Carbohydrate Modified Catanionic Vesicles: Probing Multivalent Binding at the Bilayer Interface

Abstract

This article reports on the synthesis, characterization, and binding studies of surface-functionalized, negatively charged catanionic vesicles. These studies demonstrate that the distribution of glycoconjugates in the membrane leaflet can be controlled by small alterations of the chemical structure of the conjugate. The ability to control the glycoconjugate concentration in the membrane provides a method to explore the relationship between ligand separation distance and multivalent lectin binding at the bilayer interface. The binding results using the O-linked glucosyl conjugate were consistent with a simple model in which binding kinetics are governed by the density of noninteracting glucose ligands, whereas the N-linked glycoconjugate exhibited binding kinetics consistent with interacting or clustering conjugates. From the noninteracting ligand model, an effective binding site separation of the sugar sites for concanavalin A of 3.6-4.3 nm was determined and a critical ligand density above which binding kinetics are zeroth order with respect to the amount of glycoconjugate present at the bilayer was observed. We also report cryo-transmission electron microscopy (cryo-TEM) images of conjugated vesicles showing morphological changes (multilayering) upon aggregation of unilamellar vesicles with concanavalin A.

Novel Catanionic Surfactant Vesicle Vaccines Protect against Francisella tularensis LVS and Confer Significant Partial Protection against F. tularensis Schu S4 Strain

“…We theorized that a strong pathogen-specific inflammatory response, coupled with a specific high-titer IgG anti-F. tularensis antibody response, would protect not only against F. tularensis LVS challenge but also against F. tularensis Schu S4 challenge. To this end, we prepared control vesicles by combining anionic and cationic surfactants in endotoxin-free water (50). To prepare vesicles containing F. tularensis components, the anionic surfactant was first added to pelleted cultures of F. tularensis LVS or F. tularensis Schu S4 to lyse the bacteria, and then the cationic surfactant was added to produce vesicles that incorporated bacterial components from the bacterial lysates.…”

“…tularensis is found primarily in North America (1). F. tularensis Schu S4 is a highly virulent prototypic type A strain, with a 50% lethal dose (LD 50 ) of Ͻ10 CFU in mice for intranasal/aerosol infections (3).…”

Monophosphoryl Lipid A Enhances Efficacy of a Francisella tularensis LVS-Catanionic Nanoparticle Subunit Vaccine against F. tularensis Schu S4 Challenge by Augmenting both Humoral and Cellular Immunity

“…These can be "functionalized" by incorporation of lipid-conjugated molecules (23,24) or bacterial lysates (25). Thus, V represent a potentially effective vehicle for vaccine delivery, with significant advantages over those composed of phospholipids or nonionic surfactants, liposomes and niosomes, e.g., low cost, ease of formation, and high stability (22,26).…”

High‐Density Display of Protein Ligands on Self‐Assembled Capsules via Noncovalent Fluorous Interactions

“…A value of 0.2 molecule/nm 2 of sugar loading has been the largest value so far reported for a lipid vesicle. [8] Interaction of V2 with ConA was next probed according to the known protocol for assessment of sugar-protein binding Figure S1 in the Supporting Information for the original DLS data. [15] Methyl a-d-mannopyranoside (3000 equiv) added after 20 min competes with the FT-Man 1 on the vesicle, and hence partially destroys the network structure (i.e., turbidity decrease, red line).…”

“…We can load the sugar molecules on the vesicle to a level of saturation-15 times more densely than on a lipid vesicle, which becomes [a] Dr. K. Harano, J. Yamada, S. Mizuno, Prof. Dr. E. Nakamura + Department of Chemistry The University of Tokyo 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)unstable upon high-density loading of sugar. [8] Given the ability of the fullerene self-assembly to deliver small-molecule drugs, [9] DNA, and siRNA, [10] we expect that this strategy of ligand functionalization by noncovalent postmodification will be useful for targeted drug delivery.…”