Electroactive Surfaces Research Articles

Electrocatalytic Conversion of CO2 to Formic Acid: A Journey from 3d-Transition Metal-Based Molecular Catalyst Design to Electrolyzer Assembly.

ConspectusElectrochemical CO2 reduction to obtain formate or formic acid is receiving significant attention as a method to combat the global warming crisis. Significant efforts have been devoted to the advancement of CO2 reduction techniques over the past few decades. This Account provides a unified discussion on various electrochemical methodologies for CO2 to formate conversion, with a particular focus on recent advancements in utilizing 3d-transition-metal-based molecular catalysts. This Account primarily focuses on understanding molecular functions and mechanisms under homogeneous conditions, which is essential for assessing the optimized reaction conditions for molecular catalysts. The unique architectural features of the formate dehydrogenase (FDH) enzyme provide insight into the key role of the surrounding protein scaffold in modulating the active site dynamics for stabilizing the key metal-bound CO2 intermediate. Additionally, the protein moiety also triggers a facile proton relay around the active site to drive electrocatalytic CO2 reduction forward. The fine-tuning of FDH machinery also ensures that the electrocatalytic CO2 reduction leads to the production of formic acid as the major yield without any other carbonaceous products, while limiting the competitive hydrogen evolution reaction. These lessons from the enzymes are key in designing biomimetic molecular catalysts, primarily based on multidentate ligand scaffolds containing peripheral proton relays. The subtle modifications of the ligand framework ensure the favored production of formic acid following electrocatalytic CO2 reduction in the solution phase. Next, the molecular catalysts are required to be mounted on robust electroactive surfaces to develop their corresponding heterogeneous versions. The surface-immobilization provides an edge to the molecular electrocatalysts as their reactivity can be scaled up with improved durability for long-term electrocatalysis. Despite challenges in developing high-performance, selective catalysts for the CO2 to formic acid transformation, significant progress is being made with the tactical use of graphene and carbon nanotube-based materials. To date, the majority of the research activity stops here, as the development of an operational CO2 to formic acid converting electrolyzer prototype still remains in its infancy. To elaborate on the potential future steps, this Account covers the design, scaling parameters, and existing challenges of assembling large-scale electrolyzers. A short glimpse at the utilization of electrolyzers for industrial-scale CO2 reduction is also provided here. The proper evaluation of the surface-immobilized electrocatalysts assembled in an electrolyzer is a key step for gauging their potential for practical viability. Here, the key electrochemical parameters and their expected values for industrial-scale electrolyzers have been discussed. Finally, the techno-economic aspects of the electrolyzer setup are summarized, completing the journey from tactical design of molecular catalysts to their appropriate application in a commercially viable electrolyzer setup for CO2 to formate electroreduction. Thus, this Account portrays the complete story of the evolution of a molecular catalyst to its sustainable application in CO2 utilization.

Real-time monitoring of voltage-responsive biomolecular binding onto electro-switchable surfaces.

Voltage-responsive biosensors capable of monitoring real-time adsorption behavior of biological analytes onto electroactive surfaces offer attractive strategies for disease detection, separations, and other adsorption-dependent analytical techniques. Adsorption of biological analytes onto electrically switchable surfaces can be modelled using neutravidin and biotin. Here, we report self-assembled monolayers formed from voltage-switchable biotinylated molecules on gold surfaces with tunable sensitivity to neutravidin in response to applied voltages. By using electrochemical quartz crystal microbalance (EQCM), we demonstrated real-time switchable behavior of these bio-surfaces and investigate the range of sensitivity by varying the potential of the same surfaces from -400 mV to open circuit potential (+155 mV) to +300 mV. We compared the tunability of the mixed surfaces to bare Au surfaces, voltage inert surfaces, and switchable biotinylated surfaces. Our results indicate that quartz crystal microbalance allows real-time changes in analyte binding behavior, which enabled observing the evolution of neutravidin sensitivity as the applied voltage was shifted. EQCM could in principle be used in kinetic studies or to optimize voltage-switchable surfaces in adsorption-based diagnostics.

In situ fabrication of Cu2O array electrode for efficient detection of acetaminophen

In this paper, Cu(OH)2 nanosheet arrays were directly grown in an upright manner on the surface of copper foam (CF) through a simple solvent reaction, followed by the successful reduction of Cu(OH)2 into Cu2O using hydrazine hydrate vapor, resulting in a binder-free Cu2O@CF array electrode. The in situ growth technique guarantees robust bonding between Cu2O and the conductive substrate, thereby enhancing electron transfer among various electrode components. Additionally, the vertically aligned array structures facilitate rapid penetration and transfer of the analyte, while also allowing for thorough exposure of the electroactive surfaces to the electrolyte. When utilized as an adhesive-free biosensor, the obtained Cu2O@CF array electrode exhibited sensitive catalytic oxidation activity toward acetaminophen (AP), providing a wide linear range of 2–200 [Formula: see text]M and a low detection limit of 0.6 [Formula: see text]M for AP detection. Furthermore, the developed Cu2O@CF array electrode was successfully utilized to detect AP in medicine samples. With its simple fabrication method, broad linear range, low detection limit, and excellent stability, this electrode holds significant promise for the detection of AP in pharmaceuticals.

Self-signal generating bioelectronic sensor surface using gadolinium hexacyanoferrate nanocomposite for oral cancer diagnosis

External redox reagents and chemical mediators in measuring solutions are extensively used to monitor the analytical signals in electrochemical immunosensors. These mediators add more steps and complications to the sensing procedures which are aggravated when testing the target molecule in real samples. Thus, it is important to resolve such issues by fabricating and engineering sensitive electroactive surfaces without the requirement of mediators in the solution phase. In this work, we report a self-reporting electrochemical biosensor for cyfra-21–1 detection in saliva samples without using any external mediator molecules in solution phase. To fabricate an electrochemically active surface, a redox active Gadolinium hexacyanoferrate (GdHCF) nanoparticles have been synthesized and deposited onto the electrode surface for label-free detection of cyfra-21–1 in combination with gold nanoparticles (AuNP) and graphene oxide (GO). The sensor probe was thoroughly characterized using X-ray diffraction (XRD), UV–vis spectroscopy, transmission electron microscopy (TEM), Raman Spectroscopy, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). An alternation in the protein biomarker concentrations led to a change in the current response of the electrode surface. differential pulse voltammetry (DPV) was used to establish the analytical performance of the fabricated biosensor. The sensor achieved a clinically relevant range as well as a wide linear dynamic range (LDR) of 2–50 ng/mL of cyfra-21–1 and a detection limit (DL) of 0.039 ( ± 0.01) ng/mL ((RSD < 4.12%, 95% confidence level, n = 3), with negligible interferences effect due to various co-existing molecules. This is the first-ever report where a redox-active surface has been fabricated comprising GdHCF for direct detection of cyfra-21–1 in human saliva samples without using any redox mediator in the solution phase.

Tailoring diamondised nanocarbon-loaded poly(lactic acid) composites for highly electroactive surfaces: extrusion and characterisation of filaments for improved 3D-printed surfaces

A new 3D-printable composite has been developed dedicated to electroanalytical applications. Two types of diamondised nanocarbons - detonation nanodiamonds (DNDs) and boron-doped carbon nanowalls (BCNWs) - were added as fillers in poly(lactic acid) (PLA)-based composites to extrude 3D filaments. Carbon black served as a primary filler to reach high composite conductivity at low diamondised nanocarbon concentrations (0.01 to 0.2 S/cm, depending on the type and amount of filler). The aim was to thoroughly describe and understand the interactions between the composite components and how they affect the rheological, mechanical and thermal properties, and electrochemical characteristics of filaments and material extrusion printouts. The electrocatalytic properties of composite-based electrodes, fabricated with a simple 3D pen, were evaluated using multiple electrochemical techniques (cyclic and differential pulse voltammetry and electrochemical impedance spectroscopy). The results showed that the addition of 5 wt% of any of the diamond-rich nanocarbons fillers significantly enhanced the redox process kinetics, leading to lower redox activation overpotentials compared with carbon black–loaded PLA. The detection of dopamine was successfully achieved through fabricated composite electrodes, exhibiting lower limits of detection (0.12 μM for DND and 0.18 μM for BCNW) compared with the reference CB-PLA electrodes (0.48 μM). The thermogravimetric results demonstrated that both DND and BCNW powders can accelerate thermal degradation. The presence of diamondised nanocarbons, regardless of their type, resulted in a decrease in the decomposition temperature of the composite. The study provides insight into the interactions between composite components and their impact on the electrochemical properties of 3D-printed surfaces, suggesting electroanalytic potential.Graphical abstract

ID: 219864 Hierarchical Surface Restructuring for Next Generation Neural Interfacing Applications

Selective and targeted stimulation of small populations of neurons in close proximity to implantable electrodes is an essential prerequisite for their success. Additionally, the trajectory for further refinement of neural interfacing devices is in large part predicated on increased miniaturization of electrodes that enables higher spatial resolution, precision, and reliability. To achieve miniaturization, the geometric surface area of the electrodes must be reduced while the electrochemical surface area is increased. Therefore, availability of highly electroactive electrode materials or surfaces capable of improving the electrodes’ electrochemical performance is paramount as it ensures delivery of enough charge across the electrode/tissue interface for stimulation as well as low impedance at the interface for sensing and recording purposes. In the past two decades, several surface treatment technologies e.g., coatings, thin films, nanomaterials, physical and electrochemical techniques have been vastly investigated. Despite varying degrees of improvement in electrochemical performance, most of these techniques are still facing several challenges and shortcomings, e.g., poor performance and durability, manufacturing, scalability, and commercialization challenges. In this research, a proprietary, innovative, tunable, scalable, and commercially viable electrode surface treatment technology (hierarchical surface restructuring) is introduced.

Covalent modification of glassy carbon surface via radical-induced grafting from electrochemical oxidation of imine derivatives

The selective surface modification and functionalization methods through organic or inorganic grafting are a permanent challenge for constructing custom-made molecular interfaces with high performance as part of electroactive surfaces. We report the novel use of imine derivatives as a source of radical species for modifying a glassy carbon (GC) surface using electrochemical grafting. Based on the above work related to imine compounds, we designed and synthesized two structural isomers, ferrocenyl-nitro imine derivatives. These electroactive ferrocenyl and nitro functional groups served as redox signaling. In order to identify which part of the imine derivatives was grafted on the GC surface, they were subjected to electrolysis at a constant potential to monitor changes in its imine fragment response. Electrochemical and spectroelectrochemical results suggested that just one of two synthesized isomers (η5-C5H4-CH=N-C6H4-NO2)Fe(η5-C5H5) produced a radical species by electrochemical oxidation of the imine with bond cleavage. After the electrolysis process, the cyclic voltammetry and spectroscopic studies showed that a covalent modification of GC surfaces took place via forming a new bond from a nitro-aryl species on the GC surface. Due to imine bond cleavage, the ferrocenyl scissioned fragment was lost far from the electrode surface.

Promising Electrode Surfaces, Modified with Nanoparticles, in the Sensitive and Selective Electroanalytical Determination of Antibiotics: A Review

This review highlights the importance of monitoring the levels of antibiotics in different matrices and the need for sensitive and selective detection methods of antibiotic residues in various samples. Additionally, this article discusses the use of modified electrodes, specifically those modified with nanoparticles, for the detection of antibiotics using electroanalytical techniques. These modified electrodes have been found to have advantages over unmodified electrodes, such as enhanced sensitivity, selectivity, and stability. Nanoparticles such as graphene, carbon nanotubes, metal nanoparticles, and metal oxides have been used to modify electrodes because of their excellent properties, such as their large electroactive surfaces. The review provides examples of nanoparticle-modified electrodes that have been used successfully for the determination of a broad range of antibiotics.

Electrochemical control of bone microstructure on electroactive surfaces for modulation of stem cells and bone tissue engineering

ABSTRACT Controlling stem cell behavior at the material interface is crucial for the development of novel technologies in stem cell biology and regenerative medicine. The composition and presentation of bio-factors on a surface strongly influence the activity of stem cells. Herein, we designed an electroactive surface that mimics the initial process of trabecular bone formation, by immobilizing chondrocyte-derived plasma membrane nanofragments (PMNFs) on its surface for rapid mineralization within 2 days. Moreover, the electroactive surface was based on the conducting polymer polypyrrole (PPy), which enabled dynamic control of the presentation of PMNFs on the surface via electrochemical redox switching, further resulting in the formation of bone minerals with different morphologies. Furthermore, bone minerals with contrasting surface morphologies had differential effects on the differentiation of human bone marrow-derived stem cells (hBMSCs) cultured on the surface. Together, this electroactive surface showed multifunctional characteristics, not only allowing dynamic control of PMNF presentation but also promoting the formation of bone minerals with different morphologies within 2 days. This electroactive substrate could be valuable for more precise control of stem cell growth and differentiation, and further development of more suitable microenvironments containing bone apatite for housing a bone marrow stem cell niche, such as biochips/bone-on-chips.

Bacterial Membrane Mimetics: From Biosensing to Disease Prevention and Treatment

Plasma membrane mimetics can potentially play a vital role in drug discovery and immunotherapy owing to the versatility to assemble facilely cellular membranes on surfaces and/or nanoparticles, allowing for direct assessment of drug/membrane interactions. Recently, bacterial membranes (BMs) have found widespread applications in biomedical research as antibiotic resistance is on the rise, and bacteria-associated infections have become one of the major causes of death worldwide. Over the last decade, BM research has greatly benefited from parallel advancements in nanotechnology and bioelectronics, resulting in multifaceted systems for a variety of sensing and drug discovery applications. As such, BMs coated on electroactive surfaces are a particularly promising label-free platform to investigate interfacial phenomena, as well as interactions with drugs at the first point of contact: the bacterial membrane. Another common approach suggests the use of lipid-coated nanoparticles as a drug carrier system for therapies for infectious diseases and cancer. Herein, we discuss emerging platforms that make use of BMs for biosensing, bioimaging, drug delivery/discovery, and immunotherapy, focusing on bacterial infections and cancer. Further, we detail the synthesis and characteristics of BMs, followed by various models for utilizing them in biomedical applications. The key research areas required to augment the characteristics of bacterial membranes to facilitate wider applicability are also touched upon. Overall, this review provides an interdisciplinary approach to exploit the potential of BMs and current emerging technologies to generate novel solutions to unmet clinical needs.

Electrochemical Polymerisation of Glutamic Acid on the Surface of Graphene Paste Electrode for the Detection and Quantification of Rutin in Food and Medicinal Samples.

Rutin (RU) is one of the best-known natural antioxidants with various physiological functions in the human body and other plant species. In this work, an efficient voltammetric sensor to detect RU in food samples was explicated using a poly (glutamic acid)-modified graphene paste electrode (PGAMGPE). In order to detect RU, the proposed sensor diminishes material resistance and overpotential while increasing kinetic rate, peak currents, and material conductance. Using differential pulse voltammetry (DPV) and cyclic voltammetry (CV), the analysing efficiency of a PGAMGPE and a Bare graphene paste electrode (BGPE) was evaluated in 0.2 M phosphate buffer (PB) at an ideal pH of 6.5. in a potential window of -0.25 V to 0.6 V. Electrochemical impedance spectroscopy (EIS) was used to analyse the prepared electrode materials' conductivity, charge transfer resistance, and the kinetics of electron transport. Field emission scanning electron microscopy (FE-SEM) images were considered to compare the exterior morphology of the PGAMGPE and the BGPE. It was discovered that the PGAMGPE and the BGPE have electroactive surfaces of 0.062 cm2 and 0.04 cm2, respectively. It was determined that two protons and two electrons participated in the redox process. The resultant limit of detection (LOD) was found to be 0.04 µM and 0.06 µM, respectively, using DPV and CV methods. In spite of common interferents such as metal ions and chemical species, the developed sensor's selectivity for RU detection was impressive. For the simultaneous analysis of RU in the presence of caffeine (CF), the PGAMGPE affords a good electrochemical nature for RU with good selectivity. Due to the good stability, repeatability, reproducibility, and ease of use of the present RU sensor, it is useful for real sample analysis such as food and medicinal samples with recovery ranging from 94 to 100%.

Potential-Dependent Adhesion Forces between dsDNA and Electroactive Surfaces

A promising approach to regulating the interactions between polyelectrolytes and materials is the use of electroactive surfaces that can change their charge state. However, common electroactive groups are too unstable to be practical for this purpose. Here we have performed a single molecule force spectroscopy study of the interactions between dsDNA and an 1,1'-biferrocenylene (BFD = bis(fulvalene)diiron)-terminated self-assembled monolayer surface that allows us to reversibly change the charge state. We found that the interaction force between DNA and the surface is correlated to the oxidation state of the BFD groups, which is conveniently controlled by the electrochemical potentials. We discovered that the electroactive SAM produces much stronger interaction forces than its nonelectroactive counterpart. A model based on the Grahame equation was able to quantitatively reproduce the experimentally observed relation between the applied potentials and adhesion forces. Our electroactive surface provides a model system for quantitative studies of the interactions between polyelectrolyte and charged surfaces in liquid. These insights may enable new opportunities for actively manipulating the binding, orientations, and conformations of polyelectrolytes for biosensing, nanomotors, and other applications.

Multiphysics design and fabrication of 3D electroplated VIA materials topographies for next generation energy and sensor technologies

3D micro and nanoconductors have emerged as essential components of next generation energy and sensor technologies. This work investigates novel methods to tailor the topography of electroplated 3D conductive components, such as VIAs, using the FEM in COMSOL Multiphysics. This enables meeting the design specifications of flat, convex, or concave substrate-distal electroactive surfaces. Flat conductor surfaces are ideal for microbump soldering and flip-chip fabrication methods and concave/convex designs increase the number of available electrode reaction sites for sensor applications. 2D/3D multiphysics simulations are performed comprising: (1) electrochemistry modeling with the Nernst-Planck and Butler-Volmer formulations for mass transfer and reaction kinetics, and (2) a deformed geometry physics module to track the growing electrode during electrodeposition. Simulation results are compared to directly corresponding experimental work, with positive correlation. Our findings enable tailored and scalable electroactive surface processing options, which can be readily integrated into pre-existing research and industry standard operating procedures.

Multifunctional and Mechanically Robust Porous Diamond with Large Electroactive Surfaces via Electrically Conductive and Insulating Templates for 3D Electrode Applications (Adv. Mater. Interfaces 15/2022)

Porous Diamond with Large Electroactive Surfaces In article number 2200375, Petr Ashcheulov, Ondřej Hák, and co-workers demonstrate fabrication of diamond with porous structure. Porous diamond enables effective electrochemical treatment of water pollutants and sensing of biomolecules. The reported strategy allows for manufacturing of porous diamond over large areas, which is of interest for many applications.

Multifunctional and Mechanically Robust Porous Diamond with Large Electroactive Surfaces via Electrically Conductive and Insulating Templates for 3D Electrode Applications

AbstractHighly functional 3D biological systems, which are ordinary in this physical world, suggest that traditional planar/flat materials when assembled into 3D variants, can deliver significantly higher levels of functionality and efficiency. Thanks to its set of unique properties, diamond has received significant recognition as the material of choice for a variety of functional platforms, however, implementation of diamond in real‐world applications has lagged behind alternative materials, which offer a greater degree of versatility. In this regard, for applications to benefit from diamond‐specific properties, approaches on fabrication of diamond beyond the common planar form in a practical and scalable manner are required today. Capitalizing on the ability to synthesize diamond over large areas, this study demonstrates fabrication of porous boron‐doped diamond (BDD) in freestanding form and on wafer‐compatible sizes. Porous BDD electrodes deliver robust electrochemical stability and exceptional electrical characteristics. Aiming to utilize the full potential of diamond properties, this study examines the impact of the BDD porous structure on the ability of electrodes to effectively remove organic pollutants from simulated wastewater and to provide enhanced sensitivity/selectivity of biologically active compounds. This study represents an important step in achieving diamond with extended functionality suitable for industrial/commercial scale implementation.

In Situ Fabrication of Porous Cox P Hierarchical Nanostructures on Carbon Fiber Cloth with Exceptional Performance for Sodium Storage.

Superior high-rate performance and ultralong cycling life have been constantly pursued for rechargeable sodium-ion batteries (SIBs). In this work, a facile strategy is employed to successfully synthesize porous Cox P hierarchical nanostructures supported on a flexible carbon fiber cloth (Cox P@CFC), constructing a robust architecture of ordered nanoarrays. Via such a unique design, porous and bare structures can thoroughly expose the electroactive surfaces to the electrolyte, which is favorable for ultrafast sodium-ion storage. In addition, the CFC provides an interconnected 3D conductive network to ensure firm electrical connection of the electrode materials. Besides the inherent flexibility of the CFC, the integration of the hierarchical structures of Cox P with the CFC, as well as the strong synergistic effect between them, effectively help to buffer the mechanical stress caused by repeated sodiation/desodiation, thereby guaranteeing the structural integrity of the overall electrode. Consequently, Cox P@CFC as an anode shows a record-high capacity of 279mAhg-1 at 5.0Ag-1 with almost no capacity attenuation after 9000 cycles.

DNA ‘Velcro’ to Interface Electron Transfer-Competent Cells with Electrodes

Microbial fuel cells offer promising technology for clean energy. However, challenges remain with the broad implementation of these systems, especially due to inconsistent interactions between microbes and electrode surfaces. A key challenge is to maintain specificity in the placement of cells while facilitating electron transfer between the cells and the surface. DNA can both self-recognize and act as a molecular wire. By applying the inherent specificity of DNA hybridization, we have used DNA as ‘velcro’ to control the interactions between cells and electroactive surfaces. DNA-modified electrodes were used to capture and quantify non-adherent cells, including the electron transfer-proficient organism Shewanella oneidensis. When immobilized on electrodes using this biological ‘velcro,’ Shewanella preserve their electron transfer capabilities prior to biofilm formation. We attribute this ability, at least in part, to the conductivity of DNA. Our DNA-based technique to interface cells with electrodes has significantly improved the ease of fabrication and generation of current from microbe-modified electrodes.

Modulating the Enantiodiscrimination Features of Inherently Chiral Selectors by Molecular Design: A HPLC and Voltammetry Study Case with Atropisomeric 2,2'-Biindole-Based Monomers and Oligomer Films.

A family of inherently chiral electroactive selectors based on the 2,2’‐biindole atropisomeric scaffold, of easy synthesis and modulable functional properties, is studied in cascade in two enantioselection contexts. They are at first investigated as probes in enantioselective HPLC, studying molecular structure and temperature effects, and achieving very efficient semipreparative enantioseparation. The enantiomers thus obtained, of remarkable chiroptical features (optical rotation as well as circular dichroism), are successfully applied as selectors in chiral voltammetry in different media for discrimination of the enantiomers of chiral electroactive probes, either by conversion into enantiopure electroactive electrode surfaces by electrooligomerization on glassy carbon substrate (the two monomers with shorter alkyl chains), or as chiral additive in achiral ionic liquid (the monomer with longest alkyl chains). Discrimination is conveniently and reproducibly achieved in terms of significant potential differences for the two enantiomers, specularly inverting either probe or selector configuration. In one case successful discrimination is also observed with the two probe enantiomers concurrently present, either as racemate or with enantiomeric excesses, neatly accounted for by the peak current ratios.

(Invited) Controlled DNA Bioconjugations to Electroactive Surfaces

DNA is unique in its abilities to both self-assemble and recognize biomolecules, enabling its application in a variety of fundamental scientific and medical devices. Many DNA-based platforms depend on thiol groups to tether DNA to gold surfaces, but this method suffers from the lack of control over DNA assembly. We have developed multiple, complementary, one-pot bioconjugation reactions to attach oligonucleotides to electroactive surfaces. With these methods, we can control the final DNA surface coverage by varying the reaction time and concentration of reactive species. We have shown the broad applicability of these methods by developing electrochemical biosensors using them and by specifically capturing living nonadherent cells through DNA hybridization. These methods have shifted the paradigm of DNA attachment to metal surfaces and represents a new direction for selective biomolecule attachment to surfaces.

Fabrication of electro-active nano-trans surfaces to design label free electrochemical aptasensor for ochratoxin A detection

The importance of developing multifunctional nanohybrid materials for sensing technologies is rising with the advent of nanotechnology. Herein, we present integration of a novel nanohybrid electro-active material in the construct of electrochemical aptasensor. Electrochemical aptasensor was based on the electroactive composite of fGO/ Fe3O4NP/PPY (functionalized graphene oxide/ iron oxide nanoparticles/ polypyrrole) and analyte specific DNA aptamer. The sensing architecture was relatively less complex, highly sensitive and multi-functional in design. The Pencil electrode was modified with fGO/Fe3O4NP/PPY to work as a multifunctional electrochemical transduction platform. The nano-transducer surface not only served as a conductive and immobilization support, but also functioned as an electrochemical signal generating probe. Ochratoxin A (OTA) was used as target analyte to demonstrate the working principle of the developed aptasensor. The introduction of the target analyte (OTA) on designed probe triggered switching of the aptameric structure resulting in the marked decrement of the redox current. This decrease was proportional to the analyte concentration, thus featuring signal on/off strategy. The aptasensors showed linear range of 10 pg/mL-200 ng/mL, limit of detection (LOD) and limit of quantification (LOQ) of 5 pg/mL and 40 pg/mL, respectively. Real sample analysis was performed in spiked wheat samples to demonstrate the real-life applicability of the designed aptasensor.