Designing polymeric biomaterial inks for 3D printing

Abstract

Event Abstract Back to Event Designing polymeric biomaterial inks for 3D printing Murat Guvendiren1, Koustubh Dube1, Joseph Molde1 and Joachim Kohn1 1 Rutgers University, New Jersey Center for Biomaterials, United States Introduction: Recent studies have shown that 3D printing has a significant potential to respond to the need for structural complexity in biomaterial design[1]-[3]. However, the currently printed devices only serve as a structural support. They permit but do not promote biological function, due to a lack of bioactivity of the available polymers (including poly(lactic acid) (PLA), and polycaprolactone (PCL))[4]. In this study, our goal is to develop a novel biodegradable polymer family, for fused deposition modeling (FDM) and solvent-based printing, with user controlled functionalizability (post- or pre-printing) to develop bioactive scaffolds and medical devices. Methods: A family of tyrosol-based polyesters was developed via carbodiimide reaction of diphenol with dicarboxylic acid (at 1:1 molar ratio). Thermal properties were characterized by differential scanning calorimetry (DSC). Melt rheology studies of the compression-molded films were performed on a Kinexus rheometer. 3D scaffolds were printed using FDM (Type A Machines, San Leandro, CA) and solvent-based printer (BioBots, Philadelphia, PA). Filaments for FDM (1.75 mm diameter) were fabricated using a benchtop melt extruder. Polymer inks were fabricated by dissolving polymers in DCM (30wt%). Results and Discussion: In this study, poly(4-hydroxyphenethyl 2-(4-hydroxyphenyl) acetate) (PHTy), and poly(4-hydroxyphenethyl 3-(4-hydroxyphenyl)propanoate) (PDTy) were developed due to their semicrystalline properties for FDM and excellent solubility in low boiling point water-miscible solvents for solvent-based printing. For FDM, the melt-to-solid transition properties were further enhanced by incorporation of 2,2’-(1,4-phenylene)diacetic acid (PDA) into the polymer design forming copolymers of p(HTy-PDA) and p(DTy-PDA) (Fig 1). The PDA group increased the crystallinity and significantly reduced (an order of magnitude) the melt viscosity values to 5x105 (for p(HTy-PDA)) and 106 (for p(DTy-PDA)) making these polymers printable by FDM printer. To enable functionalizability of the polymers, glutamic acid (Glu) was incorporated into the polymer design (using carbodiimide reaction) without altering the melt rheological properties (including the viscosity). The amine group in Glu was used to incorporate a wide range of reactive groups (R) via carbodiimide chemistry (Fig 2A). This step can be performed before (bulk chemistry) or after printing (surface chemistry). These reactive groups can further be used to incorporate biochemical cues. To demonstrate functionalizability, fluorescently labeled molecules (methacrylated rhodamine and avidin-rhodamine) were tethered to the scaffolds functionalized with photo-chemistry enabled molecules (alkene and alkyne) and scaffolds functionalized with biotin (Fig.2 E-H). Conclusions: A novel family of tyrosol-based polyesters was developed for FDM and solvent-based printing. The printability and functionalizability was tuned using chemistry. This novel polymer family is a potential candidate system to fabricate 3D scaffolds with user-defined and tunable biactivity. This work was supported by Award Number P41EB001046 from the National Institute of Biomedical Imaging and Bioengineering and discretionary funds from the New Jersey Center for Biomaterials at Rutgers University.