Issue 21, 2013

Microstructural and electrochemical impedance characterization of bio-functionalized ultrafine ZnS nanocrystals–reduced graphene oxide hybrid for immunosensor applications

Abstract

We report a mercaptopropionic acid capped ZnS nanocrystals decorated reduced graphene oxide (RGO) hybrid film on a silane modified indium-tin-oxide glass plate, as a bioelectrode for the quantitative detection of human cardiac myoglobin (Ag-cMb). The ZnS nanocrystals were anchored over electrochemically reduced GO sheets through a cross linker, 1-pyrenemethylamine hydrochloride, by carbodiimide reaction and have been characterized by scanning electron microscopy, transmission electron microscopy and energy dispersive X-ray spectroscopy. The transmission electron microscopic characterization of the ZnS–RGO hybrid shows the uniform distribution of ultra-fine nanoparticles of ZnS in nano-sheets of GO throughout the material. The protein antibody, Ab-cMb, was covalently linked to ZnS–RGO nanocomposite hybrid for the fabrication of the bioelectrode. A detailed electrochemical immunosensing study has been carried out on the bioelectrode towards the detection of target Ag-cMb. The optimal fitted equivalent circuit model that matches the impedance response has been studied to delineate the biocompatibility, sensitivity and selectivity of the bioelectrode. The bioelectrode exhibited a linear electrochemical impedance response to Ag-cMb in a range of 10 ng to 1 μg mL−1 in PBS (pH 7.4) with a sensitivity of 177.56 Ω cm2 per decade. The combined synergistic effects of the high surface-to-volume ratio of ZnS(MPA) nanocrystals and conducting RGO has provided a dominant charge transfer characteristic (Ret) at the lower frequency region of <10 Hz showing a good biocompatibility and enhanced impedance sensitivity towards target Ag-cMb. The impedance response sensitivity of the ZnS–RGO hybrid bioelectrode towards Ag-cMb has been found to be about 2.5 fold higher than that of a bare RGO modified bioelectrode.

Graphical abstract: Microstructural and electrochemical impedance characterization of bio-functionalized ultrafine ZnS nanocrystals–reduced graphene oxide hybrid for immunosensor applications

Article information

Article type
Paper
Submitted
18 May 2013
Accepted
16 Aug 2013
First published
22 Aug 2013

Nanoscale, 2013,5, 10494-10503

Microstructural and electrochemical impedance characterization of bio-functionalized ultrafine ZnS nanocrystals–reduced graphene oxide hybrid for immunosensor applications

S. K. Mishra, A. K. Srivastava, D. Kumar, A. M. Biradar and Rajesh, Nanoscale, 2013, 5, 10494 DOI: 10.1039/C3NR02575F

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