Non-enzymatic Electrochemical Sensor Research Articles

GOLD MICROFLOWER MODIFIED SCREEN‐PRINTED CARBON ELECTRODE FOR THE ELECTROCHEMICAL DETECTION OF LACTIC ACID IN BLOOD AND SWEAT

A nonenzymatic electrochemical lactic acid sensor was fabricated by electrodepositing gold microflowers on a screen‐printed carbon electrode and used to determine lactic acid in human serum and sweat quantitatively. Extensive voltammetric studies with lactic acid in phosphate‐buffer saline (PBS) and the analysis of the reduction product proved beyond doubt that lactic acid undergoes two‐electron reduction to form lactaldehyde. The reduction current increased quantitively with lactic acid concentration from 0.5 to 8.5 mM in 0.1 M PBS. The sensor showed excellent sensitivities of 1243 µA mM‐1 cm‐2 and 2752 µA mM‐1 cm‐2 in two linear ranges, 0.5 to 2.5 mM and 2.5 to 8.5 mM, respectively with a detection limit of 0.012 ± 0.0014 mM. The performance of the sensor was validated by estimating lactic acid in human serum and the sweat generated through physical exercise. The estimated lactic acid concentrations are in good agreement with clinical analysis data.This indicates the potential applicability of the sensor in the point‐of‐care detection of lactic acid.

One-step green synthesis of flower-like non-precious metal (Cu, Ni, Fe or Zn) doped ZIF-67 and its application as non-enzymatic electrochemical glucose sensors

Co ions and imidazolate ligands can be self-assembled into a novel metal-organic frameworks (MOFs) with zeolite-like topological structures, which is named as ZIF-67. Flower-like ZIF-67 can be precisely prepared by one-step green synthesis method under specific experimental conditions, and has excellent enzyme-like electrocatalytic activity toward glucose. Non-precious metal (Cu, Ni, Fe or Zn) can be doped into flower-like ZIF-67 while maintaining zeolite-like topological structures, which may also be an important way to enhance the electrocatalytic performances of ZIF-67. In this study, flower-like non-precious metal (Cu, Ni, Fe or Zn) doped ZIF-67 was contrastively researched by physical characterizations and electrochemical techniques, and was employed as electrocatalysts for non-enzymatic electrochemical glucose sensors. Flower-like non-precious metal (Cu, Ni, Fe or Zn) doped ZIF-67 all exhibits perfect electrocatalytic activities toward glucose, among them the performance of Fe(5 %)-ZIF-67 is the most outstanding.

Nanostructured metallic enzymes mimic for electrochemical biosensing of glucose

In many domains, the creation of nonenzymatic glucose sensors with robust electrocatalytic activity and chemical stability is indispensable. However, the design of nanoarchitecture transition metals and their nanocomposites as sensing interfaces for nonenzymatic recognition groups remains a formidable challenge. This review discusses the engineered nanoarchitecture transition metals used as non-enzymatic glucose sensors, with a particular focus on their applications characterized by low cost, high sensitivity, and long-term durability. Central to our discussion is the imperative of crafting nanostructured transition materials with expansive specific surface areas and well-defined active sites to serve as electrochemical sensing platforms. Our objective is to shed light on the enhanced electrochemical behavior toward glucose without reliance on mediators or templates. Leveraging advancements in nanotechnology, this review seeks to elucidate strategies for refining conventional nanostructures to optimize enzyme-free glucose sensing applications. Additionally, we delve into the inherent challenges and potential applications of these sensors for detecting glucose and outline ways to develop better non-enzymatic electrochemical glucose sensors.

Enhanced sensing performance of flexible non-enzymatic electrochemical glucose sensors using hollow Fe3O4 nanospheres of controllable morphologies

Rapid and accurate monitoring of glucose concentration is of great significance in clinical diagnosis and treatment of diabetes and hence, it is necessary to develop glucose sensors of superior electro-catalytic capacity. Most literature utilize synergistic effect of nanocomposites to enhance glucose sensing performance, whereas it suffers from crucial restriction in physical and chemical characteristics of each constituents. Morphology of nanostructures significantly affects the electro-catalytic capacity, thus it is a novel route to improve glucose sensing performance to adjust morphology of nanostructures. Herein, we presented highly sensitive non-enzymatic electrochemical sensors for rapid and accurate glucose analysis with hollow Fe3O4 nanospheres (Fe3O4NSs) of controllable morphologies decorated on flexible fibers. The morphologies of the Fe3O4NSs were evaluated with quantitative parameters like diameter, roundness, roughness, skewness, and kurtosis acquired from SEM images and image processing algorithms, and their effect on the interfacial characteristics and the electro-catalytic capacity of the glucose sensors was investigated. Owing to the unique spherical nanostructures and superior catalysis, the Fe3O4NSs exhibit desirable solid/liquid interface for mass diffusion and abundant active sites for sufficient oxidation of glucose. Moreover, much rounder and rougher Fe3O4NSs of near Gaussian surface are readily produced at a higher Fe3+ concentration and result in favorable sensing performance. Accordingly, the optimal glucose sensor shows sensitivities of 96.1 ± 5.4 μA mM−1 cm−2 and 38.2 ± 2.2 μA mM−1 cm−2 over a preferable range of 0–18.0 mM, and a lower detection limit of 19.2 μM. Besides, the glucose sensors remain acceptable response after continuous testing for 20 times and repetitive bending for 50 times, and display superior selectivity to glucose and accurate analysis to practical samples. It is a facile and effective methodology to regulate the morphologies of the Fe3O4NSs for enhanced electro-catalytic capacity of glucose sensors.

Development of Highly Sensitive and Selective Electrochemical Glucose Sensors Based on the Modification of the Surface, Structural, and Morphological Properties of ZnO Using Vitamin-B Complexes

Non-enzymatic electrochemical glucose sensors are particularly advantageous because of their simplicity, low cost, efficiency, and long storage life. ZnO structures were modified with water-soluble vitamin B12, B9, and B6 complexes in alkaline 0.1 M NaOH solutions to enhance glucose sensing. ZnO samples were hydrothermally synthesized using 5 mg fixed masses of B12, B9, and B6 complexes. X-ray diffraction, scanning electron microscopy, UV-visible spectrometry, and Fourier transform infrared spectroscopy were used to determine crystalline properties, morphology, and optical band gap. Zinc oxide obtained from vitamin B complexes had a hexagonal structure similar to wurtzite, modified nanorods on its surface, and a reduced optical band gap. The molecular weight, size, and number of functional groups vitamins also influenced surface and structural characteristics of ZnO. Zinc oxide from the B12 complex proved excellent for non-enzymatic glucose sensing in alkaline conditions. B12-derived ZnO glucose sensors have a linear range of 0.1 to 10 mM with a detection limit of 0.005 mM. In the glucose sensing process, a satisfactory level of stability, reproducibility, and selectivity was observed. Furthermore, it was found that ZnO derived from B12 had a high electrical conductivity, which facilitated electron transfer during glucose oxidation.

A Flexible Highly Sensitive Non-Enzymatic Electrochemical Urea Sensor Based on Nonwoven Fabric That Uses Ag-Doped NiO

A Flexible Highly Sensitive Non-Enzymatic Electrochemical Urea Sensor Based on Nonwoven Fabric That Uses Ag-Doped NiO

Highly sensitive and selective detection of dopamine using atomic layer deposited HfO2 ultra-thin films

The development of non-enzymatic and binder-free biosensors plays a vital role, and it possesses main benefits for effective biomolecule recognition with high sensitivity and preferred selectivity. Herein, an atomic layer deposition (ALD) was employed to develop the hafnium oxide (HfO2) nanofilm on silicon (Si) for fabricating binder-free selective and sensitive determination of the non-enzymatic electrochemical dopamine sensor. The prepared HfO2 nanofilm selectively acted as a local dopamine binding site because of the hydrophobic-hydrophobic interaction between fabricated film and dopamine, electrostatic attraction between negatively charged hydroxyl group on film surfaces, and positively charged amino group of dopamine. The developed insufficient oxygen vacancies on the HfO2 could have behaved as a charge-trapping site for better sensing properties. The developed sensor demonstrated excellent realization in sensing dopamine with a very low detection limit (0.4 pM) and swift response time of 3s which is quite precise compared with various reported literature. The fabricated HfO2/Si electrode sensor has exhibited high sensitivity, stability, and repeatability. The selectivity of dopamine sensors was at least three orders greater than other interfering biomolecules. This work proposes the essential track for the practical realization of dopamine detection in human serum and biomedical applications.

Non-Enzymatic Electrochemical Detection of Urine Creatinine Using Cobalt-Gold Bimetallic Nanoparticles

This work presents the development of a non-enzymatic electrochemical sensor for creatinine in a neutral medium using a cobalt-gold bimetallic nanoparticles modified platinum electrode. The voltammetric detection of creatinine in a neutral phosphate buffer was based on the formation of a soluble cobalt-creatinine complex. The sensor exhibited good selectivity and a detection limit (S/N = 3) of 2.25 mM with two linear ranges from 6.4 to 83.2 mM. The sensitivity of the sensor was 0.621 and 1.135 μA mM−1 cm−2 at lower (6.4–51.2 mM) and higher (51.2–83.2 mM) detection ranges, respectively. The sensor performance was validated using urine samples and creatinine spiked urine samples.

Laser chemical vapor deposition of nitrogen-doped SiC electrode for electrochemical detection of uric acid

Reasonable design and construction of high-performance electrodes are desirable for developing non-enzymatic electrochemical sensors for uric acid (UA). Herein, N-doped SiC film was prepared as an electrochemical electrode using a novel laser chemical vapor deposition (LCVD) method. Compared with its undoped counterpart, the doped electrode exhibited a low detection limit of 0.77 μM and a high detection sensitivity of 9.75 µA µM-1 cm-2 owing to its large active sites and fast electron transfer rate. Furthermore, the as-developed electrode clearly exhibited immunity towards the coexisting interfering species, such as dopamine and ascorbic acid, and facilitated the quantitative analysis of UA in real-world samples. In addition, the effects of N doping on electrochemical sensing were verified via theoretical calculations by investigating adsorption energy and Bader charge. Our works verify the feasibility of introducing N into SiC to enhance UA sensing performance and fabricating on-chip electrochemical sensors, which may spur the development of advanced and portable SiC-based biosensors for health monitoring.

Vapor phase polymerization of PEDOT on ITO/glass surfaces for nonenzymatic detection of dopamine

This study demonstrates the deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) as an electrically conductive polymer on the ITO-coated glass surfaces for the production of a non-enzymatic electrochemical sensor to detect dopamine. For this purpose, thin films of PEDOT were synthesized using vapor phase polymerization (VPP) from the corresponding monomer 3,4-ethylenedioxythiophene, in which iron(III)chloride was used as the oxidant. Films were deposited at different substrate temperatures, where the temperature dependence of doping and conjugation levels were studied using FTIR and XPS analyses. The highest doping and conjugation levels, as well as the highest film thickness (380 nm) was observed for the film deposited at 40 °C, which represented the highest conductivity of 111 S/cm. Significant differences were observed between the electrochemical responses of ITO/glass and PEDOT/ITO electrodes. Amperometric measurements indicated a limit of detection value of 2.02 µM for dopamine using as-synthesized PEDOT/ITO electrode.

Laser-induced graphene decorated with Ni[sbnd]Pt alloy nanoparticles for non-enzymatic electrochemical quantification of glucose

Enzyme-free electrochemical glucose (Glu) sensors, adopting electrochemically active catalysts, are of vital significance to effectively monitoring and analyzing the blood Glu level in diabetes diagnosis. Meanwhile, developing novel electrode substrates have been the hot research pot to meet the demand for constructing flexible sensors. In this work, porous laser-induced graphene (LIG) was prepared through a facile one-step laser-engraving technique on a polyimide thin film, and then used directly as the electrode. Furthermore, NiPt alloyed nanoparticles (NPs) were electrodeposited on the LIG electrode surface to gain the NiPt/LIG composite electrode, which was applied to construct the nonenzymatic electrochemical Glu sensor. The morphology, element and electrochemical performance of NiPt/LIG composite was characterized through various techniques. NiPt alloyed NPs were homogeneously distributed on the LIG scaffolds, which possess plenty of porous structure, high surface area and many active sites. The cooperative effect between the outstanding electrocatalytic capacity of NiPt alloyed NPs, the extraordinary electroconductibility of LIG and the numerous exposed active sites endow the NiPt/LIG sensor outstanding electrocatalytic performance for electrochemical oxidation of Glu. Under the most appropriate conditions, the obtained NiPt/LIG sensor was adopted to detect Glu, showing a broad detection concentration range of 0.5 μM to 2.1 mM and 2.1 mM to 5.6 mM, good sensitivities of 1.824 and 0.467 μA μM−1 cm−2, a low detection limit of 0.03 μM. The as-fabricated nonenzymatic Glu sensor also displays high selectivity, stability considering ageing effects under different environment conditions and prominent reproducibility. Additionally, this novel NiPt/LIG nonenzymatic Glu sensor was applied to quantify Glu successfully in blood serum and food samples and the results were in good agreement with that by UV–vis spectrophotometer, demonstrating high precision and accuracy as well as excellent recovery, showing good application prospects in Glu monitoring. This research confirmed the potential of exploiting NiPt/LIG as a highly sensitive Glu nonenzymatic electrochemical sensor and provided a practicable and suitable approach for construction of novel electrochemical sensors.

Co-Zn nanoparticles on N-doped graphene nanocomposites as bifunctional catalysts for non-enzymatic electrochemical sensor and organic dye degradation

Detection of biomolecules by advanced sensing systems and organic pollutant removal is of immense interest in biomedical and environmental remediation sectors. In this regard, effective glucose detection is dynamic in rapid-diagnosis of related diseases and in addition, removal of organic dyes by suitable adsorbent materials is vital for water treatment. The present work involves the facile fabrication of CoZn-N doped graphene nanocomposites and employed in glucose sensors and dye removal. The synthesized materials were characterized to evaluate the structural, morphological, elemental and surface characterizations such as, X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning DR-UV–vis–spectroscopy, electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM) techniques, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. SEM and TEM images revealed the Co-Zn nano particles (NPs) with respective morphologies within the N doped graphene structure. Electrochemical examinations of CoZn-N doped graphene nanocomposites/GCE sensor demonstrated superior sensitivity for the detection of commercial glucose in NaOH. Moreover, CoZnNG nanocatalyst has been investigated for the dye removal of crystal violet (CV), Rhodamine B (RB), methylene blue (MB) and congo red (CR) in the presence of H2O2. CoZnNG catalyst exhibited a maximum efficiency of 96 % over CV dye degradation in 30 min which is comparatively higher than the removal of MB, CR and RB dyes with 36 %, 41 %, 38 % for 120, 60 and 100 min, respectively. The CoZn-N doped graphene nanocomposites exhibited regeneration, reproducibility, and stability toward dye removal. Such multi-component hybrid N doped graphene could be efficacious for real-time non-enzymatic electrochemical sensor and pollutant removal applications.

A novel bifunctional electrochemical nanosensor for simultaneous detection of glucose and insulin based on NiO/Co3O4@CuAl LDH-MWCNT nanocomposite-modified carbon paste electrode

The appropriate development of electrocatalytic nanomaterials is a significant step for constructing high-quality non-enzymatic electrochemical sensors. In this work, we presented effective copper aluminum layered double hydroxide (CuAl LDH)-based nanoparticles with two consecutive optimization steps through nickel oxide/cobalt oxide (NiO/Co3O4) merging and subsequent assembly with multi-walled carbon nanotubes (MWCNT). The obtained nanostructures were characterized by using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction pattern (XRD), and field emission scanning electron microscope images (FE-SEM). The synthesized nanomaterials were used as a carbon paste electrode (CPE) material for simultaneous dual-signal evaluation of glucose and insulin. The response of the modified electrode was investigated by some electrochemical approaches, including cyclic voltammetry (CV), electrical impedance (EI), differential pulse voltammetry (DPV), and amperometric titration. The NiO/Co3O4 CuAl LDH@MWCNT electrode displayed multi-functional properties through two well-defined separated peaks toward glucose and insulin detection with a linear range of 0.01–26.5 mM and 0.02–70.0 nM, respectively. The detection limit values were obtained as 2.8 µM for glucose and 17.3 pM for insulin. The sensor showed good tolerance to common interfering agents, excellent sensitivity, and appropriate stability during 30 days of dry storage at room temperature. This sensor was also used for the quantification of glucose and insulin in human serum samples, obtaining the recovery rate of 101.0 %-103.7 % and 98.0 %-106.0 %, respectively, with all the RSD values below 3.0 %. This study represented an efficient simultaneous sensing platform for glucose and insulin detection, which warrants its operational application in clinical samples.

Recent Advances in Non-Enzymatic Electrochemical Sensors for Glyphosate Detection: A Review

Glyphosate (GLY) is the most widely used organophosphorus pesticides globally with application in shielding crops against perennial and annual the weeds, domestic garden and agriculture. It is recognized for its toxicological harm and is implicated in potential connections with human carcinogenesis. Generally, glyphosate is considered to be less toxic but excessive use leads to pollute soil, food and water. Furthermore, it strongly effects the unicellular and multicellular organism. Therefore, there is urgent need to develop specific, accurate, online, and sensitive methods for detection of glyphosate. The present review is focused on recent advances in developing non-enzymatic sensors for glyphosate detection. Non-enzymatic electrochemical sensors have emerged as promising alternatives for glyphosate detection, offering advantages such as high sensitivity, selectivity, and rapid response. The electrodes were modified with metals, carbon materials, metal organic framework and molecular imprinted polymers using various electrochemical techniques. Execution, benefits, linear range, detection limit and limitations of the modified sensors for determination of glyphosate are reviewed thoroughly.

Non-enzymatic Glucose Sensor Based on Ni(OH)2/NF Materials Using Different Pulse Voltammetry Technique

Non-enzymatic glucose sensors have gained significant attention owing to their potential for accurate and cost-effective glucose detection. Nanomaterials play a pivotal role in enhancing performance of non-enzymatic glucose sensor. In this study, a novel non-enzymatic glucose sensor based on Ni(OH)2/NF (nickel hydroxide/nickel foam) materials was developed using different pulse voltammetry technique. Chemical precipitation methods have been used to grow Ni(OH)2 nanostructures directly on a nickel foam electrode. The characterization of the synthesized materials was performed through field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDX), and X-ray diffraction (XRD). The performance of the Ni(OH)2/NF-based glucose sensor was evaluated through electrochemical measurements. Nanoscale hive-like structures of Ni(OH)2 with a diameter ranging from 450 to 530 μm and a thickness of 20 nm were formed on the NF surface. The sensor exhibited good performance, displaying a high sensitivity of 8.42mA.mM-1.cm-2 with a low detection limit of 0.84 μM. These results position the synthesized electrode as a promising contender for non-enzymatic electrochemical glucose sensors.

Tailoring the d-band center on Ru1Cu single-atom alloy nanotubes for boosting electrochemical non-enzymatic glucose sensing.

The development of cost-effective and highly efficient electrocatalysts is critical to help electrochemical non-enzymatic sensors achieve high performance. Here, a new class of catalyst, Ru single atoms confined on Cu nanotubes as asingle-atom alloy (Ru1Cu NTs), with aunique electronic structure and property, was developed to construct a novel electrochemical non-enzymatic glucose sensor for the first time. The Ru1Cu NTs with a diameter of about 24.0nm showed amuch lower oxidation potential (0.38V) and 9.0-fold higher response (66.5 μA) current than Cu nanowires (Cu NWs, oxidation potential 0.47V and current 7.4 μA) for glucose electrocatalysis. Moreover, as an electrochemical non-enzymatic glucose sensor, Ru1Cu NTs not only exhibited twofold higher sensitivity (54.9 μA mM-1cm-2) and wider linear range (0.5-8mM) than Cu NWs, but also showed alow detection limit (5.0μM), excellent selectivity, and great stability. According to theoretical calculation results, the outstanding catalytic and sensing performance of Ru1Cu NTs could be ascribed to the upshift of the d-band center that helped promote glucose adsorption. This work presents a new avenue for developing highly active catalysts for electrochemical non-enzymatic sensors.

Synthesis of citral-tryptamine fused selenium nanospheres (CT@SeNP's) and exploration of their anticancer, antibacterial, and electrochemical sensor applications

A broad spectrum of antibiotics with multiple mechanisms of action is urgently required to combat the growing public health threat posed by drug-resistant pathogenic microorganisms. Biomedical researchers have concentrated on creating novel antibacterial and anticancer therapies due to the limited availability of conventional antibacterial and anticancer medications. In this study citral-tryptamine molecule was synthesized and characterized using 1HNMR , 13CNMR , LCMS and FT-IR spectral techniques and various biological properties of synthesized molecules were investigated using several in silico approaches such as molecular docking, ADME, PASS analysis and bioactive score. Using citral-tryptamine molecule, selenium nanoparticles (CT@SeNP's) were synthesized and characterized using different spectral and imaging techniques such as UV–Visible spectra, SEM, FTIR, EDX, XRD and DLS. EDX and mapping were used to investigate the relevant atoms and their distribution. Three significant signals from the EDX corresponding to C atom (15.4 %), along with signals from the Se atom (80.9 %) and the N atom (3.7 %). CT@SeNP's showed excellent antibacterial property against MRSA. The minimum inhibitory concentration of CT@SeNP's was found to be 20±0.36 mm with a good zone of inhibition in a dose dependent manner. CT@SeNP's was treated with both normal and cervical cancer cell lines such as SiHa to investigate the dose optimization and cytotoxicity by MTT assay. The nanoparticle showed an IC50 value is 0.68 µM and the data strongly suggested that CT@SeNP's could have a high potential in future medication development against MRSA and cervical cancer cells. The proper development and manufacturing of electrocatalytic nanomaterials are essential for enhancing the performance of non-enzymatic electrochemical sensors. The electrochemical sensing of H2O2 was enhanced by nanocomposite CT@SeNPs, which have a low detection limit of 60.96 nM and can detect H2O2 in a wide range of concentrations, from 25 µM to 250 µM. Thus, an efficient sensing platform for non-enzymatic H2O2 detection was discovered by this investigation.

CuCo2O4 nanoneedle arrays growth on carbon cloth as a non-enzymatic electrochemical sensor with low detection limit ketoprofen recognition.

An electrochemical sensor for detecting ketoprofen was constructed by in-situ grown copper cobaltate (CuCo2O4) nanoneedle arrays on a carbon cloth (CC) substrate. The resulting porous nanoneedle arrays not only expose numerous electrochemically active sites but also significantly enhance the electrochemical apparent active area and current transmission efficiency. By leveraging its electrochemical properties, the sensor achieves an impressive detection limit for ketoprofen of0.7 pM, with a linear range spanning from 2 pM ~ 2 µM. Furthermore, the sensor exhibits remarkable reproducibility, anti-interference capabilities, and stability. Notably, the developed sensor also performed ketoprofen detection on real samples (including drug formulations and wastewater) and demonstrated excellent recognition ability. These exceptional performances can be attributed to the direct growth of CuCo2O4 nanoneedle arrays on the CC substrate, which facilitates a robust electrical connection, provides abundant electrocatalytic active sites, and expands the apparent active area. Consequently, these improvements contribute to the efficient trace detection capabilities of the ketoprofen sensor.

Non-enzymatic electrochemical impedance sensor for selective detection of electro-inactive organophosphate pesticides using Zr-MOF/ZrO2/MWCNT ternary composite

The existence of multiple pesticide residues in fruits and vegetables constitutes a direct peril to living organisms. Therefore, it is crucial to develop a low-cost screening method for determining organophosphate pesticides (OPPs) in food samples. This study describes the solvothermal synthesis of a ternary composite comprising multi-walled carbon nanotubes (MWCNT), zirconium oxide, and a zirconium-metal-organic framework (Zr-MOF). The ternary composite was characterised using XRD, FESEM, FTIR, and BET. The ternary composite provides a large surface area (1158 m2/g) compared with the pristine Zr-MOF (868 m2/g). The composite-modified glassy carbon electrode was used to determine nine pesticides, including organophosphate (malathion, dimethoate, chlorpyrifos, monocrotophos, and glyphosate) and non-organophosphate (thiophanate methyl, carbendazim, atrazine, and 2,4, D). In particular, various chemical combinations of OPPs were selected, such as S–P=S, P=S, P=O, and non-OPPs such as C=S (with sulphur), and without sulphur. The sensor results show that the sensor selectivity is high for OPPs containing both phosphorus and sulphur molecules. The low detection limit of the sensor was 2.02, 2.8, 2.5, 1.11, and 2.01 nM for malathion, chlorpyrifos, dimethoate, monocrotophos, and glyphosate, respectively. The electrode exhibited significant chemical stability (93%) after 100 cycles, good repeatability, and a long shelf life. The sensor is reliable for qualitative real-time applications.

Electrochemical Characterization of a Novel Organoelectrocatalyst, 7-Azabicyclo[2.2.1]heptan-7-ol (ABHOL), and Its Application to Electrochemical Sensors.

Electrochemical enzyme sensors are suitable for simple monitoring methods, for example, as glucose sensors for diabetic patients; however, they have several disadvantages arising from the properties of the enzyme. Therefore, non-enzymatic electrochemical sensors using functional molecules are being developed. In this paper, we report the electrochemical characterization of a new hydroxylamine compound, 7-azabicyclo[2.2.1]heptan-7-ol (ABHOL), and its application to glucose sensing. Although the cyclic voltammogram for the first cycle was unstable, it was reproducible after the second cycle, enabling electrochemical analysis of ethanol and glucose. In the first cycle, ABHOL caused complex reactions, including electrochemical oxidation and comproportionation with the generated oxoammonium ions. The electrochemical probe performance of ABHOL was more efficient than the typical nitroxyl radical compound, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), and had similar efficiency to 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO), which is activated by the bicyclic structure. The results demonstrated the advantages of ABHOL, which can be synthesized from inexpensive materials via simple methods.