Binding of β-amyloid to sulfated sugar residues in a polymer brush

Glycopolymer Brushes by Reversible Deactivation Radical Polymerization: Preparation, Applications, and Future Challenges

The cellular surface contains specific proteins, also known as lectins, that are carbohydrates receptors involved in different biological events, such as cell-cell adhesion, cell recognition and cell differentiation. The synthesis of well-defined polymers containing carbohydrate units, known as glycopolymers, by reversible deactivation radical polymerization (RDRP) methods allows the development of tailor-made materials with high affinity for lectins because of their multivalent interaction. These polymers are promising candidates for the biomedical field, namely as novel diagnostic disease markers, biosensors, or carriers for tumor-targeted therapy. Although linear glycopolymers are extensively studied for lectin recognition, branched glycopolymeric structures, such as polymer brushes can establish stronger interactions with lectins. This specific glycopolymer topology can be synthesized in a bottlebrush form or grafted to/from surfaces by using RDRP methods, allowing a precise control over molecular weight, grafting density, and brush thickness. Here, the preparation and application of glycopolymer brushes is critically discussed and future research directions on this topic are suggested.

Protecting-Group-Free Synthesis of Well-Defined Glycopolymers Featuring Negatively Charged Oligosaccharides

Control of the macromolecular architecture is essential to enable sophisticated functions for glycopolymers and to allow a precise correlation between these functions and the polymer structure. A number of biologically important ligands are negatively charged oligosaccharides that are difficult to manipulate in organic solvent and that are hardly amenable to protection/deprotection strategies. RAFT polymerization is a simple and robust technique that enables the synthesis of well-defined glycopolymers directly in aqueous solution and starting from unprotected vinyl glycomonomers. Here I describe how RAFT polymerization can be combined with reductive amination to transform negatively charged oligosaccharides having 5-20 monosaccharide units into well-defined glycopolymers directly in water and without the need to resort to protecting-group chemistry.

Syntheses of sulfo-glycodendrimers using click chemistry and their biological evaluation

A series of novel glycol-clusters containing sulfonated N-acetyl-D-glucosamine (GlcNAc) have been synthesized using click chemistry. Three dendrimers with aromatic dendrons were synthesized using chlorination, azidation and click chemistries. The resulting dendrimers were modified with azide-terminated sulfonated GlcNAc using click chemistry. The sulfonated dendrimers showed affinity for proteins, including the lectin wheat germ agglutinin and amyloid beta peptide (1-42). The dendrimers of G1 and G2 in particular showed the largest affinity for the proteins. The addition of the sulfonated GlcNAc dendrimers of G1 and G2 exhibited an inhibition effect on the aggregation of the amyloid beta peptide, reduced the β-sheet conformation, and led to a reduction in the level of nanofiber formation.