Preparation And Properties Of Bio-based Dynamic Hydrogel

Biomedical materials are an important part of current pharmaceutical products,and have good application prospects in promoting wound healing,drug delivery,and cell and tissue culture scaffolds.Natural polysaccharides,polyphenols and proteins have been widely reported in the construction of polymer materials to improve the biological functional properties of the materials because their excellent biological activities.Dynamic covalent bonds provide new opportunities for the development of smart biomaterials,bringing more functional properties such as stimuli responsiveness and self-healing.This research aims to promote the use of natural biomacromolecules,such as polysaccharides,proteins and polyphenols as starting materials,with further cross-linking with synthetic compounds through dynamic chemical bonds,resulting in biological material hydrogels with good biodegradability,stimuli responsiveness and biocompatibility.In project(1),biomacromolecules(O-Carboxymethyl Chitosan and heparin)and synthetic polymers were prepared into antibacterial injectable hydrogels through dynamic imine bond cross-linking and electrostatic interaction,which were futher used for 3D cell culture.We present here an imine-PEGylated dynamer containing positively-charged guanidinium groups,the dynamer-1 can encapsulate heparin through electrostatic interactions,and then form imine cross-links through dynamic exchange with the amino group of O-CMCS,leading to a double network heparin based dynamic hydrogel.The obtained dynamic hydrogel exhibited good pH responsiveness,injectability,rapid self-repair(the instantaneous recovery rate of storage modulus can reach 93%),suitable biodegradability and biocompatibility.The hydrogels can release the encapsulated drugs in response to different pH values and delivere by injection.They also can provide more space for cell growth.It can be seen from the experimental results that the obtained heparin based dynamic hydrogel exhibited good antibacterial activity and positive impacts on 3D cell culture,showing excellent biomedical research potential.In project(2),biomacromolecules(gelatin)and synthetic polymers were prepared into temperature-responsive adhesive injectable hydrogels through dynamic imine bond and dynamic borate bond.We used tannic acid and 4-formylphenylboronic acid to prepare dynamic polymer dynamer-2 based on borate crosslinking under different oxidation degrees of sodium periodate,they can be dynamically cross-linked with gelatin through imine bonds to prepare injectable adhesive hydrogels.The obtained hydrogels showed temperature-responsive adhesion,injectability,biodegradability and tensile properties.Owing to the suitable viscosity of tannic acid and gelatin,the formed double dynamic cross-linked hydrogel showed better adhesion properties.The adhesive stress can reach 30 kPa at 37 ℃.When the hydrogels were cooled to 25 ℃ due to the existence of dynamic bonds and the inherent heat sensitivity of gelatin constituent,the hydrogel exhibited relatively low adhesion,leading to easy removal of the solid adhesive hydrogels by cooling as needed,thus,avoiding secondary tearing of the adhesive part.These results indicated that the hydrogels have potential applications as wound adhesives.