A novel voltammetric sensor based on gold nanoparticles involved in p-aminothiophenol functionalized multi-walled carbon nanotubes: Application to the simultaneous determination of quercetin and rutin

Graphical abstract: - Highlights: • The p-MWCNs and AuNPs/p-MWCNs nanocomposites were synthesized. • The prepared nanocomposites were characterized. • The nanocomposites were applied to simultaneous determination of flavanoids. • The developed electrodes showed long-term stability and reproducibility. - Abstract: Carbon nanotubes are expected to play a significant role in the design and manufacture of many nano-material devices in the future. Carbon nanotubes exhibit many unique properties which generate strong interests in studying their applications. In addition, certain properties of gold nanoparticles (e.g., conductivity, catalytic and photocatalytic activity) suggest that gold-nanoparticle-functionalized carbon nanotubes may prove applicable in future fabrication of nanodevices. In this study, gold nanoparticles (AuNPs) with the mean diameters of 20-25 nm were self-assembled onto the surfaces of p-aminothiophenol functionalized multi-walled carbon nanotubes (p-MWCNs) sheets. The p-MWCNs and AuNPs/p-MWCNs nanocomposites were characterized by reflection–absorption infrared spectroscopy (RAIRS), transmission electron microscope (TEM), x-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS) and x-ray diffraction (XRD) method. The simultaneous determination of quercetin (QR) and rutin (RT) was performed by square wave voltammetry (SWV) on glassy carbon electrode (GCE) modified with AuNPs/p-MWCNs nanocomposite (AuNPs/p-MWCNs-GCE). QR presented two oxidation steps at Ea1 of 270 mV and Ea2 of 450 mV and RT presented only one oxidation step at Ea of 360 mV at AuNPs/p-MWCNs-GCE. The linearity ranges and the detection limits of QR and RT were 1.0 × 10−9 - 5.0 × 10−8 M and 3.3 × 10−10. The application of the prepared nanocomposite to the analysis of real sample was also investigated