Chitosan/collagen-based hydrogels for sustainable development: Phycocyanin controlled release

Marine biopolymers obtained from fishery by-products, such as chitosan and collagen, are sustainable alternatives to developing eco-friendly hydrogels. This work focused on the development of composite hydrogels based on blue crab chitosan (Cs) and bluefin tuna collagenous protein (BTCP), at different concentrations (10%, 20%, and 50%; w/w Cs), by using a freezing/thawing approach. Cs-BTCP composite hydrogels were characterized in terms of structural, morphological, thermal, mechanical, rheological, and antioxidant properties. A highly interconnected porous structure is shown for all the freeze-dried composite chitosan hydrogels by SEM imaging. Additionally, by increasing the concentration of BTCP, the porosity, and swelling degree of the composite hydrogels were improved. Data also revealed that BTCP addition enhanced the elasticity and mechanical resistance of composite hydrogels, especially HG prepared with 50% of BTCP, which explain its high swelling ability which reaches 2160% compared to 1396% for HG-C, at pH 5.5. HG-50 was selected for the in vitro release study of phycocyanin as a bioactive molecule and the results revealed that the release depends on the medium pH. Kinetic studies show that phycocyanin release is mainly governed by drug diffusion. Therefore, pH-sensitive Cs-BTPC composite hydrogels could provide an appropriate and supportive microenvironment for the loading and administration of drugs.