Microviscoelastic moduli of biomimetic cell envelopes

Bioanalogue models of composite cell envelopes were designed by electrostatically driven self-assembly of actin shells inside giant vesicles. Viscoelastic relaxation moduli were measured between 0.03 and 20 s as a function of actin density by magnetic bead microrheometry. The shear relaxation spectra exhibited by the composite shells compare well with those of natural cell envelopes and bulk entangled actin networks. Absolute value of the shear modulus was measured for the first time by deformation field mapping. Shear and bending moduli agree well with values obtained by bead fluctuations analysis.