Methylene Blue-Modified Biochar from Sugarcane for the Simultaneous Electrochemical Detection of Four DNA Bases

The abnormal levels of four DNA bases, namely guanine (G), adenine (A), thymine (T), and cytosine (C) are implicated in several cancers, metabolic diseases, and HIV/AIDS. Therefore, the accurate detection and concentration measurement of these four DNA bases is of significant interest. Furthermore, there has recently been a push towards developing chemical sensors which are more sustainable and cost-effective. Herein, we developed a graphite paste electrode which incorporated the biochar of sugarcane and methylene blue (GPE-SC-MB) in order to simultaneously detect these four DNA bases. The linear ranges obtained for the four DNA bases are 0.67–38.67 µM for G, 0.67–126.67 µM for A, and 6.67–1600 µM for T and C. The limit-of-detection (LOD) values obtained were 0.037 μM for G, 0.042 µM for A, 4.25 μM for T, and 5.33 µM for C. The electroactive surface area of the electrode as well as the diffusion coefficients for each analyte were determined. Lastly, the GPE-SC-MB was tested in real samples using human saliva with recovery values between 99.0 and 103.0%. Thus, biochar from sugarcane proved to be an effective electrode modifier material for the development of sensitive electrochemical sensors.