Carbohydrate-Based Nanoparticles for Potential Applications in Medicine

Hybrid Multivalent Jack Bean α-Mannosidase Inhibitors: The First Example of Gold Nanoparticles Decorated with Deoxynojirimycin Inhitopes

Among carbohydrate-processing enzymes, Jack bean α-mannosidase (JBα-man) is the glycosidase with the best responsiveness to the multivalent presentation of iminosugar inhitopes. We report, in this work, the preparation of water dispersible gold nanoparticles simultaneously coated with the iminosugar deoxynojirimycin (DNJ) inhitope and simple monosaccharides (β-d-gluco- or α-d-mannosides). The display of DNJ at the gold surface has been modulated (i) by using an amphiphilic linker longer than the aliphatic chain used for the monosaccharides and (ii) by presenting the inhitope, not only in monomeric form, but also in a trimeric fashion through combination of a dendron approach with glyconanotechnology. The latter strategy resulted in a strong enhancement of the inhibitory activity towards JBα-man, with a K_i in the nanomolar range (K_i = 84 nM), i.e., more than three orders of magnitude higher than the monovalent reference compound.

Assessing the Biocompatibility of Multi-Anchored Glycoconjugate Functionalized Iron Oxide Nanoparticles in a Normal Human Colon Cell Line CCD-18Co

We have previously demonstrated that iron oxide nanoparticles with dopamine-anchored heterobifunctional polyethylene oxide (PEO) polymer, namely PEO-IONPs, and bio-functionalized with sialic-acid specific glycoconjugate moiety (Neu5Ac(α2-3)Gal(β1-4)-Glcβ-sp), namely GM3-IONPs, can be effectively used as antibacterial agents against target Escherichia coli. In this study, we evaluated the biocompatibility of PEO-IONPs and GM3-IONPs in a normal human colon cell line CCD-18Co via measuring cell proliferation, membrane integrity, and intracellular adenosine triphosphate (ATP), glutathione GSH, dihydrorhodamine (DHR) 123, and caspase 3/7 levels. PEO-IONPs caused a significant decrease in cell viability at concentrations above 100 μg/mL whereas GM3-IONPs did not cause a significant decrease in cell viability even at the highest dose of 500 μg/mL. The ATP synthase activity of CCD-18Co was significantly diminished in the presence of PEO-IONPs but not GM3-IONPs. PEO-IONPs also compromised the membrane integrity of CCD-18Co. In contrast, cells exposed to GM3-IONPs showed significantly different cell morphology, but with no apparent membrane damage. The interaction of PEO-IONPs or GM3-IONPs with CCD-18Co resulted in a substantial decrease in the intracellular GSH levels in a time- and concentration-dependent manner. Conversely, levels of DHR-123 increased with IONP concentrations. Levels of caspase 3/7 proteins were found to be significantly elevated in cells exposed to PEO-IONPs. Based on the results, we assume GM3-IONPs to be biocompatible with CCD-18Co and could be further evaluated for selective killing of pathogens in vivo.

SERS monitoring of local pH in encapsulated therapeutic cells

Microencapsulation of therapeutic cells has widely advanced toward the development of treatments for various diseases, in particular seeking the protection of cell transplants from immune rejection. However, several challenges in cell therapy remain due to the lack of suitable methods to monitor in vivo microcapsule tracking, microcapsule stability and/or altered cell viability and proliferation upon transplantation. We propose in this work the incorporation of contrast agents in microcapsules, which can be easily visualized by SERS imaging. By placing SERS probes in the alginate extracellular layer, a high contrast can be obtained with negligible toxicity. Specifically, we used a pH-sensitive SERS tracking probe consisting of gold nanostars encoded with a pH-sensitive Raman-active molecule, and protected by a layer of biocompatible polymer coating, grafted on the nanoparticles via electrostatic interactions. This nanomaterial is highly sensitive within the biologically relevant pH range, 5.5-7.8. We demonstrate that this SERS-based pH sensor can provide information about cell death of microencapsulated cells, in a non-invasive manner. As a result, we expect that this approach should provide a general strategy to study biological interactions at the microcapsule level.

Fabrication and Application of Levan-PVA Hydrogel for Effective Influenza Virus Capture

To prevent the transmission of pathogenic microorganisms such as the influenza virus, efficient pathogen-capturing materials are required. Here, we report a new pathogen-capturing and recovery material using levan polysaccharide. We fabricated hydrogels by blending levan and poly(vinyl alcohol) (PVA) and by using glutaraldehyde as a cross-linking agent. Fabricated levan-PVA hydrogels have a high water solubility and water adsorption ability. SEM observations showed that levan-PVA hydrogels have a 3D porous structure. We confirmed by RT-PCR analysis that the influenza virus capture efficiency of levan-PVA hydrogels is higher than that of commercial cotton swabs. Moreover, we confirmed that levan-PVA hydrogels on gauze as a filter material effectively captured bioaerosol samples. Therefore, levan-PVA hydrogels are expected to serve as simple and efficient pathogen capture and recovery materials.

Synthesis and application of glycoconjugate-functionalized magnetic nanoparticles as potent anti-adhesion agents for reducing enterotoxigenic Escherichia coli infections

Polyethylene oxide stabilized magnetic nanoparticles (PEO-MNPs) bio-functionalized with glycoconjugate (Neu5Ac(α2-3)Gal(β1-4)Glcβ-sp) (GM3-MNPs) are synthesized using click chemistry. Interaction of GM3-MNPs with Enterotoxigenic Escherichia coli (ETEC) strain K99 (EC K99) is investigated using different microscopic techniques. Our results suggest that GM3-MNPs can effectively act as non-antibiotic anti-adhesion agents for treating ETEC infections.

Synthesis and evaluation of glyco-coated liposomes as drug carriers for active targeting in drug delivery systems

Novel sugar-conjugated cholesterols, β-Gal-, α-Man-, β-Man-, α-Fuc-, and β-Man-6P-S-β-Ala-Chol, were synthesized and incorporated into liposomes. In vitro experiments using the glyco-coated liposomes showed that the glyco-coated liposomes are efficiently taken up by cells expressing carbohydrate-binding receptors selectively. Glyco-coated liposomes are promising candidates for drug delivery vehicles.

Glycodendrimers: versatile tools for nanotechnology

Combining nanotechnology with glycobiology has triggered an exponential growth of research activities in the design of novel functional bionanomaterials (glyconanotechnology). More specifically, recent synthetic advances towards the tailored and versatile design of glycosylated nanoparticles namely glyconanoparticles, considered as synthetic mimetics of natural glycoconjugates, paved the way toward diverse biomedical applications. The accessibility of a wide variety of these structured nanosystems, in terms of shapes, sizes, and organized around stable nanoparticles have readily contributed to their development and applications in nanomedicine. In this context, glycosylated gold-nanoparticles (GNPs), glycosylated quantum dots (QDs), fullerenes, single-wall natotubes (SWNTs), and self-assembled glycononanoparticles using amphiphilic glycopolymers or glycodendrimers have received considerable attention to afford powerful imaging, therapeutic, and biodiagnostic devices. This review will provide an overview of the most recent syntheses and applications of glycodendrimers in glycoscience that have permitted to deepen our understanding of multivalent carbohydrate-protein interactions. Together with synthetic breast cancer vaccines, inhibitors of bacterial adhesions to host tissues including sensitive detection devices, these novel bionanomaterials are finding extensive relevance.

Pharmacokinetic considerations for targeted drug delivery

Drug delivery systems involve technology designed to maximize therapeutic efficacy of drugs by controlling their biodistribution profile. In order to optimize a function of the delivery systems, their biodistribution characteristics should be systematically understood. Pharmacokinetic analysis based on the clearance concepts provides quantitative information of the biodistribution, which can be related to physicochemical properties of the delivery system. Various delivery systems including macromolecular drug conjugates, chemically or genetically modified proteins, and particulate drug carriers have been designed and developed so far. In this article, we review physiological and pharmacokinetic implications of the delivery systems.

On the roles of polyvalent binding in immune recognition: perspectives in the nanoscience of immunology and the immune response to nanomedicines

Immunology often conveys the image of large molecules, either in the soluble state or in the membrane of leukocytes, forming multiple contacts with a target for actions of the immune system. Avidity names the ability of a polyvalent molecule to form multiple connections of the same kind with ligands tethered to the same surface. Polyvalent interactions are vastly stronger than their monovalent equivalent. In the present review, the functional consequences of polyvalent interactions are explored in a perspective of recent theoretical advances in understanding the thermodynamics of such binding. From insights on the structural biology of soluble pattern recognition molecules as well as adhesion molecules in the cell membranes or in their proteolytically shed form, this review documents the prominent role of polyvalent interactions in making the immune system a formidable barrier to microbial infection as well as constituting a significant challenge to the application of nanomedicines.