The adhesion dynamics of circulating tumor cells in a bio-functionalized microchannel under hydrodynamic loading is explored experimentally and analyzed theoretically. EpCAM antibodies are immobilized on the microchannel surface to specifically capture EpCAM-expressing target breast cancer cells MDA-MB-231 from a homogeneous cell suspension in shear flow. In the cross-stream direction, gravity is the dominant physical mechanism resulting in continuous interaction between the EpCAM cell receptors and the immobilized surface anti-EpCAM ligands. Depending on the applied shear rate, three dynamic states have been characterized: firm adhesion, rolling adhesion and free rolling. The steady-state velocity under adhesion- and free-rolling conditions as well as the time-dependent velocity in firm adhesion has been characterized experimentally, based on video recordings of target cell motion in functionalized microchannels. A previously reported theoretical model, utilizing a linear spring to represent the specific receptor-ligand bonds, has been adopted to analyze adhesion dynamics including features such as the cell-surface binding force and separation gap. By fitting theoretical predictions to experimental measurements, a unified exponential decay function is proposed to describe the target cell velocity evolution during capture; the fitting parameters, velocity and time scales, depend on the particular cell-surface system.

Original languageEnglish (US)
Article number054033
JournalJournal of Micromechanics and Microengineering
Issue number5
StatePublished - May 2011

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Mechanics of Materials
  • Mechanical Engineering
  • Electrical and Electronic Engineering


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