Non-enzymatic Electrochemical Sensor Research Articles

An enhanced non-enzymatic electrochemical sensor based on the Bi2S3-TiO2 nanocomposite with HNTs for the individual and simultaneous detection of 4-nitrophenol and nitrofurantoin in environmental samples.

In the current era of rapid population growth, there has been an increase in resource consumption and the subsequent release of organic pollutants into water bodies by various industries. To address this issue, we have developed a nanocomposite material, Bi2S3-TiO2/HNTs, for electrochemical sensors capable of simultaneously detecting nitrofurantoin (NFT) and 4-nitrophenol (4-NP) contaminants. The nanocomposite material was synthesized using a novel one-pot sol-gel method, and its structural morphology was characterized using techniques such as FE-SEM, FT-IR, HR-TEM, and XRD. The electrochemical sensor exhibited a remarkably low limit of detection (3.2 nM for NFT and 3.5 nM for 4-NP) and a wide concentration range from 0 μM to 260 μM for both NFT and 4-NP, demonstrating their high sensitivity and accuracy for pollutant detection, and furthermore its potential for real-world application was assessed considering pond and tap water as real samples.

An electrochemical sensor based on copper oxide nanoparticles loaded on a mesoporous MCM-41 for non-enzymatic detection of glucose

Numerous researchers are interested in glucose monitoring systems for diabetes mellitus, which is a serious health problem on a global scale. Due to its low detection limit, quick reaction, and good stability, the new generation of electrochemical glucose biosensors has attracted a lot of research attention. However, enzymatic electrochemical sensors are highly susceptible to changes in temperature, humidity, and pH, which can adversely affect their performance. Herein, we developed a non-enzymatic electrochemical sensor for the detection of glucose by using copper oxide (CuO) nanoparticles loaded on mesoporous substrate mobile crystalline material-41 (MCM-41) by the standard solvothermal method and confirmed by standard characterization techniques. The CuO@MCM-41-based electrochemical sensor having redox properties was designed to quantitatively determine glucose, and the relative mechanism was explored. The designed sensor showed a broad linear response in the range of 83 μM - 1.5 mM for glucose with a rapid response time of 4 s, a sensitivity of 17.23 mAcm−2mM−1, and a LOD of 16 nM. The CuO@MCM-41 composite possesses good characteristics that point to the possible commercial applications of mesoporous material-based composites for nonenzymatic electrochemical glucose sensing.

Green synthesis of reduced graphene oxide (rGO) and its applications in non-enzymatic electrochemical glucose sensors

The synthesis of reduced graphene oxide (rGO) is a challenging task for industrial applications due to the absence of a simple and cost-effective synthesis method. This study proposes an environmentally friendly approach to synthesizing rGO using cow urine as a reducing agent, which eliminates the use of hazardous chemicals. The efficacy of this method was confirmed through various analyses, including UV Vis, Fourier transform infrared, and X-ray diffraction, which demonstrated the successful removal of oxygen-containing functions in GO via reduction with cow urine. The synthesized rGO-10 was utilized to fabricate electrochemical nonenzymatic glucose sensors, which exhibited a rapid response time and excellent amperometry response. The sensors used in this study demonstrated a sensitivity of 19.17 μAcm−2mM−1 when optimized for a glucose concentration of 2 mM in human serum. The sensors demonstrated a wide response range, covering a range of 0.2 to 10 mM, and a low detection limit of 1.9019 µM. Additionally, the sensors displayed desirable attributes about repeatability, reproducibility, and stability.

Non-Enzymatic Lactose Sensor Based on Mxene-NiO Modified Nickel Foam Electrode

Lactose, a disaccharide present in milk and dairy items, serves as the sole carbohydrate source in milk, typically occurring at concentrations ranging from 4.4 to 5.2%. Analyzing the lactose content in milk and dairy products holds significant importance as it serves as a fundamental marker for assessing milk quality and identifying any irregularities [1, 2]. Additionally, lactose intolerance is a prevalent condition in regions like Europe, the Middle East, India, and among the Maasai population in East Africa. As a result, the accurate determination of lactose content holds substantial relevance for both the industry and public health.In this study, we have developed a non-enzymatic lactose sensor, utilizing a nickel foam electrode that has been enhanced with MXene-nickel oxide (MXene/NiO) composites. This was achieved by synthesizing nanostructures of NiO and physically combining them with MXene on nickel foam (NF). The three-dimensional porous configuration of NF provides a substantial specific surface area, an increased number of diffusion pathways, and convenient accessibility for lactose to engage in electrochemical reactions. To confirm the presence and growth of MXene/NiO on the NF electrode, various characterization techniques were employed, including SEM, EDX, XRD, FT-IR, and UV spectroscopy. In this work, cyclic voltammetry (CV) and amperometric techniques were carried out in a three-electrode system with an oxygen-saturated environment where MXene-NiO/NF, pt wire, and Ag/AgCl were used as a working, counter, and reference electrode respectively. Further investigations were conducted using the modified electrode in 0.1 M NaOH solutions containing lactose, aiming to determine the suitability of the modified electrode for subsequent lactose monitoring. All electrochemical properties of the modified electrode were evaluated through CV in the 0.1 M NaOH solution at a scan rate of 0.05V/s and amperometry in 0.1M NaOH with successive addition of lactose (1 to 3.5 mM). Additionally, the hydrophilic nature of MXene ensures thorough contact with the lactose-containing electrolyte, promoting ample redox reactions. So, this research introduces two key novelties, NF and MXene, both possessing a high surface area and excellent conductivity. Consequently, these innovations offer heightened sensitivity (better than the NiO/CFC lactose sensor of 1.73 mA/mM/cm2), a wide detection range, and faster response time. These findings are particularly noteworthy because conventional non-enzymatic electrochemical sensors documented in the literature that are typically limited to glucose detection and cannot effectively determine lactose concentrations in dairy food samples. Therefore, this approach provides an opportunity to develop a straightforward analytical tool for the rapid and accurate assessment of lactose concentrations in dairy food applications.Reference Islam, H. Shao, M. M. R. Badal, K. M. Razeeb, & M. Jamal, 2021, PloS one, 16 (3), e0248142.Jamal, M. K. Razeeb, H. Shao, J. Islam, I. Akhter, H. Furukawa, A. Khosla, 2019, Scientific Reports, 9, 4659.M. Razeeb et al., Vertically Aligned Nanowire Array-Based Sensors and Their Catalytic Applications. In: Vestergaard, M., Kerman, K., Hsing, IM., Tamiya, E. (eds) Nanobiosensors and Nanobioanalyses, Springer, Tokyo, 2015.

Development of Glutamate Sensor Based on Mxene/NiO Modified Screen Printed Carbon Electrode

Glutamate plays a vital role as a neurotransmitter, contributing significantly to both physiological and pathological processes. Although enzymatic electrochemical sensors exhibit the ability to selectively detect glutamate, the presence of enzymes introduce sensor instability. Consequently, there is a pressing need for the advancement of enzyme-free glutamate sensors [1-3]. In this study, we have developed an incredibly sensitive non-enzymatic electrochemical sensor for detecting glutamate.This was achieved by synthesizing nanoparticles of nickel oxide (NiO) and physically combining them with MXene on a Screen-printed carbon electrode (SPCE)[2]. Fig. 1 shows the MXene-NiO nanoparticles (NPs) modification process on SPCE. In this work, cyclic voltammetry and amperometric techniques were carried out in a three-electrode system with an oxygen-saturated environment, where MXene-NiO/SPCE, pt wire, and Ag/AgCl electrode were used as working, counter, and reference electrode respectively. MXene-NiO/SPCE showed significant electro-catalytic activity in catalyzing the oxidation of glutamate in 0.1 M NaOH solution. A linear relationship was established between the current response and Glutamate concentration after the electrochemical experiments were conducted while working parameters were optimized. We conducted an extensive investigation of glutamate-sensing mechanism. The optimized sensor exhibited an irreversible oxidation process for glutamate, involving the transfer of one electron and one proton. It displayed a fast response time of < 5 s and a linear response within the concentration range of 20 to 300 µM at a pH of 7, with a LOD of 17.5 µM, sensitivity of 4500 µA.mM−1.cm−2. The morphology of the MXene-NiO composites was characterized using SEM, EDX, XRD, FT-IR, and UV spectroscopy techniques. The investigation into interference on the MXene-NiO/SPCE revealed a noteworthy current response to glutamate even in the presence of uric acid and ascorbic acid. As a result, the development of a reliable, enzyme-free glutamate sensor could be enabled by this simple sensor based on MXene-NiO composites.Fig. 1. The process of MXene/NiO/SPCE electrode.Reference[1] M. Jamal et al., Microsyst. Technol., 24, 4217–4223, 2018. doi: 10.1007/s00542-018-3724-6.[2] M. Jamal et al., Biosens. Bioelectron., 40, 213–218, 2013. doi: 10.1016/j.bios.2012.07.024.[3] K. M. Razeeb et al., Vertically Aligned Nanowire Array-Based Sensors and Their Catalytic Applications. In: Vestergaard, M., Kerman, K., Hsing, IM., Tamiya, E. (eds) Nanobiosensors and Nanobioanalyses, Springer, Tokyo, 2015. Figure 1

Investigation of glucose concentration in banana as a function of ripening time using Ni-Ca2CuO3 based electrochemical sensor

Chemical composition of fruits, particularly banana undergoes continuous metabolic changes as a function of ripening period and storage conditions. In this study, we report the development of a simple non-enzymatic electrochemical sensor based on Ni-Ca2CuO3 for the cost-effective and rapid determination of glucose content in banana fruits as a function of ripening period. Chronoamperometric analyses using Ni-Ca2CuO3 nanoparticles modified glassy carbon electrode (GCE) exhibited the lowest detection limit of 0.11 µM over a wider linear range of 0.55 µM to 23.3 mM of glucose. The potential applicability of the fabricated Ni-Ca2CuO3/GCE was evaluated by measuring glucose in green, red and yellow banana. Glucose concentrations of bananas have been determined for five successive days in order to understand the metabolic changes as a function of post-harvest storage time. The results showed that the glucose concentration increased for the first two days in the case of red and yellow banana and then decreased as the fruit ripened. Green banana showed highest glucose concentration on the first day itself and then decreased rapidly. In addition, yellow banana cooked in water has been tested separately and the result indicated that a sizeable amount of glucose is dissolved in water. These findings suggested that the fabricated non-enzymatic electrochemical sensor could be useful for monitoring glucose levels in starchy fruits and vegetable juices.

Non-Enzymatic Co3O4 Nanostructure-Based Electrochemical Sensor for H2O2 Detection

Abstract This article describes the synthesis of nanostructured cobalt oxide on iron wires and its application for the detection of hydrogen peroxide as working electrode for non-enzymatic electrochemical sensor. Cobalt oxide was obtained by the hydrothermal synthesis method using chloride and acetate anions. The resulting nanostructured coating obtained from the chloride precursor is a uniform homogeneous porous network of long nanofibers assembled into regular honeyсomb-like formations. In the case of an acetate precursor, instead of nanofibers, petal-like nanostructures assembled into honeycomb agglomerates are observed. The structure, surface, and composition of the obtained samples were studied using field-emission scanning electron microscopy along with energy-dispersive spectroscopy and X-ray diffractometry. The resultant nanostructured specimens were utilized to detect H2O2 electrochemically through cyclic voltammetry, differential pulse voltammetry, and i-t measurements. A comparative research has demonstrated that the nanostructures produced from the chloride precursor exhibit greater sensitivity to H2O2 and have a more appropriate morphology for designing a nanostructured sensor. A substantial linear correlation between the peak current and H2O2 concentration within the 20 to 1300 μM range was established. The Co3O4 electrode obtained exhibits a sensitivity of 505.11 μA·mM−1, and the electroactive surface area is calculated to be 4.684 cm2. Assuming a signal-to-noise ratio of 3, the calculated limit of detection is 1.05 μM. According to the interference study, the prevalent interfering agents, such as ascorbic acid, uric acid, NaCl, and glucose, do not influence the electrochemical reaction. The obtained results confirm that this sensor is suitable for working with complex analytes.The actual sample assessment demonstrated a recovery rate exceeding 95 %.

Developments of Materials for Nonenzymatic Biosensing Applications

Nonenzymatic electrochemical biosensors, characterized by high sensitivity, good tolerance, simple preparation and low cost, have become a new research focus in recent years. Nanomaterials exhibit nonenzymatic catalytic mechanisms that enhance electrocatalytic activity and promote electron transfer, making them the popular materials used in nonenzymatic electrochemical sensors. Although catalytic activity and electrical conductivity of conductive polymers are not as good as inorganic nanomaterials, the introduction and doping of metal or carbon nanoparticles as well as the construction of composites with various modified groups can improve the performance of the sensors, and at the same time endow the sensors with the properties of lightweight, flexibility, plasticity, and better biocompatibility, which develops up a great potential opportunity of application in biosensing. This review summarizes the latest research developments of conductive polymer-based materials in nonenzymatic electrochemical sensors in recent years to provide ideas for the construction of sensors.

An alkaline ferrocyanide non-enzymatic electrochemical sensor for creatinine detection

Creatinine is a useful metabolite for the evaluation of Chronic Kidney Disease (CKD). Creatinine concentrations in urine outside of the healthy range of 4 to 15 mM may indicate CKD and other kidney conditions. Early detection and monitoring can provide lifesaving intervention, and as such there is a need to develop rapid, cheap and selective electrochemical creatinine sensors. A simple non-enzymatic creatinine sensing platform enabled by the electrocatalytic response of the metabolite to ferricyanide in alkaline conditions is presented. Studies were made on unmodified glassy carbon (GCE) and screen printed carbon electrodes (SPCE), both giving sensitivity of 21 ± 5 µA mM−1 cm−2 and limit of detection of ca. 60 µM.

Fabrication of a non-enzymatic electrochemical sensor based on magnesium oxide nanosheets for selective and sensitive detection of hydrogen peroxide in food samples

Fabrication of a non-enzymatic electrochemical sensor based on magnesium oxide nanosheets for selective and sensitive detection of hydrogen peroxide in food samples

Detection of Environmentally Harmful Malathion Pesticides Using a Bimetallic Oxide of CuO Nanoparticles Dispersed over a 3D ZnO Nanoflower.

Super-sensitive malathion detection was achieved using a nonenzymatic electrochemical sensor based on a CuO/ZnO-modified glassy carbon electrode (GCE). Due to the high affinity between the Cu element and the sulfur groups in malathion, the developed CuO-ZnO/GCE sensor may bond malathion with ease, inhibiting the redox signal of the Cu element when malathion is present. In addition to significantly increasing the ability of electron transfer, the addition of 3D-flower-like ZnO enhances active sites of the sensor interface for the high affinity of malathion, giving the CuO-ZnO/GCE composite an exceptional level of sensitivity and selectivity. This enzyme-free CuO-ZnO/GCE malathion sensor demonstrates outstanding stability and excellent detection performance under optimal operating conditions with a wide linear range of malathion from 0 to 200 nM and a low detection limit of 1.367 nM. A promising alternative technique for organophosphorus pesticide (OP) determination is offered by the analytical performance of the proposed sensor, and this method can be quickly and sensitively applied to samples that have been contaminated with these pesticides.

PANI: Ni(Leu)2 based non-enzymatic electrochemical dopamine sensor

In this study, metal complexes of Leucine (Leu) and Tryptophan (Trip), namely nickel(Leucine)2 (Ni(Leu)2), zinc(Leucine)2 (Zn(Leu)2), cobalt(Leucine)2 (Co(Leu)2), copper(Leucine)2 (Cu(Leu)2), nickel(Tryptophan)2 (Ni(Trip)2), zinc(Tryptophan)2 (Zn(Trip)2), cobalt(Tryptophan)2 (Co(Trip)2), and copper(Tryptophan)2 (Cu(Trip)2), were synthesized. These complexes were then utilized to fabricate nanocomposites (NCs) based on polyaniline (PANI) through a straightforward sonochemical technique. These NCs were then used to fabricate non-enzymatic electrochemical sensors for detecting dopamine (DOP). The results indicate that the PANI:Ni(Leu)2 NCs based sensor has a high sensitivity of 28.47 μAμM−1 cm−2 and a low limit of detection (LOD) of 9.24 μM. Also, the sensor was tested against fructose, glucose, lactose, and maltose. The sensitivities of the sensor against fructose, glucose, and lactose were calculated as 2.90 μAcm−2 mM−1, 2.14 μAcm−2 mM−1, 2.81 μAcm−2 mM−1, respectively. Due to the use of Ni(Leu)2 composition, the DOP detection sensitivity was higher in PANI:Ni(Leu)2 NCs which can be explained by an enhanced redox mechanism. Furthermore, PANI:Ni(Leu)2 sensor is selectively detect DOP. The PANI:Ni(Leu)2 NCs based sensor is a particularly promising candidate for application in biomedical test kits due to its rapid detection.

Highly responsive and sensitive non-enzymatic electrochemical sensor for the detection of β-NADH in food, environmental and biological samples using AuNP on polydopamine/titanium carbide composite.

In this study, a polydopamine/titanium carbide adorned with gold nanoparticles (Au@PDA/TiC) composite was prepared by a simple stirring technique and it was used for the dual-technique detection of β-Nicotinamide adenine dinucleotide (NADH). The Au@PDA/TiC-modified glassy carbon electrode (GCE) oxidized NADH at a very low oxidation potential of approximately 0.60V vs Ag/AgCl in pH=7.0 (0.1M PBS) via the transfer of two electrons and one proton (from NADH to NAD+). Based on the (i-t) amperometry mode, NADH can be quantified with a linear range of 0.018-674μM and LOD of 0.0062µM. In addition to the DPV mode, the electrochemical sensor had a linearity of 5-450µM with a LOD of 3.17µM. The developed sensor exhibited remarkable analytical performances concerning high sensitivity, electrocatalytic activity, low detection limit, wide linearity, appreciable specificity, repeatability, stability, reproducibility, and adequate recovery results in food, environmental and biological samples.

CoCr2O4/Graphene modified glass carbon electrode for highly dual-sensing detection of hydrogen peroxide and glucose

The development of a non-enzymatic electrochemical sensor possessing well dual-sensing to H2O2 and glucose remains challenging due to less report. Herein, spinel CoCr2O4 nanoparticles with small size were synthesized by sol–gel reaction, which were then simply mixed with commercial graphene under ultrasonic to obtain uniformly dispersed CoCr2O4/Graphene composite. They were deposited onto the surface of bare glassy carbon electrode (GCE) through a common drop-coating method. The CoCr2O4/Graphene/GCE sensor firstly achieves highly dual-sensing to H2O2 and glucose in 0.1 M NaOH solution. At 0.4 and 0.55 V, its sensitivities to H2O2 and glucose can separately reach up to 1168.6 and 1722.5 μA mM−1 cm−2, and the corresponding detection limits are as low as 18 nM and 12 nM. These key indexes are the best among reported dual-functional spinel oxide-based electrodes. This excellent electrochemical sensing ability stems from its large electrode active area, good conductivity, and the synergism between graphene and CoCr2O4 nanoparticles with mixed redox couplings, which provides an efficient platform for dual-sensing detection. In addition, the modified electrode can accurately determine glucose in human tears, rat serum and orange juice, as well as H2O2 in milk whey, mouthwash and disinfectant, thus predicting its good application prospects.

Copper nanoparticles/polyaniline/molybdenum disulfide composite as a nonenzymatic electrochemical glucose sensor

A Cu@Pani/MoS2 nanocomposite was successfully synthesized via combined in-situ oxidative polymerization and hydrothermal reaction and applied to an electrochemical nonenzymatic glucose sensor. The morphology of the prepared Cu@Pani/MoS2 nanocomposite was characterized using FE-SEM and Cs-STEM, and electrochemical analysis was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and chronoamperometry techniques. Electrostatic interaction between Cu@Pani and MoS2 greatly enhanced the charge dispersion, electrical conductivity, and stability, resulting in excellent electrochemical performance. The Cu@Pani/MoS2 was used as an electrocatalyst to detect glucose in an alkaline medium. The proposed glucose sensor exhibited a sensitivity, detection limit, and wide linear range of 69.82 μAmM−1cm−2, 1.78 μM, and 0.1–11 mM, respectively. The stability and selectivity of the Cu@Pani/MoS2 composite for glucose compared to that of the potential interfering species, as well as its ability to determine the glucose concentration in diluted human serum samples at a high recovery percentage, demonstrated its viability as a nonenzymatic glucose sensor.

NiCo2O4/Ti2NbC2 (double MXene) nanohybrid-based non-enzymatic electrochemical biosensor for the detection of glucose in sweat.

The non-enzymatic electrochemical sensors are attractive due to their high sensitivity, quick detection, low cost, and simple construction. Hence, in this work, a non-enzymatic biosensor was constructed with NiCo2O4 nanoparticles (~ 82nm) decorated over Ti2NbC2 nanosheets by an in-situ method. The crystal structure, phase purity, morphology and elemental composition of the synthesized NiCo2O4/Ti2NbC2 nanohybrid was investigated using XRD, Raman and FESEM analysis. The electrocatalytic and electrochemical behaviour of the prepared nanohybrid was investigated using cyclic voltammetry and amperometry analysis. Hybrid of NiCo2O4/Ti2NbC2 produces a biocompatible, electrochemically active surface with enhanced electrical conductivity. The enhanced surface area of NiCo2O4 and superior electrical conductivity of Ti2NbC2 nanosheets helped to develop non-enzymatic electrochemical glucose sensor with enhanced sensitivity (425.6 µA mM-1cm-2), low limit of detection and quick response time that satisfy glucose detection applications. Thus, the developed non-enzymatic electrochemical glucose sensor has excellent electrochemical properties and making it as a strong candidate for the detection of glucose concentration in sweat.

Assessment of Oxidative Stress by Detection of H2O2 in Rye Samples Using a CuO- and Co3O4-Nanostructure-Based Electrochemical Sensor

Hydrogen peroxide is essential for biological processes and normally occurs in low concentrations in living organisms. However, exposure of plants to biotic and abiotic stressors can disrupt their defense mechanisms, resulting in oxidative stress with elevated H2O2 levels. This oxidative stress can damage cell membranes, impair photosynthesis, and hinder crucial plant functions. The primary focus of this article is to investigate the effects of salt and herbicide stress factors on the growth of rye samples. For precise quantification of the released H2O2 concentration caused by these stress factors, a non-enzymatic electrochemical sensor was developed, employing nanostructured CuO and Co3O4 oxides. Nanostructured electrodes exhibit high sensitivity and selectivity towards H2O2, making them suitable for detecting H2O2 in real samples with complex compositions. Rye samples exposed to NaCl- and glyphosate-induced stress demonstrated notable concentrations of released H2O2, displaying an increase of up to 30% compared to the control sample. Moreover, optical absorption measurements revealed a substantial decrease in chlorophyll concentration (up to 35% compared to the control group) in rye samples where elevated H2O2 levels were detected through electrochemical methods. These findings provide further evidence of the harmful effects of elevated H2O2 concentrations on plant vital functions.

Ultrafast Response in Nonenzymatic Electrochemical Glucose Sensing with Ni(II)-MOFs by Dimensional Manipulation.

Metal-organic frameworks (MOFs) are emerging as promising candidates for electrochemical glucose sensing owing to their ordered channels, tunable chemistry, and atom-precision metal sites. Herein, the efficient nonenzymatic electrochemical glucose sensing is achieved by taking advantage of Ni(II)-based metal-organic frameworks (Ni(II)-MOFs) and acquiring the ever-reported fastest response time. Three Ni(II)-MOFs ({[Ni6L2(H2O)26]4H2O}n (CTGU-33), {Ni(bib)1/2(H2L)1/2(H2O)3}n (CTGU-34), {Ni(phen)(H2L)1/2(H2O)2}n (CTGU-35)) have been synthesized for the first time, which use benzene-1,2,3,4,5,6-hexacarboxylic acid (H6L) as an organic ligand and introduce 1,4-bis(1-imidazoly)benzene (bib) or 1,10-phenanthroline (phen) as spatially auxiliary ligands. Bib and phen convert the coordination mode of CTGU-33, affording structural dimensions from 2D of CTGU-33 to 3D of CTGU-34 or 1D of CTGU-35. By tuning the dimension of the skeleton, CTGU-34 with 3D interconnected channels exhibits an ultrafast response of less than 0.4 s, which is superior to the existing nonenzymatic electrochemical sensors. Additionally, a low detection limit of 0.12 μM (S/N = 3) and a high sensitivity of 1705 μA mM-1 cm-2 are simultaneously achieved. CTGU-34 further showcases desirable anti-interference and cycling stability, which demonstrates a promising application prospect in the real-time detection of glucose.

Non-enzymatic electrochemical sensor based on Pt/MoSe2 nanomesh for the detection of hydrogen peroxide

The development of diagnostic methods that are sensitive and selective for detection of reactive oxygen species (ROS) is crucial for early diagnosis of bladder cancer. Herein, a new electrochemical sensing platform for hydrogen peroxide (H2O2) was created based on the Pt/MoSe2 nanomesh with more active sites and larger specific surface area. The Pt/MoSe2 nanomesh sensors exhibited highly sensitive and selective for H2O2, wherein the correlation coefficient (R2) and the limit of detection (LOD) were 0.9983 and 2.56 μM obtained at the signal/noise (S/N) ratio of 3, respectively. Additionally, Pt/MoSe2 nanomesh possessed a good anti-interference performance even in the presence of potentially interfering small molecules within cells, such as ascorbic acid (AA), glucose (Glc) and so on. More importantly, the detection of H2O2 in tap, rain Water, urine FBS, human serum and bladder cancer T24 cells could be successfully detected by the Pt/MoSe2 nanomesh electrochemical sensor.

Non-enzyme picomolar sensing of acephate by modified glassy carbon electrode using bimetallic Zn-Cu metal-organic framework

Organophosphate pesticides are used ubiquitously in agriculture; however, their excessive use can cause problems for human health and the environment. Herein, a non-enzymatic electrochemical sensor has been designed and developed for sensing acephate, which is based on modifying a glassy carbon electrode (GCE) with a zinc-copper metal–organic framework (Zn-Cu MOF) as a sensing material and activated charcoal (AC) as an additive for enhancing conductivity and charge transfer rate. Bimetallic Zn-Cu MOF was synthesized using the one-pot solvothermal method and was characterized by different analytical techniques, viz., Field Emission scanning microscope (FE-SEM), High-Resolution Transmission Electron Microscopy (HR-TEM), X-ray Photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), Raman spectroscopy, and Fourier-transform infrared (FTIR) spectroscopy. The electro-catalytic behavior of the modified GCE was studied using Cyclic voltammetry (CV), Electrochemical impedance spectroscopy (EIS), and Differential pulse voltammetry (DPV), which shows better performance as compared to the bare electrode. The modified GCE demonstrates excellent electro-catalytic activity towards acephate molecules, which may be attributed to the synergistic effect of metal ions, high porosity, enhanced active sites, superior conductivity, higher specific surface area, and faster electron transfer rate. After optimization of parameters such as electrolyte pH and volume of coating on GCE, the Zn-Cu MOF/AC/GCE-based electrochemical sensor provides excellent performance in terms of a more comprehensive linear range from 0.1 to 10 nM, the limit of detection (LOD) of 3.3 pM (S/N = 3), excellent selectivity and reproducibility. The extract of vegetable samples spiked with acephate gave satisfactory recovery results in 95.2–103% for tomato juice and 97–107% for cucumber juice.