The G4 forming and complementary oligos were mixed with a ratio of 1.2:1, respectively, to a final concentration of 5 μM in the annealing buffer (20 mM Tris–HCl buffer (pH 7.5), with 50 mM LiCl or KCl). The sample was thermally annealed in a water bath, by keeping it at 95°C for 5 min, followed by gradual cooling to room temperature over 24 h.