Davide Campagna Abstract

Frontier research on soft materials with active, dynamic and functional features entail a wide array of systems, among which responsive and dynamic polymer hydrogels as biomaterials for cell cultures and tissue engineering. The ability of these systems to transform their properties in a diverse fashion and over a long timeframe certainly represents a key aspect and may open new possibilities to study cell cultures in transformative environments under multiple aspects. On the other hand, dynamic covalent chemistry (DCC) has been deeply studied and implemented in soft materials to make them able to self-heal and be reprocessed. However, DCC may offer new opportunities for transformative features in hydrogels as biomaterials, beyond the more established advantage of stress relaxation and related effects of cells behavior. Hereby, we developed the idea of taking advantage of a certain DCC with strongly imbalanced equilibrium, that is an imine exchange from hydrazone to oxime. We therefore applied this chemistry in a polymer gel to fully exchange and thus substitute the crosslinking segments bearing aromatic disulfide as orthogonal, functional, and photoresponsive moieties. This resulted in a post-fabrication reconfiguration of the material in different aspects: responsivity, static and dynamic mechanical properties. We envisioned that this concept of replacing functional crosslinking segments using adequately selected dynamic chemistry could represent a novel method to transform materials over a long-time frame, and thus serve as versatile approach and inspiration to further progress the design of dynamic and adaptive biomaterials.