Digital micromirror device (DMD)-based 3D printing of poly(propylene fumarate) scaffolds

Abstract

Our recent investigations into the 3D printing of poly(propylene fumarate) (PPF), a linear polyester, using a DMD-based system brought us to a resin that used titanium dioxide (TiO2) as an ultraviolet (UV) filter for controlling cure depth. However, this material hindered the 3D printing process due to undesirable lateral or “dark” curing (i.e., in areas not exposed to light from the DMD chip). Well known from its use in sunscreen, another UV filter, oxybenzone, has previously been used in conjunction with TiO2. In this study we hypothesize that combining these two UV filters will result in a synergistic effect that controls cure depth and avoids dark cure. A resin mixture (i.e., polymer, initiator, UV filters) was identified that worked well. The resin was then further characterized through mechanical testing, cure testing, and cytotoxicity testing to investigate its use as a material for bone tissue engineering scaffolds. Results show that the final resin eliminated dark cure as shown through image analysis. Mechanically the new scaffolds proved to be far weaker than those printed from previous resins, with compressive strength of 7.8 ± 0.5 MPa vs. 36.5 ± 1.6 MPa, respectively. The new scaffolds showed a 90% reduction in elastic modulus and a 74% increase in max strain. These properties may be useful in tissue engineering applications where resorption is required. Initial cytotoxicity evaluation was negative. As hypothesized, the use of TiO2 and oxybenzone showed synergistic effects in the 3D printing of PPF tissue engineering scaffolds.

Photo‐Crosslinked Elastomeric Bimodal Poly(trimethylene carbonate) Networks

“…Cubic porous structures with a diamond pore network architecture were designed as described previously . To obtain structures measuring 7 × 7 × 7 mm with a porosity of 70% after building, extraction, and drying, the designs were adjusted to account for removal of the diluent.…”

“…High porosities are preferred to be able to minimize the amount of implanted polymer and increase the surface area . Tissue engineering scaffolds have been prepared by conventional pore forming techniques such as by salt leaching and polymer phase separation, as well as by additive manufacturing techniques such as fused deposition modeling, extrusion‐based 3D printing and by stereolithography (SLA) …”

Advances in bioinks and in vivo imaging of biomaterials for CNS applications

“…Additionally, unpolymerized material will maintain the liquid form, allowing to be easily washed away [8]. This technique can be performed in a focal manner (laser beam that scans along the biomaterial) or using Digital Light Processing (DPL)-based bioprinting where the bioprinted polymer layer is cured entirely at once (decreasing production time and avoiding artificial interfaces) [2,34]. Biomaterials are so versatile that is also possible to combine techniques for production of specific, customizable scaffolds, or to improve their characteristics, as for example stability or detail resolution.…”

Preparation of Designed Poly(trimethylene carbonate) Meniscus Implants by Stereolithography: Challenges in Stereolithography

“…3D printing allows the preparation of designed scaffolds and patient‐specific implants for application in tissue engineering . Porous 3D scaffolds with high porosity and pore interconnectivity are important support structures that ensure ingrowth and proliferation of cells facilitating the regeneration of tissues.…”

“…Biodegradable functionalized oligomers (or macromers) that have been developed for these purposes have been based on ε‐caprolactone, trimethylene carbonate, and d , l ‐lactide . Also poly(propylene fumerate) materials have been investigated. However, these macromers require the addition of a reactive diluent like diethyl fumarate to obtain resins with appropriate reaction rates and viscosities …”