Abstract
We have investigated the influence exerted by the concentration of graphene oxide (GO) dispersion as a modifier for screen printed carbon electrodes (SPCEs) on the fabrication of an electrochemical biosensor to detect DNA hybridization. A new pretreatment protocol for SPCEs, involving two successive steps in order to achieve a reproducible deposition of GO, is also proposed. Aqueous GO dispersions of different concentrations (0.05, 0.1, 0.15, and 0.2 mg/mL) were first drop-cast on the SPCE substrates and then electrochemically reduced. The electrochemical properties of the modified electrodes were investigated after each modification step by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), while physicochemical characterization was performed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Finally, the sensing platform was obtained by the simple adsorption of the single-stranded DNA probe onto the electrochemically reduced GO (RGO)-modified SPCEs under optimized conditions. The hybridization was achieved by incubating the functionalized SPCEs with complementary DNA target and detected by measuring the change in the electrochemical response of [Fe(CN)6]3–/4– redox reporter in CV and EIS measurements induced by the release of the newly formed double-stranded DNA from the electrode surface. Our results showed that a higher GO concentration generated a more sensitive response towards DNA detection.
Highlights
Increased prevalence of genetic analysis fosters development of biosensors for rapid and cost-effective detection of specific DNA sequences within a broadening range of human diseases.Several approaches for DNA analysis systems such as optical [1,2,3,4,5], piezoelectric [6], or electrochemical [7,8,9] have been proposed
Electrochemical characterization of functionalized electrodes was done by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS)
This work presents a study on the influence induced by the concentration of graphene oxide (GO) dispersion as a modifier on commercially available screen printed printed carbon carbon electrode electrode (SPCE) for developing reduced GO (RGO)-SPCEs for electrochemical detection of
Summary
Increased prevalence of genetic analysis fosters development of biosensors for rapid and cost-effective detection of specific DNA sequences within a broadening range of human diseases.Several approaches for DNA analysis systems such as optical (fluorescent, surface plasmon resonance luminescent, colorimetric, etc.) [1,2,3,4,5], piezoelectric [6], or electrochemical [7,8,9] have been proposed. An impedimetric DNA biosensor converts the biochemical affinity binding event of the target molecule with the DNA probe into an analytical signal corresponding to the charge-transfer resistance (Rct ) between a redox-active species from the solution and the electrode surface. In contrast to classic approaches for DNA sensors, with target DNA labeled by an enzyme or a fluorophore, electrochemical impedance spectroscopy (EIS) offers label-free detection in addition to the advantages of relative simplicity, low cost, ease of miniaturization, and portability [13,14]. EIS is a technique of choice because it can detect significant changes in the signal in a low target concentration range [14,17] and is non-destructive, due to the low amplitude voltage perturbation that is much smaller than that used in amperometric testing [18,19,20,21]
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