Microstructural and electrochemical impedance characterization of bio-functionalized ultrafine ZnS nanocrystals-reduced graphene oxide hybrid for immunosensor applications.
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 cm(2) 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 (R(et)) 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.
CSIR-National Physical Laboratory, Dr K. S. Krishnan Road, New Delhi, 110012, India. rajesh_csir@yahoo.com.
Sujeet K
SK
Mishra
Avanish K
AK
Srivastava
Devendra
D
Kumar
Ashok M
AM
Biradar
Rajesh
D000906:Antibodies / Q000276:immunology; D015374:Biosensing Techniques; D002234:Carbodiimides / Q000737:chemistry; D058266:Dielectric Spectroscopy; D055664:Electrochemical Techniques; D004566:Electrodes; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D009211:Myoglobin / Q000032:analysis* / Q000276:immunology; D010087:Oxides / Q000737:chemistry; D045663:Quantum Dots / Q000737:chemistry*; D013440:Sulfides / Q000737:chemistry*; D017971:Tin Compounds / Q000737:chemistry; D017967:Zinc Compounds / Q000737:chemistry*
D000906:Antibodies; D002234:Carbodiimides; D009211:Myoglobin; D010087:Oxides; D013440:Sulfides; D017971:Tin Compounds; D017967:Zinc Compounds; C109984:indium tin oxide; D006108:Graphite; C031238:zinc sulfide