Multimodal 3D printing of biodegradable shape memory elastomer resins for patient specific soft tissue repair

Acrylated poly(glycerol-dodecanedioate) (APGD), a biodegradable shape memory polymer, is a photocurable resin developed for 3D printing of biomaterial implants that is especially suited for minimally invasive procedures. 3D printing has numerous advantages over traditional manufacturing modalities including production of complex porous geometries, improved feature resolution, and lower production costs on a per part basis for low volume clinical production. Material extrusion (ME) and vat photopolymerization (VP) printing are two prevalent 3D printing modalities used in tissue engineering. Compared to VP printing, ME printing offers a higher degree of customization by allowing co- or multi-material prints, along with biologic cell printing. VP printing offers higher throughput and capability for printing more complex geometries, versus ME printing, with shorter manufacturing times, making it a more commercially viable choice for clinically translatable materials. Motivated by each printing modalities’ unique advantages, APGD resins for ME and VP printing were developed and assessed for crosslinker and photoinitiator (PI) concentration effect on resin time to gel point, storage modulus and viscosity. Increasing crosslinker concentration decreased the gel time and increased the storage modulus of cured resin. Significant differences in printed sample geometry along with material and mechanical properties resulted from using the two printing modalities. ME samples had larger void volume (6.1 ± 1.2% vs. 0.2 ± 0.4%), lower gel content (55.3 ± 2.6% vs. 68.7 ± 1.9%), and less shape fixity (77.4 ± 4.7 vs. 97.3 ± 3.7%) compared to VP samples. VP printing generated complicated 3D anatomic shapes of higher quality than ME printing. In conclusion, this manuscript provides the first report of APGD 3D printing that can be applied to shape memory, resorbable medical devices.