Power-Law Stress and Creep Relaxations of Single Cells Measured by Colloidal Probe Atomic Force Microscopy

Abstract

We measured stress and creep relaxations of mouse fibroblast cells arranged and cultured on a microarray, by colloidal probe atomic force microscopy (AFM). A hydrophobic monolayer coating of perfluorodecyltrichlorosilane (FDTS) on the surface of colloidal silica beads significantly reduced the adhesion force of live cells, compared with untreated beads. The rheological behaviors of cells were estimated by averaging several relaxation curves of cells measured by the AFM. Longer-time tailing of both stress and creep relaxation curves followed single power-law behavior over a time scale of 60 s, with exponents in the range 0.1–0.4, varying with cells. The results were in good agreement with previous measurements of the frequency-domain rheology of cells using the force modulation mode.