In this paper, a novel electrochemical sensor was developed for the rapid detection of G-G mismatched DNA based on hexaammineruthenium(III) chloride ([Ru(NH3)6]Cl3) as a redox indicator. The sensor platform was constructed by immobilizing small molecules (NC-linker) on the gold electrode via amide bonds. The as-prepared NC-linker as the nucleic acids recognition molecule can interact with the G base of DNA. After the sensor was incubated with G-G mismatched DNA, the double-stranded DNA (dsDNA) acted as carriers of the signal tags-[Ru(NH3)6]Cl3, which resulted in a remarkable electrochemical signal. More binding of [Ru(NH3)6]Cl3 led to increases of the electrochemical signal. Other mismatched DNA produced only a low response, as well as complementary DNA. Thus G-G mismatched DNA can be easily discriminated from other mismatched and complementary DNA based on the sensor. Furthermore, the method was simple, rapid and repeatable for the detection of G-G mismatched DNA. The selective detection of target dsDNA was achieved by a relative current ratio of the target and control DNA. These results demonstrated that this strategy could provide great promise for the rapid and specific detection of other sequence-specific DNA.
Keywords: Electrochemical sensor; G-G mismatch; hexaamminerutheniumm(III) chloride; recognition; small molecule.