Physicochemical design of functional biopolymeric hydrogels

A challenging aspect of the development of functional materials relies in the conceptual design and practical realization of innovative hydrogels, with superior, stimuli-responsive, and pre-programmable physicochemical properties. Compared to petroleum-based synthetic polymers, biopolymers offer higher biodegradability and biocompatibility as well as better recyclability, and lower environmental footprint. These attributes make them ideal candidates for food packaging, drug delivery, and tissue engineering applications. However, despite the intense research in the shifting from synthetic to natural polymers, many challenges remain unsolved in the development of engineered biopolymeric materials with proper physicochemical properties. In this framework, this thesis aims at the design, preparation, and physicochemical characterization of functional biopolymeric hydrogels employing conventional and advanced processing techniques in combination with physical or chemical crosslinking treatments according to the different chemistry shown by the three biopolymers studied, namely pullulan, gelatin, and alginate. The grafting of photo-reactive groups on pullulan backbone results in a photo-polymerizable materials, which finds applications as inks for 3D printing and for the realization of antimicrobial cross-linked silver nanoparticles-integrated hydrogels (Case study I). Gelatin-based architectures, e.g., microparticles and macroscopic hydrogels, are investigated in terms of processing techniques and chemical crosslinking approaches, demonstrating the potentiality and efficiency of innovative less toxic cross-linking treatments (Case study II). From an applicative point of view, alginate ability to bind divalent cations represents a feasible route, enabling the design and preparation of hybrid fibers by wet-spinning (Case study III) as well as pullulan/alginate blended active films enriched with natural compounds, which provide new functionalities, i.e., antioxidant and antimicrobial properties (Case study IV). The results reported in this thesis pave the way towards the design of new biopolymeric hydrogels with enhanced physicochemical functionalities.