Figure 3.
Decoupling the electrostatic and steric interactions between GAG-chains. (a and b) The axial stiffness Ea and hydraulic permeability k of the newborn human aggrecan is estimated using the transversely isotropic finite element model at solutions with ionic strength of 0.001,0.01,0.1, and 1 M NaCl under strain values in the range of 0.2–0.7. The axial stiffness Ea has shown statistically significant strain-dependence for IS = 0.01, 0.1, and 1.0 M, but not for IS = 0.001. The hydraulic permeability k showed statistically significant strain-dependence for IS = 0.001,0.01, and 0.1 M, but not for IS = 1.0 M (p <0.05; using one way analysis of variance; data are mean ± SE). (c and d) The dependence of axial stiffness Ea and hydraulic permeability k on the height of the aggrecan monolayer, H, at which the dynamic measurement is performed. The height of the aggrecan is altered by changes in the ionic strength (i.e., data points with different colors) and by applying compressive stress via the AFM tip (changes in height within each color; see Supporting Information Figure S1).