I'd like as sensitive a method as possible to detect nucleic acids. There are many papers using different methods: amperometry, electrochemical impedance spectroscopy, square wave voltammetry, differential pulse voltammetry, cyclic voltammetry, etc. I'm not sure what the benefits of each are, but I am interested in a simple and sensitive method.
Hi Dale,
It certainly depends on the kind of information you want to obtain from the study. It may not be enough to say 'detect'. The techniques you have stated have differences in terms of what information they can give best. For example, if all you want to see is a qualitative assurance of the presence of a nucleic acid, then the difference between a background and 'analyte' CV should be enough. If you want to plot a calibration curve and determine parameters like LOD, chronoamperometry may be suited for that. If you want to determine parameters like diffusion coefficient, most people use chronocoulometry (essentially chronoamp too). SWV and DPV are also very good Electroanalytical techniques. I am not sure how beneficial EIS will be except to evaluate resistances of the solution and/or electrode (I stand to be corrected).
I suggest you define your research goals and read about these techniques to know which one is best suited.
Thanks for your reply. I am interested in quantitating nucleic acids. I'll look into chronoamperometry. Some people have functionalized gates with the complementary nucleic acid and that's where EIS comes into play, I believe.
Most of the electrochemical techniques mentioned so far demand an electro-active compound in order to be oxidized or reduced and the current or voltage is recorded. Labelling DNA with a reversible redox-system complicated the situation. In addition the background of the sample should not interfere in this electrochemical process. This favors EIS. However the double layer capacitance is also influenced by other parameters (e.g., ionic strength, unspecific adsorption, etc.) which renders this technique into a method with interferences as long as those are not very well controlled before the analytical measurement. I would suggest a more reliable method working like a molecular switch: allowing the electrochemical reaction of an added redox-couple at a micro-electrode if no hybridization is occurring and stopping this reaction (current decrease) when the latter occurs. The electrochemical switch is based on available nano-magnetical beads. See last chapters of the publication below.
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