Nitinol Drug Eluting Surfaces for Coronary Stents

Nowadays, drug eluting stents (DES) are the treatment of choice for de novo atherosclerotic lesions. Novel DES are shifting to polymer-free (PF) drug delivery in order to avoid the problem of late stent thrombosis associated with long term polymer presence in the vessel lumen. The scope of this study was to assess the potential of a microporous layer of TiO2 produced on Nitinol by means of electropolishing followed by plasma electrolytic oxidation (EP+PEO) to act as a PF carrier for 6-mercaptopurine, which is a novel anti-restenotic drug. The surface porosity obtained was characterised and the roughness and hydrophilicy of the samples were measured. The drug has been loaded by spray coating and its release in acidified Phosphate Buffered Saline over a period of 5 days was analysed by high performance liquid chromatography. The results obtained were compared to those obtained from electropolished samples loaded under similar conditions.The findings revealed that EP samples had a drug loading efficiency of 26.8%, a drug reservoir capacity of 18.2?g/cm2 and released 95% of the loaded drug within 10 minutes of immersion. On the other hand, EP+PEO samples, with a surface porosity of about 10%, showed a drug loading efficiency of 41.9%, a drug reservoir capacity of 30.6 ?g/cm2 and released 42% of the drug within 10 minutes and a total of 52% within the 5 day immersion period studied. PEO treated surfaces showed two-phase release kinetics where a short fast release phase was followed by a long-term slow release phase and was therefore modelled by means of a two-phase Fickian diffusion model (r = 0.99866). The preliminary findings of this study indicate that PEO-treated NiTi surfaces have potential as PF drug carrier for DES.

Subject

Nitinol
Drug Elution
PEO

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http://resolver.tudelft.nl/uuid:c2980ed5-fcfb-4c25-813f-99308e66b773

Embargo date

2016-10-29

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Student theses

Document type

master thesis

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Thesis_Martina_Cuschieri.pdf

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