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The p-n junction (Ni/Zn)O and its reduced graphene oxide nanocomposites ((Ni/Zn)O@rGO) has been synthesized through the hydrothermal method and used for effective electrochemical determination analgesic drug acetaminophen (AAP). In addition, the XRD characteristic peak and Raman modes confirm the formation of a p-n junction (Ni/Zn)O@rGO nanocomposites. The morphology of the as-prepared nanocomposites exposes nano-sized spherical particles that were well decorated on the rGO sheets, which results in a larger surface area. Further, the incorporation rGO and (Ni/Zn)O induced the catalytic properties and electrochemical performance. The electrochemical characterization of AAP was investigated at ((Ni/Zn)O@rGO/GCE) glass carbon electrode and differential pulse voltammetry (DPV) were adopted for the quantitative analysis of AAP. As a result, the prepared nanocomposite possessed great sensitivity, selectivity and stability. Further, the prepared sensor shows the wider linear range of 0.009-0.096 μM and 0.096-413 μM with a very low detection limit of 2.2 nM. Moreover, the practical applicability of the prepared sensor was tested in the pharmaceutical and human urine samples. Also, the developed method would widen the application of nanocomposites materials in the fabrications of more novel electrochemical sensing platforms. [ABSTRACT FROM AUTHOR]

We described a nanocomposite material that consists of gold nanorods self-assembled on functionalized multiwalled-carbon nanotubes (Au NRs@f-MWCNTs). It was deposited on a screen-printed carbon electrode (SPCE) which then is well suited for sensitive and selective determination of dopamine. Au NRs are prepared by silver ion-assisted seed-mediated method and the Au NRs@f-MWCNTs was prepared by self-assembly of Au NRs on f-MWCNTs. The composite was characterized by X-ray diffraction, transmission electron microscopy, Raman, UV-visible, and energy-dispersive X-ray spectroscopy. The electrochemical analyses were carried out using inexpensive SPCE to modify nanocomposite and visualized signals by cyclic voltammetry and amperometric instrument. The electrode displays excellent electrocatalytic ability to catalyze the redox reaction of dopamine. The modified SPCE, best operated at a working potential as low as 0.12 V (vs. Ag/AgCl), responds linearly to dopamine in the 3.5 nM to 1550 μM concentration range. The detection limit is 5.0 × 10-10 (±0.82) M, and the sensitivity is 4.04 (±0.58) μA.μM-1.cm-2. The limit of quantification (LOQ) of the method was 16.6 × 10-10 (±1.2) M. The sensor has good selectivity, appreciable stability, and reproducibility. It was applied to the determination of dopamine in (spiked) human serum and rat brain samples. [ABSTRACT FROM AUTHOR]