Three different signal amplification strategies for the impedimetric sandwich detection of thrombin

Abstract

In this work, we report a comparative study on three highly specific amplification strategies for the ultrasensitive detection of thrombin with the use of aptamer sandwich protocol. The protocol consisted on the use of a first thrombin aptamer immobilized on the electrode surface, the recognition of thrombin protein, and the reaction with a second biotinylated thrombin aptamer forming the sandwich. Through the exposed biotin end, three variants have been tested to amplify the electrochemical impedance signal. The strategies included (a) silver enhancement treatment, (b) gold enhancement treatment and (c) insoluble product produced by the combination of the enzyme horseradish peroxidase (HRP) and 3-amino-9-ethylcarbazole (AEC). The properties of the sensing surface were probed by electrochemical impedance measurements in the presence of the ferrocyanide/ferricyanide redox marker. Insoluble product strategy and silver enhancement treatment resulted in the lowest detection limit (0.3 pM), while gold enhancement method resulted in the highest reproducibility, 8.8% RSD at the pM thrombin concentration levels. Results of silver and gold enhancement treatment also permitted direct inspection by scanning electron microscopy (SEM).

G-Quadruplex-Forming Aptamers—Characteristics, Applications, and Perspectives

“…Furthermore, atomic force microscopy (AFM) [127], surface plasmon resonance spectroscopy (SPR) [128], and Raman spectroscopy [129] were used as alternative detection methods. Signal amplification was achieved by using gold nanoparticles [130], silver [129,131,132], carbon nanotubes [133], graphene [134,135], and enzymatic reactions [130].…”

Aptamer-modified nanomaterials: principles and applications

“…In search of mechanisms to amplify attained signals and enhance specificity, some assays rely on sandwich formats where aptamer-conjugated nanoparticles can serve as secondary capture probes and labels [77,78]. While the advantages and different applications for aptamer-functionalized nanoparticles will be discussed in the next chapter, herein, we would like to give one example where both, a nanostructured material and nanoparticles are implemented with aptamer-assisted target capture.…”

Aptamer–Molecularly Imprinted Polymer Multiple-Recognition System: Construction and Application

“…They are good candidates for antibodies. The sandwich type consists of a MIP/target/aptamer [31], which combines the specific recognition capabilities of MIPs and aptamers to achieve signal amplification [32]. The MIP material acts as a pre-concentration part for the targets, while the aptamer is responsible for signaling the presence of the target on the MIP platform.…”

“…the specific recognition capabilities of MIPs and aptamers to achieve signal amp [32]. The MIP material acts as a pre-concentration part for the targets, while the is responsible for signaling the presence of the target on the MIP platform.…”