Application of optical trapping for detection of Calcium induced morphological changes of red blood cells

This work investigates an optical trap based method for detection of structural changes of the red blood cell (RBC) membrane affected by Ca²⁺ ions. Individual cells are immobilized by use of optical tweezers and are monitored live while the concentration of Ca²⁺ ions in the buffer is changed simultaneously. Ca²⁺ ions affect cells´ membrane morphology, which results in the change of effective radius as well as drag coefficient of the cell, both of which affect the Brownian motion of the cell in solution. This motion is measurable indirectly by tracking the forward scattering light and its dependence on size and drag coefficient of the cell. We show the relationship between Ca²⁺ ion concentration and optical trap specifications.