Search

The field of stimuli-responsive supramolecular biomaterials has rapidly advanced in recent years, with potential applications in diverse areas such as cancer theranostics, tissue engineering, and catalysis. However, designing molecular materials that exhibit predetermined hierarchical self-assembly to control the size, morphology, surface chemistry, and responsiveness of the final nanostructures remains a significant challenge. In this study, we present a divergent synthetic approach for the fabrication of spherical micelles and functional 1D-glyconanotube-based photoresponsive gels from structurally related diazobenzene/diacetylene glycolipids. The resulting nanostructures were characterized using NMR, TEM, and SEM, confirming the formation of spherical and tubular nanostructures in both the gel and solution states. Upon UV irradiation, a reversible gel-sol transition was observed, resulting from the photoswitching of the azobenzene unit from the stretched trans form to the compact, metastable cis form. Our gels were shown to enable spatio-temporal control of the adhesion and release of the lectin Concanavalin A, demonstrating potential use as regenerable biomaterials to fight against infections with toxins and pathogens. Additionally, our micelles and gels were evaluated as nanocontainers for loading and controlled release of hydrophobic dyes and antitumoural agents, suggesting their possible use as smart theranostic drug delivery systems.

To take full advantage of the remarkable applications of carbon nanotubes in different fields, there is a need to develop effective methods to improve their water dispersion and biocompatibility while maintaining their physical properties. In this sense, current approaches suffer from serious drawbacks such as loss of electronic structure together with low surface coverage in the case of covalent functionalizations, or instability of the dynamic hybrids obtained by non-covalent functionalizations. In the present work, we examined the molecular basis of an original strategy that combines the advantages of both functionalizations without their main drawbacks. The hierarchical self-assembly of diacetylenic-based neoglycolipids into highly organized and compacted rings around the nanotubes, followed by photopolymerization leads to the formation of nanotubes covered with glyconanorings with a shish kebab-type topology exposing the carbohydrate ligands to the water phase in a multivalent fashion. The glyconanotubes obtained are fully functional, and able to establish specific interactions with their cognate receptors. In fact, by taking advantage of this selective binding, an easy method to sense lectins as a working model of toxin detection was developed based on a simple analysis of TEM images. Remarkably, different experimental settings to assess cell membrane integrity, cell growth kinetics and cell cycle demonstrated the cellular biocompatibility of the sugar-coated carbon nanotubes compared to pristine single-walled carbon nanotubes.

We present a mild and practical carbon nanotubes rings (CNRs) synthesis from non-covalent functionalized and water-soluble linear single-wall carbon nanotubes. The hemi-micellar-supramolecular self-organization of lactose-based glycolipid 1 on the ring surface, followed by photo-polymerization of the diacetylenic function triggered by UV light afforded the first water-soluble and biocompatible CNRs. The obtained donut-like nanoconstructs expose a high density of lactose moieties on their surface, and are able to engage specific interactions with Arachis hypogea lectin similar to glycoconjugates on the cell membrane.

Remarkably stable, water-soluble glyconanoring-coated SWCNTs were prepared by self organization and photopolymerization of neutral diacetylene-based glycolipids on the nanotube surface; the nanoconstructs are able to engage in specific ligand-lectin interactions in a similar way to glycoconjugates on cell membranes.

The specific interaction of hevein with GlcNAc-containing oligosaccharides has been analyzed by1H-NMR spectroscopy. The association constants for the binding of hevein to a variety of ligands have been estimated from1H-NMR titration experiments. The association constants increase in the order GlcNAc-alpha(1-->6)-Man < GlcNAc < benzyl-beta-GlcNAc < p-nitrophenyl-beta-GlcNAc < chitobiose < p-nitrophenyl-beta-chitobioside < methyl-beta-chitobioside < chitotriose. Entropy and enthalpy of binding for different complexes have been obtained from van't Hoff analysis. The driving force for the binding process is provided by a negative DeltaH0which is partially compensated by negative DeltaS0. These negative signs indicate that hydrogen bonding and van der Waals forces are the major interactions stabilizing the complex. NOESY NMR experiments in water solution provided 475 accurate protein proton-proton distance constraints after employing the MARDIGRAS program. In addition, 15 unambiguous protein/carbohydrate NOEs were detected. All the experimental constraints were used in a refinement protocol including restrained molecular dynamics in order to determine the highly refined solution conformation of this protein-carbohydrate complex. With regard to the NMR structure of the free protein, no important changes in the protein nOe's were observed, indicating that carbohydrate-induced conformational changes are small. The average backbone rmsd of the 20 refined structures was 0.055 nm, while the heavy atom rmsd was 0.116 nm. It can be deduced that both hydrogen bonds and van der Waals contacts confer stability to the complex. A comparison of the three-dimensional structure of hevein in solution to those reported for wheat germ agglutinin (WGA) and hevein itself in the solid state has also been performed. The polypeptide conformation has also been compared to the NMR-derived structure of a smaller antifungical peptide, Ac-AMP2.