title: Cleavage of metal-ion-induced DNAzymes released from nanolabels for highly sensitive and specific immunoassay.
abstract: This work reports a novel electrochemical immunoassay protocol with signal amplification for determination of low-abundance protein (free prostate-specific antigen, PSA, used as a model) with high sensitivity and high selectivity by coupling metal sulfide (PbS)-based nanolabels with cleavage of the corresponding lead ion-induced DNAzymes. The assay mainly consists of an antigen-antibody immunoreaction with metal nanolabel in a transparent 96-well polystyrene microplate, the release of metal ions from the nanolabel, and cleavage of metal ion-induced DNAzyme. The signal is amplified by the labeled redox tag (ferrocene) on the DNAzyme-based sensor. In the presence of target analyte, the sandwiched immunocomplex can be formed between the primary antibody on the microplate and the corresponding metal sulfide nanolabel. The carried nanolabel can release numerous metal ions by acid, and induce the cleavage of the corresponding DNAzyme, thus resulting in the change of electrochemical signal. Under optimal conditions, the DNAzyme-based immunoassay presents an obvious electrochemical response for the detection of PSA, and allows detection of PSA at a concentration as low as 0.1 pg mL(-1). Intra-assay and interassay coefficients of variation (CV) were less than 9.5% and 10%, respectively. No significant differences at the 0.05 significance level were encountered in the analysis of 12 clinical serum specimens between the developed immunoassay and a commercially available enzyme-linked immunosorbent assay (ELISA).
authors: Key Laboratory of Analysis and Detection for Food Safety (Fujian Province & Ministry of Education of China), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors: Bing
authors: B
authors: Zhang
authors: Bingqian
authors: B
authors: Liu
authors: Junyang
authors: J
authors: Zhuang
authors: Dianping
authors: D
authors: Tang
mesh_terms: D000937:Antigen-Antibody Reactions / Q000276:immunology; D021881:DNA, Catalytic / Q000737:chemistry / Q000378:metabolism*; D055664:Electrochemical Techniques; D004566:Electrodes; D007118:Immunoassay / Q000379:methods*; D007854:Lead / Q000737:chemistry / Q000378:metabolism*; D053768:Metal Nanoparticles / Q000737:chemistry*; D010316:Particle Size; D013440:Sulfides / Q000737:chemistry / Q000378:metabolism*; D013499:Surface Properties
chemical_list: D021881:DNA, Catalytic; D013440:Sulfides; C018391:lead sulfide; D007854:Lead