Radial Compressive Property and the Proof-of-Concept Study for Realizing Self-expansion of 3D Printing Polylactic Acid Vascular Stents with Negative Poisson's Ratio Structure.

Wenzheng Wu,Peipei Wang,Bofan Wang,Guiwei Li,Shuo Zhang,Ji Zhao,Zichao Wu

doi:10.3390/ma11081357

Abstract

Biodegradable stents offer the potential to reduce the in-stent restenosis by providing support long enough for the vessel to heal. The polylactic acid (PLA) vascular stents with negative Poisson’s ratio (NPR) structure were manufactured by fused deposition modeling (FDM) 3D printing in this study. The effects of stent diameter, wall thickness and geometric parameters of arrowhead NPR structure on radial compressive property of 3D-printed PLA vascular stent were studied. The results showed that the decrease of stent diameter, the increase of wall thickness and the increase of the surface coverage could enhance the radial force (per unit length) of PLA stent. The radial and longitudinal size of PLA stent with NPR structure decreased simultaneously when the stent was crimped under deformation temperature. The PLA stent could expand in both radial and longitudinal direction under recovery temperature. When the deformation temperature and recovery temperature were both 65 °C, the diameter recovery ratio of stent was more than 95% and the maximum could reach 98%. The length recovery ratio was above 97%. This indicated the feasibility of utilizing the shape memory effect (SME) of PLA to realize the expansion of 3D-printed PLA vascular stent under temperature excitation.

Highlights

Vascular stent implantation is one of the main therapies used to treat vascular occlusion diseases [1]
The experiment was performed on each vascular stent, and results of each group are shown in stents in each group had the same wall results of each group are shown in stents in each group had the same wall results of and eachgeometric group areparameters shown in of stents in each group had the same wall thickness arrowhead structure, but had different diameters
The results showed that 3D-printed polylactic acid (PLA) vascular stents had favorable shape memory effect (SME)

Summary

Introduction

Vascular stent implantation is one of the main therapies used to treat vascular occlusion diseases [1]. In-stent restenosis is the re-blockage of vascular stent after stent implantation, which is the main failure form of stents and a key problem remaining to be solved [2]. Drug-eluting stents depend on antiproliferative drugs to prevent repairing of damaged vascular endothelium, which delays the in-stent restenosis but cannot fundamentally solve the problem of stent restenosis [4,5]. Biodegradable stents can generally degrade in the human body after expansion and support of narrow vessels. Biodegradable stents can eliminate the problem of long-term rejection of the stents and avoid the damage and stimulation of the surrounding vessel wall, which effectively solves the problem of in-stent restenosis [6,7,8]

Methods

Results

Conclusion