title: Label-free electrochemical aptasensor for sensitive thrombin detection using layer-by-layer self-assembled multilayers with toluidine blue-graphene composites and gold nanoparticles.
abstract: In the present study, toluidine blue-graphene (Tb-Gra) nanocomposites were prepared to design a Lable-free electrochemical aptasensor for highly sensitive detection of thrombin based on layer-by-layer (LBL) technology. The nanocomposites with excellent redox electrochemical activities were first immobilized on the gold nanoparticles (nano-Au) modified glassy carbon electrodes (GCE). Then, the LBL structure was performed by electrostatic adsorption between the positively charged Tb-Gra and negatively charged nano-Au, which formed {Tb-Gra/nano-Au}(n) multilayer films for electroactive species enrichment and biomolecule immobilization. Subsequently, the thiolated thrombin binding aptamer (TBA) was assembled on the nano-Au surface through Au-S bond. In the presence of target thrombin (TB), the TBA on the multilayer could catch the thrombin onto the electrode surface, which resulted in a barrier for electro-transfer, leading to the decrease of the electrochemical signal of Tb-Gra nanocomposites. Under the optimal conditions, a wide detection range from 0.001 nM to 80 nM and a low detection limit of 0.33 pM (defined as S/N=3) for thrombin were obtained. In addition, the sensor exhibited excellent selectivity against other proteins.
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: Ruo
authors.initials: R
authors.lastname: Yuan
authors.forename: Yaqin
authors.initials: Y
authors.lastname: Chai
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*; D002244:Carbon; D055664:Electrochemical Techniques; D004566:Electrodes; D004867:Equipment Design; D006046:Gold / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry; D057230:Limit of Detection; D053768:Metal Nanoparticles / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D010084:Oxidation-Reduction; D015203:Reproducibility of Results; D055672:Static Electricity; D013917:Thrombin / Q000032:analysis*; D014048:Tolonium Chloride / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; C081676:thrombin aptamer; D014048:Tolonium Chloride; D002244:Carbon; D006046:Gold; D006108:Graphite; D013917:Thrombin