Electrospinning Equipment:Fabrication of Multilayer Bioabsorbable Composite Vascular Stent

Introduction

Cardiovascular diseases are a major global health challenge, often requiring coronary stenting to restore blood flow. Traditional metal or permanent polymer stents risk long-term complications like restenosis and thrombosis. Bioabsorbable polymers such as polycaprolactone (PCL) offer advantages like biocompatibility, but they suffer from insufficient mechanical strength and hydrophobicity, which can compromise structural integrity during deployment.

To address these limitations, this study presents a hybrid composite vascular stent combining ​oxidized starch (OS)​ functionalized with ​Fe₃O₄ nanoparticles​ and ​PCL nanofibers, fabricated via ​electrospinning​ and CO₂ laser cutting. OS is oxidized using FeCl₃/FeCl₂/H₂O₂ to introduce carboxyl and hydroxyl groups, enhancing hydrophilicity. PCL nanofibers are produced using ​an electrospinning machine​ to ensure uniform diameter (1.2–1.5 μm) and alignment, reinforcing the composite’s mechanical properties. Thermoplastic starch (TP), plasticized with sesame oil, citric acid, and glycerol, forms self-adhesive layers that bond without adhesives. CO₂ laser cutting shapes the stent into an origami-inspired tube (strut width 600–650 μm, diameter 1.9–2 mm), balancing radial strength with controlled degradation.

This design merges the osteogenic potential of Fe₃O₄-starch with PCL’s toughness, while TP’s self-adhesion simplifies manufacturing. The composite not only addresses PCL’s weaknesses but also promotes endothelialization for vascular healing, representing a promising solution for transient cardiovascular implants.

Abstract​ 

This study presents a novel multilayer bioabsorbable composite vascular stent fabricated using oxidized starch (OS)-Fe₃O₄ nanoparticles and polycaprolactone (PCL) nanofibers. The stent leverages self-adhesive properties of thermoplastic starch (TP) and CO₂ laser cutting to form a rigid-swelling scaffold. Key findings include enhanced mechanical properties, biocompatibility, and controlled degradation in vitro. The hybrid composite addresses limitations of conventional PCL-based stents, such as low mechanical strength and hydrophobicity, through oxidation and nanoparticle integration. Notably, PCL nanofibers were produced using an electrospinning machine to ensure uniform fiber diameter and alignment, contributing to the composite’s structural integrity. The innovation lies in the self-adhesive multilayer structure, which balances mechanical integrity with biodegradability.

The schematic of stent fabrication.

Research content and results

This study fabricated a multilayer bioabsorbable composite vascular stent using oxidized starch (OS) functionalized with Fe₃O₄ nanoparticles and polycaprolactone (PCL) nanofibers to overcome the limitations of traditional PCL-based materials, such as low mechanical strength and hydrophobicity. OS was synthesized via co-precipitation of FeCl₃/FeCl₂ with H₂O₂, introducing carboxyl and hydroxyl groups for enhanced hydrophilicity and stability. Thermoplastic starch (TP) was prepared by plasticizing OS with sesame oil, citric acid, and glycerol to form a gel-like matrix. A two-nozzle electrospinning system equipped with adjustable voltage and flow rates was used to create nanocomposite (NC) sheets, combining TP (2.5% w/v in DMSO) and PCL (13.3% w/v in chloroform/methanol) solutions. Beeswax (0.44%) was added to the PCL solution to reduce fiber diameter. The multilayer structure was formed by self-adhesion of TP sheets through water absorption-induced swelling, and CO₂ laser cutting shaped the stent into an origami-patterned tube (strut width 600–650 μm, diameter 1.9–2 mm).

Characterization confirmed the presence of carboxyl and hydroxyl groups on the NC surface via XPS, while HRTEM revealed Fe₃O₄ nanoparticles (7.3 ± 1.2 nm) embedded within the starch matrix. TGA analysis showed NC degraded at 395°C, lower than pure TP (312°C) but higher than PCL (415°C), balancing thermal stability. Mechanical testing demonstrated that NC exhibited superior tensile strength (25–30 kPa) compared to PBW (16–18 kPa) and PCL (10–12 kPa), attributed to TP reinforcement. Compressive strength remained stable (~25 kPa) after 12 weeks of incubation, while single-layer samples showed modulus decline without structural collapse. Swelling behavior indicated slower water absorption in NC (188% at 10 h) than PBW (166%), preserving structural integrity due to TP’s gel-forming capacity. Biocompatibility tests revealed hemolysis<0.5% and="" normal="" clotting="" parameters="" with="" endothelial="" cell="" attachment="" confirmed="" via="" sem="" dapi="" staining="">70% viability in direct/indirect assays). Degradation analysis showed gradual mass loss over 20 weeks, driven by TP hydrolysis, while PCL ensured long-term stability.

The hybrid NC design achieved balanced mechanical robustness, biodegradability, and endothelialization potential, with CO₂ laser cutting enabling precise fabrication. Self-adhesive layers addressed PCL’s limitations, though acute recoil was minimal, suggesting further optimization is needed for long-term radial strength in vascular applications.

Conclusion

The developed stent combines PCL and OS-Fe₃O₄ nanocomposites to achieve balanced mechanical performance, biodegradability, and endothelialization potential. Self-adhesive layers and CO₂ laser cutting enable precise fabrication. While acute recoil is minimal, long-term radial strength requires further optimization. This approach represents a promising advancement in bioabsorbable cardiovascular implants.

Electrospinning Nanofibers Article Source:

https://doi.org/10.1038/s41598-025-86111-x