New composite biomaterials for tissue regeneration from sea urchin waste

Sea urchins are well known as food delicacies worldwide, but the edible part is represented only by their gonads, whereas all the rest is discharged as waste. We recently demonstrated that a highly valuable collagen can be extracted from part of this waste and used to produce innovative biomaterials for tissue regeneration. In addition, we also recently showed that from the remaining part of the waste (shell and spines) potent natural antioxidant pigments (polyhydroxynaphtoquinones-PHNQ) can be extracted. As a step forward, in this work we performed preliminary experiments to develop a composite biomaterial properly combining these two compounds in order to 1) improve the properties of the collagen-based sponge with the antioxidant and wound promoting features of PHNQ; 2) completely recycle all the sea urchin waste and produce a truly green biomaterial. Different collagen/PHNQ were tested and various biomaterial prototypes therefore produced. These were characterized by scanning electron microscopy (SEM) to evaluate structural aspects (“porosity”, collagen fibrils disposition, etc…). Furthermore, a full characterization and evaluation of physico-chemical properties of the resulting material have been performed mainly using spectroscopic and analytical techniques. In addition, preliminary results regarding the kinetic release of the antioxidants from the biomaterial have been obtained in physiological solutions and enzymatic (collagenase) conditions. Furthermore, the antioxidant activity has been evaluated using ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)) assay. Overall, these data pave the way for the development of a second-generation of bioactive and wound healing promoting sea urchin-derived biomaterials, completely obtained from the valorization of a food by-product.