Amperometric immunosensor for carbofuran detection based on MWCNTs/GS-PEI-Au and AuNPs-antibody conjugate

• Published in: Sensors (Basel, Switzerland) Switzerland), 2013-04, Vol.13 (4), p.5286-5301
• Main Authors: Zhu, Ying, Cao, Yaoyao, Sun, Xia, Wang, Xiangyou
• Format: Article
• Language: English
• Subjects: amperometric immunosensor; Antibodies; Antibodies - metabolism; Binding sites; Biocompatibility; Biosensing Techniques - instrumentation; Biosensors; carbofuran; Carbofuran - analysis; Carbon; Composite materials; Electrochemical Techniques - instrumentation; Electrodes; Fruit - chemistry; Gold - chemistry; gold nanoparticles-antibody conjugation; Graphene; graphene sheets-PEI-Au nanocomposites; Graphite - chemistry; Metal Nanoparticles - ultrastructure; multiwall carbon nanotubes; Nanocomposites; Nanocomposites - chemistry; Nanoparticles; Nanotechnology; Nanotubes, Carbon - chemistry; Nanotubes, Carbon - ultrastructure; Polyethyleneimine - chemistry; Reproducibility; Reproducibility of Results; Sensors; Vegetables - chemistry; X-Ray Diffraction
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s130405286

In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs) and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au) nanocomposites were modified onto the surface of a glass carbon electrode (GCE) via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab) and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD), ultraviolet and visible absorption spectroscopy (UV-vis) and scanning electron microscopy (SEM), respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3). The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication.