Self-assembled monolayer of SH-DNA strand on a magnetic bar carbon paste electrode modified with Fe3O4@Ag nanoparticles for detection of breast cancer mutation

• We have designed the MBCPE/Fe3O4NPs@Ag for determination of breast cancer mutation (BRCA1).
• Use of magnetic bar for fabrication of MBCPE for completely attraction of Fe3O4@Ag on the electrode surface.
• The thiolated single stranded DNA (SH-DNA) molecules were self-assembled at the surface of MBCPE/Fe3O4@Ag.
• The proposed electrode showed a detection limit as low as 3.0 × 10-17 M for BRCA1.
• The high sensitivity, selectivity, repeatability and stability are the advantages of the proposed electrode.

In the present work, a simple and new electrochemical biosensor was designed based on a magnetic bar carbon paste electrode (MBCPE) modified with iron oxide and silver nanoparticles (Fe3O4@Ag) for DNA detection. MBCPE/Fe3O4@Ag composite was used for the self-assembly monolayer (SAM) of thiolated single stranded DNA (SH-DNA). The morphology of Fe3O4NPs and Fe3O4NPs@Ag was studied by scanning electron microscopy (SEM), infrared spectroscopy (IR) and UV/Vis methods. Also, electrochemical techniques were applied for characterization of the designed biosensor. The experimental conditions (the immobilization and hybridization processes) were optimized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques. MBCPE/Fe3O4@Ag/ssDNA biosensor revealed a wide liner range and low detection limit (0. fM) for detection of BRCA1 5382 mutation by EIS method. Under the optimum conditions, the suggested biosensor revealed high selectivity for discriminating the complementary sequences from non-complementary sequences.

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