Theory 33/Cytoskeletal Mechanics
Network Stiffness Is a Crosslink Ratio
The claim
The stiffness of an actin network is set by the ratio of crosslink density to filament length, so dense short filaments form stiff gels while sparse long ones form compliant ones.
01The mechanism
Stiffness requires load paths between crosslinks; the ratio sets how many crosslinks a filament must traverse, which determines whether the network is bending- or stretch-dominated.
02Predictions
- P1Stiffness should collapse onto the ratio.
- P2Crosslink density alone should mispredict.
03Refutation
Stiffness tracking crosslink density would remove the length term.