Functional Nanoarchitectures For Enhanced Drug Eluting Stents

Abstract

Different strategies have been investigated to allow for optimum duration and conditions for endothelium healing through the enhancement of coronary stents. In this study, a nanoarchitectured system is proposed as a surface modification for drug eluting stents. Highly oriented nanotubes were vertically grown on the surface of a new Ni-free biocompatible Ti-based alloy, as a potential material for self-expandable stents. The fabricated nanotubes were self-grown from the potential stent substrate, which are also proposed to enhance endothelial proliferation while acting as drug reservoir to hinder Vascular Smooth Muscle Cells (VSMC) proliferation. Two morphologies were synthesized to investigate the effect of structure homogeneity on the intended application. The material was characterized by field-emission scanning electron microscope (FESEM), X-ray diffraction (XRD), Raman spectroscopy, energy dispersive X-ray spectroscopy (EDX), and X-ray photoelectron spectroscopy (XPS). Nanoindentation technique was used to study the mechanical properties of the fabricated material. Cytotoxicity and proliferation studies were performed and compared for the two fabricated nanoarchitectures, versus smooth untextured samples, using in-vitro cultured endothelial cells. Finally, the drug loading capacity was experimentally studied and further supported by computational modeling of the release profile.

Drug-Eluting Stents and Balloons—Materials, Structure Designs, and Coating Techniques: A Review

“…Titanium (Ti) and its alloys have been reported as potential materials for the stent backbone, with excellent biocompatibility and corrosion resistance as a result of a stable oxide layer on the surface. A new Ti-based alloy was proposed by Saleh et al [ 13 ] as the stent platform with decorated nanostructures on the surface. So far, there are limited reports on the application of Ti and its alloys for the stent material.…”

“…Serious clinical events cast doubt on the efficiency of DES in terms of its long-term safety because of the increased risk of late and very late ST. Thus, potential technical problems associated with the use of DES include: delayed endothelialization caused by the locally delivered drugs, inherent thrombogenicity of the stent as a foreign body to the immune system, hypersensitivity and inflammatory reactions due to the base framework and/or polymeric coatings, insufficient drug amount in addition to a lack of sustained drug release, and stent displacement [ 13 ]. …”

“…Despite the supreme advantages of DESs over BMSs, in-stent restenosis (ISR) and long-term safety remain ongoing concerns in the clinical application of DESs. The prospective success of DES for long-term clinical applications depends on the following areas: permanent polymeric coating materials; metallic stent platforms; optimal drug-releasing condition, and the factors that have recently been identified as disadvantages, such as: the degradation of the products of polymers and the presence of metal ions due to the erosion and degradation of metals and their alloys utilized in some stents as a metal base [ 13 ]. …”

“…the presence of metal ions due to the erosion and degradation of metals and their alloys utilized in some stents as a metal base [ 13 ].…”

Recent advances to accelerate re-endothelialization for vascular stents

“…In addition, nano-depot can store biomolecules or drugs and control release based on nanotube diameter and aspect ratio. 130 – 132 The small bioactive molecules could be released within weeks, whereas the big molecules could be released within several months. 131 The diameter of hexagonally close-packed rigid nanopatterned adhesive dots interfaces ranged between 58 and 73 nm is required for cell attachment.…”