Sea urchin waste valorization for the development of innovative tools for regenerative medicine

Marine organisms are highly exploited as a source of food and their consumption often produces large amount of waste and by-products. Their valorisation and recycling towards high added-value products is one of the current main societal challenge. In line with this “circular economy approach”, we recently developed innovative sea urchin collagen-based biomaterials for skin regeneration. Native collagen was obtained from part of the wastes (up to 90% of the animal mass) of the sea urchin food industry. These biomaterial prototypes were partially characterized in term of structure, mechanical properties, in vitro biocompatibility, and preliminary in vivo tests. The aim of this work was to: 1) further characterize these prototypes in terms of degradation kinetics and antioxidant activity and 2) pave the way for the development of a second-level bioactive composite biomaterial, combining collagen and antioxidants always extracted from sea urchin wastes, for a 100% recycling. 1) We evaluated the in vitro biomaterial degradation kinetics in both physiological and enzymatic (collagenase) conditions, trying to simulate the in vivo performance of the collagen-based biomaterials. Indeed, the in vivo physiological degradation of these biomaterials leads to the formation of collagenous peptides, which display certain antioxidant properties. The degradation test showed that in enzymatic conditions the biomaterial is degraded more than 50% after 48 hours, while a commercial bovine collagen membrane used as control (Integra®), by less than 10%. Subsequently, the antioxidant activity of collagen peptides was evaluated, in comparison to Integra, using ABTS assay. The analyses show that collagen peptides have greater antioxidant activity than both collagen-based biomaterial and the commercial membrane. 2) A preliminary protocol was developed for collagen-antioxidant composite preparation, testing different molecule ratios. Obtained biomaterials were characterized in terms of structure and antioxidant release capacity using ABTS assay. Results indicate that composite prototypes are structurally similar to the simple collagen-based counterpart and that antioxidants apparently remain adsorbed in the matrix of the biomaterial, without a significant release over time. Overall, the results suggest that sea urchin wastes can be efficiently valorised obtaining high value molecules which can be used for the development of innovative biomaterial for tissue regeneration.