Discrimination between Normal and Cancerous Cells from Dynamic Viscoelastic Properties with a Laser-induced Surface Deformation Microscope.

We have clarified the differences in the power-law between normal and corresponding cancerous cells from dynamic viscoelastic measurements in a frequency range of 102 to 105 Hz with a laser-induced surface deformation (LISD) microscope. From the differences in the power spectra at higher frequencies, it has been clarified that a normal cell obeys the power-law with a single exponent, while a cancer cell with two exponents, indicating that the plasma membrane in the cancerous cell has at least two layers with different viscoelastic properties. In LISD measurements, the extension of the upper limit of the applied frequency up to 105 Hz allows us to clarify the existence of the two power-law exponents in the cancerous cell. Understanding the differences between normal and cancerous cells from the power-law in addition to conventional elasticity would be useful for the identification of cancerous cells and for the construction of a mechanical model for their invasion.