Development of a Tunable Dextran-PCL Biomaterial Photoink for High-Resolution DLP 3D Printing in Biomedical Applications

Digital light processing (DLP) is a technique that offers higher printing speeds and high spatial resolution compared to other additive manufacturing techniques. However, in biomedical applications, the biomaterials used do not provide a good balance between biocompatibility, mechanical performance, and controlled degradation. To overcome these limitations, this study aims to develop a biomaterial photoink formulation using two FDA-approved polymers. Dextran, which has high biocompatibility, was modified with glycidyl methacrylate to introduce photoreactive groups, and poly(ε-caprolactone) (PCL), a biodegradable synthetic polymer known for its mechanical reinforcement properties and slower degradation rate, was functionalized with 2-isocyanatoethyl methacrylate. To optimize the formulation, various parameters were systematically investigated, including different polymer concentrations (10-40% w/v), concentrations of photoabsorber (0.075-0.2%) and photoinitiator (LAP) (0.3-1.25%), exposure time (13-21 s), and light intensity (45-65%). Once the optimal composition of the biomaterial photoink was determined, the effect of different polymer contents on the physicochemical, mechanical, and cytotoxic properties of the printed structures was investigated. It was found that increasing the proportion of PCL in the biomaterial photoink can lead to a slower degradation rate, reduced swelling capacity, and improved mechanical properties; however, cytocompatibility was negatively affected after 14 days of indirect contact. Direct cytotoxicity testing revealed cytocompatibility after 3 days. This study enabled the development of a highly tunable biomaterial photoink that can be adapted to different biomedical application requirements. The optimized biomaterial photoink exhibited good mechanical properties, lower viscosity, and excellent printability, enabling the printing of complex geometries (e.g., tubes), including hollow structures.