A Review based on Biodegradable and Bioabsorbable Stents for Coronary Artery Disease

Nanotechnology in development of next generation of stent and related medical devices: Current and future aspects

Coronary stents have saved millions of lives in the last three decades by treating atherosclerosis especially, by preventing plaque protrusion and subsequent aneurysms. They attenuate the vascular SMC proliferation and promote reconstruction of the endothelial bed to ensure superior revascularization. With the evolution of modern stent types, nanotechnology has become an integral part of stent technology. Nanocoating and nanosurface fabrication on metallic and polymeric stents have improved their drug loading capacity as well as other mechanical, physico-chemical, and biological properties. Nanofeatures can mimic the natural nanofeatures of vascular tissue and control drug-delivery. This review will highlight the role of nanotechnology in addressing the challenges of coronary stents and the recent advancements in the field of related medical devices. Different generations of stents carrying nanoparticle-based formulations like liposomes, lipid-polymer hybrid NPs, polymeric micelles, and dendrimers are discussed highlighting their roles in local drug delivery and anti-restenotic properties. Drug nanoparticles like Paclitaxel embedded in metal stents are discussed as a feature of first-generation drug-eluting stents. Customized precision stents ensure safe delivery of nanoparticle-mediated genes or concerted transfer of gene, drug, and/or bioactive molecules like antibodies, gene mimics via nanofabricated stents. Nanotechnology can aid such therapies for drug delivery successfully due to its easy scale-up possibilities. However, limitations of this technology such as their potential cytotoxic effects associated with nanoparticle delivery that can trigger hypersensitivity reactions have also been discussed in this review. This article is categorized under: Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement Therapeutic Approaches and Drug Discovery > Nanomedicine for Cardiovascular Disease Therapeutic Approaches and Drug Discovery > Emerging Technologies.

Evaluation of coronary stents: A review of types, materials, processing techniques, design, and problems

In the world, one of the leading causes of death is coronary artery disease (CAD). There are several ways to treat this disease, and stenting is currently the most appropriate way in many cases. Nowadays, the use of stents has rapidly increased, and they have been introduced in various models, with different geometries and materials. To select the most appropriate stent required, it is necessary to have an analysis of the mechanical behavior of various types of stents. The purpose of this article is to provide a complete overview of advanced research in the field of stents and to discuss and conclude important studies on different topics in the field of stents. In this review, we introduce the types of coronary stents, materials, stent processing technique, stent design, classification of stents based on the mechanism of expansion, and problems and complications of stents. In this article, by reviewing the biomechanical studies conducted in this field and collecting and classifying their results, a useful set of information has been presented to continue research in the direction of designing and manufacturing more efficient stents, although the clinical-engineering field still needs to continue research to optimize the design and construction. The optimum design of stents in the future is possible by simulation and using numerical methods and adequate knowledge of stent and artery biomechanics.

Finite element analysis of the mechanical performance of a zinc alloy stent with the tenon-and-mortise structure

BACKGROUND

Inadequate scaffolding performance hinders the clinical application of the biodegradable zinc alloy stents.

OBJECTIVE

In this study we propose a novel stent with the tenon-and-mortise structure to improve its scaffolding performance.

METHODS

3D models of stents were established in Pro/E. Based on the biodegradable zinc alloy material and two numerical simulation experiments were performed in ABAQUS. Firstly, the novel stent could be compressed to a small-closed ring by a crimp shell and can form a tenon-and-mortise structure after expanded by a balloon. Finally, 0.35 MPa was applied to the crimp shell to test the scaffolding performance of the novel stent and meanwhile compare it with an ordinary stent.

RESULTS

Results showed that the novel stent decreased the recoiling ratio by 70.7% compared with the ordinary stent, indicating the novel structure improved the scaffolding performance of the biodegradable zinc alloy stent.

CONCLUSION

This study proposes a novel design that is expected to improve the scaffolding performance of biodegradable stents.

A Microscale 3D Printing Based on the Electric-Field-Driven Jet

This study presents a novel microscale three-dimensional (3D) printing based on the electric-field-driven (EFD) jet. Differing from the traditional electrohydrodynamic jet printing with two counter electrodes, the EFD jet 3D printing forms electric field between the nozzle electrode and the top surface of the substrate or printed structure only using a single potential by the nozzle electrode. The numerical simulations and experimental studies were carried out to verify the capabilities and advantages of the proposed approach, which includes the suitability of substrates, the potentials of the conformal printing, and the large size 3D printing. Besides, considering the high-resolution and high-efficiency printing of various materials with different viscosities, two working modes, including the pulsed cone-jet mode and the continuous cone-jet mode, were proposed and investigated by the CCD camera. Finally, several typical printed structures were provided to demonstrate the feasibility of the proposed technology for microscale two-dimensional patterning and macro/micro-3D structure fabrication. As a conclusion, this breakthrough technique provides a high-efficiency and high-resolution 3D printing technique enabling direct-write, noncontact, and additive patterning at microscale for a variety of ink systems and melted polymer materials, especially for the multiscale and multimaterial additive manufacturing.