Tailor-made Glycopolymers via Reversible Deactivation Radical Polymerization: Design, Properties and Applications

Investigating the underlying mechanism of biological interactions using glycopolymer is becoming increasingly important owing to their unique recognition properties. The multivalent interactions between lectin and glycopolymer are significantly influenced by...

Design of Thermoresponsive Elastin-Like Glycopolypeptides for Selective Lectin Binding and Sorting

Selective lectin binding and sorting was achieved using thermosensitive glycoconjugates derived from recombinant elastin-like polypeptides (ELPs) in simple centrifugation-precipitation assays. A recombinant ELP, (VPGXG)₄₀, containing periodically spaced methionine residues was used to enable chemoselective postsynthetic modification via thioether alkylation using alkyne functional epoxide derivatives. The resulting sulfonium groups were selectively demethylated to give alkyne functionalized homocysteine residues, which were then reacted with azido-functionalized monosaccharides to obtain ELP glycoconjugates with periodic saccharide functionality. These modifications were also found to allow modulation of ELP temperature dependent water solubility. The multivalent ELP glycoconjugates were evaluated for specific recognition, binding and separation of the lectin Ricinus communis agglutinin (RCA₁₂₀) from a complex protein mixture. RCA₁₂₀ and ELP glycoconjugate interactions were evaluated using laser scanning confocal microscopy and dynamic light scattering. Due to the thermoresponsive nature of the ELP glycoconjugates, it was found that heating a mixture of galactose-functionalized ELP and RCA₁₂₀ in complex media selectively yielded a phase separated pellet of ELP-RCA₁₂₀ complexes. Based on these results, ELP glycoconjugates show promise as designer biopolymers for selective protein binding and sorting.

Controlling pre-osteoblastic cell adhesion and spreading on glycopolymer brushes of variable film thickness

Controlling the cell behavior on biocompatible polymer surfaces is critical for the development of suitable medical implant coatings as well as in anti-adhesive applications. Synthetic glycopolymer brushes, based on sugar methacrylate monomers have been reported as robust surfaces to resist protein adsorption and cell adhesion. In this study, poly(D-gluconamidoethyl methacrylate) (PGAMA) brushes of various chain lengths were synthesized directly from initiator functionalized glass substrates using surface-initiated atom transfer radical polymerization. The glycopolymer film thicknesses were determined by ellipsometry, whereas the wettability and the morphology of the surfaces were characterized by static water contact angle measurements and atomic force microscopy, respectively. Stable, grafted films with thicknesses in the dry state between 4 and 20 nm and of low roughness (~1 nm) were obtained by varying the polymerization time. Cell experiments with MC3T3-E1 pre-osteoblasts cultured on the PGAMA brushes were performed to examine the effect of film thickness on the cell morphology, cytoskeleton organization and growth. The results revealed good cell spreading and proliferation on PGAMA layers of low film thickness, whereas cell adhesion was prevented on polymer films with thickness higher than ~10 nm, indicating their potential use in medical implants and anti-adhesive surfaces, respectively.