Emission detection of mercuric ions in aqueous media based-on dehybridization of DNA duplexes

Abstract

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 Hg 2+ 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 +, Ca 2+, Mg 2+, Zn 2+, Mn 2+, Co 2+, Ni 2+, Cu 2+, Cd 2+, Cr 3+, Fe 3+, 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.