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. 2017 Sep 20;18(10):3310–3317. doi: 10.1021/acs.biomac.7b00964

Figure 2.

Figure 2

Rheological analysis of PIC-DNA hydrogels with 0.9 equiv DNA cross-linker at 30 °C in PBS, 10 × 10–3 M MgCl2, pH 7.4. (a) Time evolution of the storage modulus (G′) after addition of cross-linker DNA C (green), LC (blue), or LC + LC′ (orange) to DNA A and DNA B functionalized PIC polymers. (b) Strain stiffening profile of the PIC-DNA hydrogel with cross-linker DNA C. The gel stiffness is represented as the differential modulus K′(δσ/δγ) as a function of stress σ. At low stress, K′ equals G0, the plateau modulus. The nonlinear regime sets in beyond a critical stress σc, where K′ increases with applied stress and finally ruptures at maximum stress σmax. (c) Normalized differential modulus (K′/G0) as a function of stress σ of PIC-DNA hydrogels cross-linked with DNA C (green), LC (blue), or LC + LC′ (orange). (d) K′/G0 as a function of σ of PIC-DNA hydrogels, covalently cross-linked with DNA AB (black) or DNA AB + C (orange).