Electrochemical Detection Of Thrombin Research Articles

Aptamer conjugated Si nanowire network/poly(pyrrole)-NTA structure for electrochemical sensing

The current study describes the design, analytical characterization, and testing of aptamer sensors based on Si nanonets (Si NN) for thrombin electrochemical detection. Si nanonets are thin sheet arrays of randomly aligned Si nanowires with controlled and programmable properties that may be transported and integrated on a variety of substrates. Si nanonets were placed onto a commercial glassy carbon working electrode to create our aptasensor. Then they were functionalized by conductive pyrrole polymerization, which was followed by aptamer bioreceptor grafting. Electrochemical detection of thrombin was carried out after optimizing the electrode properties. On the one hand, cyclic voltammetry analyses demonstrated a linear association between the acquired current and the logarithm of thrombin concentration from 5 nmol L−1 to 2 µmol L−1. Impedance measurements, on the other hand, revealed a linear relationship between the charge transfer resistance as well as the impedance modulus. Thus, for the first time, Si nanonet thin sheets were used as constitutive nanoporous parts of electrodes capable of detecting thrombin at concentration limits of 5 nM, considered as a risk factor or presence of thrombosis. This demonstrates the concept of using this type of nanomaterial to detect molecules of biological interest.

Inhibition of catalytic activity of fibrinogen-stabilized gold nanoparticles via thrombin-induced inclusion of nanoparticle into fibrin: Application for thrombin sensing with more than 104-fold selectivity.

Citrate-capped gold nanoparticles (AuNPs) modified with thrombin-binding aptamer are often implemented for colorimetric, fluorescent, and electrochemical detection of thrombin in an aqueous solution. However, researchers have rarely explored the application of fibrinogen-modified AuNPs (F-AuNPs) for thrombin sensing. We present a simple, inexpensive, sensitive, and selective probe for colorimetric assay of thrombin through combining thrombin-induced inclusion of F-AuNPs into Fibrin and F-AuNPs-catalyzed reduction of 4-nitrophenol with an excess amount of NaBH4. Considering that fibrinogen stabilized citrate-capped AuNPs against a high-ionic-strength buffer, F-AuNPs efficiently catalyzed the NaBH4-mediated decrease of yellow 4-nitrophenol to colorless 4-aminophenol. The presence of thrombin converted fibrinogen into fibrin on the nanoparticle surface, leading to the inclusion of nanoparticles into fibrin. The formation of fibrin inhibited that the AuNPs catalyzed the NaBH4-mediated reduction of 4-nitrophenol. Consequently, the color of the solution gradually varied from colorless to yellow with increasing thrombin concentration. The proposed system was shown to be accurate in the quantification of small differences in the concentration of human thrombin over the range of 4-60 pM. The lowest detectable concentration of human thrombin by the naked eye was as low as 16 pM. We demonstrated the practical application of the proposed system in quantifying 1-15 nM human thrombin in human plasma.

A novel silver nanocluster in situ synthesized as versatile probe for electrochemiluminescence and electrochemical detection of thrombin by multiple signal amplification strategy

In this work, a novel silver nanoclusters (AgNCs) were in situ synthesized and used as versatile electrochemiluminescence (ECL) and electrochemical (EL) signal probes for thrombin detection by using DNAzyme-assisted target recycling and hybridization chain reaction (HCR) multiple amplification strategy. The presence of target thrombin firstly opened the hairpin DNA, followed by DNAzyme-catalytic recycling cleavage of excess substrates, which could generate large number of substrate fragments (s1). Then these s1 fragments were captured by SH–DNA on the Au nanoparticle-modified electrode, which further triggered the subsequent HCR of the hairpin DNA probes (H1 and H2) to form the long dsDNA. The numerous AgNCs were thus in situ synthesized by incubation the dsDNA template (with cytosine-rich loop)-modified electrode in solution with AgNO3 and sodium borohydride. By integrating the DNAzyme recycling and HCR dual amplification strategy, the amount of AgNCs is dramatically enhanced, leading to substantially amplified ECL and electrochemical signals for sensitive thrombin detection. Importantly, this design introduces the novel AgNCs into versatile ECL and EL bioassays by multiple amplification strategy, thus it is promising to provide a highly sensitive platform for various target biomolecules.

Label-free Elechochemical Aptasensor Based on Nickel Hexacyanoferrate for the Detection of Thrombin

A label-free electrochemical aptasensor has been constructed for the electrochemical detection of thrombin. Two layers of nickel hexacyanoferrate redox probes sandwiched with multi-walled carbon nanotubes for the sensitivity enhancement were directly immobilized on the electrode surface by electrodeposition,and gold nanoparticles was used as the immobilization matrix for the aptamers. SEM was used to characterize the morphologies of multi-walled carbon nanotubes and nickel hexacyanoferrate. Electrochemical impedance spectroscopy was used to monitor the self-assembly process of aptamer biosensors. Electrochemical behaviors of aptamer biosensors were studied by cyclic voltammetry and differential pulse voltammetry. The biosensor shows a good linear range of 1. 0 ng / L ~ 1. 0 mg / L( R = 0. 998) for the electrochemical detection of thrombin with a detection limit of 0. 2 ng / L( S / N = 3).

Electrochemical detection of thrombin by sandwich approach using antibody and aptamer

The goal of this work was to introduce a modified electrochemical sandwich model for target protein detection, exploiting antibody as the capturing probe, aptamer as the detection probe and methylene blue as the electrochemical active marker intercalating in the probing aptamer without previous labeling. With appropriate design of the sequence of the aptamer, the aptamer was successfully utilized instead of antibody for obtaining the electrochemical detection. A special immobilization interface consisting of nanogold-chitosan composite film was used to improve the conductivity and performance characteristics of the electrode. The capturing antibody was linked to the glassy carbon electrodes modified with composite film via a linker of glutaraldehyde. Differential pulse voltammetry was performed to produce the response signal. Thrombin was taken as the model target analyte to demonstrate the feasibility of proposed methodology. The sensor shows the linear response for thrombin in the range 1–60 nM with a detection limit of 0.5 nM. The proposed approach provides an alternative approach for sandwich protein assay using aptamers.

Label‐Free Electronic Detection of Thrombin in Blood Serum by Using an Aptamer‐Based Sensor

Blue, gold, and DNA: A methylene blue (MB) tagged, thrombin-binding DNA aptamer immobilized on a gold surface undergoes a large conformational change upon target binding (see schematic representation; eT: electron transfer). This folding produces a large, readily measurable change in redox current and allows the electrochemical detection of thrombin in blood serum.