A highly selective electrochemiluminescent biosensor for the detection of target nephrotoxic toxin, ochratoxin A (OTA), was
developed using a DNA aptamer as the recognition element and N-(4-aminobutyl)-N-ethylisoluminol (ABEI) as the signal-producing compound. The electrochemiluminescent aptamer biosensor was fabricated by
immobilizing aptamer complementary DNA 1 sequence onto the surface of a gold-nanoparticle (AuNP)-modified gold electrode.
ABEI-labeled aptamer DNA 2 sequence hybridized to DNA 1 and was utilized as an electrochemiluminescent probe. A decreased
electrochemiluminescence (ECL) signal was generated upon aptamer recognition of the target OTA, which induced the dissociation
of DNA 2 (ABEI-labeled aptamer electrochemiluminescent probe) from DNA 1 and moved it far away from the electrode surface.
Under the optimal conditions, the decreased ECL intensity was proportional to an OTA concentration ranging from 0.02 to 3.0 ng mL-1, with a detection limit of 0.007 ng mL-1. The relative standard deviation was 3.8% at 0.2 ng mL-1 (n = 7). The proposed method has been applied to measure OTA in naturally contaminated wheat samples and validated by an official
method. This work demonstrates the combination of a highly binding aptamer with a highly sensitive ECL technique to design
an electrochemiluminescent biosensor, which is a very promising approach for the determination of small-molecule toxins. 相似文献
An electrochemiluminescence (ECL) biosensor for simultaneous detection of adenosine and thrombin in one sample based on bifunctional aptamer and N-(aminobutyl)-N-(ethylisoluminol) functionalized gold nanoparticles (ABEI-AuNPs) was developed. A streptavidin coated gold nanoparticles modified electrode was utilized to immobilize biotinylated bifunctional aptamer (ATA), which consisted of adenosine and thrombin aptamer. The ATA performed as recognition element of capture probe. For adenosine detection, ABEI-AuNPs labeled hybridization probe with a partial complementary sequence of ATA reacted with ATA, leading to a strong ECL response of N-(aminobutyl)-N-(ethylisoluminol) enriched on ABEI-AuNPs. After recognition of adenosine, the hybridization probe was displaced by adenosine and ECL signal declined. The decrease of ECL signal was in proportion to the concentration of adenosine over the range of 5.0 × 10−12–5.0 × 10−9 M with a detection limit of 2.2 × 10−12 M. For thrombin detection, thrombin was assembled on ATA modified electrode via aptamer–target recognition, another aptamer of thrombin tagged with ABEI-AuNPs was bounded to another reactive site of thrombin, producing ECL signals. The ECL intensity was linearly with the concentration of thrombin from 5 × 10−14 M to 5 × 10−10 M with a detection limit of 1.2 × 10−14 M. In the ECL biosensor, adenosine and thrombin can be detected when they coexisted in one sample and a multi-analytes assay was established. The sensitivity of the present biosensor is superior to most available aptasensors for adenosine and thrombin. The biosensor also showed good selectivity towards the targets. Being challenged in real plasma sample, the biosensor was confirmed to be a good prospect for multi-analytes assay of small molecules and proteins in biological samples. 相似文献
A label‐free electrochemical impedance based protein biosensor was introduced by using aptamer as recognition tool. Our sensing protocol utilizes the affinity interaction between the thrombin and the self‐assembled DNA aptamer on gold electrode. This specific interaction increases the electrode interfacial electronic transfer resistance. The resistance signal is then “amplified” by using guanidine hydrochloride to denature the captured thrombin for increasing the hydrated radius of the thrombin, consequently blocking the electron transfer from solution to electrode. The sensor sensitivity is improved using this strategy and as low as 1.0×10?14 mol L?1 thrombin (enzymatic activity 10 U/mg) can be detected out. 相似文献
This paper presents a simple electrochemical approach for the detection of thrombin, using aptamer-modified electrodes. The
use of gold nanoparticles results in significant signal enhancement for subsequent detection. 1,6-Hexanedithiol was used as
the medium to link Au nanoparticles to a bare gold electrode. Anti-thrombin aptamers were immobilized on the gold nanoparticles’
surfaces by self-assembly. The packing density of aptamers was determined by cyclic voltammetric (CV) studies of redox cations
(e.g., [Ru(NH3)6]3+) which were electrostatically bound to the DNA phosphate backbones. The results indicate that the total amount of aptamer
probes immobilized on the gold nanoparticle surface is sixfold higher than that on the bare electrode, leading to increased
sensitivity of the aptasensor and a detection limit of 1 pmol L−1. Based on the Langmuir model, the sensor signal displayed an almost perfect linear relationship over the range of 1 pmol
L−1 to 30 nmol L−1. Moreover, the proposed aptasensor is highly selective and stable. In summary, this biosensor is simple, highly sensitive,
and selective, which is beneficial to the ever-growing interest in fabricating portable bio-analytical devices with simple
electrical readout procedures. 相似文献
A novel biosensor by electrochemically codeposited Pt nanoclusters and DNA film was constructed and applied to detection of dopamine (DA) and uric acid (UA) in the presence of high concentration ascorbic acid (AA). Scanning electron microscopy and X‐ray photoelectron spectroscopy were used for characterization. This electrode was successfully used to resolve the overlapping voltammetric response of DA, UA and AA into three well‐defined peaks with a large anodic peak difference (ΔEpa) of about 184 mV for DA and 324 mV for UA. The catalytic peak current obtained from differential pulse voltammetry was linearly dependent on the DA concentration from 1.1× 10?7 to 3.8×10?5 mol·L?1 with a detection limit of 3.6×10?8 mol·L?1 (S/N=3) and on the UA concentration from 3.0×10?7 to 5.7×10?5 mol·L?1 with a detection limit of 1.0×10?7 mol·L?1 with coexistence of 1.0×10?3 mol·L?1 AA. The modified electrode shows good sensitivity and selectivity. 相似文献
A simple and rapid colorimetric approach for the determination of adenosine has been developed via target inducing aptamer structure switching, thus leading to Au colloidal solution aggregation. In the absence of the analytes, the aptamer/gold nanoparticle (Au NP) solution remained well dispersed under a given high ionic strength condition in that the random‐coil aptamer was readily wrapped on the surface of the Au NPs, which resulted in the enhancement of the repulsive force between the nanoparticles due to the high negative charge density of DNA molecules. While in the presence of adenosine, target‐aptamer complexes were formed and the conformation of the aptamer was changed to a folded structure which disfavored its adsorption on the Au NP surface, thus leading to the reduction of the negative charge density on each Au NP and then the reduced degree of electrostatic repulsion between Au nanoparticles. As a result, the aggregation of the Au colloidal solution occurred. The changes of the absorption spectrum could be easily monitored by a UV‐Vis spectrophotometer. A linear correlation exists between the ratio of the absorbance of the system at 522 to 700 nm (A522 nm/A700 nm) and the concentration of adenosine between 100 nmol·L?1 and 10 µmol·L?1, with a detection limit of 51.5 nmol·L?1. 相似文献
Herein, a signal‐on sandwich‐type electrochemiluminescence (ECL) aptasensor for the detection of thrombin (TB) was proposed. The graphene (GR) doped thionine (TH) was electropolymerized synchronously on the bare glassy carbon electrode (GCE) to form co‐polymer (PTG) electrode. The gold nanoparticles (AuNPs) were decorated on the surface of the PTG by in‐situ electrodeposition, and the functional co‐polymer (PTG‐AuNPs) electrode was utilized as sensing interface. Then, TB binding aptamer I (TBA I) as capture probes were modified on the PTG‐AuNPs electrode to capture TB, and Ru(bpy)32+/silver nanoparticles doped silica core‐shell nanocomposites‐labeled TB binding aptamer II (RuAg/SiO2NPs@TBA II) were used as signal probes to further bind TB, resulting in a sandwich structure. With the assistant of silica shell and AgNPs, the enrichment and luminous efficiency of Ru(bpy)32+ were significantly improved. Under the synergy of PTG‐AuNPs and RuAg/SiO2NPs, the ECL signal was dramatically increased. The proposed ECL aptasensor displayed a wide linear range from 2 fM to 2 pM with the detection limit of 1 fM, which is comparable or better than that in reported ECL aptasensors for TB using Ru(bpy)32+ and its derivatives as the luminescent substance. The excellent sensitivity makes the proposed aptasensor a promising potential in pharmaceutical and clinical analysis. 相似文献
Graphene oxide doped with nitrogen and sulfur was decorated with gold nanoparticles (AuNP-SN-GO) and applied as a substrate to modify a glassy carbon electrode (GCE). An aptamer against the model protein thrombin was self-assembled on the modified GCE which then was exposed to thrombin. Following aptamer-thrombin interaction, biotin-labeled DNA and aptamer 2 are immobilized on another AuNP-SN-GO hybrid and then are reacted with the thrombin/AuNP-SN-GO/GCE to form a sandwich. The enzyme label horseradish peroxidase (HRP) was then attached to the electrode by biotin–avidin interaction. HRP catalyzes the oxidation of hydroquinone by hydrogen peroxide. This generates a strong electrochemical signal that increases linearly with the logarithm of thrombin concentration in the range from 1.0?×?10?13 M to 1.0?×?10?8 M with a detection limit of 2.5?×?10?14 M (S/N?=?3). The assay is highly selective. It provides a promising strategy for signal amplification. In our perception, it has a large potential for sensitive and selective detection of analytes for which appropriate aptamers are available.
Graphic abstract A sandwich-type electrochemical aptasensor is fabricated for detection of thrombin using a glassy carbon electrode modified with nitrogen- and sulfur-doped graphene oxide and gold nanoparticles.