Sustained drug release using cobalt oxide nanowires for the preparation of polymer-free drug-eluting stents

Abstract

Polymer-based drug-eluting stents (DESs) represented attractive application for the treatment of cardiovascular diseases; however, polymer coating has caused serious adverse responses to tissues such as chronic inflammation due to acidic by-products. Therefore, polymer-free DESs have recently emerged as promising candidates for the treatment; however, burst release of drug(s) from the surface limited its applications. In this study, we focused on delivery of therapeutic drug from polymer-free (or -less) DESs through surface modification using cobalt oxide nanowires (CoO NWs) to improve and control the drug release. The results demonstrated that CoO NWs could be simply fabricated on cobalt-chromium substrate by ammonia-evaporation-induced method. The CoO NWs were uniformly arrayed with diameters of 50-100 nm and lengths of 10 µm. It was found that CoO NWs were comparatively stable without any delamination or change of the morphology under in vitro long-term stability using circulating system. Sirolimus was used as a model drug for studying in vitro release behavior under physiological conditions. The sirolimus release behavior from flat cobalt-chromium showed an initial burst (over 90%) after one day. On the other hand, CoO NWs presented a sustained sirolimus release rate for up to seven days. Similarly, the polymer-less specimens on CoO NWs substrates sustained sirolimus release for a longer-period of time when compared to flat Co-Cr substrates. In summary, the current approach of using CoO NWs-based substrates might have a great potential to sustain drug release for drug-eluting implants and medical devices including stents.

Nanostructured Titanium for Improved Endothelial Biocompatibility and Reduced Platelet Adhesion in Stent Applications

“…The water contact angle was the only parameter affected by the QR coating, and this decrease was expected due to the presence of the biomolecule on the implant surface. The use of a coating that is covalently linked to the surface, as demonstrated by FTIR spectroscopy and XPS in previous studies [18,19], could provide an alternative to the use of a polymer, which is considered as one of the leading causes of late stent thrombosis in DES [8,9]. Similar to previous reports [19,35], QR coated surfaces were also biocompatible on HUVEC cells, and remarkably showed higher metabolic activity in all evaluated time points, similar to other studies with mesenchymal stem cells [18,19].…”

“…Drug eluting stents (DESs) are used to inhibit the proliferation of smooth muscle cells, decreasing the risk of in-stent restenosis by the delivery of an appropriate concentration of an effective agent locally without systemic toxicity [7]. Usually, this controlled liberation of the therapeutic agent is achieved due to the use of a polymer coating; however, there are some complications associated to the use of polymers, considered as one of the leading causes of late stent thrombosis [8,9]. Thus, the use of a nanostructured surface could provide an alternative for the application of the stent coating without the need of using a polymer.…”

Flexible 3D Nanonetworked Silica Film as a Polymer‐Free Drug‐Eluting Stent Platform to Effectively Suppress Tissue Hyperplasia in Rat Esophagus

“…In contrast, bottom-up approaches use zero-dimensional and one-dimensional nanomaterials (e.g., nanoparticles and nanowires) as drug delivery platforms to coat the stent surface. [17,23,24] These methods do not affect the mechanical properties of SEMSs and are suitable for coating nanomaterials on a microscopic scale via a relatively simple process. [25] However, because the coating layer is an aggregate of individual nanomaterials, it can easily get detached, thereby reducing the therapeutic effect.…”

CoO Nanozymes with Multiple Catalytic Activities Regulate Atopic Dermatitis

“…Cobalt oxide, especially Co 3 O 4 nanozymes, have CAT-like, POD-like, and SOD-like catalytic activities [48]. Co 3 O 4 nanozymes are widely used in cancer therapy, antiviral, magnetic resonance imaging (MRI), and targeted drug delivery [49][50][51]. At present, many studies have reported that CoO nanozymes with POD-like activity prepared by a variety of synthetic methods have extremely high application value in biosensing [52][53][54][55]; CoO nanostructures have the advantages of high stability, large specific surface area, and easy redox [56,57].…”