Abstract
In this study, a porous oxide layer was formed on the surface of 316L stainless steel (SS) by combining Ti magnetron sputtering and plasma electrolytic oxidation (PEO) with the aim to produce a polymer-free drug carrier for drug eluting stent (DES) applications. The oxidation was performed galvanostatically in Na3PO4 electrolyte. The surface porosity, average pore size and roughness varied with PEO treatment duration, and under optimum conditions, the surface showed a porosity of 7.43%, an average pore size of 0.44 µm and a roughness (Ra) of 0.34 µm. The EDS analyses revealed that the porous layer consisted of Ti, O and P. The cross-sectional morphology evidenced a double-layer structure, with a porous titania surface and an un-oxidized dense Ti film towards the interface with 316L SS. After the PEO treatment, wettability and surface free energy increased significantly. The results of the present study confirm the feasibility of forming a porous TiO2 layer on stainless steel by combining sputtering technology and PEO. Further, the resultant porous oxide layer has the potential to be used as a drug carrier for DES, thus avoiding the complications associated with the polymer based carriers.
Highlights
In recent years, the combination of stents, able to inhibit recoil and negative tissue remodeling with drugs that inhibit neointimal hyperplasia has emerged as a highly promising alternative to reduce in-stent restenosis in the treatment of atherosclerosis [1,2]
The results indicated that surface porosity and average pore size increased with increasing voltage while pore density decreased
A porous oxide layer was formed on the surface of 316L stainless steel by combining
Summary
The combination of stents, able to inhibit recoil and negative tissue remodeling with drugs that inhibit neointimal hyperplasia has emerged as a highly promising alternative to reduce in-stent restenosis in the treatment of atherosclerosis [1,2]. Despite the advantages over bare metal stents, the incidence of late stent thrombosis and the development of late restenosis have raised issues about the long-term safety and efficacy of DES [5,6] Both late occurring complications have been related to the characteristics of the polymer matrix, which can cause a marked inflammatory response leading to incomplete re-endothelialization and neointimal proliferation after completion of drug release [7]. It is suggested that a TiO2 layer can protect a metallic stent from direct contact with the vessel wall after drug elution is completed
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