Three-Dimensional Tubular Printing of Bioabsorbable Stents: The Effects Process Parameters Have on In Vitro Degradation

Abstract Bioresorbable stents (BRSs) offer the potential to improve long-term patency rates by providing support just long enough for an artery to heal. However, producing a BRS for an intended period of support time is rather difficult. Nowadays in the stent industry, the current manufacturing process used is laser microcutting. Nevertheless, in the case of BRSs based on polymers, three-dimensional (3D) additive manufacturing (AM) techniques could be the better solution. Developing AM techniques to produce BRSs and studying how these technologies affect the stents' properties are indispensible nowadays. In this context, the present work aims to study the effect that the 3D printing process has on the degradation rate of polycaprolactone (PCL) stents. This is because degradation rate is one of the most important properties of a stent if the appropriate amount of time to heal atherosclerosis is to be provided. This work employs a 3D tubular printer designed by our group and presents the effects that printing temperature, flow rate, and speed have on the degradation rate of PCL stents in both dynamic and static conditions. Tests on the molecular weight, material structure, degradation rate, and radial expansion were performed. Results showed that the printing process does in fact influence the degradation rate by accelerating it as the printing temperature and flow rate increase. Furthermore, the static method degraded the samples faster. Finally, all samples showed great stability in their radial behavior, barely changing after 8 weeks of degradation. The results encourage us to believe that tubular 3D printing could well be a solution for BRS production.