Tyrosol-Derived Biodegradable Inks with Tunable Properties for 3D Printing
Three-dimensional (3D) printing has emerged as a valuable tool in medicine over the past few decades. With a growing number of applications using this advanced processing technique, new polymer libraries with varied properties are required. Herein, we investigate tyrosol-based poly(ester-arylate)s as biodegradable inks in fused deposition modeling (FDM). Tyrosol-based polycarbonates and polyesters have proven to be useful biomaterials due to their excellent tunability, nonacidic degradation components, and the ability to be functionalized. Polymers are synthesized by polycondensation between a custom diphenol and commercially available diacids. Thermal properties, degradation rates, and mechanical properties are all tunable based on the diphenol and diacid chosen. Evaluation of material print as it relates to chemical structure, molecular weight, and thermal properties was explored. Higher-molecular-weight polymers greater than 50 kDa exhibit thermal degradation during printing and at some points are too viscous to print. It was determined that polymers with lower processing temperatures and molecular weights were printable regardless of the structure. An exception to this was pHTy6 that was printed at 65 kDa with minimal degradation. This is most likely due to its low melting temperature and, as a result, lower printing temperatures. Additionally, chemical improvements were made to incorporate thiol–alkene click chemistry as a means for postprint curing. Low-molecular-weight pHTy6 was end-capped with alkene functionality. This material was then formulated with either a dithiol for chain extension or tetrathiol for cross-linking. Scaffolds were cured after printing for 5, 15, 30 and 60 min intervals where longer cure times resulted in a tougher material. This design builds on the library of biologically active materials previously explored and aims to bring new biomaterials to the field of 3D-printed personal medicine.