FIB Patterning of Stainless Steel for the Development of Nano-structured Stent Surfaces for Cardiovascular Applications
Stent implantation is a percutaneous interventional procedure that mitigates vessel stenosis, providing mechanical support within the artery and as such a very valuable tool in the fight against coronary artery disease. However, stenting causes physical damage to the arterial wall. It is well accepted that a valuable route to reduce in-stent re-stenosis can be based on promoting cell response to nano-structured stainless steel (SS) surfaces such as by patterning nano-pits in SS. In this regard patterning by focused ion beam (FIB) milling offers several advantages for flexible prototyping. On the other hand FIB patterning of polycrystalline metals is greatly influenced by channelling effects and redeposition. Correlative microscopy methods present an opportunity to study such effects comprehensively and derive structure–property understanding that is important for developing improved patterning. In this chapter we present a FIB patterning protocol for nano-structuring features (concaves) ordered in rectangular arrays on pre-polished 316L stainless steel surfaces. An investigation based on correlative microscopy approach of the size, shape and depth of the developed arrays in relation to the crystal orientation of the underlying SS domains is presented. The correlative microscopy protocol is based on cross-correlation of top-view scanning electron microscopy, electron backscattering diffraction, atomic force microscopy and cross-sectional (serial) sectioning. Various FIB tests were performed, aiming at improved productivity by preserving nano-size accuracy of the patterned process. The optimal FIB patterning conditions for achieving reasonably high throughput (patterned rate of about 0.03 mm2/h) and nano-size accuracy in dimensions and shapes of the features are discussed as well.
KeywordsStents FIB Polycrystalline austenitic medical grade stainless steel 316L substrate Nano-surface patterning with pits Concaves Holes Endothelial cell adhesion Correlative microscopy EBSD SEM AFM Serial FIB–SEM sectioning
This work was supported through a Starting Investigator Research Grant (09/SIRG/I1621) of the Science Foundation Ireland (SFI), the National Biophotonics and Imaging Platform, Ireland (NBIPI) and the Integrated NanoScience Platform for Ireland (INSPIRE) initiatives funded by the Irish Government’s Programme for Research in Third Level Institutions, Cycle 4, National Development Plan 2007–2013. The authors are grateful to Dr Shanthi Muttukrishna (Department of Obstetrics and Gynaecology, University College Cork) for the gift of the human umbilical vein endothelial vein. Dr Lynette Keeney is gratefully acknowledged for performance of the AFM scans and line profiles for the correlative microscopy part of this chapter. Dr Calum Dickinson is gratefully acknowledged for contributing the EBSD measurements.
- 1.Dugdale, D.C.: Stent, in Medicine Plus, 2012. http://www.nlm.nih.gov/medlineplus/ency/article/002303.htm
- 6.Craig, C., Friend, C., Edwards, M., Gokcen, N.: Tailoring radiopacity of austenitic stainless steel for coronary stents. In: Medical Device Materials: Proceedings from the Materials & Processes for Medical Devices Conference 2003, 8–10 September 2003, Anaheim, California. 2004. American Society for MetalsGoogle Scholar
- 9.Daemen, J., Wenaweser, P., Tsuchida, K., Abrecht, L., Vaina, S., Morger, C., Kukreja, N., Jüni, P., Sianos, G., Hellige, G.: Early and late coronary stent thrombosis of sirolimus-eluting and paclitaxel-eluting stents in routine clinical practice: data from a large two-institutional cohort study. Lancet 369(9562), 667–678 (2007)CrossRefGoogle Scholar
- 10.Chou, L., Firth, J.D., Uitto, V.-J., Brunette, D.M.: Substratum surface topography alters cell shape and regulates fibronectin mRNA level, mRNA stability, secretion and assembly in human fibroblasts. J. Cell Sci. 108(4), 1563–1573 (1995)Google Scholar
- 21.Yim, E.K.F., Leong, K.W.: Significance of synthetic nanostructures in dictating cellular response. Nanomedicine 1(1), 10–21 (2005)Google Scholar
- 48.Kalantar-Zadeh, K., Fry, B.: Nanotechnology Enabled Sensors. Springer, New York, NY (2007)Google Scholar
- 55.Misra, R.D., Nune, C., Pesacreta, T.C., Somani, M.C., Karjalainen, L.P.: Understanding the impact of grain structure in austenitic stainless steel from a nanograined regime to a coarse-grained regime on osteoblast functions using a novel metal deformation–annealing sequence. Acta Biomater. 9, 6245–6258 (2013)CrossRefGoogle Scholar
- 57.Shi, D.: Introduction to Biomaterials. World Scientific, London (2006)Google Scholar
- 61.Nazneen, F., Schmidt, M., McLoughlin, E., Petkov, N., Herzog, G., Arrigan, D., Galvin, P.: Nano-texturing of medical-grade 316L stainless steel by focused ion beam for endothelial cell studies. J. Nanosci. Nanotechnol. 13, 5283–5290 (2013)Google Scholar
- 68.Schmidt, M., Nazneen, F., Herzog, G., Arrigan, D., Galvin, P., Keeney, L., Petkov, N., Holmes, J.D.: to be submittedGoogle Scholar
- 69.Schmidt, M., Nazneen, F., Herzog, G., Arrigan, D., Galvin, P., Dickinson, C., de Silva, J.P., Scanlan, D., O’Hara, N., Cross, G.L.W.: Correlative microscopy study of FIB patterned stainless steel surfaces as novel nano-structured stents for cardiovascular applications. MRS Proc 2012. 1466(1)Google Scholar