Label‐Free Electrochemical Thrombin Aptasensor Based on Ag Nanoparticles Modified Electrode

Abstract

A novel label-free electrochemical method for protein detection based on redox properties of silver was developed. As recognition elements, thrombin-binding aptamers were used. Screen printed electrodes modified with silver nanoparticles (AgNP) were employed as a sensing platform for aptasensor devices. The oxidation of silver upon polarization served as a basis for analytical response. Three different thrombin binding aptamers with various surface concentrations were studied. Linear range of aptasensor response corresponded to the 10 À9 M to 10 À7 M thrombin concentration range and the detection limit was 10 À9 M.

Fractal gold modified electrode for ultrasensitive thrombin detection

“…The detection limit of the proposed biosensor was 10-times lower than that of the reported one step label-free electrochemical thrombin sensor. [42][43][44][45] The fractal structure of the electrode surface not only improved the probe-binding capacity, but also magnified the response signals of the aptasensor. The enhanced performance was attributed to the large surface area, multi-directionality, high porosity and 3D nanostructure of the fractal surface.…”

Electrochemical Aptasensor Based on a Macrocyclic Ligand Bearing Neutral Red

“…Even though the aptamer used in the aptasensor assembly is specific to thrombin, the NR signal can be affected by other charged compounds that electrostatically accu- Ferrocene DC signal in sandwich immunoassay on Au nanorods doped with conducting polymer with DNA aptamer and anti-thrombin antibodies bearing ferrocene labels LOD 0.14 pM, 0.14-56 pM [17] DPV signal of ferrocene label after magnetic separation of thrombin complex with two aptamers attached to silica nanoparticles bearing ferrocene units and magnetic beads, respectively LOD 0.06 nM, 0.1-5 nM [18] Anodic current of dissolution of Ag nanoparticles bearing aptamer deposited onto screen-printed electrode LOD 1 nM, 1-100 nM [19] Redox activity of Au nanoparticles modified with aptamer via avidine-biotin binding in the presence of dissolved oxygen LOD 1 nM, 10 nM-10 mM [20] Anodic current of Pb dissolution after sandwich type binding of thrombin with the aptamer bearing Au followed by hybridization with DNA sequence labeled with Pb nanoparticles LOD 6.2 fM, 0.04-0.75 pM [21] Anodic DPV current of Au dissolution in displacement type assay of thrombin based on its interaction with aptamer -oligonucleotide duplex followed by magnetic separation of thrombin-DNA complex and determination of the DNA sequence labeled with Au nanoparticles LOD 0.66 pM, 1.5-45 pM [22] Changes in charge transfer resistance of PAMAM dendrimer layer with covalently linked aptamer molecules LOD 0.01 nM, 1-50 nM [27] Redox current of terminal MB label as a measure of binding-induced conformational changes of the DNA aptamer LOD 3 nM, detection up to 300 nM [34] Potentiometric detection of the potential shift of GCE covered with electropolymerized phenothiazine dyes and electrostatically accumulated aptamer 1 nM-1 mM (Methylene Green), 10-100 nM (Methylene Blue) [35] DPV signal of ferrocene label or changes in charge transfer resistance within self-assembled monolayer of thiolated aptamer LOD 0.5 nM, 5-225 nM [36] DC, DPV and square-wave voltammetry signal of ferrocene on polycrystalline Au electrode with self-assembled layer including ferrocene labeled aptamer…”

“…In many cases, electrochemically active labels are combined with nanosized materials which both increase the specific concentration of aptamers onto the surface and electrically wire the labels to the electrode. Until now, electroconductive nanoparticles were predominantly used for assembling such a biorecognition layer, e.g., colloidal gold [19][20][21][22], single- [23,24] and multiwalled [25,26] carbon nanotubes. To some extent, they also participate in the signal generation and improve the operational performance of the aptasensors due to a faster electron exchange and a lower working potential.…”

Aptasensors Based on Stripping Voltammetry

“…Several works on protein aptasensors based on stripping voltammetry have been reported [26,63,[70][71][72][73]. Usually only one type of nanoparticles, such as QDs, are used as labels for stripping voltammetric analysis of thrombin [73] but, compared with a single nanoparticle, nanocomposite materials can obviously achieve signal amplification.…”

“…Both of these two works utilized nanocomposite materials as signal amplification strategy. Additionally, Shumyantseva and his group developed two similar label-free stripping voltammetric analyses of thrombin, respectively using Au + stripping signals 2008 [71] and using Ag + stripping signals in 2010 [72]. As shown in Figure 4 [72], a screen-printed electrode (SPE) modified with AgNPs served as the sensing platform and the oxidation of AgNPs (Ag 0 → Ag + ) upon polarization (+100 mV) supplied the detection signals for the proposed aptasensor.…”