Poly (alanine)/NaOH/ MoS2/MWCNTs modified carbon paste electrode for simultaneous detection of dopamine, ascorbic acid, serotonin and guanine

Abstract The detection of biomolecules such as dopamine (DA), ascorbic acid (AA), serotonin (5-HT), and guanine (GU) is essential for biomedical chemistry and disease diagnosis. In this work, MoS2/acid-treated MWCNTs composite (Ms-atCNTs) was first prepared and then used to modify carbon paste electrode (CPE), followed by electropolymerization of alanine in the presence of NaOH. The resulting modified electrode (p-Aln/Ms-atCNTCPE) was tested for the simultaneous detection of DA, AA, 5-HT, and GU using cyclic voltammetry and differential pulse voltammetry in phosphate buffer solution (PBS). The p-Aln/Ms-atCNTCPE showed excellent electrochemical response towards the detection of DA, AA, 5-HT, and GU. The electrode was also effectively utilized for concentration variation studies of a mixture containing these biomolecules. The detection limits were found to be 0.08 µM, 3.9 µM, 0.1 µM, and 0.1 µM for DA, AA, 5-HT, and GU, respectively. Furthermore, the proposed sensor displayed favorable repeatability, stability, and selectivity, as well as the usefulness for the detection of target molecules in real samples, such as DA injections, vitamin C tablets, herring sperm DNA, and human blood serum.