All synthetic oligonucleotide stock solutions were prepared
using TE (10 mM Tris–HCl, 1 mM EDTA, pH 8.00) and were kept
frozen. The tris(1,10-phenanthroline) cobalt (III) perchlorate indicator
was synthesized as previously described [31]. All other
chemicals were of analytical grade. Doubly distilled water (DDW)
was used throughout the experiments