Abstract
In this paper, we propose an improved electrochemical platform based on graphene for the detection of DNA hybridization. Commercial screen-printed carbon electrodes (SPCEs) were used for this purpose due to their ease of functionalization and miniaturization opportunities. SPCEs were modified with reduced graphene oxide (RGO), offering a suitable surface for further functionalization. Therefore, aryl-carboxyl groups were integrated onto RGO-modified electrodes by electrochemical reduction of the corresponding diazonium salt to provide enough reaction sites for the covalent immobilization of amino-modified DNA probes. Our final goal was to determine the optimum conditions needed to fabricate a simple, label-free RGO-based electrochemical platform to detect the hybridization between two complementary single-stranded DNA molecules. Each modification step in the fabrication process was monitored by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) using [Fe(CN)6]3−/4− as a redox reporter. Although, the diazonium electrografted layer displayed the expected blocking effect of the charge transfer, the next steps in the modification procedure resulted in enhanced electron transfer properties of the electrode interface. We suggest that the improvement in the charge transfer after the DNA hybridization process could be exploited as a prospective sensing feature. The morphological and structural characterization of the modified electrodes performed by scanning electron microscopy (SEM) and Raman spectroscopy, respectively, were used to validate different modification steps in the platform fabrication process.
Highlights
Deoxyribonucleic acid (DNA) is a biopolymer that can self-assemble from two singlestrands in a unique way that conforms to the Watson−Crick base pairing rules [1]
The hybridization event can be employed in the detection of DNA or messenger ribonucleic acid oligonucleotides, which can be extremely valuable in point-of-care applications [9], as well as for the diagnosis of various genetic mutations and diseases [10,11]
Themorphology morphologyof ofthe themodified modifiedelectrodes electrodeswas wasinvestigated investigatedby bySEM, scanning electron microscopy (SEM),which whichisisalso aa useful to determine determineififthe thesurface surface working electrodes is uniformly useful technique to of of thethe working electrodes is uniformly covcovered with graphenic material
Summary
Deoxyribonucleic acid (DNA) is a biopolymer that can self-assemble from two singlestrands (ss) in a unique way that conforms to the Watson−Crick base pairing rules [1].This process of specific self-assembly between two complementary polynucleotides is called hybridization and it is centered around the hydrogen bonds formed between the nucleobase base pairs, producing a double-helix structure [2]. Deoxyribonucleic acid (DNA) is a biopolymer that can self-assemble from two singlestrands (ss) in a unique way that conforms to the Watson−Crick base pairing rules [1]. Electrochemical DNA biosensors are highly advantageous for the detection of particular ssDNA molecules due to their fast response time, inexpensive instrumentation and miniaturization potential [12]. Due to these advantages, DNA biosensors have been used so far in various applications, such as clinical diagnostics [13], drug interactions [14]
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