A Strategy for Restraining Interlacing Points of Biodegradable Braided Stents by Elastomer: Regulate Radial and Flexuous Performance

The inadequate radial performance of poly (L-lactic acid) (PLLA)-braided stents has hindered the development of the treatment of peripheral vascular diseases. As the basic unit of the stent, the restraint form between monofilaments is the key factor affecting the radial performance. In this study, different concentrations of solutions are prepared using six-arm poly (lactide-co-ε-caprolactone) (6SPLCL) and hexamethylene diisocyanate at a mass ratio of 5:1 to restrain every interlacing point of the stent (full restraint). The findings reveal that fully restraining the interlacing points of the stent substantially improves radial strength, increasing the chronic outward force (COF) value by 30%, but concurrently, the flexibility is reduced, which could cause damage to blood vessels and lead to secondary thrombosis when used in curved vessels. Accordingly, the innovative structure of the stent is designed by restraining part of the interlacing points (restraint on both ends). The results show that the radial stiffness is increased by 16%, and the COF value is increased by up to 12% under the premise of keeping the flexibility basically unchanged. This research advances the ongoing efforts to enhance the understanding of the structural design for biodegradable braided stents to obtain appropriate mechanical properties and ultimately promote clinical outcomes.