DNAzyme-functionalized gold-palladium hybrid nanostructures for triple signal amplification of impedimetric immunosensor

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• 作者：Li Hou ; Zhuangqiang Gao ; Mingdi Xu ; Xia Cao ; Xiaoping Wu ; Guonan Chen ; Dianping Tang
• 关键词：Impedimetric immunosensor ; Catalytic precipitation ; DNAzyme ; Prostate specific antigen ; Triple signal amplification ; Gold&ndash ; palladium hybrid nanostructures
• 刊名：Biosensors and Bioelectronics
• 出版年：15 April, 2014
• 年：2014
• 卷：54
• 期：Complete
• 页码：365-371
• 全文大小：1830 K

文摘

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^鈭? to 50 ng mL^鈭? PSA with a detection limit of 0.73 pg mL^鈭?. 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.