Dhulfiqar S. Mutashar
Department of Physics, College of Science, University of Baghdad, Baghdad, Iraq
Wasan R. Saleh
Department of Physics, College of Science, University of Baghdad, Baghdad, Iraq
Ilham A. khalaf
Corporation of Research and Industrial Development, Baghdad, Iraq
ABSTRACT
Background: Electrochemical DNA sensors are emerging as sensitive and selective tools for biomedical diagnostics, enabling the detection of genetic mutations, infectious diseases, and cancer biomarkers. Surface modification of electrodes enhances DNA adsorption, improving sensor stability and performance. Objective: This study aimed to develop a high-performance electrochemical DNA sensor by modifying an indium tin oxide (ITO) electrode with fluorinated multi-walled carbon nanotubes (F-MWCNTs), polypyrrole (PPy), and gold nanoparticles (AuNPs), and to investigate its efficiency in DNA adsorption and detection. Methods: The ITO electrode was modified using a layer-by-layer electrochemical deposition method. The structural and morphological characteristics of the modified electrode were analyzed using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and cyclic voltammetry (CV). DNA adsorption efficiency was assessed by differential pulse voltammetry (DPV) using methylene blue (MB) as an electrochemical indicator. The stability, sensitivity, and selectivity of the sensor for DNA detection were evaluated. Results: The F-MWCNT/PPy/AuNP-modified ITO electrode exhibited enhanced electrochemical conductivity, as confirmed by CV measurements. FTIR analysis confirmed successful surface functionalization, while SEM imaging showed a uniform and well-distributed nanocomposite layer. The sensor demonstrated high DNA adsorption capacity, with a significant increase in oxidation peak current upon DNA immobilization. The modified electrode exhibited excellent stability, sensitivity, and selectivity for DNA detection, with a low detection limit (LOD) and wide linear range. Conclusion: The F-MWCNT/PPy/AuNP-modified ITO electrode enhances DNA adsorption and provides a promising platform for electrochemical DNA sensing applications. This approach could be valuable for the early detection of genetic mutations and disease biomarkers in clinical diagnostics and biomedical research. Further studies are recommended to optimize sensor performance for real-world biological sample analysis.
Keywords: Immobilization, DNA Adsorption, Polypyrrole, Nanomaterials.
