Non-enzymatic Sensor Research Articles

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.

Rapid electrodeposition of Cu nanoparticle film on Ni foam as an integrated 3D free-standing electrode for non-invasive and non-enzymatic creatinine sensing.

High cost, inherent destabilization, and intricate fixing of enzyme molecules are the main drawbacks of enzyme-based creatinine sensors. The design of a low-cost, stabilizable, and enzyme-free creatinine sensing probe is essential to address these limitations. In this work, an integrated three-dimensional (3D) free-standing electrode was designed to serve as a non-enzymatic creatinine sensing platform and was fabricated by rapid electrodeposition of a dense copper nanoparticle film on nickel foam (Cu NP film/NF). This low-cost, stable, easy-to-fabricate, and binder-free Cu NP film/NF electrode has abundant active sites and excellent electrochemical performance. Cyclic voltammetry measurements show a wide linear range (0.25-24 mM), low detection limit (0.17 mM), and high sensitivity (306 μA mM-1 cm-2). The developed sensor shows high recovery of creatinine concentration in real urine. Besides, it has better specificity, reproducibility, and robustness in detecting creatinine. These excellent results suggest that a non-enzymatic creatinine sensor based on an integrated 3D free-standing Cu NP film/NF electrode has good potential for non-invasive detection of urinary creatinine.

ZIF-8/Cu@Co-MOFs/TiO2 electrode materials based on nickel foam for high-sensitivity non-enzymatic vitamin B2 sensors and high-performance supercapacitors

ZIF-8/Cu@Co-MOFs/TiO₂ electrode materials based on nickel foam for high-sensitivity non-enzymatic vitamin B2 sensors and high-performance supercapacitors

Rapid detection of caffeic acid in food beverages using a non-enzymatic electrochemical sensor based on a Bi2S3/CNF nanocomposite

Synthesizing and fabricating Bi2S3/CNF nanocomposites for non-enzymatic electrochemical sensors.

One-step synthesis of an organotin-functionalized polyoxometalate@ZIF-67 composite: an effective non-enzymatic colorimetric acetone sensor

One-step synthesis of an organotin-polyoxometalate@ZIF-67 composite as a peroxidase mimic for colorimetric detection of acetone.

Development of a Non-Enzyme Sensor to Detect Glucose Based on the Modification of Copper Electrode

Development of a Non-Enzyme Sensor to Detect Glucose Based on the Modification of Copper Electrode

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

Electro-Structured Cu Distorted Nanopyramids for Superior Sweat Glucose Sensing

There is a rising global demand for non-invasive glucose monitoring devices, due to an increase in diabetes and its associated health problems. Nanostructures, including needles, fibers, and rods, have drawn considerable attention due to their unique structural-based physical and chemical features in non-enzymatic electrochemical sensing. Copper is a potential candidate for applied research because of its higher electrical conductivity, low cost, and strong reactivity. To create 3-D nano copper structures, researchers have investigated chemical, electrochemical, and hydrothermal techniques. The electrochemical method can better control the formation reaction for these structures. The electrochemical process has better control over the formation reaction for these structures.Distinctive and self-supported copper nanopyramids were electrochemically created on a copper substrate within a few seconds by electrochemical deposition in a one pot synthesis. The SEM image of the constructed nano copper pyramids are shown in figure 1a. The built nano pyramids have a length of ~200 nm. The generated nanostructures display excellent catalytic activity for non-enzymatic glucose sensing. The created nonenzymatic sensor was tested for glucose detection in synthetic sweat and it displayed a linear response in the range of 20 µM- 2000 µM, making it appropriate for practical applications. The chrono amperometry for glucose sensing was performed at 0.5V for 60s. Figure 1b shows the calibration plot for glucose sensing. Linear response for the glucose was observed in the range from 20µM – 2000µM. The device showed a very low interference for uric acid and ascorbic acid. The device is stable upto 60 days, highly reproducible and can be reused upto 5 times. The correlation coefficient was 0.9857 for the linear equation I(μA) = (9.52*10-3) *C (in µM) + 5.065 and a sensitivity of 1.17 nA/(μM-cm2) was observed Figure 1

Nonenzymatic Glucose Sensor Using Bimetallic Catalysts.

Bimetallic glucose oxidation electrocatalysts were synthesized by two electrochemical reduction reactions carried out in series onto a titanium electrode. Nickel was deposited in the first synthesis stage followed by either silver or copper in the second stage to form Ag@Ni and Cu@Ni bimetallic structures. The chemical composition, crystal structure, and morphology of the resulting metal coating of the titanium electrode were investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and electron microscopy. The electrocatalytic performance of the coated titanium electrodes toward glucose oxidation was probed using cyclic voltammetry and amperometry. It was found that the unique high surface area bimetallic structures have superior electrocatalytic activity compared to nickel alone. The resulting catalyst-coated titanium electrode served as a nonenzymatic glucose sensor with high sensitivity and low limit of detection for glucose. The Cu@Ni catalyst enables accurate measurement of glucose over the concentration range of 0.2-12 mM, which includes the full normal human blood glucose range, with the maximum level extending high enough to encompass warning levels for prediabetic and diabetic conditions. The sensors were also found to perform well in the presence of several chemical compounds found in human blood known to interfere with nonenzymatic sensors.

Electrochemical and Computational Studies of Citrate-modified β-cyclodextrin@Fe3O4 Nanocomposite as a Nonenzymatic Sensor for Cholesterol

Electrochemical and Computational Studies of Citrate-modified β-cyclodextrin@Fe3O4 Nanocomposite as a Nonenzymatic Sensor for Cholesterol

NiTiO3/Bi2O3/MoS2 double Z-type heterojunction catalysts realize dual-function applications of photocatalytic fuel cells and lactic acid sensing

Sensors in intelligent monitoring and personal healthcare generally face power supply problems, such as cycle charging, regular maintenance, and battery replacement, which greatly limit the applications of sensing devices. Self-powered sensing system with a visible-light-driven photo-fuel cell (PFC) exhibits the advantage of not requiring any external power source for the chemical sensing of analytes. In this work, an enzyme-free PFC self-powered sensing platform was established for sensing sweat lactate using photoelectric conversion technology. A NiTiO3/Bi2O3/MoS2 double Z-type heterojunction system was prepared by electrostatic interaction and self-assembly as the anode of the PFC. NiTiO3, Bi2O3 and MoS2 formed a double Z-type heterojunction system accelerated the electron transfer and improved the light absorption and photocatalytic efficiency, which in turn improved the perception of LA. In addition. lactic acid sensing experiments showed that the prepared non-enzymatic photoelectrochemical sensors had good detection performance. The assay results showed that the prepared biosensor has a wide detection range (30 μM-5 mM), low detection limit (6 μM), high selectivity(8μA μM−1 cm−2) and long-term stability. These assay results demonstrate its potential for applications in fields such as biomedicine and drug analysis.

Novel synthesis of AuPt bimetallic nanocubes combined with graphene quantum dots for non-enzymatic sensor of glucose determination by electrochemical method

Novel synthesis of AuPt bimetallic nanocubes combined with graphene quantum dots for non-enzymatic sensor of glucose determination by electrochemical method

Optimized Copper-Based Microfeathers for Glucose Detection.

Diabetes is expected to rise substantially by 2045, prompting extensive research into accessible glucose electrochemical sensors, especially those based on non-enzymatic materials. In this context, advancing the knowledge of stable metal-based compounds as alternatives to non-enzymatic sensors becomes a scientific challenge. Nonetheless, these materials have encountered difficulties in maintaining stable responses under physiological conditions. This work aims to advance knowledge related to the synthesis and characterization of copper-based electrodes for glucose detection. The microelectrode presented here exhibits a wide linear range and a sensitivity of 1009 µA∙cm-2∙mM-1, overperfoming the results reported in literature so far. This electrode material has also demonstrated outstanding results in terms of reproducibility, repeatability, and stability, thereby meeting ISO 15197:2015 standards. Our study guides future research on next-generation sensors that combine copper with other materials to enhance activity in neutral media.

A General Review of Methodologies Used in the Determination of Cholesterol (C27H46O) Levels in Foods.

Cholesterol (C27H46O) is a lipid-derived substance found in lipoproteins and cell membranes. It is also one of the main sources for the production of bile acids, vitamin D, and steroid hormones. Today, foods are evaluated by consumers not only according to their taste and nutritional content but also according to their effects on consumer health. For example, many consumers choose foods according to their cholesterol level. The cholesterol in the food can directly affect the blood cholesterol level when consumed, which can lead to cardiovascular diseases. High levels of cholesterol can lead to diet-related human diseases such as cardiac arrest, paralysis, type II diabetes, and cerebral hemorrhage. In societies with high living standards, interest in and consumption of foods that lower or have low cholesterol levels have increased recently. Accordingly, efforts to increase the variety of foods with reduced cholesterol levels are on the rise. This has indirectly led to the accurate measurement of cholesterol levels in blood and food being of great importance. Classical chemical, enzymatic, colorimetric, polarographic, chromatographic, and spectrophotometric methods; enzymatic, nonenzymatic, and electrochemical sensors; and biosensors are used for the determination of cholesterol in foods. The purpose of this review is to reveal and explore current and future trends in cholesterol detection methods in foods. This review will summarize the most appropriate and standard methods for measuring cholesterol in biological components and foods.

Non-enzymatic glucose electrochemical sensor based on nitrogen-doped graphene modified with polyaniline and Fe3O4@MIL-101-NH2 nano framework

In this study, a novel highly sensitive and selective non-enzymatic glucose sensor was fabricated by coating simple and cheap graphite sheet (GS) electrodes with a proper conductive nanocomposite containing nitrogen-doped functionalized graphene (NFG), conductive polyaniline (PANI), and core–shell nanoparticles (Fe3O4@MIL-101-NH2). The results revealed that the core centers of iron oxide nanoparticles shelled by MIL-101-NH2 enhanced the electron transfer and led to more conductivity, also their existence caused the limitation of the MOF’s low conductivity. In addition, using Fe3O4@MIL-101-NH2 in the nanocomposite structure led to more sensitivity and selectivity at glucose monitoring due to its amine groups and unique structure. The results showed that NFG/PANI/Fe3O4@MIL-101-NH2 nanocomposite provided a large surface area besides enhanced electron transfer and catalytic properties that lead to proper oxidation of glucose with two linear ranges of 0.5 – 10 µM and 100 µM – 25 mM and a low detection limit of 0.3 µM (S/N = 3). Furthermore, the relative standard deviation (RSD%) in all detection processes was lower than 9 %. Finally, the performance of fabricated non-enzymatic sensor (GS/NFG/PANI/Fe3O4@MIL-101-NH2) in human fluids real samples including serum and plasma was acceptable which significantly indicates that it is toward monitoring of glucose in clinical applications.

Hierarchical composites based on near-spherical ZnO attached on nitrogen-doped reduced graphene oxide for enhanced nitrite electrochemical sensing property

A hierarchical near-spherical ZnO (ns-ZnO)/Nitrogen-doped reduced graphene oxide (N-rGO) nanocomposite was synthesized via a facile hydro/solvo-thermal route. Then, a non-enzymatic nitrite electrochemical sensor (ns-ZnO/N-rGO/GCE) was obtained by modifying glassy carbon electrode (GCE) with the prepared nanocomposite. More adsorption sites and electro-catalytic active sites were provided at the electrode interface thanks to the formation of hierarchical structure, making the fabricated GCE possess a remarkable amperometric sensing property for nitrite. The limit of detection (LOD) was as low as 0.08 μM, and the detection range was as broad as 0.037 μM–5.9 mM. Furthermore, this sensor showed satisfactory recovery for nitrite in genuine samples including ham sausage, pickle and tap water, suggesting the potential practical application performance of ns-ZnO/N-rGO/GCE in the fields of food analysis and environmental monitoring.

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.

A Highly Sensitive Non-Enzymatic Glucose Electrochemical Sensor Electrode Material of CuO Nanospheres/Activated Carbon Composites

A Highly Sensitive Non-Enzymatic Glucose Electrochemical Sensor Electrode Material of CuO Nanospheres/Activated Carbon Composites

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 %.