Bistable Nucleic Acid Switch Sensor using Square-Wave Voltammetry

Graduate #38
Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)

Katarena Ford - Auburn University
Co-Author(s): Subramaniam Somasundaram, Auburn University, AL; Christopher J. Easley*, Auburn University, AL

There has been increased interest in the development of fast, sensitive, and cost-effective DNA sensing devices for DNA-specific detection of clinically, environmentally, and government security-relevant nucleic acid targets. Recent observations have shown DNA immobilization at the surface of a gold electrodes play a vital role in the performance of any DNA-based sensor. With the assistance of a distance-dependence study via square wave voltammetry (SWV) as a function of frequency. We employed the redox-tag Methylene Blue (MB) bound to DNA to verify appropriate lengths of a spacer region in the DNA sequence for the finalized switch. We then DNA engineered an electrochemical bistable switch sensor that can detect DNA with the assistance of an in-house polydimethylsiloxane electrochemical cell that is temperature controlled. Our switch can utilize a strand displacement mechanism that gives us a signal-ON and signal-OFF complex, by the addition or removal of the target DNA. Our results show that as the concentration of the target increases, the current increases with respect to the frequency. The sensor response changes from a square-root dependence on frequencies at low concentrations of target to a more linear dependence on frequencies at high concentrations of target. Notice that the higher the concentration the switch is having absorbed like behavior and when there is no target the switch is considered to be diffusion-limited. With these findings, we strongly believe that this sensor can easily measure other forms of nucleic acids such as Messenger RNA (mRNA) and Micro RNA (miRNA). Specifically related to our target goal, we will be verifying this for mRNA and miRNA that correlate to diabetic research such as miRNA-375 and insulin-1 mRNA.

Not Submitted

Funder Acknowledgement(s): NSF

Faculty Advisor: Christopher Easley, cje0003@auburn.edu

Role: I completed 100% of the research on this project. The Co-Authors listed mentored me through the process and Chris Easly is my research advisor. But all experiments are performed by me.