Injectable Hydrogels for Therapeutic Delivery and 3D Printing

Abstract

Injectable hydrogels are an important class of biomaterials for therapeutic delivery, tissue engineering, and 3D bioprinting. Owing to the complexity of medical procedures, next generation of injectable hydrogels with programmed and personalized functions could be a great aid for treating diseases and tissue regeneration. Moreover, in emerging technology platforms of 3D bioprinting and tissue modeling, injectable hydrogels play an important role due to their good rheological properties and biocompatibility. In this thesis, we investigated the dynamic interactions of nanomaterials, stimuli-responsive polymers, dynamic covalent bonds, and microgels to design three novel injectable hydrogels. First, NIR light-triggered gelation system utilized the hydrophobic interaction of nanoparticles and polymers to accelerate the crosslinking of nanocomposite hydrogels. This system has shown its great potential uses in small molecular drug delivery, photothermal therapy, and 3D bath printing. Second, an adaptable to mechanically stable hydrogel was programmed based on the redox reactions of gold ions and disulfide groups. The hydrogel has shown dynamic changes in mechanical, rheological, and electrochemical properties in temperature and time-dependent manners. These interesting properties could be desired for the applications of 3D printing and drug delivery. Third, a microgel assembly with thermos-responsive reinforcement of mechanical stability was developed through the integration of dynamic covalent chemistry, stimuli-responsive polymer, and microgel technology. This work has demonstrated the potential applications of programmed microgel assembly with rheological properties adapted to environmental stimuli as an injectable hydrogel. We envision that the new concepts for tailoring injectable hydrogel by dynamic interactions of miscellaneous materials presented in our research can facilitate a greater use of injectable hydrogels in biomedical engineering.