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  • A pseudo triple-enzyme electrochemical aptasensor based on the amplification of Pt-Pd nanowires and hemin/G-quadruplex.

A pseudo triple-enzyme electrochemical aptasensor based on the amplification of Pt-Pd nanowires and hemin/G-quadruplex.

Analytica chimica acta (2014-06-15)
Yingning Zheng, Yaqin Chai, Yali Yuan, Ruo Yuan
ABSTRACT

Our present work aimed at developing a pseudo triple-enzyme cascade electrocatalytic electrochemical aptasensor for determination of thrombin with the amplification of alcohol dehydrogenase (ADH)-Pt-Pd nanowires bionanocomposite and hemin/G-quadruplex structure that simultaneously acted as NADH oxidase and HRP-mimicking DNAzyme. With the addition of ethanol to the electrolyte, the ADH immobilized on the Pt-Pd nanowires catalyzed ethanol to acetaldehyde accompanied by NAD(+) being converted to NADH. Then the hemin/G-quadruplex firstly served as NADH oxidase, converting the produced NADH to NAD(+) with the concomitant local formation of high concentration of H2O2. Subsequently, the hemin/G-quadruplex acted as HRP-mimicking DNAzyme, bioelectrocatalyzing the produced H2O2. At the same time, the Pt-Pd nanowires employed in our strategy not only provided a large surface area for immobilizing thrombin binding aptamer (TBA) and ADH, but also served as HRP-mimicking DNAzyme which rapidly bioelectrocatalyzed the reduction of the produced H2O2. Thus, such a pseudo triple-enzyme cascade electrochemical aptasensor could greatly promote the electron transfer of hemin and resulted in the dramatic enhancement of electrochemical signal. As a result, a wide dynamic concentration linear range from 0.2 pM to 20 nM with a low detection limit of 0.067 pM for thrombin (TB) determination was obtained. The excellent performance indicated that our strategy was a promising way for ultrasensitive assays in electrochemical aptasensors.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
1-Hexanethiol, 95%
Sigma-Aldrich
Trizma® hydrochloride, pH 3.5-5.0 (0.5 M in H2O), BioXtra, ≥99.0% (titration)
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Hemin, BioXtra, from Porcine, ≥96.0% (HPLC)
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Hemin, from bovine, ≥90%
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1-Hexanethiol, 99% (GC)
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Trizma® hydrochloride, BioPerformance Certified, suitable for cell culture, ≥99.0% (titration)
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Trizma® hydrochloride, reagent grade, ≥99.0% (titration), crystalline
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Trizma® hydrochloride, BioUltra, for molecular biology, ≥99.0% (AT)
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Trizma® hydrochloride, anhydrous, free-flowing, Redi-Dri, ≥99.0%