Zwitterionic/nano modification of natural polymer-based bioinks for 3D bioprinting of advanced functional biomaterials

3D Bioprinting has recently emerged as a novel technology for developing customised, complex 3D biological constructs with great benefits for regenerative medicine. However, a significant challenge in implementing this technology is the lack of biomaterials (a key component of bioinks) that can simultaneously meet the desired bioprinting and scaffolding requirements such as printability, biocompatibility, biodegradability, and mechanical properties. Thus, we propose in this project a new generation of natural polymer-based bioinks having zwitterionic moieties in their structures. This zwitterionic modification is expected to enhance non-covalent interactions (e.g., electrostatic interactions), overcome the compromise among printability and other properties, and endow the hydrogel with biomimicry such as self-healing and strain-stiffening. Moreover, zwitterions are well-known to have exciting antifouling property which is needed for implants to protect them from the immunological response. The zwitterionic modification (carboxybetaine and/or sulfobetaine groups) of natural polymers (e.g., gelatin, alginate, carrageenan) will be realised by different approaches. Direct ink writing will be employed for the 3D printing of the developed zwitterionic hydrogel inks. We will explore different biocompatible crosslinking strategies (e.g., UV photo-crosslinking and ionic gelation) to allow high print resolution without compromising the biological properties. Besides zwitterionic modification, further enhancements in mechanical properties and printability will be explored by adding nanomaterials (e.g., cellulose nanocrystals or nano-clay) into the zwitterionic ink. The nanomaterial can reinforce the covalent network and form physical networks with the polymeric chains. The results of this project will generate extensive fundamental knowledge of zwitterionically modified bioinks for 3D bioprinting of advanced functional healthcare products.