Thesis Defence: Construction of Dual-Beam Optical Tweezer for Single-Molecule Study

Scott Minh An, supervised by Dr. Isaac T.S. Li, will defend their thesis titled “Construction of Dual-Beam Optical Tweezer for Single-Molecule Study” in partial fulfillment of the requirements for the degree of Master of Science in Biochemistry and Molecular Biology.

An abstract for Scott Minh An’s thesis is included below.

Defences are open to all members of the campus community as well as the general public. Registration is not required for in person defences.

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ABSTRACT

Optical tweezer is a well-established and continually evolved microscopic trapping and manipulation technique widely employed across numerous disciplines. A tightly focused Gaussian laser can be used to confine homogenous particles by exerting two forces: 1. Scattering force which maintains the target particles along the axis of the laser and 2. Gradient forces prevent the particles from laterally drifting off the beam. We constructed a dual-beam variant of the optical tweezer for single-molecule studies. This system allows simultaneous trapping of two particles, where one serves as an anchor point and the other moves to stretch DNA-based nanostructures. The decoupling from surface anchoring enables the system to achieve sub-piconewton resolution measurement with minimal environmental noise. We developed in-house programs facilitating data acquisition and control of various components. This allows rapid testing and deployment of custom features tailored for different experiment types and DNA structures. Finally, we established comprehensive user protocols and calibrated the system force measurement. The development of this instrument provides a powerful approach for any future investigators in single molecular and cellular studies.