A dual-amplification aptasensor for highly sensitive detection of thrombin based on the functionalized graphene-Pd nanoparticles composites and the hemin/G-quadruplex |
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Authors: | Shunbi Xie Yaqin ChaiLijuan Bai Yali YuanYan Wang |
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Institution: | Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, Key Laboratory of Eco-environments in Three Gorges Reservoir Region, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China |
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Abstract: | In this work, an advanced sandwich-type electrochemical aptasensor for thrombin was proposed by integrating hemin/G-quadruplex with functionalized graphene-Pd nanoparticles composites (PdNPs-RGs). The hemin/G-quadruplex formed by intercalating hemin into thrombin binding aptamer (TBA), firstly acted as a NADH oxidase, assisting the oxidation of NADH to NAD+ accompanying with the generation of H2O2 in the presence of dissolved O2. Subsequently, the hemin/G-quadruplex acted as HRP-mimicking DNAzyme that rapidly bioelectrocatalyze the reduction of the produced H2O2. At the same time, the Pd nanoparticles supported on p-iodoaniline functionalized graphene were also adopted to catalyze the reduction of H2O2. Thus, with the dual catalysis, a dramatically amplified electrochemical signal could be obtained. Besides, the avidin–biotin system for binding aptamer sequences on electrodes not only improved the sensitivity of thrombin analysis but also obtained an acceptable repeatability of the aptasensor. With several factors mentioned above, a wide linear ranged from 0.1 pM to 50 nM was acquired with a relatively low detection limit of 0.03 pM (defined as S/N = 3). These excellent performances provided our approach a promising way for ultrasensitive assay in electrochemical aptasensors. |
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Keywords: | Aptasensor Functionalized graphene Pd nanoparticles Thrombin Hemin/G-quadruplex |
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