| Evaluation of hydroxyapatite/poly(caprolactone)–poly(ethylene glycol) bilayer coatings on Nitinol superelastic alloy |
| Paper ID : 1153-UFGNSM-FULL |
| Authors: |
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Mohamadreza Etminanfar *1, Jafar Khalil-Allafi2, Soheil Mahdavi2 1Sahand University of Technology, 5133511996, Tabriz, Iran 2Research Center for Advanced Materials, Faculty of Materials Engineering, Sahand University of Technology, 5133511996, Tabriz, Iran. |
| Abstract: |
| In this study the bioactivity of hydroxyapatite/poly(caprolactone)–poly(ethylene glycol) bilayer coatings on Nitinol superelastic alloy was investigated. The surface of Nitinol alloy was activated by a thermo-chemical treatment and hydroxyapatite coating was electrodeposited on the alloy, followed by applying the polymer coating. The surface morphology of coatings was studied using FE-SEM and SEM. The data revealed that the hydroxyapatite coating is composed of one-dimensional nano sized flakes and the polymer coating is uniformly covered the sublayer. Also, High resolution TEM studies on the hydroxyapatite samples revealed that the flakes of the coating are composed of nano crystalline grains. The hydroxyapatite single layer coating was rapidly covered by calcium phosphate crystals after immersion in simulated body fluid confirming an appropriate bioactivity of the nanostructured flakes. However, the coating was weak against applied shear forces because of their ultra-fine thickness. Scratch test was applied on hydroxyapatite/polymer coating to evaluate their adhesion to the substrate. It was shown that, the polymer coating has a great influence on toughening the hydroxyapatite coating. To assess the degradation effect of the polymer layer on hydroxyapatite coating, samples were immersed in phosphate-buffered saline at 37 ᵒC for three days. SEM studies on the samples revealed that the beneath layer of hydroxyapatite appears after the degradation of the polymer film without any visible change in morphology. It seems that, application of a biodegradable polymer film on the nanostructured hydroxyapatite coating is a good way to support the coating during implantation processes. |
| Keywords: |
| Hydroxyapatite; Nano-structured; PCL-PEG copolymer; Nitinol |
| Status : Paper Accepted (Oral Presentation) |
