Multi-material volumetric bioprinting and plug-and-play suspension bath biofabrication via bioresin molecular weight tuning and multiwavelength optics

Volumetric Bioprinting (VBP), enables to rapidly build complex, cell-laden hydrogel constructs for tissue engineering and regenerative medicine. Light-based tomographic manufacturing enables spatial-selective polymerization of a bioresin, resulting in higher throughput and resolution than what achieved using traditional techniques. However, methods for multi-material printing are needed for a broad VBP adoption and applicability. Although converging VBP with extrusion bioprinting in support baths offers a novel, promising solution, further knowledge on the engineering of hydrogels as light-responsive, volumetrically printable baths is needed. Therefore, this study investigates the tuning of gelatin macromers, in particular leveraging the effect of molecular weight and degree of modification, to overcome these challenges, creating a library of materials for VBP and Embedded extrusion Volumetric Printing (EmVP). Bioresins with tunable printability and mechanical properties are produced, and a novel subset of gelatins and GelMA exhibiting stable shear-yielding behavior offers a new, single-component, ready-to-use suspension medium for in-bath printing, which is stable over multiple hours without needing temperature control. As proof-of-concept biological application, bioprinted gels are tested with insulin-producing pancreatic cell lines for 21 days of culture. Leveraging a multi-color printer, complex multi-material and multi-cellular geometries are produced, enhancing the accessibility of volumetric printing for advanced tissue models.