title: Electrochemical aptasensor based on the dual-amplification of G-quadruplex horseradish peroxidase-mimicking DNAzyme and blocking reagent-horseradish peroxidase.
abstract: A simple electrochemical aptasensor for sensitive detection of thrombin was fabricated with G-quadruplex horseradish peroxidase-mimicking DNAzyme (hemin/G-quadruplex system) and blocking reagent-horseradish peroxidase as dual signal-amplification scheme. Gold nanoparticles (nano-Au) were firstly electrodeposited onto single wall nanotube (SWNT)-graphene modified electrode surface for the immobilization of electrochemical probe of nickel hexacyanoferrates nanoparticles (NiHCFNPs). Subsequently, another nano-Au layer was electrodeposited for further immobilization of thrombin aptamer (TBA), which later formed hemin/G-quadruplex system with hemin. Horseradish peroxidases (HRP) then served as blocking reagent to block possible remaining active sites and avoided the non-specific adsorption. In the presence of thrombin, the TBA binded to thrombin and the hemin released from the hemin/G-quadruplex electrocatalytic structure, increasing steric hindrance of the aptasensor and decomposing hemin/G-quadruplex electrocatalytic structure, which finally decreased the electrocatalytic efficiency of aptasensor toward H(2)O(2) in the presence of NiHCFNPs with a decreased electrochemical signal. On the basis of the synergistic amplifying action, a detection limit as low as 2 pM for thrombin was obtained.
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: Yali
authors.initials: Y
authors.lastname: Yuan
authors.forename: Xuxu
authors.initials: X
authors.lastname: Gou
authors.forename: Ruo
authors.initials: R
authors.lastname: Yuan
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhuo
authors.forename: Li
authors.initials: L
authors.lastname: Mao
authors.forename: Xianxue
authors.initials: X
authors.lastname: Gan
mesh_terms: D052157:Aptamers, Nucleotide; D015374:Biosensing Techniques / Q000379:methods* / Q000706:statistics & numerical data; D021881:DNA, Catalytic; D055664:Electrochemical Techniques; D054856:G-Quadruplexes; D006046:Gold; D006427:Hemin; D006735:Horseradish Peroxidase; D053768:Metal Nanoparticles; D015203:Reproducibility of Results; D013917:Thrombin / Q000032:analysis*
chemical_list: D052157:Aptamers, Nucleotide; D021881:DNA, Catalytic; C081676:thrombin aptamer; D006427:Hemin; D006046:Gold; D006735:Horseradish Peroxidase; D013917:Thrombin