title: A novel strategy for ultra-sensitive electrochemical immunoassay of biomarkers by coupling multifunctional iridium oxide (IrO(x)) nanospheres with catalytic recycling of self-produced reactants.
abstract: In this study, a novel and enzyme-free electrochemical immunoassay was developed for the detection of alpha-fetoprotein (AFP; as a model biomarker) by using a novel redox nanocatalyst, patterned gold-iridium oxide nanoparticle assemblies (Au-IrO(x)), on a Prussian blue (PB) functionalized glassy carbon electrode. The as-prepared Au-IrO(x) nanospheres were not only used for the labeling of secondary anti-AFP antibody but also executed for water oxidation. With a sandwich immunoassay format, the electrochemical measurement was carried out in 0.1 M KNO(3)-HCl, pH 3.2, containing 1.0 mM p-aminophenol (AP). Initially, the added AP was oxidized to p-quinone imine (QI) with the help of the immobilized PB on the electrode, and then the generated QI was reduced back to AP by hydrogenation reaction from water oxidation. The self-produced QI reactants were catalytically recycled and thus amplified the signal of electrochemical response. Under optimal conditions, the electrochemical immunosensor displayed a wide working range of 0.005 to 200 ng/mL with a low detection limit of 0.5 pg/mL AFP (at 3s(B)). Intra- and inter-assay coefficients of variation were below 10%. In addition, the methodology was validated with real serum samples, receiving a good agreement with the results obtained from commercially available electrochemiluminescence automated analyzer.
authors: Ministry of Education Key Laboratory of Analysis and Detection for Food Safety, Department of Chemistry, Fuzhou University, Fuzhou, 350108, China.
authors: Juan
authors: J
authors: Tang
authors: Dianping
authors: D
authors: Tang
authors: Reinhard
authors: R
authors: Niessner
authors: Dietmar
authors: D
authors: Knopp
mesh_terms: D015415:Biomarkers / Q000032:analysis*; D002384:Catalysis; D004563:Electrochemistry / Q000379:methods*; D007118:Immunoassay / Q000379:methods*; D007495:Iridium / Q000737:chemistry*; D057230:Limit of Detection; D046529:Microscopy, Electron, Transmission; D053758:Nanoparticles; D010084:Oxidation-Reduction; D000509:alpha-Fetoproteins / Q000032:analysis
chemical_list: D015415:Biomarkers; D000509:alpha-Fetoproteins; C044458:iridium oxide; D007495:Iridium