AVS 50th International Symposium
    Plasma Science and Technology Wednesday Sessions
       Session PS2-WeA

Paper PS2-WeA7
Microplasma Surface Modification of the Inner Surface of Small Diameter Polyethylene Tubing for Improved Hematocompatibility

Wednesday, November 5, 2003, 4:00 pm, Room 315

Session: Atmospheric Plasmas & Micro Discharges
Presenter: J.L. Lauer, University of Wisconsin, Madison
Authors: J.L. Lauer, University of Wisconsin, Madison
J.L. Shohet, University of Wisconsin, Madison
C. Pratoomtong, University of Wisconsin, Madison
R.D. Bathke, University of Wisconsin, Madison
R.M. Albrecht, University of Wisconsin, Madison
S. Esnault, University of Wisconsin, Madison
J.S. Malter, University of Wisconsin, Madison
S.B. Shohet, University of California, San Francisco
U. von Andrian, Harvard Medical School
Correspondent: Click to Email
Microplasma surface modification was used to modify the inner surface of small diameter (280 and 800 µm and up to 1 meter in length) polyethylene (PE) tubing. Polyethylene glycol was grafted to the lumenal surface using an oxygen plasma and then cross-linked with an argon plasma. The plasma was created by placing hollow cathodes electrodes, in vacuum, at the ends of the PE tubing. The electrodes were powered by a 15 kV pulsed a.c. supply. Since feedstock gases and reaction products must pass along the length of the tubing, the resulting pressure drop has the potential to cause nonuniform plasma chemistry and thus a nonuniform treatment along the tubing. Emitted light from the plasma was analyzed with a monochromator, that was moved along the length of the tubing, giving insight on plasma uniformity. Treatment effectiveness on the lumenal surface was evaluated using a capillary rise method, which can be directly related to the contact angle. Uniformity of the atomic surface composition along the length of the inner surface of the PE tubing was analyzed by XPS. To test for hematocompatibility, a loop, powered by a peristaltic pump, circulated heparinized human blood for times up to one hour at flow rates of the order of 1 ml/minute at 37 C. After the flow test, the tubing was rinsed with phosphate buffer solution (PBS) for 10 minutes (with the same flow rate as the blood). The cells were fixed for 30 minutes with 1.25% by volume glutaraldehyde and 0.5% by weight tannic acid dissolved in PBS. After the fixation, the tubing was rinsed with PBS for another 10 minutes. It was then dehydrated with two-minute exposures to ethanol of increasing concentration from 50% to 95%. Plasma-treated and untreated tubing were then evaluated by studying the morphology of adhering platelets along the tubing with SEM. By suitably modifying the plasma parameters, the degree of uniformity as a function of distance along the tubing and proximity to the peristaltic pump can be optimized.