1. Optical Tweezers at The National Institute of Standards and Technology and Davidson College Research performed by: Rachel Patton McCord

2. Background: Optical Tweezers Physics Balancing Forces: Scattering Force- “Radiation Pressure” Gradient Force- Restoring force analogy to spring Figure from: Svoboda and Block, 1994.

3. Physics, cont. Tight focus = largest gradient force obtained with microscope objective Images from: http://www.olympusmicro.com/primer/java/nuaperture/index.html

4. Basic Components Objective Lens L2L2 L3L3 L1L1 f 1 + f 2 f3f3 16 cm Image created from Physlet at http://webphysics.davidson.edu/Course_Material/Py230L/optics/lenses.htm Physlet by Dr. Wolfgang Christian and Mike Leehttp://webphysics.davidson.edu/Course_Material/Py230L/optics/lenses.htm Laser

5. NIST Alignment Gained experience with alignment by working on a two-laser trap setup.

6. Results Single Trap Both Traps Together

7. NIST Optical Tweezers Applications Liposomes Stretching/Nanotubes Microreaction Vesicles Single Mitochondria Isolation and Sorting Available for PCR and genetic analysis Antigen/Antibody Binding Quantum Dots in Polymersomes Fluorescence Resonance Energy Transfer and single molecule imaging

8. Davidson Setup

9. Results Trapping microspheres in 3D 10 mW minimum power from laser (about 2 mW at the slide) Trapping single celled chlamydomonas Image from: http://www.ucmp.berkeley.edu/greenalgae/chlo rophyceae.html

10. Future Plans Force calibration Measuring the swimming force of chlamydomonas Flagellar mutants Further in the future: Physics Applications Stretching- elasticity, determining shear moduli Biology Applications More chlamy- phototaxis Virus adhesion

11. Acknowledgments Dr. Kris Helmerson, Jeff Wells, Lara Crigger, Rani Kishore, Joe Reiner at NIST Dr. John Yukich and Dr. Karen Bernd