Abstract
A simple method for electrochemical detection of a synthetic 20-bpoligonucleotide sequence related with dengue virus genome was developed. Acomplimentary DNA probe sequence was electrostatically immobilized onto a glassycarbon electrode modified with chitosan. Electrochemical detection of hybridizationbetween probe and target was performed by cyclic voltammetry, using ferrocene (Fc ) as ahybridization label. After hybridization, the peak current response of Fc oxidationincreased around 26%. A higher voltammetric decay rate constant (kd) and a lower half-lifeperiod (t1/2) for the interaction of Fc with dsDNA compared to those with ssDNAquantitatively characterize the different strengths of interaction with both types of DNA.By combining the simplicity of DNA immobilization onto a chitosan film and suitablevoltammetric detection of hybridization concomitant with ferrocene attachment, a gooddiscrimination between ssDNA and dsDNA was obtained.
Highlights
Biosensors have found many applications in both research and industry, namely in clinics diagnosis, for detection of bacterial and viral nucleic-acids in biological samples
Erdem et al [17] detected short oligonucleotides related to the hepatitis B virus after electrochemical adsorption on a pretreated carbon paste electrode, the same immobilization strategy previously used by Wang et al [18], working with carbon paste and strip electrodes, to detect short DNA sequences related to HIV by chronopotentiometry
The present paper proposes a simple method to detect a 20-bp oligonucleotide from the most conserved dengue genomic sequence, the 3’-noncoding region [26], envisaging detection of all the four antigenically-related dengue virus serotypes (DENV1-4)
Summary
Biosensors have found many applications in both research and industry, namely in clinics diagnosis, for detection of bacterial and viral nucleic-acids in biological samples. Interesting works were carried out by Xu’s team towards sequence-specific voltammetric detection of PCR-derived DNA with graphite [22], platinum [12] and glassy carbon [23] electrodes, using ferrocene derivatives as hybridization markers that covalently label the DNA probes. The natural cationic chitosan polymer forms stable complexes with the polyanionic phosphodiester backbones of either native or denatured DNA [24], providing a very stable immobilization In another approach, Ju et al [25] used ferrocenium ion as a groove-binder to detect yeast DNA covalently attached to a gold electrode through a SAM. One major novelty of this work is the combination of previously confirmed simplicity of DNA immobilization onto a chitosan-modified glassy carbon electrode with straightforward detection of the hybridization event through the oxidation peak current of Fc+ by cyclic voltammetry. Unlike in many other reports, we included the indicator into the voltammetric solution itself, avoiding a previous binding step
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