Figure 2.

¹⁹F NMR spectra of ¹⁹F-labeled ODN 1 in PEG 200. (A) ¹⁹F NMR of ¹⁹F-labeled 22-mer DNA at different concentration of PEG 200 in K⁺ solution. (B) ¹⁹F NMR of ¹⁹F-labeled ODN 1 at different temperatures in 40% PEG 200. Green indicated hybrid-1 and hybrid-2 G-quadruplexes conformations. Orange and black spots indicated parallel G-quadruplex and single strand, respectively. PEG 200 ratio and temperatures indicated on the right. Condition: 0.1 mM DNA in 100 mM KCl and 20 mM K-PO₄ buffer (pH 7.0). The sample is kept for 10 min of each temperature for ¹⁹F NMR detection.