A novel label-free electrochemical aptasensor for thrombin based on the {nano-Au/thionine} n multilayer films as redox probes

• Published in: Analytica chimica acta Vol. 668; no. 2; pp. 171 - 176
• Main Authors: Yuan, Yali, Yuan, Ruo, Chai, Yaqin, Zhuo, Ying, Liu, Zhongyuan, Mao, Li, Guan, Shu, Qian, Xiaoqing
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 04.06.2010; Elsevier
• Subjects: Analytical chemistry; Animals; Aptamer; Aptamers, Nucleotide - chemistry; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Cattle; Chemistry; Electrochemical aptasensor; Electrochemical methods; Electrochemical Techniques - instrumentation; Electrochemical Techniques - methods; Electrodes; Equipment Design - methods; Exact sciences and technology; Gold; Metal Nanoparticles; Oxidation-Reduction; Phenothiazines; Redox probe; Thrombin (TB); Thrombin - analysis; Thrombin (TB); Aptamer; Electrochemical aptasensor; Redox probe; Self-assembled layer; Chemisorption; Gold; Multilayer; Electrochemical method; Immobilization; Barrier; Thionine; Probe; Chemical enrichment; Target; Chemical modification; Sensitivity; Thrombin(drug); Adsorption; Detection limit; Linearity; Transfer; Ion exchange
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2010.04.020

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.