As an important natural polysaccharide biomaterial from marine organisms, alginate and its derivatives have shown great potential in the fabrication of biomedical materials such as tissue engineering, cell biology, drug delivery, and pharmaceuticals due to their excellent biological activity and controllable physicochemical properties. Ionic crosslinking is the most common method used in the preparation of alginate-based biomaterials, but ionic crosslinked alginate hydrogels are prone to decompose in physiological solution, which hinders their applications in biomedical fields. In this study, dual crosslinked alginate hydrogel microfibers were prepared for the first time. The ionic crosslinked methacrylated alginate (Alg-MA) hydrogel microfibers fabricated by Microfluidic Fabrication (MFF) system were exposed to ultraviolet (UV) light and covalent crosslink between methacrylate groups avoided the fracture of dual crosslinked macromolecular chains in organizational environment. The chemical structures, swelling ratio, mechanical performance, and stability were investigated. Cell-encapsulated dual crosslinked Alg-MA hydrogel microfibers were fabricated to explore the application in tissue engineering for the first time. The hydrogel microfibers provided an excellent 3D distribution and growth conditions for cells. Cell-encapsulated Alg-MA microfibers scaffolds with functional 3D tissue structures were developed which possessed great potential in the production of next-generation scaffolds for tissue engineering and regenerative medicine.

As derivatives from marine natural biomaterials, alginate-based and chitosan-based biomaterials are commonly used in wound dressings. Calcium alginate fiber (CAF) dressings possess excellent absorption and unique gel forming performance, but the low bioactivity limits its application in wound healing. Carboxymethyl chitosan (CM-Chit) has excellent antibacterial activity, but the gel structure with weak mechanical properties restricts its application. In this study, minocycline (Mino)/CM-Chit solution was coated on the surface of plasma treated CAF needle-punched nonwovens, and then Mino loaded CM-Chit gel/CAF nonwovens composite dressings were fabricated by EDC/NHS (1-3-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxysuccinimide) crosslinking. The dressings had a porous composite structure, which allowed them to quickly absorb and store a large number of wound exudates. Skin-like tensile performance allowed the dressings to provide a better healing environment. Antibacterial assay against Escherichia coli and Staphylococcus aureus indicated that the addition of Mino significantly improved the antibacterial activity of the wound dressings. The tight structure of CM-Chit gel prevented the burst release of Mino so that the dressings had antibacterial activity in a certain period of release time. Cell culture assay showed that the dressings had excellent cell biocompatibility. As new functional dressings, the prepared composite dressings had excellent potential in the clinical healing of wounds.