Effect of Salt Concentration on Electrochemical Detection of DNA

Electrochemical approaches for biological sensing offer the potential advantages of facile sample preparation, fast response times, ease of parallel and multiplexed measurements, and the possibility of miniaturization (of sample sizes, electrodes, and associated electronics). All of these factors contribute towards the feasibility of electrochemical methods in biological sensing and analysis. This potential has already been achieved with the commercialization of blood glucose meters, which often rely on an electrochemical transduction mechanism. We have previously demonstrated the ability to electrochemically detect and differentiate complementary and mismatched DNA using our method of melting DNA duplexes at electrified gold surfaces, i.e. e-melting. Recently, we have optimized a new approach for preparing our DNA modified gold electrodes, and we are now able to precisely control the DNA surface coverage. In this work, we are using our improved methodology to explore the effects of electrolyte concentration (NaCl) on the electrochemical signal and the e-melting behavior. More specifically, our approach assumes a linear relationship between the amount of duplex DNA and the measured electrochemical signal. Here, we show that the concentration of salt in our buffer effects both the signal and the melting behavior. An understanding of these results are necessary for accurate interpretation of e-melting data.