Non-enzymatic Electrochemical Sensor Research Articles

Fouling-resistant electrode for electrochemical sensing based on covalent-organic frameworks TpPA-1 dispersed cabon nanotubes

The key problem that limits the practical applications of nonenzymatic electrochemical sensors in biological media, is the biofouling and chemical fouling of electrodes due to the adsorption of biological molecules and oxidation (reduction) products. Electrode fouling will cause low accuracy, poor stability, and low sensitivity. Here, a simple and efficient antifouling electrode was demonstrated for electrochemical sensing based on covalent-organic framework (COF) TpPA-1 and carboxylic multi-walled carbon nanotubes (CNT) composites. COF TpPA-1 possesses abundant hydrophilic groups, which assisted the dispersion of CNT in water and formed uniform composites by π-π interaction. In addition, the introduction of CNT into the composites improved the electron transfer rate of COF TpPA-1. The antifouling interface was characterized by electrochemistry, contact angle measurement, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). The electrode showed good chemical and bio-fouling resistant performance for the electrochemical detection of β-nicotinamide adenine dinucleotide (NADH) and uric acid (UA) in real serum samples.

Current advancements and prospects of enzymatic and non-enzymatic electrochemical glucose sensors

This review discusses the most current developments and future perspectives in enzymatic and non-enzymatic glucose sensors, which have notably evolved over the preceding quadrennial period. Furthermore, a thorough exploration encompassed the sensor's intricate fabrication processes, the diverse range of materials employed, the underlying principles of detection, and an in-depth assessment of the sensors' efficacy in detecting glucose levels within essential bodily fluids such as human blood serums, urine, saliva, and interstitial fluids. It is worth noting that the accurate quantification of glucose concentrations within human blood has been effectively achieved by utilizing classical enzymatic sensors harmoniously integrated with optical and electrochemical transduction mechanisms. Monitoring glucose levels in various mediums has attracted exceptional attention from industrial to academic researchers for diabetes management, food quality control, clinical medicine, and bioprocess inspection. There has been an enormous demand for the creation of novel glucose sensors over the past ten years. Research has primarily concentrated on succeeding biocompatible and enhanced sensing abilities related to the present technologies, offering innovative avenues for more effective glucose sensors. Recent developments in wearable optical and electrochemical sensors with low cost, high stability, point-of-care testing, and online tracking of glucose concentration levels in biological fluids can aid in managing and controlling diabetes globally. New nanomaterials and biomolecules that can be used in electrochemical sensor systems to identify glucose concentration levels are developed thanks to advances in nanoscience and nanotechnology. Both enzymatic and non-enzymatic glucose electrochemical sensors have garnered much interest recently and have made significant strides in detecting glucose levels. In this review, we summarise several categories of non-enzymatic glucose sensor materials, including composites, non-precious transition metals and their metal oxides, hydroxides, precious metals and their alloys, carbon-based materials, conducting polymers, metal-organic framework (MOF)-based electrocatalysts, and wearable device-based glucose sensors deeply.

Direct co-deposition of binder-free Cu-biochar-based nonenzymatic disposable sensing element for electrochemical glucose detection

This work is the first attempt to incorporate biochar on a pencil graphite electrode via one-step electrodeposition as a rational route for refining a copper-based biosensor for a high-performance nonenzymatic electrochemical glucose sensor. Biochar undecorated electrode counterpart was also fabricated for comparison. The cyclic voltammetry graph showed that co-deposition with biochar enhanced the electrocatalytic activity toward glucose oxidation in an alkaline medium. The surface morphology of the copper-biochar hybrid coating demonstrated an attractive three-dimensional structure that had not been reported in the literature. The results indicated that the supplied extending surface area due to biochar modification was the controlling factor for the improved electrochemical reactivity for glucose sensing. The amperometric analysis at an optimum potential of +0.70 V showed linear detection ranges from 0.8 µM to 1 mM and from 1 mM to 5 mM, and good characteristics, such as high sensitivity (6214.4 µA mM−1 cm–2), low limit of detection (0.8 µM), a fast response time (less than 2 s), and excellent anti-interference capability toward the oxidation of glucose. The cost-effective and facile fabrication suggests that the prepared glucose-sensing element can be potentially adapted for construction as a disposable.

Non-Enzymatic Electrochemical Sensors for Accurate and Accessible Uric Acid Detection

Gout arthritis, a painful condition characterized by the accumulation of uric acid (UA) crystals in the joints, necessitates the development of efficient and accessible diagnostic methods. In this study, we present the design and fabrication of non-enzymatic electrochemical sensors based on molecularly imprinted conducting polymer nanostructures for the selective detection and monitoring of UA. To overcome the limitations of current point-of-care (POC) diagnostics, we developed a disposable voltammetric sensor capable of selectively and accurately analyzing UA concentrations at room temperature and pH 7.4. The sensor utilizes a selective polythiophene layer, deposited on disposable screen-printed electrodes, for the reversible binding and recognition of UA. Extensive electrochemical measurements employing electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and differential pulse voltammetry (DPV) demonstrate excellent UA sensing performance in the wider concentration range of 1–500 μM using a standard redox solution with 2.91 μA cm−2·μM−1 sensitivity, 354 nM detection limit, and substantial selectivity over common interferents. The sensor is capable of analyzing complex mixtures such as human saliva with 90.4% recovery of the spiked UA concentration. This highly sensitive and cost-efficient electrochemical sensor offers great promise for POC testing, disease monitoring, and predicting treatment outcomes related to gout arthritis.

A novel sensor based on P-Ru/NC for sensitive electrochemical detection of H2O2

The reasonable design and construction of electrocatalytic nanomaterial is crucial to improve the performance of non-enzymatic electrochemical sensors. Here, P-Ru/NC nanocomposite was synthesized for boosting electrochemical H2O2 sensing. The anchoring of ruthenium nanoparticles (Ru NP) and the doping of P are achieved by one-step pyrolysis. The synergistic effect between Ru NP and P doping made P-Ru/NC possess larger electrochemical surface area, rich active sites and fast electron transfer rate. The electrochemical results reveal that P-Ru/NC/GCE shows higher electrocatalytic activity toward H2O2 than Ru/NC/GCE and P-NC/GCE. The sensor based on P-Ru/NC can detect H2O2 in a wide range from 0.02 mM to 6.1 mM with a high sensitivity of 544.57 µA·mM−1·cm−2 and a low detection limit (4.41 µM). Therefore, this work demonstrated an effective sensing platform for non-enzymatic detection of H2O2.

TiO2-doped LTA zeolite as a sensitive non-enzymatic electrochemical sensor toward hydrogen peroxide detection

Hydrogen peroxide (H2O2) is widely developed in various fields such as industry, biochemistry, and the environment. A titanium dioxide-doped Linde Type-A (TiO2 LTA) zeolite has been hydrothermally prepared and used as an electrochemical catalyst for the detection of H2O2. The morphology and structure of the TiO2 LTA zeolite were analyzed through a series of characterization tests. Results indicated that the TiO2 was partly and highly dispersed on the zeolitic surface, which improved the catalytic site. Moreover, the zeolite showed good adsorption and adsorbed more H2O2 molecules, improving the sensitivity of detection· H2O2 was measured accurately through the square wave voltammetry (SWV) by the TiO2-doped LTA modified electrode (TiO2 LTA/GCE). The electrode had the characteristics of a wide detection range, good stability, and good repeatability, with a detection limit (LOD) of 10 nM, linear range of 78.0 nM-19.9 μM and 96.6–3848.8 μM. In addition, the sensor has been successfully used for analysis in tap water and cell fluid, which has the potential to become a candidate material for environmental and biological sensing applications.

Efficient recycling of Co3O4 from spent lithium-ion batteries and its application as an electrochemical sensor and photocatalyst

Green recycling of spent lithium-ion batteries (LIBs) is a fundamental step toward environmental preservation and increased recovery of raw materials. In this study, lactic acid was used to leach the cathode active material of LIBs. The recycled material (Co3O4) was obtained by selective precipitation of the leachate with KOH, followed by calcination for 4.5 h at 450 °C. The composition and microstructure of the recycled material were confirmed by X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and energy dispersive spectroscopy. Co3O4 was applied as a non-enzymatic electrochemical sensor for determination of ascorbic acid and as a photocatalyst in the degradation of methylene blue. The electrochemical sensor consisted of a printed electrode of carbon nanotubes modified with an 85:10:5 (w/w/w) mixture of recycled material, carbon black, and polyvinylidene fluoride (PVDF), respectively. Linear sweep voltammetry was used to measure the oxidation of ascorbic acid at 0.10 V. The analytical curve of the sensor had a coefficient of determination of 0.9915, sensitivity of 0.0498 ± 0.0023 μA mol L−1, and detection limit of 0.0245 mol L−1 in the concentration range of 0.166 to 1.0 mmol L−1. Co3O4 applied as a photocatalyst reached an efficiency of 61.47% in the decolorization of methylene blue after 120 min of reaction in the presence of H2O2 and UV light. Co3O4 recycled from spent LIBs is a promising source of raw materials for the development of non-enzymatic electrochemical sensors and photocatalysts via a sustainable and environmentally friendly route.

Probing the crystal plane effect of Co3O4 for non-enzymatic electrochemistry sensing performance toward hydrogen peroxide

The crystalline structure of catalyst surfaces has an important effect on the catalytic activity. However, the crystal plane effects of Co3O4 catalysts towards H2O2 activation are rarely reported. In this work, Co3O4 hexagon nanosheets, nanosheets, nanorods and nanocubes with respective {111}, {112}, {110} and {001} dominant exposed facets were synthesized by hydrothermal synthesis, and the crystal plane effects of these Co3O4 nanocrystals were compared with respect to their viability as potential for non-enzymatic H2O2 sensors. Co3O4 as a hexagonal nanosheet with a {111} crystal plane exhibited the best performance for H2O2 detection, and exhibited a fast response of 3 s, a wide linear range from 0.0005 ∼ 8.5 mM with sensitivity of 1160.2 μA·mM-1cm-2, and detection limit of 0.049 μM. Overall, the H2O2 detection performance of Co3O4 with different exposed facets was ranked as {111} > {112} > {110} > {001}, which is consistent with the proportion of surface Co3+, indicating that the surface Co3+ exhibit higher activity for H2O2 oxidation. This study indicates that tuning of thecrystal plane of nanocrystals is important to enhancement of non-enzymatic H2O2 detection, and provides an important constraint when developing high efficiency catalysts for non-enzymatic electrochemical H2O2 sensors.

Pyridine-Regulated Lamellar Nickel-Based Metal-Organic Framework (Ni-MOF) for Nonenzymatic Electrochemical Glucose Sensor.

2D metal-organic frameworks (MOFs) are considered as promising electrochemical sensing materials and have attracted a lot of attention in recent years. Compared with bulk MOFs, the construction of 2D MOFs can increase the exposure of active sites by obtaining a larger surface area ratio. Herein, a facile one-pot hydrothermal synthesis of pyridine-regulated lamellar Ni-MOFs with ultrathin and well-defined 2D morphology is described. Compared with the bulk structure, the 2D lamellar Ni-MOF has higher surface area and active site density, showing better electrochemical glucose sensing performance. The 2D lamellar Ni-MOF exhibits a fast amperometric response of less than 3 s and a high sensitivity of 907.54µA mm-1 cm-2 toward glucose with a wide linear range of 0.5-2665.5 µm. Furthermore, the 2D lamellar Ni-MOF also possesses excellent stability and reproducibility, and can be used to detect glucose with high accuracy and reliability in different environments.

ZnO nanoparticles-copper metal-organic framework composite on 3D porous nickel foam: a novel electrochemical sensing platform to detect serotonin in blood serum

Herein, we report a simple non-enzymatic electrochemical sensor for the detection of serotonin (5-HT) in blood serum using ZnO oxide nanoparticles-copper metal-organic framework (MOF) composite on 3D porous nickel foam, namely, ZnO-Cu MOF/NF. The x-ray diffraction analysis reveals the crystalline nature of synthesized Cu MOF and Wurtzite structure of ZnO nanoparticles, whereas SEM characterization confirms the high surface area of the composite nanostructures. Differential pulse voltammetry analysis under optimal conditions yields a wide linear detection range of 1 ng ml−1 to 1 mg ml−1 to 5-HT concentrations and a LOD (signal to noise ratio = 3.3) of 0.49 ng ml−1, which is well below the lowest physiological concentration of 5-HT. The sensitivity of the fabricated sensor is found to be 0.0606 mA ng−1 ml−1.cm2, and it exhibited remarkable selectivity towards serotonin in the presence of various interferants, including dopamine and AA, which coexist in the real biological matrix. Further, successful determination of 5-HT is achieved in the simulated blood serum sample with a good recovery percentage from ∼102.5% to ∼99.25%. The synergistic combination of the excellent electrocatalytic properties and surface area of the constituent nanomaterials proves the overall efficacy of this novel platform and shows immense potential to be used in developing versatile electrochemical sensors.

Highly sensitive Non-enzymatic, Non-Invasive Disposable Electrochemical Polyaniline Nanocaps based Sweat Sensor for Glucose Monitoring

Diabetes has surged dramatically, leading to a significant healthcare burden worldwide. Consequently, there is a growing need for reliable non-invasive alternatives for glucose monitoring, replacing traditional blood-based analysis. Despite this, enzyme degradation and stability have posed challenges for sweat sensors. To address these obstacles, the present study emphasizes the development of a novel, non-enzymatic electrochemical sweat sensor for glucose monitoring that is painless, reliable, and based on polyaniline nanocaps. Polyaniline (PANI) nanostructures, including nanocaps, nanowires, and nanocollides, were successfully synthesized using sodium dodecyl sulphate (SDS) as a template at varying ratios. The obtained nanostructures were characterized using XRD, FTIR, FESEM, and TEM. For electrochemical analysis, a screen-printed carbon electrode (SPCE) was employed. The presence of subsistent polyaniline nanocaps structure resulted in better catalytic performance, exhibiting superior sensitivity of 94.3859 µA mM−1 cm−2 and a limit of detection (LOD) of 0.04 µM in the linear range of 10–500 µM for glucose monitoring. Furthermore, the stability of the modified PANI nanocaps@SPCE sensor was tested using a mimic sweat sample. These results suggest that the fabricated PANI nanocaps@SPCE sensor holds promise as a non-invasive sweat sensor for glucose monitoring.

Performance comparison of non-enzymatic electrochemical glucose sensor with bimetallic NiMo–MOF and CoMo–MOF

Performance comparison of non-enzymatic electrochemical glucose sensor with bimetallic NiMo–MOF and CoMo–MOF

Recent Advances in Metal-Organic Frameworks (MOFs) and Their Composites for Non-Enzymatic Electrochemical Glucose Sensors.

In recent years, with pressing needs such as diabetes management, the detection of glucose in various substrates has attracted unprecedented interest from researchers in academia and industry. As a relatively new glucose sensor, non-enzymatic target detection has the characteristics of high sensitivity, good stability and simple manufacturing process. However, it is urgent to explore novel materials with low cost, high stability and excellent performance to modify electrodes. Metal-organic frameworks (MOFs) and their composites have the advantages of large surface area, high porosity and high catalytic efficiency, which can be utilized as excellent materials for electrode modification of non-enzymatic electrochemical glucose sensors. However, MOFs and their composites still face various challenges and difficulties that limit their further commercialization. This review introduces the applications and the challenges of MOFs and their composites in non-enzymatic electrochemical glucose sensors. Finally, an outlook on the development of MOFs and their composites is also presented.

Copper decorated polyaniline nanowires: A tow-step electrochemical synthesis and a development of a non-enzymatic electrochemical glucose sensor

In this work, a nanostructured electrode material based on copper metal decorated polyaniline nanowires (PANi NWs@Cu) was directly fabricated on a Pt (Pt/PANi NWs@Cu) microelectrode using a novel and effective two-step electrochemical procedure. Herein, the polyaniline nanowires were firstly electropolymerized on the Pt microelectrode using a cyclic voltammetry method, and the copper metal coated onto the polyaniline nanowires were fabricated via a chronoamperometry deposition to form the PANi NWs@Cu with an average diameter of 85 nm. The electrocatalytic activity showed that the as-synthesized PANi NWs@Cu can directly oxidize glucose in alkaline medium, which suggested that the PANi NWs@Cu can be applied as an artificial enzyme for development of a non-enzymatic electrochemical glucose sensor. Obtained results exhibits that the Pt/PANi NWs@Cu has the ability to directly detect glucose with a rapid response, high selectivity, good repeatability, excellent stability with a wide linear range of glucose concentration from 0.5 mM to 50.0 mM and a low detection limit of 94 μM. The developed Pt/PANi NWs@Cu-based electrochemical sensor also shows the ability to directly detect glucose in a 5% glucose intravenous infusion sample with an error of 1.21% from a labelled value.

PANI: silicene nanocomposites based non-enzymatic electrochemical voltammetric sensor for dopamine detection

PANI: silicene nanocomposites based non-enzymatic electrochemical voltammetric sensor for dopamine detection

Carbon nanomaterials and their composites for electrochemical glucose biosensors: A review on fabrication and sensing properties

BackgroundWith the increasing prevalence of diabetes that increases the risk of cardiovascular diseases, kidney failure, nerve degeneration, eye damage, lower extremity amputations and birth defects, the demand for highly efficient glucose sensors has attracted significant attention worldwide. In this regard, carbon nanomaterials-based electrochemical glucose sensors have shown great potential in the detection and monitoring of glucose. MethodsDifferent forms of carbon such as carbon nanotubes, graphene, reduced graphene oxide, carbon nanofibers, activated and amorphous carbon, carbon spheres, carbon nanoparticles, carbon quantum dots, carbon nanorods, carbon nanocages etc. and their hybrids have been extensively researched for highly efficient glucose sensors due to their large surface area, porosity, lightweight, thermal stability, excellent mechanical properties, ease of fabrication, high electrical conductivity, excellent catalytic properties and fast electron transfer kinetics. Significant findingsDue to their large surface area and tunable porosity, carbon nanomaterials have been used as a scaffold for the immobilization of large quantities of bioreceptor units such as enzymes and highly catalytic metal or metal oxide nanostructures, which can enhance the electroanalytical properties of the biosensor. In this review paper, the fabrication and electroanalytical properties of carbon nanomaterials based enzymatic and nonenzymatic electrochemical glucose sensors have been reviewed and their sensing mechanisms are discussed.

Review of oxygen-vacancies nanomaterials for non-enzymatic electrochemical sensors application

Review of oxygen-vacancies nanomaterials for non-enzymatic electrochemical sensors application

Manganese cobalt-MOF@carbon nanofiber-based non-enzymatic histamine sensor for the determination of food freshness.

Early detection of histamine in foodstuffs/beverages could be useful in preventing various diseases. In this work, we have prepared a free-standing hybrid mat based on manganese cobalt (2-methylimodazole)-metal organic frameworks (Mn-Co(2-MeIm)MOF) and carbon nanofibers (CNFs) and explored as a non-enzymatic electrochemical sensor for determining the freshness of fish and bananas based on histamine estimation. As-developed hybrid mat possesses high porosity with a large specific surface area and excellent hydrophilicity those allow easy access of analyte molecules to the redox-active metal sites of MOF. Furthermore, the multiple functional groups of the MOF matrix can act as active adsorption sites for catalysis. The Mn-Co(2-MeIm)MOF@CNF mat-modified GC electrode demonstrated excellent electrocatalytic activities toward the oxidation of histamine under acidic conditions (pH = 5.0) with a faster electron transfer kinetics and superior fouling resistance. The Co(2-MeIm)MOF@CNF/GCE sensor exhibited a wide linear range from 10 to 1500µM with a low limit of detection (LOD) of 89.6nM and a high sensitivity of 107.3 µA mM-1cm-2. Importantly, as-developed Nb(BTC)MOF@CNF/GCE sensor is enabled to detect histamine in fish and banana samples stored for different periods of time, which thus indicates its practical viability as analytical histamine detector.

A nonenzymatic electrochemical sensor for the detection of hydrogen peroxide in vitro and in vivo fibrosis models

Fibrosis occurs due to the excessive deposition of extracellular matrix caused by cell injury. After various types of tissue injury, the dysregulation of the internal response can eventually lead to the destruction of organ structure and dysfunction. There is increasing evidence that oxidative stress, which is characterized by excessive production of hydrogen peroxide (H2O2), is an important cause of fibrosis. Therefore, we synthesized a biosensitive and efficient electrochemical H2O2 sensor based on PtNi nanoparticle-doped N-reduced graphene oxide (PtNi-N-rGO) to detect H2O2 released from transforming growth factor β1 (TGFβ1)-induced myofibroblast. In addition, the sensor could easily detect changes in H2O2 in the lung and bronchoalveolar lavage fluid (BALF) of mice with pulmonary fibrosis. Furthermore, the sensor could also detect H2O2 in activated hepatic stellate cells and the liver of carbon tetrachloride (CCl4)-induced liver fibrosis. Moreover, the alterations in H2O2 detected by the sensor were consistent with nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) protein expression and the staining results of pathological sections. Taken together, these results highlight the use of H2O2 sensors for the rapid detection of fibrosis and facilitate the rapid evaluation of antifibrotic drug candidates.

An ultrasensitive non-enzymatic electrochemical cholesterol sensor based on copper foam/CuO/Pt/ p-phenylenediamine molecularly imprinted polymer

An ultrasensitive non-enzymatic electrochemical cholesterol sensor based on copper foam/CuO/Pt/ p-phenylenediamine molecularly imprinted polymer