Voltammetric immunosensor for E-cadherin promoter DNA methylation using a Fe3O4-citric acid nanocomposite and a screen-printed carbon electrode modified with poly(vinyl alcohol) and reduced graphene oxide
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Silencing of tumor suppressor genes (E-cadherin) by promoter DNA methylation may lead to the development of invasive phenotypes in epithelial tissues. The authors describe an electrochemical nanobiosensor for early detection and screening of circulating methylated DNA as a biomarker for cancers. First, the antibody against 5-methylcytosine was physically immobilized onto modified with reduced graphene oxide and polyvinylalcohol. In the next step, methylated target DNA in samples was hybridized with ssDNA probe conjugated to Fe3O4-citric acid nanocomposites and placed on the modified electrode. Then, the hexacyanoferrate redox system was added and electron transfer recorded. Cyclic voltammetry and electrochemical impedance spectroscopy showed that the modification process was well accomplished. Quantitative measurement of E-cadherin DNA promoter methylation was performed using differential pulse voltammetry. The electrochemical analysis achieved in the presence and absence of nonmethylated DNA mixed with samples indicated the high specificity and selectivity in methylation analysis using this system. With the linear range of concentration from 1 × 10−4 ng.mL−1 to 20 ng.mL−1 and the detection limit of 9 × 10−5 ng.mL−1, this method represents a promising approach for analysis of other biomarkers.
KeywordsDNA nanobiosensor Nanocomposite Magnetic nanoparticle DNA methylation Anti-5-methylcytosine antibody
Research reported in this publication was supported by Elite Researcher Grant Committee under award number  from the National Institutes for Medical Research Development (NIMAD), Tehran, Iran.
Compliance with ethical standards
all procetures performed in this study were in accordance with the ethical stamdards of the Tehran University Of Medical Sciences and with the 1964 Helsinki declaration.
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