Electrochemical Aptasensor For Sensitive Detection Research Articles

New electrocatalyst of Ni6MnO8@AB/PtNPs with efficient synergistic enhancement in electrochemical aptasensor for sensitive detection of neuron specific enolase

As one of the specific markers for small cell lung cancer (SCLC), the clinical value for serum neuron-specific enolase (NSE) detection in diagnosis, monitoring and therapy of SCLC is considerable. Herein, a sensitive amperometric aptasensor was developed for the detection of NSE based on nickel-manganese oxide@acetylene black/platinum nanoparticles (Ni6MnO8@AB/PtNPs) composite as signal amplifier. The combination of Ni6MnO8, AB and PtNPs not only showed synergistically catalytic activity to hydrogen peroxide (H2O2), but also possessed lots of binding sites for loading the thiol-terminated signal probes (TSPs) through Pt-S bonds. Additionally, nitrogen-doped carbon nanotubes/poly (diallyldimethylammonium chloride)/ZnO microflowers (N-CNTs/P/ZnO MFs) exhibited outstanding electric conductivity and was used as substrate material to load more biotin-terminated capture probes (BCPs). In the presence of the NSE, the TSPs and BCPs specifically recognized the NSE to form a sandwich-type electrochemical aptasensor, which exhibited a broad linear response range from 0.00001 ∼ 100 ng mL−1 and a low detection limit of 2.86 fg mL−1 (S/N = 3). In addition, the electrochemical aptasensor obtained favorable detection results in diluted human serum, indicating that it had potential application in clinical NSE detection.

A ratiometric electrochemical aptasensor for sensitive detection of kanamycin in food based on entropy-driven strand displacement reaction

Kanamycin (KAN) has the potential to cause significant harm to human health, so the KAN residue present in food should be subject to strict regulation and control. Therefore, we constructed an enzyme-free ratiometric electrochemical aptasensor based on entropy-driven strand displacement reaction (ESDR) for sensitive detection of KAN in food. In the presence of KAN, it binds specifically to the aptamer, causing KAN-sensitive aptamer-tDNA (A-T) complex dissociation and the release of the tDNA, which triggers ESDR and results in an IFc/IMB maximum. In the absence of KAN, the release of the tDNA is not possible, leading to minimal IFc/IMB value. The aptasensor has a LOD of 74 fg/mL, enabling trace detection of KAN. In addition, the aptasensor demonstrated high specificity for KAN and remarkable reproducibility (RSD: 2.455%), which can be utilised for evaluating KAN concentrations in real samples. Moreover, the recovery rate of KAN in food samples ranged from 93.4% to 105.4%, suggesting that the ratiometric electrochemical aptasensor holds great potential in food safety detection.

Sandwich-type electrochemical aptasensor for sensitive detection of myoglobin based on Pt@CuCo-oxide nanoparticles as a signal marker

When an acute myocardial infarction (AMI) occurs, myoglobin (Mb) is the biomarker whose concentration firstly increases, and the high sensitive detection of Mb is critical for early diagnosis of AMI. Herein, a sandwich-type electrochemical aptasensor for the sensitive detection of Mb was constructed by using Pt@Cu1.33OCo0.83O as the signal marker. On one hand, nano-flower-like Cu1.33OCo0.83O was synthesized by hydrothermal method and Pt nanoparticles (Pt NPs) were loaded on its surface. Pt@Cu1.33OCo0.83O could immobilize aptamer 2 (Apt2) successfully by the Pt–S bond. And because of the synergistic effect between Pt and bimetallic oxide, Pt@Cu1.33OCo0.83O had an excellent catalytic effect on the signal source of hydrogen peroxide (H2O2) to amplify the current signal, which enhance the sensitivity of the aptasensor. On the other hand, the screen-printed gold electrode (SPGE) was used as the sensing base, which had good conductivity and ensured the immobilization of aptamer 1 (Apt1). The quantitative detection of Mb was achieved by specific recognition between Mb and Apt1, Apt2. As a result, the constructed electrochemical aptasensor had a good linear range (1–1500 ng/mL) with a low detection limit (LOD) of 0.128 ng/mL (S/N = 3), and a high sensitivity of 29.47 μA dec−1. The aptasensor also realized the detection of Mb in human serum samples with good accuracy, and the results were consistent with the hospital's biochemical indicators, which demonstrated the potential application of the prepared sensor in the clinical detection of Mb.

A ratiometric electrochemical aflatoxin B1 aptasensor based on DNA tetrahedral scaffold-corbelled 3D DNAzyme walker and AuNP/MOF/g-C3N4 hybrid electrode

Aflatoxin B1 (AFB1) has seriously threatened human health, so it is vital to construct an efficient detection strategy for AFB1 analysis. An exquisitely designed ratiometric electrochemical aptasensor for sensitive detection of AFB1 has been successfully developed in this work. DNA tetrahedral scaffold (DTS) is used to fix the DNA probes, 3D DNAzyme walker is employed to amplify the detection signals, and the composite material AuNP/ZIF-67/g-C3N4 acts as the sensing surface of the detection electrode. In the presence of AFB1, the 3D DNAzyme walker induced the release of the oligonucleotide attached ferrocene (Fc) from the detection electrode and is simultaneously grafted the DNA-modified methylene blue (MB) onto the electrode, leading to a seesaw-like ratiometric electrochemical aptasensor. This ratiometric electrochemical aptasensor provides an outstanding AFB1 analysis in the linear range of 2.0 fg·mL−1 to 1.0 ng·mL−1 with the limit of detection (LOD) 0.67 fg·mL−1. It provides new idea for the analysis of other contaminants in foodstuffs.

Octahedral Cu2O nanomaterials as electrochemical aptasensor for sensitive detection of tetracycline in milk

In this work, A novel label-free electrochemical biosensor based on octahedral Cu2O @ Au nanocomposites was developed for the detection of tetracycline. The gold nanoparticles (AuNPs) on the surface of Cu2O nanomaterials not only improve the electrochemical performance, but also can be used as a binding site for thiol-modified tetracycline aptamers, which can specifically bind to tetracycline. Cu2O @ Au nanocomposites provide a synergistic effect of electrochemical signal amplification and tetracycline recognition strategy. Under the optimal conditions, the proposed biosensor exhibited different electrochemical reactions for different concentrations of tetracycline, with a linear range of 1 nM-1000 μM and a detection limit of 0.16 nM. This work provides a new idea for rapid and sensitive detection of tetracycline by using a simple and economical tetracycline aptamer combined with Cu2O @ Au biosensor platform.

Label-Free Electrochemical Aptasensor for Sensitive Detection of Malachite Green Based on AuNPs/MWCNTs@TiO2 Nanocomposites

This study proposes a label-free aptamer biosensor for the sensitive detection of malachite green(MG) using gold nanoparticles/multi-walled carbon nanotubes @ titanium dioxide(AuNPs/MWCNTs@TiO2). The nanocomposite provides a large surface area and good electrical conductivity, improving current transfer and acting as a platform for aptamer immobilization. The aptamer and the complementary chain(cDNA) are paired by base complementary to form the recognition element and fixed on the AuNPs by sulfhydryl group, which was modified on the cDNA. Since DNA is negatively charged, the redox probe in the electrolyte is less exposed to the electrode surface under the repulsion of the negative charge, resulting in a low-electrical signal level. When MG is present, the aptamer is detached from the cDNA and binds to MG, the DNA on the electrode surface is reduced, and the rejection of the redox probe is weakened, which leads to an enhanced electrical signal and enables the detection of MG concentration by measuring the change in the electrical signal. Under the best experimental conditions, the sensor demonstrates a good linear relationship for the detection of MG from 0.01 to 1000 ng/mL, the limit of detection (LOD)is 8.68 pg/mL. This sensor is stable, specific, and reproducible, allowing for the detection of various small-molecule pollutants by changing the aptamer, providing an effective method for detecting small-molecule pollutants.

A signal-on electrochemical aptasensor for sensitive detection of human epididymis protein 4 based on functionalized metal–organic framework/ketjen black nanocomposite

A signal-on electrochemical aptasensor for sensitive detection of human epididymis protein 4 based on functionalized metal–organic framework/ketjen black nanocomposite

A label-free electrochemical aptasensor based on AuNPs-loaded zeolitic imidazolate framework-8 for sensitive determination of aflatoxin B1

In this study, an electrochemical aptasensor for sensitive detection of aflatoxin B1 (AFB1) was fabricated by electrodepositing gold nanoparticles (AuNPs) on the glass carbon electrode (GCE) modified with zeolitic imidazolate framework-8 (ZIF-8). The high specific surface area of AuNPs/ZIF-8 nanocomposite increased the aptamers loading on the electrode surface. When compared to other previously reported sensors, the developed aptasensor exhibited a wider linear range of 10.0 to 1.0 × 105 pg/mL with a lower limit of detection (LOD) of 1.82 pg/mL under the optimized conditions. Furthermore, the obtained results revealed that the constructed aptasensor exhibited outstanding selectivity, reproducibility and stability. Moreover, the aptasensor was successfully employed to detect the AFB1 in corn oil and peanut oil samples, with recoveries ranging from 93.49% to 106.9%, demonstrating the potential application value of this methodology.

Signal-on electrochemical aptasensor for sensitive detection of sulfamethazine based on carbon quantum dots/tungsten disulfide nanocomposites

In this paper, a novel electroactive material named as carbon quantum dots-tungsten disulfide nanocomposite (CQDs-WS2) was prepared via a facile self-assembly method. Based on CQDs-WS2 modified glassy carbon electrode (CQDs-WS2/GCE), a label-free electrochemical aptasensing strategy was proposed to sensitively determine sulfamethazine (SMZ). Cationic polyethyleneimine (PEI) were employed to form complexes with negatively charged SMZ-binding aptamers immobilized on CQDs-WS2/GCE by amidation reaction, which decreased the adsorption capacity of [Ru(NH3)6]3+ to aptamers. When SMZ existed, the change of aptamer conformation due to the formation of SMZ/aptamer complex would lead to decrease in adsorption amount of PEI. More adsorbed [Ru(NH3)6]3+ on aptamer can produce enhanced reduction current. On the basis of CQDs-WS2 as electroactive materials, aptamer as a recognition receptor, PEI as electrostatic adsorbent of aptamer, and [Ru(NH3)6]3+ as an electroactive indicator, a signal-on electrochemical aptasensor was constructed for detection of SMZ with high sensitivity. The SMZ aptasensor displayed wide linear response in the 10 pM to 1.0 µM concentration range and a low detection limit of 4.0 pM. The method can be applied to quantitation analysis of antibiotic residue in food and environmental samples.

Electrochemical aptasensor for sensitive detection of Cardiac troponin I based on CuNWs/MoS2/rGO nanocomposite

Cardiac troponin I (cTnI) is a “gold standard biomarker” for clinical diagnose of acute myocardial infarction (AMI). Rapid, accurate, and sensitive detection methods for cTnI are highly urgent and significant in early diagnosis and progression control. In this work, we proposed an electrochemical aptasensing platform for cTnI detection based on copper nanowires/molybdenum disulfide/reduced graphene oxide (CuNWs/MoS2/rGO) ternary nanostructure. The CuNWs/MoS2/rGO composite exhibited improved electrochemical activity due to the high electrochemical conductivity and the synergistic effect among each component, and the large surface area, which also facilitates the immobilization of aptamers. As a result, the constructed electrochemical cTnI aptasensor shows good selectivity, stability, and reproducibility towards cTnI. Under optimized conditions, the aptasensor responses cTnI linearly from 5.0 × 10−13 to 1.0 × 10−10 g mL−1 with a detection limit of 1.0 × 10−13 g mL−1 (S/N = 3). The analysis of cTnI in human blood samples demonstrated its practicability with comparable results. This work offers an alternative way for facile fabrication of CuNWs/MoS2/rGO based aptasensor for clinical biomarker detection.

A Multifunctional N-Doped Cu-MOFs (N-Cu-MOF) Nanomaterial-Driven Electrochemical Aptasensor for Sensitive Detection of Deoxynivalenol.

Deoxynivalenol (DON) is one of the most common mycotoxins in grains, causing gastrointestinal inflammation, neurotoxicity, hepatotoxicity and embryotoxicity, even at a low quantity. In this study, a facile electrochemical aptasensor was established for the rapid and sensitive determination of DON based on a multifunctional N-doped Cu-metallic organic framework (N–Cu–MOF) nanomaterial. The N–Cu–MOF, with a large specific surface area and good electrical conductivity, served not only as an optimal electrical signal probe but also as an effective supporting substrate for stabilizing aptamers through the interactions of amino (-NH2) and copper. Under the optimal conditions, the proposed sensor provided a wide linear concentration range of 0.02–20 ng mL−1 (R2 = 0.994), showing high sensitivity, with a lower detection limit of 0.008 ng mL−1, and good selectivity. The sensor’s effectiveness was also verified in real spiked wheat samples with satisfactory recoveries of 95.6–105.9%. The current work provides a flexible approach for the rapid and sensitive analysis of highly toxic DON in food samples and may also be easily extended to detect other hazardous substances with alternative target-recognition aptamers.

A Dual-Amplification Electrochemical Aptasensor for Profenofos Detection

The present study reported a dual-amplification electrochemical aptasensor for sensitive detection of profenofos (PFF) in vegetables. A screen-printed carbon electrode (SPCE) modified with graphitized multi-walled carbon nanotubes (MWCNTGr) and Au nanoshell was used as a test platform, which ensured a rapid detection process and showed a favorable electrochemical performance. MWCNTGr and Au nanoshell enhanced the electrical conductivity and the surface area, thus the detection signal was amplified. The affinity between PFF and its aptamer (Apt) was verified firstly by dot blot hybridization (DBH), and the result was exciting. Furthermore, the effects of the aptamers modified respectively with -NH2 and -SH on the current signal were compared with each other by cyclic voltammetry (CV), and results showed that the aptamers modified with -NH2 made the current signal change more obvious. Based on all above, a high-efficiency electrochemical aptasensor was fabricated with a wide linear range from 0.1–1 × 105 ng · ml−1 and a detection limit of 0.052 ng · ml−1 under the optimized conditions. This aptasensor had great specificity, stability and reproducibility. Hence, the developed aptasensor was successfully used to detect PFF in vegetables. The proposed method also has a potential for the detection of other organophosphorus pesticide (OPs).

Application of metal-organic framework as redox probe in an electrochemical aptasensor for sensitive detection of MUC1

In this work, an electrochemical aptasensor was developed for sensitive detection of MUC1 based on metal-organic framework-reduced graphene oxide nanocomposite (Cu-MOF-RGO). Cu- MOF-RGO appeared to be suitable as a platform for immobilization of MUC1 aptamer, and also as an electrochemical probe, which exhibited well-defined peaks with good stability and reproducibility. Cu-MOF-graphene oxide (Cu-MOF-GO) nanocomposite was prepared and cast on the electrode surface, then in order to increase the conductivity of the electrode, GO was electrochemically reduced to RGO. In the presence of MUC1, the peak current of Cu in the nanocomposite decreased, which could be explained based on the formation of MUC1–aptamer complexes on the electrode, and consequence blocking the electron transfer of Cu at the electrode surface. Under optimum experimental conditions, a linear calibration curve was obtained by differential pulse voltammetry in the concentration range of 0.1 pM–10 nM (25 pg mL−1 – 2500 ng mL−1) with a limit of detection (LOD) of 0.033 pM (7.5 pg mL−1) of MUC1. The proposed aptasensor offers acceptable selectivity, stability, and reproducibility in the determination of MUC1 spiked to human blood serum samples.

Label-Free Electrochemical Aptasensor for Sensitive Detection of Malachite Green Based on Au Nanoparticle/Graphene Quantum Dots/Tungsten Disulfide Nanocomposites.

A label-free electrochemical aptasensor was fabricated to sensitively determine malachite green (MG) based on Au nanoparticles/graphene quantum dots-tungsten disulfide nanosheet composite film modified glassy carbon electrode (AuNPs/GQDs-WS2/GCE). A facial strategy for the self-assembly of graphene quantum dots (GQDs) on tungsten disulfide nanosheets (WS2) was developed to fabricate 0D/2D nanocomposites. As-prepared GQDs-WS2 hybrids exhibited significantly enhanced electrocatalytic properties, and were first used as electroactive materials to construct electrochemical aptasensor. The AuNPs/GQDs-WS2/GCE was prepared through depositing Au nanoparticles on the surface of the GQDs-WS2 film, which acted as the electrochemical sensing matrix to covalently immobilize the aptamers of MG via the Au–S bond. In this label-free proposal, the aptasensor was applied to detect MG by monitoring voltammetric signal resulted from electrochemical oxidation of the MG captured by the aptamer. Under the optimized conditions, the aptasensor showed a wide linear range from 0.01 to 10 μM for MG detection with a low detection limit of 3.38 nM (S/N = 3). The method was applied to determination of MG in spiked fish samples and gave satisfactory results.

A nano-sized chitosan particle based electrochemical aptasensor for sensitive detection ofP. aeruginosa

In this research, a glassy carbon electrode (GCE) was modified with nano-sized chitosan particles (NCs) by the drop-casting method for ultrasensitive detection ofPseudomonas aeruginosa(P. aeruginosa).

A nanoporous gold-based electrochemical aptasensor for sensitive detection of cocaine.

The increasing application of aptamers in bioassays has triggered a lot of research interest for development of highly sensitive and selective sensing platforms. Herein, we report on the design of a sensitive cocaine biosensor by immobilizing the 5′-disulfide-functionalized end of an aptamer sequence on a nanoporous gold (NPG) electrode followed by the conjugation of its 3′-amino-functionalized end to 2,5-dihydroxybenzoic acid (DHBA) as the redox probe. In the presence of cocaine, the aptamer undergoes a conformational change from an open unfolded state to a closed conformation, which reduces the distance between DHBA and the electrode surface, resulting in the enhanced electron-transfer efficiency. Using square wave voltammetric method and under the optimal conditions, the cocaine aptasensor presented two linear responses in the concentration ranges between 0.05–1 and 1–35 μM, with an excellent detection limit of 21 nM. The proposed aptasensor provides a simple and low-cost method for cocaine detection with good reproducibility and accuracy. Furthermore, it could be regarded as a general model to investigate the unique function of aptamer-functionalized nanostructured electrodes to stablish highly advanced electrochemical biosensors for various target analytes of diagnostic importance.

A novel electrochemical aptasensor for sensitive detection of streptomycin based on gold nanoparticle-functionalized magnetic multi-walled carbon nanotubes and nanoporous PtTi alloy

A facile electrochemical aptasensor based on a novel signal amplification strategy was employed for sensitive and selective detection of streptomycin for the first time. The aptasensor was prepared by sequentially dripping a gold nanoparticle-functionalized magnetic multi-walled carbon nanotube (Au@MWCNTs–Fe3O4) composite and nanoporous PtTi (NP-PtTi) alloy onto a glassy carbon electrode (GCE) surface. The NP-PtTi alloy with a uniform nanoporous structure was successfully fabricated by selectively de-alloying Al from a PtTiAl alloy in HCl solution. The results demonstrated that the Au@MWCNTs–Fe3O4/NP-PtTi composite not only showed a remarkable synergistic effect towards the aptasensor, but also provided a beneficial immobilization platform for the streptomycin aptamer carrier. Under optimal conditions, a wide linear range from 0.05 to 100 ng mL−1 and a detection limit of 7.8 pg mL−1 were obtained. The designed aptasensor showed an excellent analytical performance with good reproducibility, high selectivity and stability. Finally, the proposed aptasensor was successfully used for the detection of streptomycin in a real sample.

A Sensitive Electrochemical Aptasensor for TNF-α Based on Bimetallic Ag@Pt Core-Shell Nanoparticle Functionalized Graphene Nanostructures as Labels for Signal Amplification

A practical and novel enzyme-free sandwich-type electrochemical aptasensor for sensitive detection of protein biomarker tumor necrosis factor-alpha (TNF-α) was designed by using bimetallic Ag@Pt core-shell nanoparticles functionalized graphene nanosheets (Ag@Pt-GRs) as novel desirable labels for signal amplification and Au nanoparticles functionalized graphene/chitosan (Au-GRs/CS) nanocomposite as sensing platform. The results showed that Ag@Pt-GRs nanocomposite exhibited attractive electrocatalytic activity without any enzyme toward the oxidation of catechol as analytical signal and also yielded large surface area, which improve the amount of immobilized aptamer and leading to the formation of Ag@Pt-GRs/apt bioconjugate. The aptasensor was constructed by modifying screen-printed electrodes with Au-GRs/CS nanocomposite which could provide a large electroconductive surface area to immobilize a large amount of aptamers, resulting in significant improvement in the sensitivity of aptasensor. The proposed electrochemical aptasensor showed a dynamic range from 5.0 pg/mL to 70 pg/mL with a low detection limit of 1.64 pg/mL for TNF-α. The analytical usefulness of the aptasensor was finally demonstrated analyzing serum samples. The main advantages of this aptasensor are the simple fabrication method, high sensitivity, specificity, good reproducibility and stability as well as acceptable accuracy for TNF-α detection in human serum, which might have broad applications in protein detection and disease diagnosis.

A label-free and sensitive electrochemical aptasensor for thrombin based on the direct electron transfer of hemin and hemin@rGO nanosheets as the signal probe

In this work, a label-free electrochemical aptasensor for sensitive detection of thrombin was fabricated and characterized.

A sensitive electrochemical aptasensor for ATP detection based on exonuclease III-assisted signal amplification strategy

A target-induced structure-switching electrochemical aptasensor for sensitive detection of ATP was successfully constructed which was based on exonuclease III-catalyzed target recycling for signal amplification. With the existence of ATP, methylene blue (MB) labeled hairpin DNA formed G-quadruplex with ATP, which led to conformational changes of the hairpin DNA and created catalytic cleavage sites for exonuclease III (Exo III). Then the structure-switching DNA hybridized with capture DNA which made MB close to electrode surface. Meanwhile, Exo III selectively digested aptamer from its 3′-end, thus G-quadruplex structure was destroyed and ATP was released for target recycling. The Exo III-assisted target recycling amplified electrochemical signal significantly. Fluorescence experiment was performed to confirm the structure-switching process of the hairpin DNA. In fluorescence experiment, AuNPs–aptamer conjugates were synthesized, AuNPs quenched fluorescence of MB, the target-induced structure-switching made Exo III digested aptamer, which restored fluorescence. Under optimized conditions, the proposed aptasensor showed a linear range of 0.1–20nM with a detection limit of 34pM. In addition, the proposed aptasensor had good stability and selectivity, offered promising choice for the detection of other small molecules.