SHEAR FIELD-MAPPING IN ACTIN NETWORKS BY USING MAGNETIC TWEEZERS

An improved magnetic bead microrheometer based on phase contrast micro scopy allowing high resolution measurements of local deformations with in macromolecular networks is applied to study local viscoelastic prop erties of cross-linked actin networks. By embedding nonmagnetic colloi dal beads as probes into the networks, the spatial variation of the st rain field within cross-linked actin networks can be mapped, Moreover, the Poisson ratio and shear modulus can be measured locally.