Influence of Graphene Oxide Concentration when Fabricating an Electrochemical Biosensor for DNA Detection

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.

Oligonucleotide Detection and Optical Measurement with Graphene Oxide in the Presence of Bovine Serum Albumin Enabled by Use of Surfactants and Salts

“…The graphene oxide had a 42-52% carbon content (dry basis) and 44-45% oxygen content for the monolayer sheets with a mean diameter of <22 µm, 90% <50 µm by laser diffraction (manufacturer's specifications, Sigma-Aldrich). The commercial GO, provided as a 2 mg/mL dispersion in water, was homogeneously gently re-dispersed by water bath sonication (300 W, 40 kHz) under ambient conditions for 10 min before use and then adjusted to 10 mM with Tris-HCl pH 8.0 buffer during the assay [48]. The critical micelle concentration (CMC) at 20-25 • C in water for the surfactants used were as follows: Triton X-100 (CMC) = 0.2-0.9 mM or 0.0125-0.0562%, Tween-20 (CMC) = 0.06 mM or 0.0074%, SDS (CMC) = 7-10 mM or 0.202-0.289% (according to manufacturer's specifications, Sigma-Aldrich).…”

Electrochemical Detection Platform Based on RGO Functionalized with Diazonium Salt for DNA Hybridization

“…[ 22 ] or by increasing their reactivity through carbodiimide chemistry [ 23 ] in order to be further covalently linked to amino-terminated molecules. As pointed out in the recent literature, reduced graphene oxide (RGO) material offers a multitude of advantages compared to other biosensing transducer materials by providing a balance between the beneficial properties of pristine graphene and GO, and through its feasibility for various functionalization schemes suitable for the biorecognition elements immobilization [ 24 , 25 ]. It was confirmed by different studies [ 26 , 27 , 28 ] that graphene functionalization is substantially enhanced when the reaction is performed under electrochemical control.…”

Development of an Electrochemical Immunosensor for Specific Detection of Visceral Leishmaniasis Using Gold-Modified Screen-Printed Carbon Electrodes

“…Meanwhile, gold electrodes enable oriented couplings that minimize the distance between the active biomolecule sites and the electrode surface, facilitating the electron transfer, and a greater number of antibodies can be immobilized on the electrode surface [ 24 , 25 , 26 ]. Considering the use of portable platforms for point-of-care diagnosis, screen-printed electrodes play a key role in the development of electrochemical biosensors for several applications, as reported in the literature [ 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ].…”