A Polyurethane-GelMA Self-Healing Hydrogel for Extrusion-Based 3D Bioprinting and Vat Photopolymerization

Successful 3D bioprinting requires bioinks that combine appropriate mechanical and biological properties to support tissue engineering applications. Beyond these fundamental requirements, increasing attention has been devoted to materials with advanced functionalities, such as self-healing behavior, which can more closely replicate selected dynamic features of native tissues and offer advantages in dynamic environments where mechanical integrity is critical. Nevertheless, despite the growing interest in self-healing hydrogels, their development for bioprinting remains limited, particularly for vat photopolymerization, which is increasingly used in bioprinting due to its higher resolution when compared to extrusion-based methods. This study addresses this gap by formulating and characterizing a nanocomposite bioink based on GelMA and waterborne polyurethane nanoparticles, designed to combine intrinsic self-healing with compatibility with both extrusion-based bioprinting and vat photopolymerization. Waterborne polyurethane nanoparticles with a diameter of 50 nm were synthesized and incorporated into a GelMA-based matrix to introduce autonomous self-healing without requiring an external trigger. The resulting material was characterized in terms of swelling behavior, degradation under physiological conditions, cytocompatibility, and rheological properties. The hydrogel exhibited a shear modulus of 8 kPa, within the range of soft hydrogel matrices, effective self-healing capability, along with a slower degradation rate than the control formulation, supporting its potential as a biofabrication platform for further biological investigation.