Fabrication of Balloon-Expandable Self-Lock Drug-Eluting Polycaprolactone Stents Using Micro-Injection Molding and Spray Coating Techniques

Abstract

The purpose of this report was to develop novel balloon-expandable self-lock drug-eluting poly(ε-caprolactone) stents. To fabricate the biodegradable stents, polycaprolactone (PCL) components were first fabricated by a lab-scale micro-injection molded machine. They were then assembled and hot-spot welded into mesh-like stents of 3 and 5 mm in diameters. A special geometry of the components was designed to self-lock the assembled stents and to resist the external pressure of the blood vessels after being expanded by balloons. Characterization of the biodegradable PCL stents was carried out. PCL stents exhibited comparable mechanical property to that of metallic stents. No significant collapse pressure reduction and weight loss of the stents were observed after being submerged in PBS for 12 weeks. In addition, the developed stent was coated with paclitaxel by a spray coating technique and the release characteristic of the drug was determined by an in vitro elution method. The high-performance liquid chromatography analysis showed that the biodegradable stents could release a high concentration of paclitaxel for more than 60 days. By adopting the novel techniques, we will be able to fabricate biodegradable drug-eluting PCL stents of different sizes for various cardiovascular applications.

Biodegradable stent

“…The surface of the stent was applied with poly (D,L-lactic acid-co-glycolic acid) (PLGA) and paclitaxel at room temperature using the spray coating method. The release of paclitaxel was confirmed for over 60 days in vitro [14]. Also, PLLA and PLGA were used in the bi-layer format of elastic memory to develop a self-expanding stent at 37˚C [15].…”

A bio-artificial poly([D,L]-lactide-co-glycolide) drug-eluting nanofibrous periosteum for segmental long bone open fractures with significant periosteal stripping injuries

“…The stent elements were produced using a laboratory-made microinjection molding machine and a mold. 13 Figure 1A displays the dimension of the stent element, while Figure 1B shows the mold used to produce the element. The machine was used to melt, transport, and pressurize the polymer into the molds.…”

Promoting endothelial recovery and reducing neointimal hyperplasia using sequential-like release of acetylsalicylic acid and paclitaxel-loaded biodegradable stents

“…Moreover, the time of peak drug release can be varied by adjusting the weight percentage of the drug in the nanofibers. 22 Following the initial burst, drug release …”

“…Chen et al 21 developed a self-expandable spiral stent that was made of a chitosan-based film that can rapidly self-expand (150 seconds) in an aqueous medium with a shape memory. Despite the fact that these biodegradable stents have so far provided satisfactory results, most require a complex manufacturing process 22 or have a complex structure that may increase the long-term risk of stent fracture upon degradation. An ideal stent should 1) possess sufficient strength to perform its mechanical function; 2) have good longitudinal flexibility to facilitate insertion; 3) deliver adequate drug concentrations to the target site to prevent restenosis via acceleration of re-endothelialization and inhibition of SMC proliferation within days and months, respectively; and 4) be biodegradable after serving its purpose and biocompatible so that the material breakdown process does not cause any tissue irritation.…”