Structural and mechanical differences between codfish skin and swimbladder collagen

Introduction: Codfish (Gadus morhua) is one of the most important fish catches worldwide, being processed abundantly in Portugal for human consumption, generating several by-products. Despite their potential high value given the presence of relevant compounds and materials, these are still underexplored, being mostly directed to animal feed [1-4]. Fish skin and swim bladder can be used as raw-material to obtain collagen which is growingly studied as alternative to mammal collagen in different areas of application, from food to medicine [1]. This alternative has been also increasing with the environmental education about the importance of conservation of the marine ecosystem, and with the scientific community work on a sustainable exploration of marine products and its by-products [3,4]. Collagen is the main protein of the connective tissue and the most abundant in vertebrate and invertebrate organisms, playing an important role in the ECM of skin and other tissues. Marine collagen is proved to be suitable for human applications as its biocompatibility, low antigenicity, biodegradability and functionality, but have not yet been made commercially available for medical uses [2]. This study aimed to analyze the properties of codfish collagens, considering different codfish by-products – skins and swim bladders – and methods, envisaging biomedical applications. Conclusions: As a conclusion, the results of the present work indicate that the used fish by-products and the methods, originate in the isolation of extracts with identical profiles, which implies that they had similar chemical structures and contents, being compatible with collagen type I. These results also indicated that all collagen extracts can be a promising alternative source in biomedical applications, particularly the Collsb that exhibited higher mechanical properties. This will be further explored with cell compatibility tests, while deepening the biochemical characterization to understand the different mechanical performance and to provide information about the suitability and feasibility of the extracts.