Label-free Electrochemical Aptasensor Research Articles

A label-free electrochemical aptasensor for low-density lipoprotein detection using MoS2-Au-Fc nanosheets as a high-performance redox indicator

Low-density lipoprotein (LDL) is a key biomarker involved in cardiovascular disease (CVD) risk assessment. Early-stage diagnosis of CVD complications by monitoring LDL levels could be a significant clinical tool and the first step toward adopting efficient therapy. Herein, a novel label-free electrochemical aptasensor for LDL detection was developed via the molybdenum disulfide-gold nanoparticle- ferrocene-carboxylic acid nanosheets (MoS2-Au-Fc NSs) enhanced signal amplification strategy. The MoS2-Au-Fc NSs were used not only as the biocompatible substrate for LDL aptamer (LDLapt) stabilization due to the increasing electrical conductivity and effective surface area, but also as a redox probe for monitoring the changes of the electrochemical signal because of good electroactive properties of Fc. The aptasensor fabrication steps were investigated by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). When LDL was captured onto the sensor via the specific affinity of the LDLapt, the formed LDLapt-LDL complexes shed from the electrode and enhanced the electron transfer rate on the electrode surface, resulting in an increase of the peak current. Thus, LDL can be easily detected by measuring the changes of peak current. Under ideal circumstances, the aptasensor was linearly correlated with logarithm LDL concentration from 0.001 to 100.0 μg/mL with R2 of 0.9914, and a low detection limit of 0.42 ng/mL. Furthermore, the LDL detected by aptasensor in actual serum samples with good actual errors (0.73%–5.00%) and satisfactory relative standard deviations (RSDs) (0.04%–0.84%). This study provides a new analytical method for measuring the level of LDL which is specifically up-regulated in CVD patients at an early stage.

Immobilization-free electrochemical homogeneous aptasensor for highly sensitive detection of carcinoembryonic antigen by dual amplification strategy

Electrochemical aptasensor has been widely studied, while its practical application is limited by the unavoidable variations of aptamer loading densities and low signal amplification efficiency. To overcome these restrictions, an immobilization-free and label-free electrochemical homogeneous aptasensor was constructed for carcinoembryonic antigen (CEA) assay by combining RecJf exonuclease-mediated target cycling strategy and rolling circle amplification technology. In this system, the pre-immobilization of aptamers or other relevant signal elements on the electrode substrate is no longer necessary, thus the electrochemical homogeneous aptasensor shows good versatility on different transducers. Moreover, the whole recognition and signal amplification process are activated instantaneously by a non-professional operation of the solution mixture. This strategy can not only increase the stability (95.1% after 30 days of storage) and reproducibility (2.12% among five independent electrodes), but also further improve the sensitivity (detection limit of fg mL−1 level) due to the free target recognition and dual signal amplification in the homogeneous solution phase. The proposed immobilization-free electrochemical homogeneous aptasensors on different electrode substrates both achieve satisfactory results in actual sample tests, which has the potential for commercial applications and the establishment of other target platforms in the future.

Designing a label-free electrochemical aptasensor based on polypyrrole-l-cysteine-reduced graphene oxide nanocomposite for detection of 25-hydroxyvitamin D3.

Reliable and precise quantification of 25-hydroxyvitamin D3 in clinical samples is vital because vitamin D3 deficiency lead to several disorders, such as mental illness, osteoporosis, and coronavirus disease. Herein, we report the fabrication of a novel electrochemical aptasensor using a nanocomposite, including reduced graphene oxide, pyrrole, and l-cysteine, for the sensitive detection of 25-hydroxyvitamin D3 . Subsequently, the aptamer of 25-hydroxyvitamin D3 was immobilized on the surface of the modified electrode. Differential pulse voltammetry signals were utilized for studying the binding and measurement of 25-hydroxyvitamin D3 based on the oxidation peak. Under the optimum conditions, the designed electrochemical aptasensor exhibited a linear detection range of 0.001-150nM, with a limit of detection of 0.006nM. Furthermore, the proposed aptasensor selectively detected 25-hydroxyvitamin D3 compared to other analogs. Moreover, this aptasensor was successfully applied for the detection of 25-hydroxyvitamin D3 in human serum samples, which were quantified by the enzyme-linked immunosorbent assay method. The acceptable recoveries of 82.67%-111.07% demonstrated that this proposed electrochemical aptasensor can be a promising alternative for clinical methods of vitamin D determination.

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.

Label-Free Electrochemical Aptasensor Based on the Vertically-Aligned Mesoporous Silica Films for Determination of Aflatoxin B1.

Herein we report a highly specific electrochemical aptasenseor for AFB1 determination based on AFB1-controlled diffusion of redox probe (Ru(NH3)63+) through nanochannels of AFB1-specific aptamer functionalized VMSF. A high density of silanol groups on the inner surface confers VMSF with cationic permselectivity, enabling electrostatic preconcentration of Ru(NH3)63+ and producing amplified electrochemical signals. Upon the addition of AFB1, the specific interaction between the aptamer and AFB1 occurs and generates steric hindrance effect on the access of Ru(NH3)63+, finally resulting in the reduced electrochemical responses and allowing the quantitative determination of AFB1. The proposed electrochemical aptasensor shows excellent detection performance in the range of 3 pg/mL to 3 μg/mL with a low detection limit of 2.3 pg/mL for AFB1 detection. Practical analysis of AFB1 in peanut and corn samples is also accomplished with satisfactory results by our fabricated electrochemical aptasensor.

Label-free electrochemical aptasensor for ultrasensitive thrombin detection using graphene nanoplatelets and carbon nano onion-based nanocomposite

Thrombin (TB) is a protease enzyme functioning in the blood coagulation cascade. It plays an important function in a number of diseases, including thromboembolic disease, Alzheimer's disease, and cancer.Therefore, precise, and sensitive detection of TB in clinical samples is of utmost importance. In this work, we have first synthesized a nanocomposite comprised of carboxyl-functionalized graphene nanoplatelets (GNPs), carbon nano-onions (CNOs), and chitosan (CS), which was used to develop an electrochemical aptasensor for selective detection of TB. This nanocomposite modified GCE exhibited a remarkable electrochemical response and a greater surface area (216 %) than the bare GCE. The morphology of the nanomaterials and nanocomposite were characterized using FESEM, TEM, and Energy-Dispersive X-ray Spectroscopy (EDS). The Layer-by-layer fabrication of the aptasensor was studied using the CV and DPV in Fe[CN]6]3/4− redox probeat pH 7.4. The designed aptasensor displayed sensitive detection of TB from 26.74 pM to 26.74 fM with a LOD of 8.61fM. Finally, this aptasensor showed promising potential in the quantitative determination of TB in human serum. This proposed aptasensor displayed excellent sensitivity, high specificity, and satisfactory reproducibility and can be useful in biomedical applications as well as for clinical purposes.

Label-free electrochemical aptasensor based on gold nanoparticles/titanium carbide MXene for lead detection with its reduction peak as index signal

Label-free electrochemical aptasensor based on gold nanoparticles/titanium carbide MXene for lead detection with its reduction peak as index signal

DNAzyme-driven tripedal DNA walker triggered hybridization chain reaction for label-free electrochemical detection of Alzheimer’s tau protein

The tau protein is considered to be a reliable molecular biomarker of Alzheimer's disease (AD). Developing sensitive and reliable techniques for tau protein detection is a vital task. In this work, we designed a label-free electrochemical aptasensor for tau protein quantification based on Mg2+-DNAzyme (MNAzyme)-driven tripedal DNA walker. With the assistance of MNAzyme, free-running tripedal DNA walkers could rapidly and continually scissor DNA molecular beacon (MBs), and the fragment as a primer initiated the hybridization chain reaction (HCR) process generating a huge amount of long DNA strand containing many adenines. Following that, the strand with long-repeated adenines (HCR product) may absorb numerous AgNPs on the surface of electrode for electrochemical stripping analysis. Benefiting from MNAzyme-tripedal DNA walker and HCR triple signal amplification, we achieved a superior detection limit of 0.43 fM as well as a broad linear range of 1 fM to 0.1 nM. After being applied to tau protein detection in human serum samples, this novel electrochemical aptasensor demonstrated a high degree of anti-interference, and reproducibility, indicating its great potential for bioanalysis in complex biological environments.

A Label-Free Electrochemical Aptasensor Based on Screen Printed Carbon Electrodes With Gold Nanoparticles-Polypyrrole Composite for Detection of Cardiac Troponin I

Cardiac troponin I (cTnI) is a specific biomarker in the diagnosis of acute myocardial infarction (AMI). In this study, a label-free electrochemical aptasensor was developed for the detection of cTnI using an aptamer probe and conductive polypyrrole (PPy)-gold nanoparticles (AuNPs) as electrode substrate. The surface modification of the electrode was characterized by cyclic voltammetry (CV) and square wave voltammetry (SWV) electrochemical methods, scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy-dispersive X-ray spectroscopy (EDX) analysis. SWV was also used to evaluate the analytical performance of the developed aptasensor using 5 mM [Fe(CN)6]3-/4- as a redox mediator. A detection limit of 25 pg mL−1 was obtained with a linear detection range from 50 to 500 pg mL−1. The proposed aptasensor exhibited good selectivity and appropriate sensitivity for clinical diagnostics compared with enzyme-linked immunosorbent assay (ELISA) analysis, allowing rapid, quantitative, and label-free detection of cardiac markers.

Fabrication of a Novel and Ultrasensitive Label-Free Electrochemical Aptasensor Based on Gold Nanostructure for Detection of Homocysteine

The current attempt was made to detect the amino acid homocysteine (HMC) using an electrochemical aptasensor. A high-specificity HMC aptamer was used to fabricate an Au nanostructured/carbon paste electrode (Au-NS/CPE). HMC at high blood concentration (hyperhomocysteinemia) can be associated with endothelial cell damage leading to blood vessel inflammation, thereby possibly resulting in atherogenesis leading to ischemic damage. Our proposed protocol was to selectively immobilize the aptamer on the gate electrode with a high affinity to the HMC. The absence of a clear alteration in the current due to common interferants (methionine (Met) and cysteine (Cys)) indicated the high specificity of the sensor. The aptasensor was successful in sensing HMC ranging between 0.1 and 30 μM, with a narrow limit of detection (LOD) as low as 0.03 μM.

Selective Label-Free Electrochemical Aptasensor Based on Carbon Nanotubes for Carbendazim Detection

One of the most widely used pesticides in Chile is carbendazim (CBZ), which in agriculture is used to protect crops from fungal diseases that commonly occur in rice, vegetable, and fruit crops. However, prolonged exposure to it, and its high persistence, can cause adverse health effects. Therefore, it is necessary to determine the presence of CBZ through rapid detection methods in food samples to prevent ingestion and exposure to this pesticide at risk concentrations. In this work, a label-free electrochemical aptasensor based on functionalized carbon nanotubes was prepared for CBZ detection. The carbodiimide reaction between the amino-terminated aptamer and the carboxylic groups of carbon nanotubes achieved the covalent immobilization of the aptamer. The immobilized aptamer changed its conformation when it detected CBZ and blocked access to the redox mediator on the electrode surface, resulting in a measurable decrease in the voltammetric response. Under the optimal conditions, the aptasensor featured a linear detection range between 1.0 and 50.0 nM, with a detection limit of 4.35 nM. Moreover, the aptasensor exhibited good selectivity for CBZ, among other pesticides, and good repeatability. For CBZ detection in tomatoes, the aptasensor accurately measured CBZ content in a sample prepared using the standard addition method. This work provides a simple, rapid, sensitive, and selective biosensor for CBZ detection and quantification in food samples.

MOF-Derived Ni-P Bundle-Like Nanorods as High-Performance Substrate for Design of Electrochemical Aptasensor Toward Cortisol Detection

The preparation of hierarchical nanostructures based on metal–organic frameworks (MOFs)-derived transition-metal phosphides (TMPs) have received much attention due to its attractive properties in the application of electrochemical sensors. In this research, a label-free and ultrasensitive electrochemical aptasensor for cortisol detection using MOF-derived Ni-P bundle-like nanorods (Ni-P) was presented as an efficient substrate for loading aptamer strings. Ni-MOF was synthesized using a facile hydrothermal method and, then, the Ni-P was obtained using a simple phosphorization of Ni-MOF precursor in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{N}_{{2}}$ </tex-math></inline-formula> atmosphere; it was found that it is made of bundle-like nanorods. The designed aptasensor showed a wide linear sensing range between charge transfer resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R}_{\text {ct}}{)}$ </tex-math></inline-formula> and increasing cortisol concentration in the range of 0.1 fM–700 nM with a low detection limit of 10 aM. It is noteworthy that the efficiency of the aptasensor designed by real urine sample was evaluated and the results were compared with the standard enzyme-linked immunosorbent assay (ELISA) method and acceptable results were obtained.

A label-free electrochemical aptasensor based on Bi-Sb alloy materials for potential POCT of HER-2.

As a prognostic biomarker for breast cancer, human epidermal growth factor receptor 2 (HER-2) is of crucial diagnostic value. Here, a label-free electrochemical aptasensor was established for the ultrasensitive detection of HER-2 using a modified electrode of Bi-Sb alloy materials (Bi-Sb AMs). The performance of the aptasensor was enhanced greatly due to the introduction of Bi-Sb alloy materials (Bi-Sb AMs) with high conductivity. Furthermore, by integrating the aptasensor with the Sensit Smart U-disk electrochemical analyzer, the point-of-care testing (POCT) for HER-2 was realized. Under the optimal experimental parameters, the POCT analyzer showed a wide linear response from 0.01 pg mL-1 to 100 ng mL-1, with a low detection limit (LOD) of 5.96 fg mL-1 for the detection of HER-2. The presented POCT analyzer exhibited good specificity, stability, and reproducibility. Benefiting from the simple operation and rapid testing, the developed analyzer will have potential application in the prognostic diagnosis and treatment of breast cancer.

Design of a label-free aptasensor for electrochemical determination of hemoglobin: investigation of the peroxidase-like activity of hemoglobin for the sensing of different substrates.

The unbalanced hemoglobin level in biological fluids can cause several diseases; hence it can be used as a biomarker for diagnosis. We aim, in the present study, to construct a label-free electrochemical aptasensor for the quantification of hemoglobin. For that, a conjugate of L-cysteine and gold nanoparticles was used for the aptamer immobilization on screen printed carbon electrodes. Using square wave voltammetry, the calibration plot was obtained and it was linear in the range of 50 ng ml-1 to 36 000 ng ml-1 while the detection limit was 1.2 ng ml-1. After the binding of Hb on the modified screen-printed carbon electrode surface, the peroxidase-like activity of the bound hemoglobin was explored in the quantification of different substrates. Hydrogen peroxide and nitrite were chosen as model analytes. Amperometric measurements showed wide linear ranges: 0.2 μM-7.7 mM and 3.6 nM-1.3 mM for H2O2 and nitrite, respectively, with detection limits of 0.044 μM and 0.55 nM. In the proposed strategy, the aptamer provides excellent orientation and a biocompatible environment for hemoglobin whose catalytic activity plays a key role in H2O2 and nitrite analysis.

A homogeneous label-free electrochemical aptasensor based on an omega-like DNA nanostructure for progesterone detection.

A novel homogeneous label-free electrochemical aptamer sensor for the detection of progesterone was prepared by combining a well-designed omega (Ω)-like DNA (Ω-DNA) nanostructure, with an isothermal cycling amplification strategy based on the highly efficient exonuclease III (Exo III). The omega-like (Ω) DNA is composed of two oligonucleotide strands: DNA1 and DNA2. The Pro aptamer triggers a chain displacement reaction of Ω-DNA nanostructures, forms a new double-stranded DNA structure (aptamer precursor-DNA2), and releases DNA1. Then, Exo III selectively cleaves the DNA duplex and releases the Pro aptamer to participate in a new displacement reaction. Meanwhile, the released DNA1 strands gain access to the strongly bound hemin, forming a hemin/G-quadruplex (DNAzyme). In the presence of hydrogen peroxide (H2O2), differential pulse voltammetry (DPV) was used to detect the current signal from the oxidation of o-phenylenediamine (OPD) to aminoazobenzene (DAP) catalyzed by DNAzyme. However, the amount of released DNA1 from the Ω-DNA nanostructures is reduced in the presence of the target Pro, and the DPV signal declines because of the small amount of DNAzyme formed. The developed electrochemical aptasensor has a wide dynamic linear relationship in the range of 1 pg mL-1 to 10 ng mL-1 under optimal conditions. Its detection limit is down to 0.3 pg mL-1, providing a potential platform for a sensitive Pro assay among electrochemical assays.

DNAzyme-driven tripedal DNA walker mediated signal-on and label-free for electrochemical detection of α-synuclein oligomers

In the case of Parkinson’s disease (PD), the soluble α-synuclein (α-syn) oligomer is considered to be a reliable molecular biomarker. Developing easy-to-prepare, cheap, sensitive, and reliable techniques for the detection of α-synuclein oligomers is therefore a vital task. In this work, based on Mg2+-dependent DNAzyme (MNAzyme) -driven tripedal DNA walker tactics, we designed an innovative label-free and signal-on electrochemical aptasensor for α-syn oligomer quantification. α-syn oligomer-triggered tripedal DNA walkers outperformed common DNA walkers with the larger area of walking and accelerated walking kinetics, and facilitated greater amplification efficiency. With the assistance of MNAzyme, free-running tripedal DNA walkers could rapidly and continually scissor DNA hairpins (HPs), thereby unlocking numerous active G-quadruplex-forming sequences. Afterwards, G-quadruplex/hemin complexes could be formed by hemin further recognizing these G-quadruplexes and generated an enhanced current signal. Benefiting from tripedal DNA walker and MNAzyme dual signal amplification, we achieved a superior detection limit of 0.46 fM as well as a broad linear range of 1 fM to 10 pM. After being applied to α-syn oligomer detection in human serum samples, this novel electrochemical aptasensor demonstrated a high degree of sensitivity, anti-interference, and reproducibility, indicating its great potential for bioanalysis in complex biological environments.

Conformational switching of aptamer biointerfacing graphene-gold nanohybrid for ultrasensitive label-free sensing of cardiac Troponin I

The development of hybrid biofunctionalized nanomaterials has emerged as an attractive substitute for development of advanced biosensing platforms with superior synergistic properties. Herein, we report a label-free ultrasensitive electrochemical aptasensor comprising nanohybrid of graphene oxide (GO) and aptamer conjugated gold nanoparticles (GNP-A) for detection of cardiac biomarker Troponin I (TnI). The GNP-A are homogenously arranged by self-assembly on GO sheet to construct nanohybrid (GO@GNP-A) onto which the biomarker protein is analysed. TnI interactions at the aptamer biointerfaced nanohybrid surface causes electrochemical signal enhancement probed by using a redox active molecule. The consecutive increase in current signal is strongly attributed to conformational switching of aptamer and charge neutralization at the interface induced by TnI binding. The sensitivity of the nanohybrid aptasensor platform was found to be 0.001 pg/mL. The study has been further substantiated in Acute Myocardial Infarction (AMI) clinical samples for usage towards early, sensitive and efficient point-of-care detection of TnI.

A Label-Free Electrochemical Aptasensor Based on a Truncated Aptamer for the Detection of Progesterone

This study built an electrochemical label-free progesterone aptasensor to detect progesterone (P4) levels in environmental water samples. The truncated aptamer-modified sulfhydryl adopted self-assembly as a way to stably immobilize at the electrode surface modified by gold nanoparticles (AuNPs). When progesterone combines with the aptamer, the complexes will inhibit electrode surface electron transfer, which reduces the redox peak current value of [Fe(CN)6]3−/4−. As a result, the amount of progesterone combined with the aptamer on the electrode reacted to the electric current’s response values. We have established the relationship between the concentration of progesterone and the current change by a standard curve that is ΔI (μA) = 11.78log CP4 (nM)+48.98. The coefficient of association was 0.9358. The test ranges were from 0.5 nM to 1000 nM. At the same time, other molecules with a similar structure, such as testosterone, estradiol, and 17α-hydroxyl progesterone, had lower response interference than P4. In conclusion, the aptasensor, which had outstanding repeatability and stability, could be applied to determine P4. Food hygiene and clinical diagnosis can be made easier with this newly developed electrochemical biosensor based on aptamers.

Label-free electrochemical aptasensor for the detection of SARS-CoV-2 spike protein based on carbon cloth sputtered gold nanoparticles

The proliferation and transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), or the (COVID-19) disease, has become a threat to worldwide biosecurity. Therefore, early diagnosis of COVID-19 is crucial to combat the ongoing infection spread. In this study we propose a flexible aptamer-based electrochemical sensor for the rapid, label-free detection of SARS-CoV-2 spike protein (SP). A platform made of a porous and flexible carbon cloth, coated with gold nanoparticles, to increase the conductivity and electrochemical performance of the material, was assembled with a thiol functionalized DNA aptamer via S–Au bonds, for the selective recognition of the SARS-CoV-2 SP. The various steps for the sensor preparation were followed by using scanning electron microscopy, cyclic voltammetry and differential pulse voltammetry (DPV). The proposed platform displayed good mechanical stability, revealing negligible changes on voltammetric responses to bending at various angles. Quantification of SARS-CoV-2 SP was performed by DPV and chronopotentiometry (CP), exploiting the changes of the electrical signals due the [Fe(CN)6]3-/4- redox probe, when SARS-CoV-2 SP binds to the aptamer immobilized on the electrode surface. Current density, in DPV, and square root of the transition time, in CP, varied linearly with the log[ SARS-CoV-2 SP], providing lower limits of detection (LOD) of 0.11 ng/mL and 37.8 ng/mL, respectively. The sensor displayed good selectivity, repeatability, and was tested in diluted human saliva, spiked with different SARS-CoV-2 SP concentrations, providing LODs of 0.167 ng/mL and 46.2 ng/mL for DPV and CP, respectively.

Development of a Nafion-MWCNTs and in-situ generated Au nanopopcorns dual-amplification electrochemical aptasensor for ultrasensitive detection of OTA

Trace detection of ochratoxin A (OTA) in foods is essential to mitigate risks to human health. Herein, a label-free electrochemical (EC) aptasensor based on dual-signal amplification of Nafion dispersed multi-walled carbon nanotubes (Nafion-MWCNTs) and Au nanopopcorns was developed for ultrasensitive detection of OTA. Nafion solution prevented the leaching of MWCNTs, and the Nafion-MWCNTs modified screen-printed carbon electrode (SPCE) acted as the sensing substrate which facilitated the uniform distribution of the electrodeposited Au nanopopcorns. The in-situ generated Au nanopopcorns could not only load a large amount of aptamers for specific identification of OTA, but also promote the electron transfer of the sensing platform. The incorporation of Nafion-MWCNTs and Au nanopopcorns realized dual-amplification of the aptasensor due to the enhanced conductivity and the increased electroactive surface area of the electrode. The modified electrodes were characterized through scanning electron microscopy, X-ray photoelectron spectroscopy and EC evaluation. Under optimal conditions, the electrochemical impedance spectroscopy (EIS) was measured for the determination of OTA. The as-fabricated Au nanopopcorns/Nafion-MWCNTs impedimetric aptasensor displayed excellent sensitivity with a detection limit as low as 1 pg/mL and a wide linear range of 1 pg/mL-10 ng/mL for OTA. Practical application of the aptasensor in the spiked malt samples achieved satisfactory recoveries of 89.82–95.65 %, which was also successfully verified to detect OTA in eleven batches of actual malt samples collected from the local market. The creative aptasensor is simple, cost-effective, sensitive, and accurate, showing great promise for on-site monitoring of other trace contaminants in foods by simply replacing the aptamers.