title: Determination of cell elasticity through hybrid ray optics and continuum mechanics modeling of cell deformation in the optical stretcher.
abstract: The optical stretcher is a dual-beam trap capable of stretching individual cells. Previous studies have used either ray- or wave-optical models to compute the optical pressure on the surface of a spherical cell. We have extended the ray-optics model to account for focusing by the spherical interface and the effects of multiple internal reflections. Simulation results for red-blood cells (RBCs) show that internal reflections can lead to significant perturbation of the deformation, leading to a systematic error in the determination of cellular elasticity. Calibration studies show excellent agreement between the predicted and measured escape force, and RBC stiffness measurements are consistent with literature values. Measurements of the elasticity of murine osteogenic cells reveal that these cells are approximately 5.4 times stiffer than RBCs.
authors.affiliation: Department of Physics, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, USA.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Ekpenyong
authors.forename: Carolyn L
authors.initials: CL
authors.lastname: Posey
authors.forename: Joy L
authors.initials: JL
authors.lastname: Chaput
authors.forename: Anya K
authors.initials: AK
authors.lastname: Burkart
authors.forename: Meg M
authors.initials: MM
authors.lastname: Marquardt
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Smith
authors.forename: Michael G
authors.initials: MG
authors.lastname: Nichols
mesh_terms: D000818:Animals; D003198:Computer Simulation; D055119:Elastic Modulus / Q000502:physiology*; D004912:Erythrocytes / Q000166:cytology* / Q000502:physiology*; D006244:Hardness / Q000502:physiology; D006245:Hardness Tests / Q000379:methods*; D006801:Humans; D008027:Light; D008955:Models, Cardiovascular; D009391:Nephelometry and Turbidimetry / Q000379:methods*; D052898:Optical Tweezers; D012542:Scattering, Radiation