Fig. 4.

Duplex melting measured by the switching method. A 24-nt single-stranded probe layer is repeatedly hybridized and subsequently dehybridized with fully complementary (mm0) and partly mismatched target sequences (mm1, mm2, mm2a); mismatches are marked as bold, underlined characters in the sequences. After hybridization at low temperature (target concentration = 1 μM), the layer is heated at a rate of 2°C/min while continuously switching the DNA conformation electrically (E = 0.1 V ± 0.2 V vs. Ag/AgCl, f = 0.2 Hz) and monitoring the switching amplitude, i.e., the fluorescence modulation.