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Proceedings Paper

The design and biological applications of dual-beam oscillating optical tweezer-based imaging cytorheometer
Author(s): H. D. Ou-Yang; J. Wang
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Paper Abstract

Because of its non-invasive nature, optical tweezers have emerged as a popular tool for the studies of complex fluids and biological cells and tissues. The capabilities of optical tweezer-based experimental instruments continue to evolve for better and broader applications, through new apparatus designs and integrations with microscopic imaging techniques. In this paper, we present the design, calibration and applications of a powerful microrheometer that integrates a novel high temporal and spatial resolution dual-beam oscillating optical tweezer-based cytorheometer (DOOTC) with spinning disk confocal microscopy. The oscillating scheme detects the position of micron-size probe particles via a phase-sensitive lock-in amplifier to greatly enhance sensitivity. The dual-beam scheme ensures that the cytorheometer is insensitive to sample specimen background parameter variances, and thus enables the investigation of micromechanical properties of biological samples, which are intrinsically inhomogeneous. The cytorheometer system is demonstrated to be capable of measuring dynamic local mechanical moduli in the frequency range of 0.1-150 Hz at up to 2 data point per second and with nanometer spatial resolutions, while visualizing and monitoring structural properties in situ. We report the results of system applications in the studies of bovine skin gelatin gel, purified microtubule assemblies, and human alveolar epithelial cells. The time evolution of the storage moduli G' and the loss moduli G'' of the gel is recorded for undisturbed gel-forming process with high temporal resolution. The micromechanical modulus G* of polymerized microtubule network as a function of frequency are shown to be both inhomogeneous and anisotropic consistent with local structures revealed by confocal imaging. The mechanical properties of A549 human lung cells as a function of temperature will be reported showing significant decrease in cell stiffness at higher temperature.

Paper Details

Date Published: 11 September 2006
PDF: 11 pages
Proc. SPIE 6326, Optical Trapping and Optical Micromanipulation III, 63261O (11 September 2006); doi: 10.1117/12.681266
Show Author Affiliations
H. D. Ou-Yang, Lehigh Univ. (United States)
J. Wang, Lehigh Univ. (United States)

Published in SPIE Proceedings Vol. 6326:
Optical Trapping and Optical Micromanipulation III
Kishan Dholakia; Gabriel C. Spalding, Editor(s)

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