Analytical Sciences

An Ultrasensitive Electrochemical DNA Biosensor Based on Carboxylated Multi-walled Carbon Nanotube/Molybdenum Disulfide Composites for KRAS Gene Detection

Xiaojing WANG,* Mei YANG,* Qingyan LIU,* Siyi YANG,* Xintong GENG,* Yixia YANG,* Huanbao FA,** Yongzhong WANG,* and Changjun HOU*

*Key Laboratory of Biorheological Science and Technology, Ministry of Education, College of Bioengineering, Chongqing University, Chongqing 400044, P. R. China
**College of Chemistry and Chemical Engineering, Chongqing University, Chongqing 400044, P. R. China

In this paper, an ultrasensitive electrochemical biosensor based on carboxylated multi-walled carbon nanotube/molybdenum disulfide composites (MWCNTs-COOH/MoS₂) for the detection of KRAS gene is described. An easy, low-cost method, named one-step hydrothermal, was used for the synthesize of MWCNTs-COOH/MoS₂ nanocomposites, and scanning electronic microscopy (SEM), high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) were used for characterizing the prepared composites. Furthermore, cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were employed for an electrochemical performance study of this biosensor. Under optimal conditions, the detection limit of target DNA achieved down to 3 fM (S/N = 3) with high sensitivity; the linear range with the logarithm of the concentrations of target DNA varied from 1.0 × 10⁻¹⁴ to 1.0 × 10⁻⁷ M. Finally, the practicality of our proposed sensor was verified by a determination of the KRAS gene in human serum samples with good accuracy and high precision due to the excellent conductivity and large active surface area of the MWCNTs-COOH/MoS₂ nanocomposites. This proposed biosensor thus provides a practical method for the rapid and sensitive analysis of gene detection.

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