A CONTROL STUDY USING DNA TO TEST THE EFFECTS OF SHEAR STRESS ON VON WILLEBRAND FACTOR

Open Access
Author:
Jankowska, Maya Ann-Marie
Area of Honors:
Biomedical Engineering
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Keefe B. Manning, Thesis Supervisor
  • William O Hancock, Honors Advisor
Keywords:
  • von willebrand factor
  • vwf
  • optical trap
  • fluid shear
  • LVADS
  • plasmid
  • fluid mechanics
  • optical tweezers
  • shear stress
  • acquired von willebrand syndrome
Abstract:
In an effort to understand how the von Willebrand Factor (vWF), a blood clotting glycoprotein, and applied shear forces are related, this project focuses on a positive control study using plasmid DNA. Elevated shear stress levels, commonly introduced after ventricular assist device (VAD) implantation, are believed to cause unfurling and subsequent enzymatic cleavage of vWF. This makes vWF impotent and subjects the patient to high risks of bleeding. However, due to vWF's large and complex structure, a positive control of plasmid DNA will produce a more predictable experiment. Through attaching enzymatically-cut and treated plasmids around the entire exterior of biotinylated polystyrene beads, an effective radius of the bead plus the DNA length is assumed. The hypothesis is the effective radius of DNA is independent of shear rates. Within this study, the aims are to (1) determine 2 plasmid-enzyme pairs with one of comparable length to unfurled vWF and one of shorter length, (2) attach the treated enzymatically-cut plasmid to beads, (3) subject the beads to shear forces in an optical trap to compare effective radii of DNA-coated beads to non-coated beads, and (4) determine the effect of shear rates on DNA-coated and non-coated bead effective radii. Thus, the control study post-processing techniques and data can be reproduced and applied to vWF. A quantifiable difference in bead effective radius is observed between the DNA-coated beads and the non-coated beads. This presumably confirms that DNA was coated onto the beads. Effective radii was not significantly affected by shear rates when comparing the beads on each slide.