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Recent development of high-resolution micro-Continuous Liquid Interface Production (microCLIP, continuous projection microstereolithography) process has enabled 3D printing of biomedical devices with 10 micron-scale precision. 3D bioresorbable vascular scaffolds (BVS) were printed using an antioxidant, photopolymerizable citric acid-based material (B-InkTM). Despite demonstrating BVS fabrication feasibility, challenges remained. According to literature, a vascular stent when placed in the body must be able to sustain a pressure loading between 10.67kPa and 13.34kPa of pressure loading. To be clinically relevant, struts for vascular scaffolds need to possess very small thickness, 100um or below. Specifically, to improve our material strength/stiffness of our 3D printed BVSs, a dissolved PLLA nanophase (10%, wt./vol in Tetrahydrofuran) and secondary temperature-sensitive initiators (V70, 1wt.%) were added to the photopolymer resin. Through temperature-induced phase separation and solvent exchange, fibrous networks were incorporated through the B-Ink 3D matrix. Secondary initiators allowed for further crosslinkage of the matrix material. Introduction of PLLA nanophase/secondary initiators greatly improved bulk stiffness and yielded BVSs with 100um strut thickness that could sustain the necessary biological radial pressure loadings. This technology and photopolymerizable material is a large step forward toward on-the-spot and on-demand fabrication of patient specific BVSs.
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