Development And Biological Applications Of Supramolecular Hydrogel Based On Substituted Glucosamine And Galactopyranose

Supramolecular hydrogel formed by the self-assembly of low-molecular weight hydrogelator through noncovalent interaction has recently emerged as "smart" biomaterial for dieverse biological applications. After conjugation with short peptides or other bioactive molecules that can form intermolecular hydrogen bonds, hydrophobic molecules with plane conjugated structure have been shown as efficient scaffolds to promote their self-assembly in aqeous solution. Addtionally, supramolecular hydrogel that could form under biocompatible conditions may serve as novel biomaterial. In this thesis, we focused on the construction of suprmoalecular hydrogel fromed by glucosamine and galactopyranose that were modified with hydrophobic molecules with plane conjugated structure. We found ring-opened spiropyran could promote the self-assembly of glucosamine and galactopyranose in neutral aqueous solution after appropriate conjugation. The formed supramolecular hydrogel was sensitive to visible light and we next explored their application in cell culture and controlled release of biomolecules.The first part of this thesis focused on the synthesis of hydrogelators that consisted of glucosamine/galactopyranose and hydrophobic molecules and on the study of their self-assembly in neutral aqueous solution. Three hydrophobic molecules with plane conjugated structure were selected, inlucding ring-opened spiropyran (MC), diaryl-tetrazole (Tet), and naphthalene (Nap). Using glycine as the linker, we modidied them with D-glucosamine (I) and amino-1-O-β-D-galactopyranose (Ⅱ). Six small molecules, MC-Ⅰ,MC-Ⅱ, Tet-Ⅰ, Tet-Ⅱ, Nap-Ⅰ and Nap-Ⅱ, were then obtained and characterized prior to further investigations. Hydrogelation test in neutral aqueous solution showed that only MC-Ⅰ and MC-Ⅱ could form hydrogel, indicating plane-conjugated spiropyran could promote self-assembly of saccharides. Since merocyanine (MC) can be quickly converted into the corresponding spiropyran (SP) under visible light irradiation, the formed supramolecular hydrogel could respond to light through the structure change between MC and SP.The second part of this thesis focused on the photo response of supramolecular hydrogel formed by MC-Ⅰ and MC-Ⅱ and their subsequent applications in controlled delivery of bioactive molecules into cells cultured on top of gel. Horse serum was entrapped inside the gel formed by MC-Ⅰ and MC-Ⅱ and was delivered into C2C12 cells to promote differentiation upon light irradiation, which were further characterized by measuring the expression level of differentiation markers by quantitative real-time PCR. Similarly, miR-122 was also trapped in the gel formed by MC-Ⅰ and MC-Ⅱ. Upon light irradiation, miR-122 was released from the gel and delivered into HepG2 cells cultured on the top of hydrogel, which were demonstrated by measuring the expression level of endogenous miR-122 by quantitative real-time PCR. Through the applications described above, we found MC-Ⅰ and MC-Ⅱ were potential smart biomaterials for controlled delivery of protein and miRNA through light irradiation. Further optimization and exploration are still underway in our group.