title: Fractal gold modified electrode for ultrasensitive thrombin detection.
abstract: We report a label-free and ultrasensitive aptasensor based on a fractal gold modified (FracAu) electrode for thrombin detection with a femtomolar detection limit. The FracAu electrode was prepared by electrodeposition of hydrogen tetrachloroaurate (HAuCl(4)) onto a bare indium tin oxide (ITO) electrode surface. After this process the electrode was characterized by SEM. A thiol-modified aptamer against thrombin was immobilized on the FracAu electrode through a self-assembling process. Upon thrombin binding, the interfacial electron transfer of the FracAu electrode was perturbed by the formation of an aptamer-thrombin complex. The concentration of thrombin in the sample solution was determined by measuring the change in the oxidation peak current of hydroxymethyl ferrocene (C(11)H(12)FeO) with differential pulse voltammetry (DPV). The current response (reduced peak current) had a linear relationship with the logarithm of thrombin concentrations in the range of 10(-15) to 10(-10) M with a detection limit of 5.7 fM. Furthermore, the as-prepared FracAu electrode exhibited high selectivity. The application of FracAu electrodes may be extended to prepare other types of biosensors, such as immunosensors, enzyme biosensors and DNA biosensors. These results show that FracAu electrodes have great promise for clinical diagnosis of disease-related biomarkers.
authors.affiliation: Research Center for Bioengineering and Sensing Technology, University of Science & Technology Beijing, Beijing 100083, China. xuliping@ustb.edu.cn
authors.forename: Li-Ping
authors.initials: LP
authors.lastname: Xu
authors.forename: Shuqi
authors.initials: S
authors.lastname: Wang
authors.forename: Haifeng
authors.initials: H
authors.lastname: Dong
authors.forename: Guodong
authors.initials: G
authors.lastname: Liu
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Wen
authors.forename: Shutao
authors.initials: S
authors.lastname: Wang
authors.forename: Xueji
authors.initials: X
authors.lastname: Zhang
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry; D055664:Electrochemical Techniques; D004566:Electrodes; D005296:Ferrous Compounds / Q000737:chemistry; D006046:Gold / Q000737:chemistry*; D000075163:Metallocenes; D049329:Nanostructures / Q000737:chemistry; D013917:Thrombin / Q000032:analysis*; D017971:Tin Compounds / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D005296:Ferrous Compounds; D000075163:Metallocenes; D017971:Tin Compounds; C081676:thrombin aptamer; C109984:indium tin oxide; D006046:Gold; D013917:Thrombin; C004998:ferrocene