title: A novel label-free electrochemical aptasensor for thrombin based on the {nano-Au/thionine}n multilayer films as redox probes.
abstract: Herein, a novel label-free electrochemical aptasensor based on direct immobilization of the redox probes on an electrode surface was reported. Gold electrode coated Nafion was firstly modified with redox probe-thionine (Thi) through ion exchange adsorption. Then, with the help of chemisorption and electrostatic adsorption, negatively charged nano-Au and positively charged Thi were layer-by-layer (LBL) self-assembled onto the modified electrode surface, which formed {nano-Au/Thi(+)}(n) multilayer films for improving the amount of redox probes and immobilizing thiolated thrombin aptamers (TBA). In the presence of target thrombin (TB), the TBA on the multilayer film could catch the TB onto the electrode surface, which resulted in a barrier for electro-transfer, leading to decrease of the current. The proposed method avoided the cubsome redox probe labeling process, increased the amount of redox probe and reduced the distance between the redox probe and electrode surface. Thus, the approach showed a high sensitivity and a wider linearity to TB in the range from 0.12 nM to 46 nM with a detection limit of 40 pM.
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: 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: Zhongyuan
authors.initials: Z
authors.lastname: Liu
authors.forename: Li
authors.initials: L
authors.lastname: Mao
authors.forename: Shu
authors.initials: S
authors.lastname: Guan
authors.forename: Xiaoqing
authors.initials: X
authors.lastname: Qian
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D002417:Cattle; D055664:Electrochemical Techniques / Q000295:instrumentation / Q000379:methods; D004566:Electrodes; D004867:Equipment Design / Q000379:methods; D006046:Gold; D053768:Metal Nanoparticles; D010084:Oxidation-Reduction; D010640:Phenothiazines; D013917:Thrombin / Q000032:analysis
chemical_list: D052157:Aptamers, Nucleotide; D010640:Phenothiazines; C081676:thrombin aptamer; D006046:Gold; D013917:Thrombin; C009469:thionine