To quantify the presence of mercuric ions in aqueous solution, double-stranded DNA (dsDNA) of poly(dT) was employed using a light switch compound, Ru(phen)2(dppz)2+ (1) which is reported to intercalate into dsDNA of a right-handed B-form. Addition of mercuric ions induced the dehybridization of poly(dT)•poly(dA) duplexes to form a hairpin structure of poly(dT) at room temperature and the metal-to-ligand charge transfer emission derived from the intercalation of 1 was reduced due to the dehybridization of dsDNA. As the concentration of Hg2+ was increased, the emission of 1 progressively decreased. This label-free emission method had a detection limit of 0.2 nM. Other metal ions, such as K+, Ag +, Ca2+, Mg2+, Zn2+, Mn 2+, Co2+, Ni2+, Cu2+, Cd 2+, Cr3+, Fe3+, had no significant effect on reducing emission. This emission method can differentiate matched and mismatched poly(dT) sequences based on the emission intensity of dsDNA.
- DNA intercalation
- Light switch Ru compound
- Mercuric ion sensing
- Metal-to-ligand transfer emission
- Mismatch detection