Suprasil synthetic quartz 10 mm path length cuvettes

The representative UV absorption curves of ONs are shown in supporting information. All thermal denaturation temperature curves were recorded at 260 nm on a Perkin Elmer Lambda 35 UV/Vis Spectrometer using Hellma SUPRASIL synthetic quartz 10 mm path length cuvettes, monitoring at 260 nm, with a concentration of 2.5 μM for each strand and a volume of 1.0 ml in a buffer (5.8 mM sodium phosphate, 100 mM NaCl and 0.10 mM EDTA). Samples were prepared as follows: The two strands were mixed in a 1:1 ratio (2.5 μM of each) in 2 ml Eppendorf tubes before addition of medium salt buffer (500 μl, 2 times, 11.7 mM sodium phosphate, 200 mM NaCl, 0.20 mM EDTA, pH 7.0, 500 μl). Milli-Q water was then added to give a total volume of 1 ml. The mixtures were heated to 90 °C in a water-bath followed by slow cooling to room temperature before they were transferred into the cuvettes. The UV absorbance at 260 nm as a function of time was recorded while the temperature was increased linearly from 8 °C to 65 °C at a rate of 1.0 °C/min programmed by a Peltier temperature controller. Three separate melting curves were measured and the duplex thermal denaturation temperatures (Tm values) calculated using UV-WinLab software as an average from the three thermal denaturation curves having deviation no more than 0.5 °C.