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Porous TiO 2 surface formed on nickel‐titanium alloy by plasma electrolytic oxidation: A prospective polymer‐free reservoir for drug eluting stent applications
Author(s) -
Huan Zhiguang,
FratilaApachitei Lidy E.,
Apachitei Iulian,
Duszczyk Jurek
Publication year - 2013
Publication title -
journal of biomedical materials research part b: applied biomaterials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.665
H-Index - 108
eISSN - 1552-4981
pISSN - 1552-4973
DOI - 10.1002/jbm.b.32872
Subject(s) - plasma electrolytic oxidation , materials science , nickel titanium , chemical engineering , oxide , wetting , surface roughness , layer (electronics) , titanium , substrate (aquarium) , electrolyte , polymer , metallurgy , composite material , chemistry , shape memory alloy , oceanography , electrode , engineering , geology
In this study, a porous oxide layer was formed on the surface of nickel‐titanium alloy (NiTi) by 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 concentrated phosphoric acid electrolyte at low temperature. It was found that the response of NiTi substrate during the PEO process was different from that of bulk Ti, since the presence of large amount of Ni delayed the initial formation of a compact oxide layer that is essential for the PEO to take place. Under optimized PEO conditions, the resultant surface showed porosity, pore density and oxide layer thickness of 14.11%, 2.40 × 10 5 pores/mm 2 and 0.8 μm, respectively. It was additionally noted that surface roughness after PEO did not significantly increase as compared with that of original NiTi substrate and the EDS analyses revealed a decrease in Ni/Ti ratio on the surface after PEO. The cross‐section morphology showed no discontinuity between the PEO layer and the NiTi substrate. Furthermore, wettability and surface free energy of the NiTi substrate increased significantly after PEO treatment. The PEO process could be successfully translated to NiTi stent configuration proving for the first time its feasibility for such a medical device and offering potential for development of alternative, polymer‐free drug carriers for NiTi DES. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.