Magnetic Tweezer System Development

1. Magnetic Tweezer System Development Probing mechanical properties across multiple scales Jason Sherfey Senior BME, Vanderbilt University Advisor: Dr. Franz Baudenbacher

2. Purpose: to design, fabricate, test and miniaturize a microrheometer to quantify cell-cell adhesion (i.e., measuring mechanical properties). • Specific structures to quantify: 1. cell-cell linkage 2. adhesion protein linker system 3. cytoskeleton

3. Motivation: - Cell-cell adhesion is essential to establishing and maintaining cell and tissue morphology and in cellular migration - Specific issue - alterations in cell morphology and migration are essential to tumor growth and metastasis - Idea. Quantify cell-cell adhesion  Better understand cellular morphology and migration  Improve diagnostics and treatments for cancer Principle Components of the Design Process: 1. System development 2. Model testing (E-cadherin system in p120 KO vs WT mdck) for error analysis and concept testing & validation

4. - E-cadherin Differentiated (Polarized/Adhesive) Dedifferentiated/Permanent EMT (Reduced or mutated E-cadherin or catenins) + E-cadherin Reduced adhesiveness Transient EMT Cancer Tissue Morphogenesis (dissociation from tumor) Invasion and Metastasis Normal Tissue (Adapted from Meiners et al, 1998 and Hirohashi, 1998).

5. Strategy • Property measured: The cell-cell adhesion mechanics targeted consist of viscoelastic parameters of adhesion protein linker systems (static & dynamic responses) • Strategy: A magnetic tweezer – based device to perturb, image, and analyze linker system mechanics.

6. Force 1 nN 3 2 T=0 s displacement [mm] 1 0 0 1 2 3 Time [s] F T=1.5 s Force displacement measurements on magnetic beads linked to the cell surface through E-Cadherin Fit to Mechanical Analog Extract Model parameter

7. Accomplishments • Developed MPT software to rapidly quantify cell mechanics from displacement videos • Fabricated magnetic tweezer and constructed 1st prototype • Established protocol to implement prototype • Validated strategy by experiment • Refined PT, MT, & protocol parameters to increase SNR & temporal resolution • Evaluated miniaturization schemes w.r.t. ability to retain critical parameters within allowable ranges • Selected one strategy based on practicality

8. Microfluidic channels Cell type 1 PDMS Cell type 2 To CCD

9. Current Status • On schedule • Effectiveness of strategy is confirmed • System parameters critical to the accuracy and reproducibility of acquired information have been identified and refined • A reduction strategy constrained by the desired critical system parameters has been identified and is in development.

10. Project Schedule • 1/29, Finish list of components that can be reduced, eliminated or subsume • 2/1, Determine relationship b/w listed mods and system parameters: • 2/5, Finish list of methods to implement “allowable” mods (brainstorm, lit review, ..) • 2/8, Selected 2-3 best methods (minimize complexity & cost; max practicality) • 2/15, Have chosen 1 method to pursue; identified resources, costs, & practical approach • 2/22, Have started implementing modifications • 3/15, Have established a new prototype & begun refining • 3/29, Obtained final design prototype • 4/5 , Completing final reports, presentations, documentation