Figure 6.

DLSμR captures the entangled dynamics of intestinal mucus of healthy and colitic mice. Top left: Dependence of the shear modulus G* on angular frequency ω of intestinal mucus isolated from healthy mice. The shear modulus exhibits three regimes, A, B, and C, which we identify as corresponding to reptation of polymers within an entangled network, elastic behavior due to entanglement constraints, and Rouse-like flexible chain dynamics at length scales below the entanglement confinement length, respectively. Solid curves represent the mean among 3 independent biological reproductions. Shading represents 90% confidence intervals of the mean generated by bootstrap resampling spectra from independent biological reproductions. The dashed line represents the high-frequency scaling behavior of a Rouse polymer G* ∼ ω^1/2, which is provided to guide the eye. Bottom left: Illustration of the physical behavior probed in time-scale regimes annotated A, B, and C, as they are interpreted in terms of the Doi and Edwards tube model of entangled polymer dynamics. Top right: Comparison of the frequency-dependent shear modulus G* of intestinal mucus isolated from healthy (control) mice and mice treated with dextran sulfate sodium (DSS) to induce colitis. The high frequency scaling behaviors of a Rouse polymer and a WLC (G* ∼ ω^1/2 and G* ∼ ω^3/4, respectively) are indicated with dashed lines for reference. Bottom right: Confocal imaging of DSS treated and control mouse colons recapitulates physical disruption of mucus. The intestinal sections were stained to highlight the mucus (UEA-1, green) and the DNA (DAPI, blue). In DSS treated mice the distal colon mucus loses much of the usual striated organization. Scale bars are 50 μm.