High-frequency microrheology reveals cytoskeleton dynamics in living cells

Living cells are viscoelastic materials, dominated by an elastic response on timescales longer than a millisecond(1). On shorter timescales, the dynamics of individual cytoskeleton filaments are expected to emerge, but active microrheology measurements on cells accessing this regime are scarce(2). Here, we develop high-frequency microrheology experiments to probe the viscoelastic response of living cells from 1 Hz to 100 kHz. We report the viscoelasticity of different cell types under cytoskeletal drug treatments. Onpreviously inaccessible short timescales, cells exhibit rich viscoelastic responses that depend on the state of the cytoskeleton. Benign and malignant cancer cells revealed remarkably different scaling laws at high frequencies, providing a unique mechanical fingerprint. Microrheology over a wide dynamic range-upto the frequency characterizing the molecular components-provides a mechanistic understanding of cell mechanics.