaker affinity than the parent glycans could be readily identified and analyzed from the lectin super-microarrays.

Direct measurement of glyconanoparticles and lectin interactions by isothermal titration calorimetry

Glyconanomaterials have shown high potential in applications including bioanalysis and nanomedicine. Here, a quantitative analytical technique, based on isothermal titration calorimetry, was developed to characterize the interactions between glyconanoparticles and lectins. By titrating lectins into the glyconanoparticle solution, the apparent dissociation constant, thermodynamic parameters, and the number of binding sites were derived simultaneously. For the glyconanoparticles-lectin binding pairs investigated, a 3-5 order of magnitude affinity enhancement over the free ligand-lectin interactions was observed which can be attributed to the multivalent ligand presentation on the nanoparticles. The impact of ligand density was also studied, and results showed that the affinity increased with the number of glycans on the nanoparticle.