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. 2015 Feb 6;15(2):3854-71.
doi: 10.3390/s150203854.

Application on gold nanoparticles-dotted 4-nitrophenylazo graphene in a label-free impedimetric deoxynivalenol immunosensor

Christopher Edozie Sunday  1 , Milua Masikini  2 , Lindsay Wilson  3 , Candice Rassie  4 , Tesfaye Waryo  5 , Pricilla G L Baker  6 , Emmanuel I Iwuoha  7
Affiliations

Application on gold nanoparticles-dotted 4-nitrophenylazo graphene in a label-free impedimetric deoxynivalenol immunosensor

Christopher Edozie Sunday et al. Sensors (Basel). .

Abstract

In this paper, we report a new concept to construct a label-free electrochemical inhibition-based immunosensor for the detection of the mycotoxin deoxynivalenol (DON) in cereal samples. The electrochemical impedance spectroscopy of tris(bipyridine) ruthenium (II) chloride was used as a marker enhanced with gold nanoparticles-dotted 4-nitrophenylazo functionalized graphene (AuNp/G/PhNO2) nanocatalyst mediated in Nafion on a glassy carbon electrode. Under the optimized conditions, the formation of immunocomplexes inhibited electron flow and increased the charge transfer resistance of the sensing interface linearly. The change in impedance was proportional to DON concentrations in the range of 6-30 ng/mL with a sensitivity and detection limit of 32.14 ΩL/ng and 0.3 µg/mL, respectively, which compares favorably with the ELISA result. The proposed sensor had a stability of 80.3%, good precision and selectivity in DON standard solution containing different interfering agents, indicating promising application prospect for this strategy in designing impedimetric, electrochemiluminescent, voltammetric or amperometric sensors.

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Figures

Figure 1.
Figure 1.
Chemical structure of the mycotoxin deoxynivalenol.
Figure 2.
Figure 2.
The illustration for simultaneous chemical reduction of diazonium cation to diazonium radical, GO to graphene, in situ PhNO2 functionalisation of graphene and the immobilization of gold nanoparticles onto nitrophenylazo functionalized graphene surface.
Figure 3.
Figure 3.
Schematic representation for stepwise fabrication of the label-free impedimetric deoxynivalenol immunosensor.
Figure 4.
Figure 4.
Electrochemical reduction of 4-nitrophenyl group to 4-aminophenyl on the electrode surface.
Figure 5.
Figure 5.
CV of (i) bare GCE, (ii) GCE/Nafion/[Ru(bpy)3]2+/G/PhNO2 and (iii) GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2 recorded in 5 mM [Ru(NH3)6]2+/3+.
Figure 6.
Figure 6.
CV response of different immobilisation steps: (i) GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2, (ii) after immobilization of DON antibody, (iii) after blocking nonspecific binding sites with BSA and (iv) after immobilization and running in standard DON solutions at scan rate of 50 mV/s, over potential range of 650–1350 mV.
Figure 7.
Figure 7.
(a) Chronoamperometric responses, and (b) bar chart for the chronoamperograms of different immobilisation steps: (i) GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2, (ii) after immobilization of DON antibody, (iii) after blocking nonspecific binding sites with BSA and (iv) after immobilization and running in standard DON solutions.
Figure 7.
Figure 7.
(a) Chronoamperometric responses, and (b) bar chart for the chronoamperograms of different immobilisation steps: (i) GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2, (ii) after immobilization of DON antibody, (iii) after blocking nonspecific binding sites with BSA and (iv) after immobilization and running in standard DON solutions.
Figure 8.
Figure 8.
The plot of Rct values versus deoxynivalenol antibody concentrations.
Figure 9.
Figure 9.
The plot of anodic peak currents from CV versus solution pH.
Figure 10.
Figure 10.
The plot of peak currents from chronoamperograms versus incubation time.
Figure 11.
Figure 11.
(a). EIS responses of GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2/DONab/BSA immunosensor to standard DONag solutions: a, b, c, d, e and f represents 0, 6, 12, 18, 24 and 30 ng/mL DON antigen respectively; (b). Expanded EIS spectra responses of GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2/DONab/BSA immunosensor to standard DONag solutions indicating the characteristic Rct semi-circle over the high frequency range and a straight line over the low frequency range.
Figure 12.
Figure 12.
The calibration plot of EIS detection data of the immunosensor.
Figure 13.
Figure 13.
The selectivity chart of GCE/Nafion/[Ru(bpy)3]2+/AuNp/G/PhNH2/DONab immunosensor.
Figure 14.
Figure 14.
The detection plot of DONag standards by ELISA.
See this image and copyright information in PMC

References

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