Functional Polypeptides-based Biohybrid: Synthesis, Characterization and Self-Assembly Behavior

• Main Authors: Yung-Chih Lin, 林詠智
• Other Authors: Shiao-Wei Kuo
• Format: Others
• Language: en_US
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/40439548090630426416

博士 === 國立中山大學 === 材料與光電科學學系研究所 === 102 === Polypeptides have been widely studied due to the potential applications in various scientific fields and the close relationship to molecular recognition, proteins and drug delivery applications. In this study, we summarize variety in the preparation of functional peptide-containing biopolymer mixtures and the supramolecular structures they form via noncovalent bonding interactions. First of all, we used click chemistry to synthesize linear polypeptide-b-polyhedral oligomeric silsesquioxane (PBLG-b-POSS) copolymers. The incorporation of the POSS unit at the chain end of the PBLG moiety allowed intramolecular hydrogen bonding to occur between the POSS and PBLG units, thereby enhancing the α-helical conformation in the solid state, Thermogravimetric analysis indicated that the thermal degradation temperature increased significantly after incorporation of the POSS moiety. Next, we linked the POSS moiety on the side chain of the oligopeptides, the incorporation of the POSS unit at the side chain of the PPLG moiety enhanced the α-helical conformation in the solid state even those with relatively low DPs. PPLG-g-POSS underwent hierarchical self-assembly, to form a hexagonal cylinder packing nanostructure featuring α-helical conformations and POSS aggregates. Furthermore, we used a combination of atom transfer radical polymerization, ring opening polymerization, and click chemistry to synthesize new hierarchical organic/inorganic nanohybrid materials of PS-b-(PPLG-g-POSS). After attaching POSS nanoparticles to the side chains of PS-b-PPLG copolymers, the fraction of α-helical secondary structures increased and exhibited greater conformation stability and superior thermal properties, including Tg behavior, relative to those of the unmodified PS-b-PPLG copolymers. TEM analyses confirmed that the PS-(b-PPLG-g-POSS) copolymers underwent hierarchical self-assembly to form hexagonally packed cylindrical nanostructures. Moreover, we also prepared cyclodextrin-containing biopolymers (PPLG-g-CD), obtaining a self-assembling structure with a highly stable α-helical conformation and water-solubility. In addition, the presence of the CD cavities allowed the grafted polymers to form inclusion complexes with low-molecular-weight compounds, providing macromolecules with potential biomedical applications. Finally, we mixing the PPLG-g-Py oligomers with multiwalled carbon nanotubes (MWCNTs) in dimethylformamide led to the formation of highly dispersible PPLG-g-Py/MWCNT biohybrid materials. Fluorescence emission spectra revealed significant π–π stacking interactions between the PPLG-g-Py oligomers and the MWCNTs in these complexes.