Silk Fibroin/PLA 3D Printed Composite Stent Fabricated through Direct Ink Write Technology

Abstract

Bioresorbable alternatives are emerging on the market as alternatives to the cardiovascular stents that are implanted nowadays. Permanent drug-eluting stents are no longer the only viable option during an angioplasty surgical procedure. The new generation of medical stents aims to degrade the device within the artery walls after its function has been completed. In this context, biological materials that degrade inside the body without creating toxic residues such as silk fibroin (SF) are very promising materials for such applications. Moreover, SF has been reported to have non-thrombogenic properties and to reduce the immune response compared to other synthetic polymers, making it ideal for this application. SF has been printed through additive manufacturing techniques such as direct ink write. This study proposes to fabricate a composite stent by combining polylactic acid (PLA) and SF. In this way, it is expected to obtain a stent with potential for a two-phase drug release. A fast burst with the degradation of the SF and a slower drug release period with the degradation of the PLA. For this purpose, stents were fabricated with a PLA and chloroform ink (24.5 % w/v). The last layer of the stent was fabricated with a SF water-based ink at 56.69-60.09 % w/w. Finally, the stents were immersed at different times in ethanol and exposed to 30' of ultraviolet light for sterilization purposes. The degradation results indicate that 24h is sufficient to degrade almost completely the last layer of SF. These results are significant as the SF layer could potentially be used as a carrier for drug delivery, providing biocompatibility and drug release at the earliest post-intervention stage.