Digital light processing of poly(ε-caprolactone)-based resins into porous shape memory scaffolds

Digital light processing (DLP) is a promising 3D printing technique with excellent resolution, enabling the fabrication of complex structures to serve the tissue engineering (TE) field. However, its full potential in this regard remains insufficiently explored by the scarcity of 'smart' photoresponsive biodegradable and biocompatible polymers. By combining biodegradable shape memory polymers with DLP printing, complex thermoresponsive structures can be developed, allowing minimally invasive TE. The current study focuses on the development of biodegradable and biocompatible photosensitive resins consisting of poly(e-caprolactone) acrylate-endcapped urethane-based polymers (AUPs) to create thermo-responsive porous scaffolds with a shape shift close to body temperature. The molar mass of the AUP along with the photo-initiator concentration are varied, enabling the investigation of the influence of these parameters on the resin properties and the DLP processability. The newly developed resins exhibit excellent properties in terms of viscosity, photocrosslinking kinetics, polymer fraction, and swelling capacity. Compression tests demonstrated that the porous scaffolds exhibit a compressive modulus around 75 kPa, making them suitable to serve a variety of soft TE applications. Additionally, the 3D printed scaffolds are biocompatible as indicated by a cell viability and metabolic activity exceeding 85%. Finally, the scaffolds' shape memory properties are evidenced both qualitatively as quantitatively via Dynamic Mechanical Analysis (DMA) experiments. These experiments indicate a shape shift around body temperature and shape fixity and shape recovery values superior to 94%, rendering them excellent candidates for, among others, minimally invasive TE strategies.