|dc.description.abstract||Hydrogels have regarded as promising biomaterials. However, most hydrogels cannot effectively resist protein adsorption, cell adhesion and microorganism growth, leading to serious infection, and foreign body reaction. Moreover, the weak mechanical properties of hydrogel also limited further application in the real world.
In this thesis, we developed a series of tough zwitterionic hydrogel by the addition of nanocomposite materials, interpenetrating networks, and double network strategies.
In chapter II, the zwitterionic poly(sulfobetaine acrylamide) nanocomposite hydrogels (pSBAA/15) have sufficient mechanical properties and good resistance against the protein, bacteria, and cell adsorption. Moreover, the pSBAA/15 hydrogel was used as a wound dressing to heal the normal wound and diabetic wound in the mice model. Comparing to the commercial dressing, the pSBAA/15 hydrogel showed a low adhesion against the wound surface, leading to the minimization of wound damage when removal of the wound dressing. Furthermore, the pSBAA/15 hydrogels were covered on normal and diabetic wounds on rat dorsal and showed a complete heal after 10 and 12 days, respectively, which was faster than commercial dressings. However, the pSBAA/15 still cannot prevent the bacteria infection on the chronic wound.
In chapter III, the silver nanoparticles were reduced and formed within the pSBAA/Ag15 hydrogels. The release rate of silver ions can be effectively controlled in the presence of the nanoclay, resulting in the negligible cytotoxicity of pSBAA/Ag15 hydrogel against human fibroblasts. Meanwhile, the pSBAA/Ag15 hydrogel showed strong antimicrobial properties by obvious inhibition of zone. In vivo experiment, the infected chronic wound on rat dorsal was complete epithelialization after 15 days with the treatment of pSBAA/Ag15. The finding indicated the great benefits of pSBAA/Ag15 for the treatment of infected chronic wounds.
In chapter IV, a salt-responsive interpenetrating network (IPN) hydrogel was engineered using the double network strategy to form loosely cross-linked zwitterionic poly(sulfobetaine vinylimidazole) (pSBVI) networks into the highly cross-linked cationic poly((trimethylamino)ethyl methacrylate chloride) (pTMAEMA) framework via photo-polymerization. The cationic pTMAEMA and zwitterionic pSBVI show opposite swelling behaviors in salt solutions due to the polyelectrolyte effect and antipolyelectrolyte effect. To this end, the pTMAEMA/pSBVI hydrogels demonstrated a series of switchable bulk and interfacial properties, including mechanical properties, optical properties, surface friction, surface charge, antimicrobial properties, and surface regeneration in response to ionic strength.
In chapter V, we demonstrated a new methodology for developing fully biocompatible double network (DN) hydrogels via using a responsive amphoteric polymer as a first framework. Whole zwitterionic DN hydrogels were synthesized by penetrating and photo-polymerizing zwitterionic poly(sulfobetaine acrylamide) (PSBAA) into a swelled amino-acid based poly(lysine acrylamide) (PLysAA) first network in an acidic or basic solution. Under a physiological condition, the DN hydrogels become fully zwitterionic. The mechanical properties of pLysAA/pSBAA hydrogel were comparable to conventional DN hydrogels. Additionally, the superior biocompatibility of the zwitterionic DN hydrogels displayed negligible thrombus formation after contacting whole blood. Furthermore, PLysAA/PSBAA hydrogels were implanted subcutaneously, showing excellent resistance against inflammatory response and long-term capsule formation.
The tough zwitterionic hydrogels showed high mechanical properties and good biocompatibility, which have a high potential for real-world biomedical applications.