Photo-sensitive Modification And Application Of Hyaluronic Acid

In this work, three photo-sensitive modification methods of hyaluronic acid were designed and established, and further study was carried out in application field in self-assembled micelles, emulsifier and composite film, respectively. The whole paper includes three parts.1. Solution behavior between hyaluronic acid and styrylpyridinium(SbQ)A novel complex micelle was obtained via weak interaction induced self-assembly from a negatively charged hyaluronic acid (HA) and an oppositely charged styrylpyridinium species (specifically SbQ). Self-assembly behavior of HA and SbQ in aqueous solution was studied. Turbidity and Zeta potential measurements were utilized to explore the formation of complex micelles. These nano-sized micellar aggregates have a core-shell structure composed of a hydrophobic inner core containing aggregated SbQ molecules and a hydrophilic HA shell layer. UV spectra and DLS experiments confirmed that the micelles are photo-crosslinkable. A dimerization reaction of the SbQ molecules induced by UV light irradiation led to the crosslinking of the inner core, resulting in a decrease in the size of the micelles.2. Self-assembly and emulsification of the photo-sensitive coumarin-grafted hyaluronic acid derivativePhoto-sensitive coumarin-grafted hyaluronic acid derivative (HA-g-C) was synthesized by the esterification between HA and coumarin with PEG as the phase transfer agent. Resultant HA-g-C self-assembled in aqueous solution to form nanosized micellar aggregates with the shape of sphere. Strong UV absorption was observed for HA-g-C from the UV-vis spectra, suggesting that such photo-sensitive micelle can be potentially utilized as sunscreen agent in cosmetic. Furthermore, the emulsification property of the HA-g-C micelle solution was better than that of pure HA solution, due to the surface activity of the micellar particles induced by the increased amphiphilicity after the introduction of hydrophobic coumarin groups.3. Preparation and properties of hyaluronic acid/PVA-SbQ composite filmsHyaluronic acid/PVA-SbQ composite film was prepared by casting method with a blending solution of HA and PVA-SbQ. The miscibility, microstructure and surface property of the films were investigated by FTIR, SEM, AFM and contact angle analysis. The thermal property and mechanical property of the composite films were examined by TGA and tensile testing respectively. The results showed strong hydrogen bonding interactions and molecular miscibility between the two polymers, while PVA-SbQ added too much cause worse compatibility resulting in phase separation. A dimerization reaction of SbQ pendant groups in PVA-SbQ chains induced by UV led to the crosslinking of the composite film. The film displayed enhanced tensile strength and slightly weakened elongation at break after being photo-crosslinked.To sum up, this work explored the photo-sensitive modification of hyaluronic acid by physical and chemical methods and provided new approach to the functionalization and modification of hyaluronic acid.