Development of biodegradable magnesium alloy stents with coating
Journal Title: Frattura ed Integrità Strutturale - Year 2014, Vol 8, Issue 29
Abstract
Biodegradable stents are attracting the attention of many researchers in biomedical and materialsresearch fields since they can absolve their specific function for the expected period of time and then graduallydisappear. This feature allows avoiding the risk of long-term complications such as restenosis or mechanicalinstability of the device when the vessel grows in size in pediatric patients. Up to now biodegradable stentsmade of polymers or magnesium alloys have been proposed. However, both the solutions have limitations. Thepolymers have low mechanical properties, which lead to devices that cannot withstand the natural contractionof the blood vessel: the restenosis appears just after the implant, and can be ascribed to the compliance of thestent. The magnesium alloys have much higher mechanical properties, but they dissolve too fast in the humanbody. In this work we present some results of an ongoing study aiming to the development of biodegradablestents made of a magnesium alloy that is coated with a polymer having a high corrosion resistance. Themechanical action on the blood vessel is given by the magnesium stent for the desired period, being the stentprotected against fast corrosion by the coating. The coating will dissolve in a longer term, thus delaying theexposition of the magnesium stent to the corrosive environment. We dealt with the problem exploiting thepotentialities of a combined approach of experimental and computational methods (both standard and ad-hocdeveloped) for designing magnesium alloy, coating and scaffold geometry from different points of views.Our study required the following steps: i) selection of a Mg alloy suitable for stent production, having sufficientstrength and elongation capability; ii) computational optimization of the stent geometry to minimize stress andstrain after stent deployment, improve scaffolding ability and corrosion resistance; iii) development of anumerical model for studying stent degradation to support the selection of the best geometry; iv) optimizationof the alloy microstructure and production of Mg alloy tubes for stent manufacturing; v) set up, in terms of lasercut and surface finishing, of the procedure to manufacture magnesium stents; vi) selection of a coating able toassure enough corrosion resistance and computational evaluation of the coating adhesion.In the paper the multi-disciplinary approach used to go through the steps above is summarized. The obtainedresults suggest that developed methodology is effective at designing innovative biomedical devices.
Authors and Affiliations
Lorenza Petrini, Wei Wu, Dario Gastaldi, Lino Altomare, Silvia Farè, Francesco Migliavacca, Ali Gökhan Demir,, Barbara Previtali, Maurizio Vedani
Keywords
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- EP ID EP105141
- DOI 10.3221/IGF-ESIS.29.32
- Views 66
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