Fig. 1.

(A) A 2D cartoon depicting the formation of a five-arm DNAns network as a function of temperature. Every DNAns has unpaired adenines at the base of each arm to enhance vertex flexibility. Each arm is a 21-bp double helix $\approx 8.5$-nm long that ends in a single-stranded overhang consisting of an unpaired adenine and a 6-nt palindromic sequence, called the sticky end (box on the right). (B) Frequency-dependent mechanical response of DNAns networks at $\gamma =5\%$ and T_ref = 20°C. The storage modulus $G\prime$ (solid lines) and the loss modulus G″ (dashed lines) cross at a frequency, ${\omega }_c$, that is the inverse of the relaxation time, ${\tau }_c$. (Inset) Arrhenius fits to ${\tau }_c\left(T\right)$ have a common slope corresponding to the activation energy for network rearrangement. Orange triangles, blue diamonds, green squares, and red circles correspond to $f=\mathrm{3,4,5},$ and 6 at DNAns concentrations of $\left(500\pm 10\right)$, (490 $\pm$ 10), (490 $\pm$ 20), and $\left(450\pm 30\right)$ $\mathrm{\mu }$M, respectively.