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Herein, a simple reduction method for decoration of reduced graphene oxide (RGO) nanosheets with AuPdPt trimetal nanoparticles was developed. The as-synthesized nanocomposite was characterized detailedly using several techniques such as SEM, TEM, FTIR, CV and EDS. The results showed that the trimetal nanoparticles are well dispersed on RGO nanosheets, preventing the serious aggregation and maintaining good electro-catalytic activity. Benefiting from synergistic effect of AuPdPt nanoparticles and RGO, the modified electrode exhibited higher and remarkable oxidation toward retigabine (REG), anti-convulsant drug, with lowered oxidation overpotential. Under the optimum conditions for electrochemical oxidation of REG, the AuPdPt NPs@RGO/GCE displayed a wide linear range of 0.1[?]40.0 x 10[?]7 M with LOD of 0.039 x 10[?]7 M if compared to LODs of bare GCE, GO/GCE and RGO/GCE with values of 1.94 x 10[?]7 M, 0.32 x 10[?]7 M and 0.11 x 10[?]7 M, respectively. The main merits of the proposed sensor are the good stability, selectivity and reproducibility which have been successfully applied for the analysis of REG in human plasma and urine samples with good percentage recoveries. The obtained results prove that the proposed sensor could be a promising and convenient material for the construction of reliable and high performance electrochemical sensors.

In the present work, a triple amplified biosensor was constructed for ultrasensitive and selective analysis of an acetylcholinesterase inhibitor; rivastigmine (RIV) in human serum. The modified biosensor based on fabrication of pencil graphite electrode (PGE) with lepidocrocite nanoparticles (g-FeOOH) dispersed in N-chitosan carbon nanosheets (N@CCNS). Pyrrolidinium acid sulfate (PAS) as an ionic liquid was added to amplify the signal of RIV. The physical properties of the modified electrodes were characterized by powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and energy dispersive X-ray (EDX) spectroscopy. The cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) were used to evaluate the performance of the modified electrode. Parameters affecting performance of the modified sensor were evaluated such as pH, scan rate, casting volume, concentration of nanocomposite ...etc. The modified sensor showed a fast and sensitive electrochemical response to RIV sensing with wide linear range (3.0-90.0 nM), low detection limit (0.99 nM) and excellent anti-interference ability. Moreover, the fabricated sensor was successfully applied for determination of RIV in pharmaceutical tablets and spiked human serum and the obtained results are quite satisfactory.