BisPNA-assisted Detection of Double-stranded DNA via Electrochemical Impedance Spectroscopy

A highly effective strategy for quantification of plasmid which was a special dsDNA based on bisPNA by electrochemical impedance spectroscopy was presented in this work. Firstly, through Au-S bond, thiol-terminated bisPNA probes were immobilized onto the gold electrode surface. Then bisPNA probes directly hybridized with target plasmid DNA pBR322 based on the PNA.DNA-PNA invasion triplex without denaturation. In the presence of redox electroactive ions [Fe(CN)(6)](3-/4-) as hybridization indicator, the charge transfer resistance (R-ct) was produced, and R-ct was measured via electrochemical impedance spectroscopy. Under optimal conditions, this strategy showed a good linear relationship between the Delta R-ct which was the difference of R-ct obtained before and after bisPNA hybridized with plasmid pBR322, and logarithm of the concentration of plasmid pBR322 within the range from 1 nM to 100 nM (R-2=0.993), with a limit of detection (LOD) of 0.1 nM. Furthermore, this bisPNA-assisted biosensor showed good stability and satisfactory analytical reliability. In addition, this novel bisPNA-assisted biosensor also exhibited excellent analytical results in human serum.