1. Modulating Surface Properties of Magnesium Through Polymeric Coatings
and Develop Flow Device for Cardiovascular Applications
Jonathan Rey1
, Wensen Jiang2
, Huinan Lui*2,3
1. Department of Mechanical Engineering, Cal State LA
2. Department of Materials Science and Engineering, University of California, Riverside
3. Department of Bioengineering, University of California, Riverside
* Corresponding author
Motivation Background
Procedure Results
Outlook Acknowledgements & References
The results of this poster are
product of MacREU R’side. The
Materials Connection Riverside
is a Research Experience for
Undergraduate students site
sponsored by the National
Science Foundation Division of
Materials Research under grant
DMR-1359136. Additional
support from [XXX]
MacREU R’side‘14
Cardiovascular Stents and Current Potentially
Lethal Biological Responses
Research Objective: Develop stent materials which
degrade, deliver drugs to avoid long term
complications and modulate endothelialization
(formation of new vessel inner-wall cells)
Degradation Testing: Using a dynamic degradation
Flow Device, samples will be tested for degradation
rates in a flowing blood-like environmental
conditions
Dynamic degradation
Flow Device based on
impedance pump
principle
Use Polymers to Create Thin Coatings on
Magnesium( a strong and safe biodegradable metal)
to Slow Degradation Rate for Years or Until Desired
Polymers Used: PLLA, PLGA (90:10), PLGA (50:50),
and PCL
Magnesium-Polymer Sample Preparation Process
Comparing Polymer surface
wetability to Nitinol (a
material already used in
cardiovascular applications)
Wettability is determined by contact angle
measurement (Right figure)
Contact angles were measured on the surface of
Nitinol, Mg, PLLA-coated Mg, PLGA (90/10)-
coated Mg, PLGA (50/50)-coated Mg and PCL-
coated Mg.
You can see through the chart that the Polymer-
coated Magnesium samples were all modulated
to have similar hydrophobicity as Nitinol and
vary from bare Magnesium
Polymer Coating Surface Height Measured with
Surface Profilometer
In Vitro Cell Study: Samples are to be incubated with
human umbilical vein endothelial cells (HUVEC) with
materials to study cell interactions with device
- Neointimal Hyperplasia: Thickening of the tunica intima(inner layer)
of a blood vessel in response to injury
- Inflammation
- Thrombosis: Deep vein blood clot initially caused by macrophages
targeting foreign material
One in every four deaths, about 600,000 people die of heart disease in the United States
every year. Coronary artery stents are a solution to treat blocked coronary arteries.
However, after a stent is implanted to the blockage site, the patient is required to take
several medications for life. If medications are not taken, the stent will be rejected by the
body and the immune response will cause a deadly blockage in the artery once more. These
risks have not been eliminated due to the life-long presence of a stent in the artery. The
motivation behind this research project is to reduce such risks in stent treatment by
developing novel stent materials that can degrade and be absorbed into the body after a
specified amount of years before severe complications of neointimal hyperplasia and
thrombosis arise, where surgery is required to remove the stent. By modulating the surface
properties of Magnesium through applying polymeric coatings the solution may be found.
The polymeric coating will coat the Magnesium stent to prevent immediate degradation of
the Magnesium. The coating will be designed to withhold stent degradation for several
years, just before severe complications start. Samples of Magnesium were spin-coated and
the thicknesses were measured to meet acceptable industry standards for coatings by using
a Scanning Electron Microscope and a Surface Profilometer. The wettability of the coated
samples demonstrated that the polymeric coatings had significantly increased the contact
angle of the polymer-coated Mg substrate to a contact angle of Nitinol, an acceptable
material in the biomedical industry for cardiovascular applications. Nitinol is known for its
hydrophobic properties that can aid to better resist an immune response. With studies
moving toward cytocompatibility, it shows promise that the contact angle for the surface of
Mg was able to be increased to that of Nitinol.
1. Carpenter, Alexis W., and Mark H.
Schoenfisch. "Nitric oxide release:
Part II. Therapeutic applications."
Chemical Society Reviews 41.10
(2012): 3742-3752
2. Murphy SL, Xu JQ, Kochanek KD.
Deaths: Final data for 2010.
Natl Vital Stat Rep.
2013;61(4).
Acknowledgements
-Dr. Huinan Liu’s Lab
-University of California, Riverside
-Material Science and engineering
Department, University of
California, Riverside
References