Dynamically crosslinked semiflexible biopolymers such as the actin cytoskeleton govern the mechanical behavior of living cells. Semiflexible biopolymers stiffen nonlinearly in response to mechanical loads, whereas the crosslinker dynamics allow for stress relaxation over time. Here we show, through rheology and theoretical modeling, that the combined nonlinearity in time and stress leads to an unexpectedly slow stress relaxation, similar to the dynamics of disordered systems close to the glass transition. Our work suggests that transient crosslinking combined with internal stress is the microscopic origin for the universal glassy dynamics as frequently observed in cellular mechanics .
Dynamically crosslinked semiflexible biopolymers such as the actin cytoskeleton govern the mechanical behavior of living cells. Semiflexible biopolymers nonlinearly stiffen in response to mechanical loads, whereas the crosslinker dynamics allow for stress relaxation over time. Here we show, through rheology and theoretical modeling, that the combined nonlinearity in time and stress leads to an unexpectedly slow stress relaxation, similar to the dynamics of disordered systems close to the glass transition. Our work suggests that transient crosslinking combined with internal stress can explain prior reports of soft glassy rheology of cells, in which the shear modulus increases weakly with frequency .
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stiffen nonlinearly
nonlinearly stiffen
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is the microscopic origin for the universal glassy dynamics as frequently observed in cellular mechanics
can explain prior reports of soft glassy rheology of cells, in which the shear modulus increases weakly with frequency