Toward Single-DNA Electrochemical Biosensing by Graphene Nanowalls

Abstract

Graphene oxide nanowalls with extremely sharp edges and preferred vertical orientation were deposited on a graphite electrode by using electrophoretic deposition in an Mg(2+)-GO electrolyte. Using differential pulse voltammetry (DPV), reduced graphene nanowalls (RGNWs) were applied for the first time, in developing an ultra-high-resolution electrochemical biosensor for detection of the four bases of DNA (G, A, T, and C) by monitoring the oxidation signals of the individual nucleotide bases. The extremely enhanced electrochemical reactivity of the four free bases of DNA, single-stranded DNA, and double-stranded DNA (dsDNA) at the surface of the RGNW electrode was compared to electrochemical performances of reduced graphene nanosheet (RGNS), graphite, and glassy carbon electrodes. By increasing the number of DPVs up to 100 scans, the RGNW electrode exhibited an excellent stability with only 15% variation in the oxidation signals, while for the RGNS electrode no detectable signals relating to T and C of 0.1 μM dsDNA were observed. The linear dynamic detection range of the RGNW electrode for dsDNA was checked in the wide range of 0.1 fM to 10 mM, while for the RGNS electrode, it was from 2.0 pM to <10 mM. The lower limits of dsDNA detection of the RGNW and RGNS electrodes were estimated as 9.4 zM (∼5 dsDNA/mL) and 5.4 fM, respectively. The RGNWs were efficient in label-free detection of single nucleotide polymorphisms of 20 zM oligonucleotides (∼10 DNA/mL) having a specific sequence. Therefore, the RGNWs can effectively contribute to the development of ultra-high-sensitive electrochemical biosensors with single-DNA resolutions.

Sensing at the Surface of Graphene Field‐Effect Transistors

“…Until now, the majority of GECs uses graphene dispersions (usually nanosheets of chemically functionalized graphene) deposited on conductive electrodes. [217,218] These graphene dispersions with large surface to volume ratio -in contrast with mono-or bilayer graphene sheets employed in GFETs -contain more defective areas. These defects enhance the density of electronic states (DOS) of graphene dispersions, which favors the electron transfer between the graphene materials and the redox biomolecules, and thus yielding a higher sensitivity.…”

“…[219] For example, reduced graphene nanowalls (rGNW) with large amount of sharp edges have been deposited vertically via electrophoresis on a graphite electrode to detect double-stranded DNA (dsDNA) with an impressively wide detection concentration range of 0.1 fM -10 mM. [218] The sensitivity of the abovementioned GEC biosensors resides in the defects of graphene. Functionalizations of these defects with electrochemical catalysts lead to further improved sensitivity and selectivity for the detection of a wide range of molecules, namely glucose, [220] cholesterol, [221] DNA, [222,223] proteins, [224] and even living cells.…”

Ultra‐Sensitive Graphene‐Plasmonic Hybrid Platform for Label‐Free Detection

“…A number of reports have appeared in the literature on the potential in sensitive and selective detection of protein and DNA using various graphene platforms. [22][23][24][25][26] Graphene has also been shown to be superior to metallic surfaces in terms of bio-compatibility and chemicalstability. [ 27 , 28 ] Molecular charge transfer between molecules and graphene has been shown to be signifi cant for selected families of molecules.…”

Human‐Like Sensing and Reflexes of Graphene‐Based Films

“…Bonanni et al immobilized hairpin–DNA probes onto graphene to fabricate a sensor to detect single nucleotide polymorphism relevant to the development of Alzheimer's disease 146. Akhavan et al introduced a “graphene nanowalls” structure towards single‐strain DNA electrochemical sensing 147. Besides, graphene was introduced into DNA sequencing.…”