title: Hierarchical dendritic gold microstructure-based aptasensor for ultrasensitive electrochemical detection of thrombin using functionalized mesoporous silica nanospheres as signal tags.
abstract: A sensitive electrochemical approach for the detection of thrombin was designed by using densely packed hierarchical dendritic gold microstructures (HDGMs) with secondary and tertiary branches as matrices, and thionine-functionalized mesoporous silica nanospheres as signal tags. To prepare the signal tags, the positively charged thionine (as an indicator) was initially adsorbed onto the mesoporous silica nanoparticles (MSNs). Then [AuCl(4)](-) ions were in situ reduced on the thionine-modified MSNs by ascorbic acid to construct nanogold-decorated MSNs (GMSNs). The formed GMSNs were employed as label of the aminated aptamers. The assay was carried out in PBS, pH 7.4 with a sandwich-type assay mode by using the assembled thionine in the GMSNs as indicators. Compared with the pure silica nanoparticles, mesoporous silica could provide a larger surface for the immobilization of biomolecules and improve the sensitivity of the aptasensor. Under optimal conditions, the electrochemical aptasensors exhibited a wide linear range from 0.001 to 600 ng mL(-1) (i.e. 0.03 pM to 0.018 μM thrombin) with a low detection limit (LOD) of 0.5 pg mL(-1) (≈15 fM) thrombin at 3σ. No obvious non-specific adsorption was observed during a series of analyses to detect target analyte. The precision, selectivity and stability of the aptasensors were acceptable. Importantly, the methodology was evaluated with thrombin spiked samples in blank fetal calf serum, and the recoveries were 94.2-112%, indicating an exciting potential for thrombin detection.
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (Ministry of Education & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Juan
authors.initials: J
authors.lastname: Tang
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
authors.forename: Reinhard
authors.initials: R
authors.lastname: Niessner
authors.forename: Dietmar
authors.initials: D
authors.lastname: Knopp
authors.forename: Guonan
authors.initials: G
authors.lastname: Chen
mesh_terms: D052158:Aptamers, Peptide / Q000737:chemistry*; D001205:Ascorbic Acid / Q000737:chemistry; D055664:Electrochemical Techniques; D006046:Gold / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry; D054118:Nanospheres / Q000737:chemistry* / Q000648:ultrastructure; D016062:Porosity; D052156:SELEX Aptamer Technique; D012822:Silicon Dioxide / Q000737:chemistry*; D013917:Thrombin / Q000032:analysis*
chemical_list: D052158:Aptamers, Peptide; D006046:Gold; D012822:Silicon Dioxide; D013917:Thrombin; D001205:Ascorbic Acid