Label-free measurements of membrane tether thickness using optical tweezers combined with SLIM

Mohammad Sarshar; Winson T. Wong; Bahman Anvari

doi:10.1117/12.2079945

11 March 2015 Label-free measurements of membrane tether thickness using optical tweezers combined with SLIM

Mohammad Sarshar, Winson T. Wong, Bahman Anvari

Proceedings Volume 9336, Quantitative Phase Imaging; 93361M (2015) https://doi.org/10.1117/12.2079945
Event: SPIE BiOS, 2015, San Francisco, California, United States

Abstract

Various cellular activities such as motility, division, and endocytosis involve a change in the cell shape. The mechanical interactions between the cell membrane and cytoskeleton play an important role in regulating changes in the cell shape. Tether formation from cell membranes provides a technique to characterize the mechanical properties of cell membranes and membrane-cytoskeleton interactions. Accurate measurement of the nano-scale tether diameter is relevant to quantification of membrane tension, bending modulus, and adhesion energy of the membrane-cytoskeleton structure. We have integrated optical tweezers with quantitative phase imaging, based on spatial light interference microscopy (SLIM), to simultaneously form tethers from HEK-293 cells and measure their diameters. Tether thickness along the illumination axis was measured using the quantitative phase map of the sample, and the refractive index (RI) mismatch between the sample and the surrounding media. The RI of the tethers ranged from 1.354 to 1.368 (cell culture medium RI=1.337). Our SLIM imaging system provided a 38 nm resolution in tether thickness measurements. Tether diameter fluctuations of <100 nm were resolved on tethers that ranged between 600-900 nm in diameter. Our integrated platform also provides the ability to simultaneously manipulate and image cell organelles in a non-contact and marker-free manner at nanometer spatial resolution.

Citation Download Citation

Mohammad Sarshar, Winson T. Wong, and Bahman Anvari "Label-free measurements of membrane tether thickness using optical tweezers combined with SLIM", Proc. SPIE 9336, Quantitative Phase Imaging, 93361M (11 March 2015); https://doi.org/10.1117/12.2079945

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