title: A dual-amplification aptasensor for highly sensitive detection of thrombin based on the functionalized graphene-Pd nanoparticles composites and the hemin/G-quadruplex.
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 H(2)O(2) in the presence of dissolved O(2). Subsequently, the hemin/G-quadruplex acted as HRP-mimicking DNAzyme that rapidly bioelectrocatalyze the reduction of the produced H(2)O(2). At the same time, the Pd nanoparticles supported on p-iodoaniline functionalized graphene were also adopted to catalyze the reduction of H(2)O(2). 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.
authors.affiliation: Key Laboratory on Luminescence and Real-Time Analysis, Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China.
authors.forename: Shunbi
authors.initials: S
authors.lastname: Xie
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
authors.forename: Lijuan
authors.initials: L
authors.lastname: Bai
authors.forename: Yali
authors.initials: Y
authors.lastname: Yuan
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry*; D002623:Chemistry Techniques, Analytical / Q000295:instrumentation*; D004355:Drug Stability; D004563:Electrochemistry; D004566:Electrodes; D054856:G-Quadruplexes; D006108:Graphite / Q000737:chemistry*; D006427:Hemin / Q000737:chemistry*; D006801:Humans; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D010165:Palladium / Q000737:chemistry*; D013917:Thrombin / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; C081676:thrombin aptamer; D010165:Palladium; D006427:Hemin; D006108:Graphite; D013917:Thrombin