title: Selective staining of CdS on ZnO biolabel for ultrasensitive sandwich-type amperometric immunoassay of human heart-type fatty-acid-binding protein and immunoglobulin G.
abstract: We report on an ultrasensitive metal-labeled amperometric immunoassay of proteins, which is based on the selective staining of nanocrystalline cadmium sulfide (CdS) on ZnO nanocrystals and in-situ microliter-droplet anodic stripping voltammetry (ASV) detection on the immunoelectrode. Briefly, antibody 1 (Ab1), bovine serum albumin (BSA), antigen and ZnO-multiwalled carbon nanotubes (MWCNTs) labeled antibody 2 (Ab2-ZnO-MWCNTs) were successively anchored on a β-cyclodextrin-graphene sheets (CD-GS) nanocomposite modified glassy carbon electrode (GCE), forming a sandwich-type immunoelectrode (Ab2-ZnO-MWCNTs/antigen/BSA/Ab1/CD-GS/GCE). CdS was selectively grown on the catalytic ZnO surfaces through chemical reaction of Cd(NO3)2and thioacetamide (ZnO-label/CdS-staining), due to the presence of an activated cadmium hydroxide complex on ZnO surfaces that can decompose thioacetamide. A beforehand cathodic "potential control" in air and then injection of 7μL of 0.1M aqueous HNO3on the immunoelectrode allow dissolution of the stained CdS and simultaneous cathodic preconcentration of atomic Cd onto the electrode surface, thus the following in-situ ASV detection can be used for immunoassay with enhanced sensitivity. Under optimized conditions, human immunoglobulin G (IgG) and human heart-type fatty-acid-binding protein (FABP) are analyzed by this method with ultrahigh sensitivity, excellent selectivity and small reagent-consumption, and the limits of detection (LODs, S/N=3) are 0.4fgmL-1for IgG and 0.3fgmL-1for FABP (equivalent to 73 FABP molecules in the 6μL sample employed).
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
authors.forename: Xiaoli
authors.initials: X
authors.lastname: Qin
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
authors.forename: Aigui
authors.initials: A
authors.lastname: Xu
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
authors.forename: Ling
authors.initials: L
authors.lastname: Liu
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
authors.forename: Yuyun
authors.initials: Y
authors.lastname: Sui
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
authors.forename: Yunlong
authors.initials: Y
authors.lastname: Li
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
authors.forename: Yueming
authors.initials: Y
authors.lastname: Tan
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Chen
authors.affiliation: Key Laboratory of Chemical Biology and Traditional Chinese Medicine Research (MOE of China), Synergetic Innovation Center for Quantum Effects and Applications, College of Chemistry and Chemical Engineering, Hunan Normal University, Changsha 410081, China. Electronic address: xieqj@hunnu.edu.cn.
authors.forename: Qingji
authors.initials: Q
authors.lastname: Xie
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation; D019187:Cadmium Compounds / Q000737:chemistry*; D055664:Electrochemical Techniques / Q000295:instrumentation*; D004566:Electrodes; D004867:Equipment Design; D000074026:Fatty Acid Binding Protein 3; D050556:Fatty Acid-Binding Proteins / Q000097:blood*; D006801:Humans; D007118:Immunoassay / Q000295:instrumentation; D007074:Immunoglobulin G / Q000097:blood*; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D037742:Nanotubes, Carbon / Q000737:chemistry / Q000648:ultrastructure; D013440:Sulfides / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D055910:Antibodies, Immobilized; D019187:Cadmium Compounds; C493408:FABP3 protein, human; D000074026:Fatty Acid Binding Protein 3; D050556:Fatty Acid-Binding Proteins; D007074:Immunoglobulin G; D037742:Nanotubes, Carbon; D013440:Sulfides; C034939:cadmium sulfide; D015034:Zinc Oxide
keywords: Human heart-type fatty-acid-binding protein; Human immunoglobulin G; In situ microliter-droplet anodic stripping voltammetry; Ultrasensitive metal-labeled amperometric immunoassay; ZnO-label/CdS-staining