Detection and discrimination of single nucleotide polymorphisms by exploiting metal ion-mediated DNA duplex

Detection of mutant DNA is necessary for early diagnosis of disease. In particular, detection of single nucleotide polymorphisms (SNPs) has become an important method for monitoring cancer and obtaining theragnostic information about it. SNPs are very difficult to detect selectively because of their similarity with wildtype DNA. In this paper, the specific binding between metal ion and DNA mismatch was used to achieve highly sensitive and selective SNP detection. Cytosine-cytosine (C-C) mismatched nucleobases capture silver (Ag) ions, and thymine-thymine (T-T) mismatched nucleobases capture mercury (Hg) ions. Metal ions bound between DNA could be reduced using a reducing agent (hydroquinone). In addition, gold (Au) amalgam could be formed around the DNA mismatch by the reduction of Au ion and mercury ion bound between T-T mismatches. Differential pulse voltammetry (DPV) was used to measure signals which are mediated by silver and Au amalgam. The detection limit of point mutation DNA obtained by the proposed detection method is 20 pM. In addition, by comparing the values of the DPV peaks by silver and Au amalgam, the types of DNA point mutations including cytosine or thymine (CT, CC, TT, AC, and TG) could be distinguished. The results obtained from our proposed method suggest its potential for diagnosing cancer patients.