Characterization and Prediction of Properties of Polymeric Materials for Extrusion-Based Bioprinting Process

Abstract Extrusion based bioprinting has enabled researchers to expand the field of tissue engineering via the construction of complex tissue structures. The main limiter within this field is the number of available bioinks that demonstrate the necessary characteristics for 3D-bioprinting and are also able to create a high-resolution intricate structure. This is mainly due to the liquid-like behavior of the material during extrusion, as it must be able to recover a required amount of viscosity immediately post deposition to hold the desired shape. Materials are often crosslinked after printing to increase shape fidelity, with ionic crosslinking being the most common. In this paper, we explored a dual-crosslinked bioink that combines both ionic and chemical crosslinking, utilizing calcium chloride and ultraviolet (UV) light, respectively. We propose dual crosslinked material that would allow scientists to crosslink during printing, creating a scaffold with a sufficient green strength (achieved solely through UV curing to temporarily hold the printed shape before undergoing final ionic crosslinking) for post printing ionic crosslinking. A series of novel bioinks comprised of Alginate, Carboxymethyl cellulose (CMC), a photoinitiator (Lithium phenyl-2,4,6-trimethylbenzoylphosphinate: LAP), and a varying amount Polyethylene glycol diacrylate (PEGDA) were formulated, and their rheological and thermal properties were thoroughly investigated. In addition to standard rotational rheology, photo-DSC, and photo-rheology were employed to better understand the materials curing kinetics. These findings were further compared to tests conducted on an in-house 3D bioprinter equipped with a custom-built dual-curing system.