title: DNAzyme-functionalized gold-palladium hybrid nanostructures for triple signal amplification of impedimetric immunosensor.
abstract: A highly sensitive and selective impedimetric immunosensor with triple signal amplification was designed for ultrasensitive detection of prostate-specific antigen (PSA) by using anti-PSA antibody and DNAzyme-functionalized gold-palladium hybrid nanotags (Ab2-AuPd-DNA). The signal was amplified based on the Ab2-AuPd-DNA toward the catalytic precipitation of 4-choloro-1-naphthol (4-CN). DNAzyme (as a kind of peroxidase mimic) could catalyze the oxidation of 4-CN, whilst AuPd hybrid nanostructures could not only provide a large surface coverage for immobilization of biomolecules but also promote 4-CN oxidation to some extent. The produced insoluble benzo-4-chlorohexadienone via 4-CN was coated on the electrode surface, and hindered the electron transfer between the solution and the electrode, thereby increasing the Faradaic impedance of the base electrode. Three labeling strategies including Ab2-AuNP, Ab2-AuPd and Ab2-AuPd-DNA were investigated for determination of PSA, and improved analytical features were obtained with the Ab2-AuPd-DNA strategy. Under optimal conditions, the dynamic concentration range of the impedimetric immunosensor spanned from 1.0 pg mL(-1) to 50 ng mL(-1) PSA with a detection limit of 0.73 pg mL(-1). Intra- and inter-assay coefficients of variation were below 8.5% and 9.5%, respectively. Importantly, no significant differences at the 0.05 significance level were encountered in the analysis of 6 clinical serum specimens and 6 diluted standards between the impedimetric immunosensor and the commercialized electrochemiluminescent method for PSA detection.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety, Ministry of Education & Fujian Province, Department of Chemistry, Fuzhou University, Fuzhou 350116, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Hou
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety, Ministry of Education & Fujian Province, Department of Chemistry, Fuzhou University, Fuzhou 350116, PR China.
authors.forename: Zhuangqiang
authors.initials: Z
authors.lastname: Gao
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety, Ministry of Education & Fujian Province, Department of Chemistry, Fuzhou University, Fuzhou 350116, PR China.
authors.forename: Mingdi
authors.initials: M
authors.lastname: Xu
authors.affiliation: School of Biochemical and Pharmaceutical Sciences, Capital Medical University, Beijing 100069, PR China.
authors.forename: Xia
authors.initials: X
authors.lastname: Cao
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety, Ministry of Education & Fujian Province, Department of Chemistry, Fuzhou University, Fuzhou 350116, PR China.
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Wu
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety, Ministry of Education & Fujian Province, Department of Chemistry, Fuzhou University, Fuzhou 350116, PR China.
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety, Ministry of Education & Fujian Province, Department of Chemistry, Fuzhou University, Fuzhou 350116, PR China. Electronic address: dianping.tang@fzu.edu.cn.
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D021881:DNA, Catalytic / Q000737:chemistry*; D017097:Electric Impedance; D055664:Electrochemical Techniques / Q000379:methods; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods; D057230:Limit of Detection; D008297:Male; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D010165:Palladium / Q000737:chemistry*; D017430:Prostate-Specific Antigen / Q000097:blood*
chemical_list: D021881:DNA, Catalytic; D010165:Palladium; D006046:Gold; D017430:Prostate-Specific Antigen
keywords: Catalytic precipitation; DNAzyme; Gold–palladium hybrid nanostructures; Impedimetric immunosensor; Prostate specific antigen; Triple signal amplification