Novel Graphene-Gold Nanoparticle Modified Electrodes for the High Sensitivity Electrochemical Spectroscopy Detection and Analysis of Carbamazepine

A novel graphene-gold nanoparticle composite deposited on gold electrode (Au-Gr-AuNPs) was employed to detect carbamazepine (CBZ), an antiepileptic drug, used here as a model system. The same approach can also be used to detect other additional organic compounds. The presence of gold nanoparticles (size between 10 and 20 nm) encased in graphene sheets was evidenced by TEM and HRTEM, while the AFM analysis was used to study the morphology of the graphene-gold nanoparticle films used for the electrochemical studies. Various electrochemical methods were employed to study carbamazepine oxidation, such as cyclic voltammetry, linear sweep voltammetry, and electrochemical impedance spectroscopy. The results clearly showed that the modified electrode exhibited excellent electrocatalytic effect toward oxidation of carbamazepine. The peak current intensity significantly increased (up to 2 times) while the peak potential shifted to lower oxidation potential (similar to 100 mV), compared with the unmodified electrode. A detection limit (DL) of 3.03 x 10(-6) M was obtained with the graphene-gold nanoparticle-modified electrode (S/N = 3). In addition, an equivalent electrical circuit was developed and used to interpret the experimental EIS data. The circuit contains the solution resistance (R-s), the charge-transfer resistance (R-ct), the Warburg impedance (Z(Wt), transmissive boundary), and the double-layer capacitance (C-dl).