Deformability of mice erythrocytes measured by oscillatory optical tweezers

We used one-dimensional oscillatory optical tweezers in a discrete scanning (or jumping) mode to trap and stretch individual mice erythrocytes and measured their deformation as a function of the jumping distance of the oscillatory trapping beam. In general, we observed that the length of the long axis of red blood cells (RBCs) decreased slightly at small jumping distance and then increased after the jumping distance exceeded a threshold value on the order of a few microns, which is consistent with a recent theoretical prediction. The deformability of three types of mice RBCs, namely the wide-type mice (serving as the control group), old mice, and gene knockout mice were measured and compared. Statistical analysis of their deformability reveals that the RBCs of old mice can be distinguished from those of knockout mice even though these two types of mice exhibit many similar aging-like features.