Figure 7.

Temperature dependence of the single-stranded elastic response. (a) Cycles of pulling and relaxing curves of ssDNA at four different temperatures (6°C, 16°C, 22°C, and 26°C) and with 1 M NaCl, pH 7.5. The ssDNA was formed by using the oligo method (34). (b) The theoretical fit was obtained by using the ext-FJC model for forces in the range of 13–40 pN outside the dark gray region (labeled as no fitting in the legend). The experimental curves were taken at 1 M NaCl, pH 7.5. (c) Kuhn length (L_K) values for ssDNA at different temperatures and 1 M NaCl as a function of the temperature. Inset: Kuhn length scaled to the thermal energy level, k_BT. (d) Stretching modulus versus temperature for ssDNA measured at 1 M NaCl. In both panels, the dots represent the average at each temperature over six experiments, each with a different molecule. To see this figure in color, go online.