An electrochemical impedance sensor for simple and specific recognition of G-G mismatches in DNA

The sequence-specific recognition of SNPs is important for disease diagnosis and human gene therapy. In this work, a simple sensor based on electrochemical impedance spectroscopy (EIS) was developed for the highly sensitive and specific detection of G-G mismatches in dsDNA using a small molecule-modified gold electrode. After the electrochemical impedance sensor was incubated with G-G mismatched dsDNA, its charge-transfer resistance (R-ct) increased significantly. Meanwhile, only a small increase in R-ct values was observed for dsDNA with other base mismatches and for complementary dsDNA. Importantly, G-G mismatched dsDNA was selectively detected based on differences in charge transfer resistance (Delta R-ct) even in the presence of other DNA and ct-DNA. Under optimal experimental conditions, the established EIS sensor was used to quantify G-G mismatched dsDNA based on the linear relationship between Delta R-ct and the logarithm of the concentration of G-G mismatched dsDNA from 1 nM to 1 mu M with a detection limit of 0.3 nmol L-1. This sensing strategy is a potential alternative tool for measuring G-G mismatched DNA for the diagnosis and early clinical detection of genetic diseases.