A Certain Electrochemical Nanosensor Based on Functionalized Multi-Walled Carbon Nanotube for Determination of Cysteine in the Presence of Paracetamol

The modified glassy carbon electrode (GCE) was prepared with 6-amino-4-(3,4-dihydroxyphenyl)-3-methyl-1,4-dihydropyrano[2,3-c]pyrazole-5-carbonitrile (pyrazole derivative (AMPC)) and functionalized multi-walled carbon nanotubes. In this research, electrocatalytic activity of nanocomposite (AMPC/MWCNTs) has been studied by cyclic voltammetry (CV), differential pulse voltammetry (DPV) and chronoamperometry (CHA) methods. The electrocatalytic properties of the AMPC/MWCNTs nanocomposite for cysteine oxidation was considerably enhanced as compared to only AMPC. The kinetic parameters including the electron transfer coefficient (α) and the heterogeneous constant rate (k’) for oxidation of cysteine was studied by CV method. The diffusion coefficient of cysteine was calculated with aid of chronoamperometry (D=9.51×10-6 cm2/s). The AMPC/MWCNTs modified electrode shows a linear response to cysteine in the range of 0.7 nM to 200.0 µM with detection limit of 0.16 nM. Also, differential pulse voltammetry was applied for the simultaneous determination of cysteine (CYS) and paracetamol (or acetaminophen, AC). Finally, the modified electrode was used for the detection of CYS and AC in human serums (real samples). The sensor produced good sensitivity, selectivity, reproducibility and stability features.