Enzyme-free Glucose Detection Research Articles

Convenient and Accurate Detection of Dopamine and Glucose by Modifying Carbon Fiber Electrodes

Fast, sensitive, and low-cost high-performance detectors have gradually become an indispensable tool for people to keep healthy, and sensors are the key devices of detection equipment. In this work, a ZnO nanocrystal modified carbon fiber electrode was prepared using a hydrothermal method, and on this basis, a galvanostatic point deposition method was used to load copper nanoparticles to prepare a sensor electrode. Scanning electron microscopy and X-ray diffraction were used to comprehensively analyze composition, morphology, and environmental adaptability of the prepared electrodes. The DPV test was used to verify the enhanced effect of ZnO nanorods on neurotransmitter detection. The ZnO/CF showed an obvious electrical signal (0.22 V, 4 × 10−5A) in the detection of dopamine (DA) solution, and the Cu-NPs/ZnO/CF also showed excellent detection results in the glucose detection experiment., providing two excellent examples for the development of low-cost electrochemical sensors. The electrodes can specifically detect DA in the presence of ascorbic acid and uric acid, and the detection limit of the electrode for detecting DA is about 0.4 μM. In addition, the Cu-NPs/ZnO/CF electrode successfully realized the enzyme-free detection of glucose, and the detection limit could reach 0.5 μM.

Enzyme-free glucose detection via scalable and economical fabrication of nickel-polyvinylpyrrolidone-modified multi-walled carbon nanotubes

Development of accurate, reliable, and affordable glucose detection tools remains a top scientific priority. Nanotechnology and related materials are frequently utilized for this purpose. In this study, polyvinylpyrrolidone (PVP)-modified nickel (Ni) nanoparticles on multi-walled carbon nanotube (MWCNT) were prepared using a unique microwave synthesis technique. The synthesized particles were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). TEM analysis revealed that well-dispersed Ni nanoparticles with an average size of about 4.11 nm were uniformly dispersed on the MWCNT surface in the presence of PVP particles. The obtained NiPVP@MWCNT was used for the glucose sensor and its performance was investigated. According to the results, the limit of detection (LOD) and limit of quantification (LOQ) values for NiPVP@MWCNT nanocomposite in the linear range of 0.1 mM - 1 mM were calculated as 0.364 mM and 1.215 mM, respectively. As a result of the selectivity test, it was observed that it was highly selective for glucose and the current values increased with increasing concentration. The developed nanostructures are efficient, highly stable, discriminative, and sensitive and have the potential to be used as glucose sensors in the market.

Benchtop Fabricated Nano-Roughened Microstructured Electrodes for Electrochemical and Surface-Enhanced Raman Scattering Sensing.

Tailoring a material's surface with hierarchical structures from the micro- to the nanoscale is key for fabricating highly sensitive detection platforms. To achieve this, the fabrication method should be simple, inexpensive, and yield materials with a high density of surface features. Here, using benchtop fabrication techniques, gold surfaces with hierarchically structured roughness are generated for sensing applications. Hierarchical gold electrodes are prepared on pre-stressed polystyrene substrates via electroless deposition and amperometric pulsing. Electrodes fabricated using 1mm H[AuCl₄] and roughened with 80 pulses revealed the highest electroactive surface area. These electrodes are used for enzyme-free detection of glucose in the presence of bovine serum albumin and achieved a limit of detection of 0.36mm, below glucose concentrations in human blood. The surfaces nanoroughened with 100 pulses also showed excellent surface-enhanced Raman scattering (SERS) response for the detection of rhodamine 6G, with an enhancement factor of ≈2×106 compared to detection in solution, and for the detection of a self-assembled monolayer of thiophenol, with an enhancement factor of ≈30 compared to the response from microstructured gold surfaces. It is envisioned that the simplicity and low fabrication cost of these gold-roughened structures will expedite the development of electrochemical and SERS sensing devices.

Smartphone-interfaced flow injection amperometric system for enzyme-free glucose detection using a palladium-PANI/carbon microsphere@carbon nanotubes modified electrode

Integrating a flow injection system with an electrochemical sensor controlled by a smartphone enables rapid, precise real-time monitoring and reduces analyte consumption, contamination and costs. An enzyme-free electrochemical sensor is presented for the monitoring of glucose, an important indicator of diabetes. The sensor integrates a smartphone and a flow injection amperometric system. The flow cell is fabricated from acrylic plastic and includes an electrochemical three-electrode cell that comprises a working electrode modified with a catalyst of palladium-polyaniline/carbon microspheres@carbon nanotubes (Pd-PANI/CM@CNTs/E) for the detection of glucose oxidation. In the optimal condition, the proposed system produced good analytical performances. The sensor determined glucose linearly in a range from 0.020 to 100 mM, with a sensitivity of 51.51 μA mM−1 cm−2, and a detection limit (LOD) of 0.0071 mM. The developed system also exhibited good repeatability, reproducibility, operational stability, and anti-interference properties, and accurately determined glucose levels in real human serum samples. This sensing platform provides an alternative tool for the development of a continuous glucose monitor system for clinical applications.

Exploring Cu0–Cu+ sites for enhancing non-enzymatic photoelectrochemical glucose sensing performance

Photoelectrochemical (PEC) sensing platforms demonstrate outstanding performances towards enzyme-free glucose detection, and exploring glucose reactive electrodes with efficient active sites and enhanced carrier transport/separation behavior would be beneficial for PEC glucose detection. Herein, we fabricated two-dimensional Cu3(PO4)2 nanosheets as the photoactive material for glucose detection. The morphology and structural characterizations prove the existence of balanced Cu0–Cu+ active sites which has been regarded as the key factor on improving PEC performance for fast glucose detection. The photocurrent of Cu3(PO4)2 nanosheets is three times that of Cu3(PO4)2 bulk in the absence of glucose, and the response performance is increased by about 9 times compared to Cu3(PO4)2 bulk at 50 µM glucose. Under light conditions, the limit of detection (LOD) as low as 17.68 µM at low concentration of 20–100 µM, and LOD of 131.69 µM at high concentration of 100–1000 µM can be achieved. This work might provide the basic understanding and new opportunities in applying two-dimensional Cu3(PO4)2 nanosheets for glucose detection.

Rational design of an innovative hybrid biosensor utilizing functionalized ZnO-Cys-graphene ternary composite for enzyme-free glucose detection

The limitations of enzymatic sensors for glucose detection have been addressed through the development of non-enzymatic sensors utilizing Zinc Oxide (ZnO). ZnO is an attractive choice due to its favourable properties, including cost-effectiveness, catalytic activity, large surface area, high adsorption capacity, and biocompatibility, which make it well-suited for glucose sensing applications. To enhance sensing performance, L-Cysteine, a low molecular weight amino acid, was employed as a capping agent for ZnO, leveraging its functional groups to improve the sensor's adsorption capacity and sensitivity. Additionally, graphene, a two-dimensional carbon material with excellent conductivity and surface area, was incorporated into the composite of cysteine-capped ZnO (ZnO-Cys), resulting in a ZnO-Cysteine-Graphene (ZnO-Cys-GNS) composite. This incorporation aimed to further enhance the sensing properties of the biosensor. The final products ZnO, ZnO-Cys, ZnO-Cys-GNS were characterized by XRD, SEM, TEM, FTIR and Raman spectroscopy to analyse its structure and morphology. CV and chronoamperometry were used for electrochemical measurements to evaluate the glucose detection capabilities of the materials. The results demonstrated ZnO-Cys-GNS composite showed higher activity towards glucose detection and exhibits sensitivity of 161.12 μA/(mM.cm2) and lower detection limit of 0.663 μM with wide linear detection range from 0.01 mM to 1 mM. The utilization of non-enzymatic sensors based on metal oxides, such as ZnO, and the incorporation of functional molecules like L-Cysteine and graphene overcome the limitations associated with enzymatic sensors, offering a more stable and efficient approach for glucose detection.

Development of non-precious metal oxide-based electrodes for enzyme-free glucose detection: A review

The progress of accurate and economical sensors for glucose determination is vital for the detection and treatment of diabetes. Even though electrochemical enzyme-based sensors have been widely utilized in the medical field for glucose determination, high preparation costs, and poor durability have led to the introduction of a novel type of enzyme-free sensor for glucose recognition. Non-precious metal oxides have been comprehensively explored for the preparation of affordable sensors for non-enzymatic, high-performance glucose detection. This review commences by clarifying the mechanistic aspects of electrochemical sensors for enzyme-free glucose detection, followed by advanced studies on metal oxides with different strategies, including morphology engineering, supported carbon materials, and noble metal doping for efficient glucose detection. Finally, formidable obstacles and future development of non-enzymatic electrochemical glucose sensing are also discussed.

Synthesis and characterization of a high-performance enzyme-free glucose sensor based on mesoporous copper oxide nanoparticles

Mesoporous copper oxide were prepared and characterized as a non-enzymatic glucose sensor. Scanning electron microscopy, X-ray diffraction and surface adsorption analysis were used to analyze the samples. Considering the normal glucose levels, the CV measurements were conducted for glucose concentrations ranging from 1 to 9 mM. Accordingly, nanoparticles with particle sizes less than 100 nm showed a desired linear response for glucose detection in the 1 to 9 mM concentration range. Also, it exhibited a reasonable detection limit of 0.05 μM and a high sensitivity of 733 μAmM−1cm−2 in the alkaline pH range. Furthermore, a relatively good sensitivity for glucose detection in phosphate buffer solution (pH 7.4) was also observed. The optimum detection performance could be attributed to the improvement of the particles size, morphology and pore structure. It was concluded that mesoporous copper oxide nanoparticles have desirable potential functionalities for enzyme-free glucose detection.

A wearable enzyme-free glucose sensor based on nickel nanoparticles decorated laser-induced graphene

• A flexible glucose sensor is fabricated based on multilayer laser-induced graphene. • The sensor exhibits wide linear range and high sensitivity towards glucose. • No signal attenuation is observed after drastic folding for 100 times. • The sensor has been applied to the determination of glucose in human serum. Wearable biosensors that can detect glucose molecules is a promising monitoring device for clinic and health-care analysis. A flexible enzyme-free glucose sensor based on multilayer porous laser-induced graphene (LIG) produced from polyimide (PI) film was developed in this work. Ni/LIG electrode was prepared by electrochemical deposition of Ni nanoparticles on LIG for enzyme-free glucose detection. Ag/AgCl/LIG was prepared as the reference by coating with silver conductive gel and electrochemical anodization methods on LIG. The Ni/LIG glucose sensor possesses excellent flexibility and can function properly after being folded for a hundred times. The sensor exhibits desirable analytical performance towards glucose with wide linear range (0.50 μM to 1666 μM), ultra-high sensitivity (2040 μA/mM·cm 2 ), and low detection limit (0.29 μM). Ni/LIG glucose sensor also shows high stability and minimal responses to the interference substances and has been successfully applied to the determination of glucose in human blood serum with a relative standard deviation (RSD, n = 10) of 0.85%, and recoveries ranging from 99.36% to 100.45%.

Progress in the study of enzyme-free glucose electrochemical sensors

<p>The detection mechanism of enzyme-free glucose electrochemical sensors, the research progress of enzyme-free glucose sensors based on composite materials such as noble metals, transition metals and doped carbon nanomaterials, and the latest progress of new wearable enzyme-free glucose detection devices are reviewed. With the development of science and technology, enzyme-free glucose sensors will potentially be applied to the in vivo detection of animal and plant species, which will become a hot spot for new research.</p>

The heterostructure of ceria and hybrid transition metal oxides with high electrocatalytic performance for water splitting and enzyme-free glucose detection

Metal oxide nanoparticles have always been promising candidates for important catalytic processes such as water splitting and glucose detection. Herein, the electrocatalytic activity of CeO2/CuO/Co3O4 heterostructure is compared with CeO2/CuO and single ceria nanostructures in water splitting and glucose sensing processes. The CeO2/CuO/Co3O4 and CeO2/CuO heterostructures are synthesized using co-precipitation method and calcination at 650 °C. The obtained nanostructures are studied by several techniques. The CeO2/CuO/Co3O4 nanoparticles exhibit an excellent catalytic performance in alkaline OER and especially HER such that the overpotential is 110 mV vs. RHE for HER and 520 mV for OER deliver a current density of 10 mA cm−2, which is very low in the comparison of CeO2/CuO and single CeO2. In a summary, the low Tafel slope, significant reduction in semicircular diameter in Nyquist plots and high stability of CeO2/CuO/Co3O4 for a long time under bulk electrolysis in HER and OER confirm an enhancement in electrical transport, low charge transfer resistance and high durability of the electrocatalyst during water splitting. In addition, glucose sensing properties of the electrocatalysts was investigated. No significant sensitivity for glucose is seen in the presence of single ceria, but the modified electrodes by CeO2/CuO/Co3O4 and CeO2/CuO exhibit high sensitivity (70.90 and 184.4 μA mM−1cm−2), a low limit of detection (0.74 and 0.83 μM), a linear range (3–12 mM), and a short-response time (3 s), along with excellent selectivity, stability, and applicability for glucose detection in real analyte.

Fabrication of Enzyme-Free and Rapid Electrochemical Detection of Glucose Sensor Based on ZnO Rod and Ru Doped Carbon Nitride Modified Gold Transducer.

Over 3 in 4 adults with diabetes live in low- and middle-income counties and health expenditure also increased 316% over the last 15 years. In this regard, we fabricate low cost, reusable and rapid detection of diabetes sensor based on zinc oxide rod inserted ruthenium-doped carbon nitride (ZnO–g–Ru–C3N4) modified sensor device. Developed sensor device physically and electrochemically characterized using X-ray diffraction (XRD), fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Sensing device as an effective enzyme-free glucose detection with high sensitivity (346 μA/mM/cm2) over the applied lower potential of +0.26 V (vs. Ag/AgCl), fast response (3 s) and broad linear range of (2–28) mM, coupled with a lower limit of detection (3.5 nM). The biosensing device gives better anti-interference ability with justifiable reproducibility, reusability (single electrode re-use 26 times in physiological buffer and 3 times in serum) and stability. Moreover, the real-time applicability of the sensor device was evaluated in human blood, serum and urine samples.

One-pot, rapid microwave-assisted synthesis of bimetallic metal–organic framework for efficient enzyme-free glucose detection

Hybrid transition metal-based compounds show excellent performance in the field of enzyme-free glucose sensing. Herein, a one-step, green, facile, highly efficient microwave-assisted strategy for fabricating bimetallic Co/Zn metal–organic frameworks (denoted as ZIF67/ZIF8) is proposed. The structural characterization and phase investigation of ZIF67/ZIF8 are assessed by microscopically studies, elemental mapping, X-ray diffraction and X-ray photoelectron spectroscopy. The proportion of Co and Zn elements of ZIF67/ZIF8 has been elaborately regulated, resulting in enhanced electro-oxidation performance toward glucose compared to mono-metal organic frameworks. The synergy effect between Co and Zn proves to be crucial for optimizing electroanalytical ability, which endows outstanding glucose sensing performance, including high sensitivity of 833.61 μA/mM/cm2, wide linear range up to 5 mM and low detection limit to be 6.5 μM. Furthermore, to demonstrate the practical application capability of ZIF67/ZIF8, real-time analysis in human serum sample is conducted, which confirms its good anti-interference ability and recovery rate. With the advantages of low cost, ease of production and high environment tolerance, this work provides a versatile method to obtain non-noble metal based biosensing materials for non-enzymatic glucose detection.

Enzyme Free Detection of Glucose Using MgO Nanocubes Based Extended Gate N-channel MOSFET

MgO nanocubes were used as a sensing electrode material for detection of glucose in the extended gate field effect transistor (EGFET) configuration. MgO nanocubes were prepared by thermal CVD approach. Morphology and elemental composition of as-prepared MgO nanocubes were obtained using the scanning electron microscope (SEM) along with EDS. The sensing electrode was prepared by coating MgO nanocubes over the copper foil by doctor blade method and it was tested with various concentrations of glucose in Phosphate Buffer Saline (PBS) buffer solution. The MgO nanocubes coated electrode showed linear response for glucose concentrations from 1.6 mM to 25.6 mM. The sensitivity was calculated as 0.12 |aA/mM.cm2.

CeO2 nanoparticles based extended gate field effect transistor for enzyme free detection of glucose

CeO2 nanoparticles based extended gate field effect transistor for enzyme free detection of glucose

Morphology control in oxygen-rich nanotubular titania for enzyme-free glucose detection

The necessity of research in food and nutrition and the emergence of diabetes mellitus call for fast and efficient glucose detection. Here, series of highly sensitive non-enzymatic photoelectrochemical glucose sensor based on engineered titanium dioxide nanotube arrays has been synthesized using a simple electrochemical approach to tune nanotubes morphology in a way that the highest sensitivity factor (525.5 µAmM−1cm−2) and saturation concentrations (0.18 mM) achieved in the photoelectrochemical sensor. The formation of oxygen-rich titanium oxide was confirmed by several techniques. Dependent on the growth condition, nanotube length changed from 1.9 to 8.4 µm while their inner diameter varied from 78 to 156 nm. According to the results, TiO2 nanotube arrays anodized for 4 h at 60 V presented the highest saturation concentration of 0.18 mM, which can be used for high glucose level demand cases. On the other hand, nanotubes anodized for 6 h at 50 V obtained the highest sensitivity factor of 525.5 µAmM−1cm−2 with an excellent detection limit and saturation level of 0.1 mM, which is beneficial for purposes involving slight changes in analyte amount. Both optimized sensors presented reasonable selectivity and stability providing optimum tubular TiO2 nanostructure morphology for developing non-enzymatic photoelectrochemical sensors.

Flower-like CuO/NiO nanostructures decorated activated carbon nanofiber membranes for flexible, sensitive, and selective enzyme-free glucose detection

Flower-like CuO/NiO nanostructures decorated activated carbon nanofiber membranes for flexible, sensitive, and selective enzyme-free glucose detection

Needle-like Co3O4 nanoarrays as a dual-responsive amperometric sensor for enzyme-free detection of glucose and phosphate anion

The high cost and easy denaturation of natural enzymes under environmental conditions largely hinder their practical usefulness in sensing devices. Currently, great efforts have been focused on exploring of novel functional nanomaterials to replace natural enzymatic systems. In this study, we developed a hydrothermal growth of free-standing cobalt oxide (Co3O4) nanoneedle arrays on a flexible carbon cloth (CC) substrate and used them as electrode materials with a high catalytic activity for nonenzymatic glucose sensing. Benefiting from the densely arrayed and free-standing Co3O4 nanoneedles with a large surface area, the resulting Co3O4/CC electrode exhibits an excellent sensing performance for glucose with a broad linear range and low detection limit (0.23 μM). More importantly, the Co3O4/CC electrode also exhibited a good performance for determining phosphate ions in a glucose containing alkaline solution. Under optimal condition, the resulted electrode exhibits a linear range of 0.1–1.0 mM and 1.0–30.0 mM with a detection limit of 10 μM for phosphate anion. The as-proposed electrode was further used for the determination of glucose and phosphate ions in human blood serum and urine samples with satisfactory recoveries, verifying the feasibility and great potential as a sensitive, selective, potable, and low-cost electrochemical electrode in sensing application.

Neutral Nonenzymatic Glucose Biosensors Based on Electrochemically Deposited Pt/Au Nanoalloy Electrodes

BackgroundType I diabetes occurs when the pancreas can only make limited or minimal insulin. Patients with type 1 diabetes need effective approaches to manage diabetes and maintain their blood-glucose concentration. Recently, continuous glucose monitoring (CGM) has been used to help control blood-glucose levels in patients with type 1 diabetes. Patients with type 2 diabetes may also benefit from CGM on multiple insulin injections, basal insulin, or sulfonylureas. Enzyme-free glucose detection in a neutral environment is the recent development trend of CGM.Materials and MethodsPt/Au alloy electrodes for enzyme-free glucose detection in a neutral environment were formed by electrochemically depositing Pt/Au alloy on a thin polycarbonate (PC) membrane surface with a uniformly distributed micro-hemisphere array. The PC membranes were fabricated using semiconductor microelectromechanical manufacturing processes, precision micro-molding, and hot embossing. Amperometry was used to measure the glucose concentration in PBS (pH 7.4) and artificial human serum.ResultsThe Pt/Au nanoalloy electrode had excellent specificity for glucose detection, according to the experimental results. The device had a sensitivity of 2.82 μA mM−1 cm−2, a linear range of 1.39–13.9 mM, and a detection limit of 0.482 mM. Even though the complex interfering species in human blood can degrade the sensing signal, further experiments conducted in artificial serum confirmed the feasibility of the proposed Pt/Au nanoalloy electrode in clinical applications.ConclusionThe proposed Pt/Au nanoalloy electrode can catalyze glucose reactions in neutral solutions with enhancing sensing performance by the synergistic effect of bimetallic materials and increasing detection surface area. This novel glucose biosensor has advantages, such as technology foresight, good detection performance, and high mass production feasibility. Thus, the proposed neutral nonenzymatic glucose sensor can be further used in CGMs.

Electrochemical glucose sensitive device based on graphene supported Co3O4@Ag NWs core-shell nanostructures

We demonstrate the fabrication of Co3O4 (derived from zeolitic imidazolate framework-67) wrapped Ag nanowires core-shell nanostructures, and support it on graphene matrix (Co3O4@Ag NWs-GR) to prepare enzymeless glucose sensor. The core-shell Co3O4@Ag nanowires possess porous surface and the proposed Co3O4@Ag NWs-GR nanocomposites exhibit hierarchical structure which could help to improve the performance of enzyme-free glucose detection. For practical application, the as-prepared Co3O4@Ag NWs-GR nanocomposites were sandwiched by nickel foam (NF) to develop a glucose detection electrode, which demonstrates good reproducibility and glucose specific selectivity. Then, the Co3O4@Ag NWs-GR/NF electrode was integrated with Pt wire, Ag/AgCl wire and polydimethylsiloxane (PDMS) to fabricate a sensitive device. The amperometric response of the as-developed device suggests that the Co3O4@Ag NWs-GR/NF based sensor presents a high sensitivity of 2.49 μA/μM/cm2 in the linear interval of 3–2000 μM, a detection limit of 0.98 μM, as well as an outstanding long-term stability. Additionally, the human serum was used to verify that the Co3O4@Ag NWs-GR based glucose sensor can detect the glucose level in serum, suggesting it is applicable to the enzymeless glucose determination.