Preliminary Application of Optical Trapping: Calculating Forces on Beads in Solution

Undergraduate #293
Discipline: Physics
Subcategory: Physics (not Nanoscience)

Ama Agyapong - Elizabeth City State University
Co-Author(s): Alexander Auner and Shane Hutson, Vanderbilt University, Nashville, TN

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Cell edge movements contribute to the tensions involved in developments of holes within amnioserosa cells of Drosophila melanogaster (fruit fly) embryos after heat shock treatments. However, characterizations of the mechanical tendencies of the cells prove to be problematic and the proposed solution is to measure the tension of cell edges using optical trapping. Optical trapping uses a tightly focused laser beam to generate forces capable of moving dielectric objects of microscopic size. The goal of this research is to execute the necessary preparations needed to obtain a strong and stable trap. During the research, a 445nm fiber-laser diode intended for trapping purposes was coupled into the optical pathway of an existing ablation laser. To enhance the accuracy of the laser alignment, the divergence of the 445nm laser was calculated. Simultaneously, protocols to focus the beam were followed. Sample slides of polystyrene beads and phosphate-buffered saline (PBS) solution were made to test trapping. Evidence of optical trapping were observed, however, the strength of the trap was inadequate for its application purpose. The next phase is to evaluate and enhance all aspects to generate a more tightly focused beam, which should lead to a better trap.

Funder Acknowledgement(s): NIH Grant # 1R01GM099107 and 1R21AR068933; MARC/NIH/NIGMS Grant # 1T34GM100831; NIH Grant #5T34GM100831; NSF Award #1358862

Faculty Advisor: Shane Hutson,