A Simple DNA-based Electrochemical Biosensor for Highly Sensitive Detection of Ciprofloxacin Using Disposable Graphene.

In this work we exploited the electrostatic interaction of double stranded DNA (dsDNA) with drug components to construct a simple, but highly sensitive, DNA-electrochemical sensor for detecting ciprofloxacin. The following straightforward three-step procedure was performed to determine ciprofloxacin: (i) dsDNA-layer immobilization on the surface of the working graphene-modified screen-printed carbon electrode; (ii) dsDNA-ciprofloxacin interaction for 2 min; and (iii) electrochemical measurement using square-wave voltammetry. An increased oxidation of the guanine component was observed, at +1.0 V, as a result of the electrostatic interaction of positively charged ciprofloxacin with the negatively charged nucleic acid sugar phosphate. Based on the International Conference on Harmonization Guidelines, a linear relationship between the guanine oxidation peak and ciprofloxacin concentration (0.1 to 100 μM) was obtained with a detection limit of 0.1 μM. Our developed sensor is straightforward to construct and use, requiring no multi-step time-consuming preconditioning of electrodes. It is highly sensitive and selective in the detection of ciprofloxacin, and has the potential to be useful in the future fabrication of rapid and portable on-site food safety analysis devices.