Collagen/Gelatin extraction from Marine Sponges - a green technology approach

Marine sponges can be regarded as a promising alternative source for collagen/gelatin, with interesting prospective for biomedical applications. Although, and despite of its unique physico-chemical properties, sponge-origin collagen/gelatin is not available in large quantities, mainly due to the lack of efficient extraction methodologies. The traditional procedures are very laborious, time consuming and present several drawbacks that are hampering the process scale up, such as the requirement of several operational steps, energy and high volumes of water and other reagents. In this sense, there is a necessity for an alternative methodology comprising fewer steps and, ideally, more environmentally sustainable. We have proposed a new technology for the extraction of marine sponge collagen/gelatin based on water pressurized with carbon dioxide. This new methodology is comprised by one single extraction step, under mild operating conditions, reducing solvent and water consumption. The objective of this work is to optimize the operating conditions to obtain the highest yields and collagen quantity and quality. Pressure and time were the parameters studied through a two-level factorial design performed by statistical analysis using the software Design-Expert (Stat - Ease^®). The extraction process was initiated by loading grinded marine sponges (small pieces with less than 0.5mm) and distilled water to the high pressure vessel. The reactor was heated to 37ºC and pressurized with CO₂. The effects of pressures ranging 10-50 bars and extraction time between 3-24 hours were studied. The collagen content of each extract was determined using a dye-binding method (Sircol Assay) and values of collagen near 36% were obtained for the sponge Chondrosia reniformis. Additionally, circular dichroism (CD) analysis shows that for all extracts the presence of the characteristic negative peak of collagen/gelatin between 197-203 nm and the FTIR spectra are similar to the controls, suggesting that the original chemical structure from collagen/gelatin is maintained. Thus, in this new methodology, the acidification of the aqueous solution promoted by CO₂ will induce collagen/gelatin solubilisation in the aqueous media and the final extracts can be easily recovered after freeze-drying. The physico-chemical characterization has shown that the proposed methodology allows high extraction yields (≈14%, quantified as the ratio of dry extract per weight of sample extracted), without affecting the fundamental material properties. In overall, the results obtained have demonstrated the effectiveness and potential of this new green technology to obtain sponge-origin collagen/gelatin with great applicability in the biomedical field.