BIOABSORBABLE MAGNESIUM CARDIOVASCULAR STENTS
OVERVIEW
While stents are a lifesaving technology, they pose risks to patients when they remain in their arteries for long periods. Biodegradable stents are a promising alternative to permanent stents and can provide a solution to the problem of in-stent restenosis. The objective of this project is to develop nanostructured variants of several magnesium alloys that can be used to make cardiovascular stents which dissolve after they have served their primary function of restoring blood circulation in occluded arteries. Magnesium is an excellent candidate bioresorbable material for fabricating stents, but lacks the strength, ductility, and corrosion resistance needed for expandable stents. However, by nanostructuring we can enhance the mechanical properties and tailor absorbability.
PROJECT DESCRIPTION
Multi-stage ECAP-C processing schemes are being developed that incorporate variable temperature and strain rates to refine grain size, increase stored dislocation density, and shear precipitates to alter their effects on bioabsorption rates. In addition, we control process conditions to alter the propensity for twin formation during and after processing to enhance the isotropy of the resulting ultrafine grained magnesium alloys.
STATUS
The project has demonstrated that a microalloyed, thixomolded Mg alloy can be modified by HSD to achieve 500 nm grain sizes, increases in ductility, controllable bioabsorption rates, and isotropic strength levels sufficient to enable implementation of the nanostructured alloy in bioabsorbable coronary stents. Prototype stents have been fabricated and tested in bench tests and animal studies. Scale up of the technology is pending market assessment by the sponsor and partner organizations.
Meanwhile, additional Mg alloys are being proposed for ECAP-C processing to create ultrafine grain variants suitable for dissolvable trauma screws and devices.
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