Continuous digital light processing (cDLP): Highly accurate additive manufacturing of tissue engineered bone scaffolds

Abstract

Highly accurate rendering of the external and internal geometry of bone tissue engineering scaffolds affects fit at the defect site, loading of internal pore spaces with cells, bioreactor-delivered nutrient and growth factor circulation, and scaffold resorption. It may be necessary to render resorbable polymer scaffolds with 50 µm or better accuracy to achieve these goals. This level of accuracy is available using Continuous Digital Light Processing (cDLP) which utilizes a DLP® (Texas Instruments, Dallas, TX) chip. One such additive manufacturing device is the envisionTEC (Ferndale, MI) Perfactory®. To use cDLP we integrate a photo-crosslinkable polymer, a photo-initiator, and a biocompatible dye. The dye attenuates light, thereby limiting the depth of polymerization. In this study we fabricated scaffolds using the well-studied resorbable polymer, poly(propylene fumarate) (PPF), titanium dioxide (TiO₂) as a dye, Irgacure® 819 (BASF [Ciba], Florham Park, NJ) as an initiator, and diethyl fumarate as a solvent to control viscosity.

Keywords:

• continuous digital light processing (cDLP)
• bone tissue engineering
• poly(propylene fumarate) (PPF)
• titanium dioxide (TiO2)
• additive manufacturing

Acknowledgements

This research was partially supported by the Research Foundation of the Department of Neurological Surgery, Case Western Reserve University, Cleveland, OH and by NIH grant R01-DE013740. We wish to thank Ms. Yueshuo Xu for her assistance in collecting the TiO₂/BAPO dye-initiator calibration data.