OEG-Based Thermoresponsive Collagen-Like Polypeptides

Thermoresponsive polypeptides have received significant interest in last decadesbecause of their excellent biocompatibilities, diverse secondary structures andthermoresponsive characteristics. Collagen is the most abundant protein in mammalswith a unique right-handed triple helix structure composed of three left-handed helicalpolypeptide chains. Modification of collagen-like polypeptides will not only providenew ideas for theoretical researches but also may pave the way for design andapplications of novel smart peptidic materials.In present thesis, we designed and synthesized two novel collagen-like polypeptides(PD and PG1), which are constituted by collagen main chain with linear or dendriticoligoethylene glycol (OEG) pendants, respectively. The parent maromoners weresynthesized by introduction of two different OEG functional pendants to4R positionof Hyp of collagen (POG) amino sequence by Williamson etherification reaction. Thethermoresponsive behavior of the polymers was investigated with UV/vis andtemperature-varied1H NMR spectroscopy, to determine their apparent phasetransition temperatures (LCSTs) and follow chain dehydration process, respectively. Itwas found that PG1showed sharp and fast transitions with small hystereses. Thephase transition temperature was located in the vicinity of physiological temperature.On the contrary, PD exhibited no detectable thermoreponsive behavior in themeasured temperature range. In addition, CD spectra from PD indicated that thispolypeptide shows a more thermally stable secondary structure in varies temperatures.In contrast, the secondary structure of PG1changes reversely upon heating andcooling around its LCST. The results in present thesis demonstrate for the first timethat pendant architecture of the collagen-like polypeptides can exibiht significantinfluence on both their thermoresponsiveness and secondary structures.