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Abstract

In the last decade, rapid advances have been made in the field of micro-rheology of cells and tissues. Given the complexity of living systems, there is a need for the development of new types of nano- and micron-sized probes, and in particular of probes with controlled interactions with the surrounding medium. In the present paper, we evaluate the use of micron-sized wires as potential probes of the mechanical properties of cells. The wire-based micro-rheology technique is applied to living cells such as murine fibroblasts and canine kidney epithelial cells. The mean-squared angular displacement of wires associated to their rotational dynamics is obtained as a function of the time using optical microscopy and image processing. It reveals a Brownian-like diffusive regime of the form <Delta psi(2)(t, L)> similar to t/L-3, where L denotes the wire length. This scaling suggests that an effective viscosity of the intracellular medium can be determined, and that in the range 1-10 mu m it does not depend on the length scale over which it is measured. (C) 2013 Elsevier Ltd. All rights reserved.