Single-nucleotide polymorphism detection withwire-like DNA probes that display quasi on-off digital action

Establishing a reliable genotyping protocol is a critical matter in postsequence genetics. In this article, we describe a highly sensitive electrochemical detection of complementary DNAs (up to 43-mer) based on hole transport with molecular-scale, wire-like DNA probes. The presence of a single-base mismatch in the DNA duplexes caused a dramatic decrease in the electrochemical response. We applied this method to detect all of the possible transition and transversion SNPs and achieved on-off-type discrimination of fully complementary DNAs from their SNPs. Furthermore, naturally occurring polymorphisms, hot spots from the p53 gene, could clearly be distinguished from wild type by using our methodology.