A collagen-based biomaterial ink for the digital light processing 3D printing of tough, dual-crosslinked hydrogels via post-print tannic acid treatment

Collagen-based biomaterial inks for digital light processing (DLP) 3D printing are particularly attractive due to their inherent biocompatibility, cell-adhesion properties, and biodegradability. However, there have been relatively few examples of collagen-based biomaterial inks without the use of synthetic co-monomers or specialized printing equipment. Furthermore, photo-crosslinked collagen hydrogels are often brittle, limiting their use in biomedical applications and regenerative medicine. In this study, we present the development of a novel collagen-based biomaterial ink for DLP 3D printing, enabling the fabrication of robust hydrogel constructs through a post-print tannic acid (TA) treatment. The biomaterial ink, composed of collagen methacrylate (ColMA) and a natural co-monomer, hyaluronic acid methacrylate (HAMA), achieves high-resolution printing of biomimetic structures. The post-print TA treatment (0.25–30 mg/mL) significantly increases mechanical strength, improves degradation rates, and reduces the size and porosity of the resulting dual-crosslinked, hybrid network structures. The biocompatibility of these constructs was assessed using adult human dermal fibroblasts, revealing optimal cell viability and adhesion at low TA concentrations (0–0.25 mg/mL). Furthermore, the antioxidant capacity of TA-treated biomaterials was evaluated, demonstrating potential for applications in environments with high reactive oxygen species (ROS). Overall, this collagen-based biomaterial ink and post-print TA treatment offers a promising solution for the DLP 3D printing of tough, biodegradable, and biocompatible constructs for biomedical applications in regenerative medicine.