title: A non-aggregation colorimetric assay for thrombin based on catalytic properties of silver nanoparticles.
abstract: In this paper, we developed a simple and rapid colorimetric assay for protein detection based on the reduction of dye molecules catalyzed by silver nanoparticles (AgNPs). Aptamer-modified magnetic particles and aptamer-functionalized AgNPs were employed as capture and detection probes, respectively. Introduction of thrombin as target protein could form a sandwich-type complex involving catalytically active AgNPs, whose catalytic activity was monitored on the catalytic reduction of rhodamine B (RhB) by sodium borohydride (NaBH4). The amount of immobilized AgNPs on the complex increased along with the increase of the thrombin concentration, thus the detection of thrombin was achieved via recording the decrease in absorbance corresponding to RhB. This method has adopted several advantages from the key factors involved, i.e., the sandwich binding of affinity aptamers contributed to the increased specificity; magnetic particles could result in rapid capture and separation processes; the conjugation of AgNPs would lead to a clear visual detection. It allows for the detection limit of thrombin down to picomolar level by the naked eye, with remarkable selectivity over other proteins. Moreover, it is possible to apply this method to the other targets with two binding sites as well.
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Li
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Weibing
authors.initials: W
authors.lastname: Qiang
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Xi
authors.initials: X
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Li
authors.affiliation: State Key Laboratory of Analytical Chemistry for Life Science, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China. Electronic address: xudanke@nju.edu.cn.
authors.forename: Danke
authors.initials: D
authors.lastname: Xu
mesh_terms: D052157:Aptamers, Nucleotide / Q000737:chemistry; D055162:Biocatalysis; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D003124:Colorimetry; D008280:Magnetics; D053768:Metal Nanoparticles / Q000737:chemistry*; D010084:Oxidation-Reduction; D012235:Rhodamines / Q000737:chemistry; D012834:Silver / Q000737:chemistry*; D013917:Thrombin / Q000032:analysis* / Q000378:metabolism
chemical_list: D052157:Aptamers, Nucleotide; D012235:Rhodamines; D012834:Silver; D013917:Thrombin; C029773:rhodamine B
keywords: Aptasensor; Catalytic reduction; Colorimetric; Rhodamine B; Silver nanoparticles