Amperometric Detection Of Glucose Research Articles

Non-enzymatic Amperometric Detection of Glucose on One-Pot Electrochemical Fabricated Pd Nanoparticles-Graphene Modified Electrodes

Non-enzymatic Amperometric Detection of Glucose on One-Pot Electrochemical Fabricated Pd Nanoparticles-Graphene Modified Electrodes

Development of Electrochemical Paper-Based Devices for Field Assays

The birth of the modern field of paper-based analytical devices (PADs) was marked by the pioneering work by the Whitesides’ group which demonstrated that it was possible to perform complex manipulation of liquids within hydrophilic paper channels delimited by hydrophobic barriers [1]. The key features of paper as a platform are: a) flexibility; b) low thickness and lightness; c) absorbency; d) high surface-to-volume ratio; e) hydrophilicity and capillary action; f) chemical and biological inertness; g) disposability and biodegradability, and; h) low cost and wide availability. Among the various detection modes that are compatible with PADs, electrochemical detection is very attractive since electrochemical transducers can be readily and rapidly patterned on paper using various approaches. Combined with low-cost and portable instrumentation, electrochemical PADs (ePADs) are well suited to on-site assays and point-of-care testing and relevant applications have been developed in various fields such as clinical diagnostics, environmental monitoring and food quality control [2-4].The methods of patterning of the hydrophobic barriers and of depositing the electrodes are critical in the fabrication of ePADs and several approaches have been proposed in the literature [2-4]. Τhe aim of this work was the development of different approaches for the fabrication of ePADs. For this purpose, hydrophobic barriers were delimited using: x-y plotting with commercial hydrophobic marker pens, wax printing and thermal printing. Electrodes were deposited on the PADs using x-y plotting with commercial writing pencils and conductive inks formulated in-house and screen-printing. Different fabrication parameters were optimized including the selection of the paper substrate, the conditions for the formation of the hydrophobic barriers and the electrode deposition parameters. Applicability of the ePADs was demonstrated for different applications for on-site assays including the enzymatic amperometric detection of glucose, the determination of trace metals by stripping analysis and the voltammetric detection of organic compounds.

Diabetes Management by Fourth-Generation Glucose Sensors Based on Lemon-Extract-Supported CuO Nanoporous Materials.

Diabetes is a major worldwide health issue, impacting millions of people around the globe and putting pressure on healthcare systems. Accurate detection of glucose is critical for efficient diabetes care, because it allows for prompt action to control blood sugar levels and avoid problems. Reliable glucose-sensing devices provide individuals with real-time information, allowing them to make more educated food, medicine, and lifestyle decisions. The progress of glucose sensing holds the key to increasing the quality of life for diabetics and lowering the burden of this prevalent condition. The present investigation addresses the synthesis of a CuO@lemon-extract nanoporous material using the sol-gel process. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to analyze the morphological properties of the composite, which revealed a homogeneous integration of CuO nanoparticles (NPs) on the surface of the matrix. The existence of primarily oxidized copper species, especially CuO, was confirmed by X-ray diffraction spectroscopy (XRD) investigation in combination with energy-dispersive X-ray (EDX) spectroscopy. The CuO@lemon-extract-modified glassy carbon electrode (CuO@lemon-extract GCE) performed well in non-enzymatic electrochemical sensing applications such as differential pulse voltammetry (DPV) and amperometric glucose detection. The electrode achieved a notable sensitivity of 3293 µA mM-1 cm-2 after careful adjustment, with a noticeable detection limit of 0.01 µM (signal-to-noise ratio of 3). The operational range of the electrode was 0.01 µM to 0.2 µM, with potential applied of 0.53 V vs. Ag/AgCl. These findings underscore the CuO@lemon-extract GCE's promise as a robust and reliable platform for electrochemical glucose sensing, promising advances in non-enzymatic glucose sensing (NEGS) techniques.

(Invited) integration of Microneedles and Electrochemical Sensors for Medical Applications

Microneedles are small-scale devices that may be used for access to interstitial fluid and/or capillary blood for transdermal monitoring of chemicals [1]. In this presentation, the integration of several types of electrochemical sensors with hollow microneedles will be considered. For example, carbon fiber electrodes have been integrated with digital micromirror device-produced microneedles; ascorbic acid and hydrogen peroxide were detected with these devices [2]. Carbon paste electrodes have also been integrated with digital micromirror device-produced microneedles; electrodes made from rhodium-dispersed carbon paste were used for hydrogen peroxide sensing [3]. In addition, lactate oxidase-modified rhodium-dispersed carbon paste electrodes were demonstrated for lactate sensing, including in the presence of interferents such as ascorbic acid, uric acid, and acetaminophen. A multiplexed microneedle array containing digital micromirror device-produced microneedles was subsequently used for amperometric detection of glucose, lactate, and pH; detection of these analytes in complex media was shown [4]. More recently, digital micromirror device-produced hollow microneedles were modified with a working sensor, which was prepared with graphene ink and 4 (3-Butyl-1-imidazolio)-1-butanesulfonate) ionic liquid. Direct oxidation of fentanyl via square-wave voltammetry was shown; a detection limit of 27.8 μM was demonstrated using this approach [5]. Two photon polymerization has also been used to create hollow microneedles for biosensing; a porous carbon electrode created using interference lithography was used for potassium ion sensing in the presence of interfering sodium ions [6]. In another study, nitrogen-incorporated ultrananocrystalline diamond coatings were deposited on Ti –6Al–4V alloy microneedles using microwave plasma enhanced chemical vapor deposition; dopamine and uric acid were electrochemically detected in an in vitro study [7]. These studies indicate that microneedles may have utility for minimally invasive detection of analytes in a real time manner. Benefits and disadvantages of the microneedle-based sensing approach as well as efforts needed for clinical translation of microneedle-based sensing technology will be considered.

Development of Wearable Microneedle-Based Platform for Real-Time Biomarkers Sensing

The wearable device technology plays a huge role in the healthcare sector owing to the aging global population and increased acquisition of the internet of things (IoT). Further, the Coronavirus Disease-2019 (COVID-19) pandemic has accelerated the emergence of wearable medical devices in the market. The patients with chronic diseases are more focused on tracking single or multiple nutrients and biomarkers in the body. Diabetes is a classic example of chronic disease where the patients need to monitor their blood glucose level for a long time. In addition, diabetic patients also face electrolyte imbalance which gives rise to several other diseases. There is an immense urgency to develop a sensing platform that can detect the essential ions as well as biomarkers from the interstitial fluid (ISF) as it contains valuable information about the physiological status of a person. According to Centers for Disease Control and Prevention (CDC), imbalance of sodium concentration in the body may lead to stroke, hypertension, and epilepsy; for potassium: arrhythmia, chronic kidney disease (CKD), and dizziness; for calcium: depression, osteoporosis, and other bone-related disease; for pH of body fluid: urinary tract infection, respiratory acidosis, and sleep apnea. Within this advent of wearables, microneedle (MN)-based transdermal sensors are well positioned to play a key role in combining the significant benefits of dermal interstitial fluid (ISF) as a source of clinical indicators and minimally invasive skin puncturing to allow the collection of real-time diagnostic data. In this context, we have developed a MNs based versatile platform for the transdermal amperometric detection of glucose and different clinically relevant biomarkers such as K+, Na+, Ca2+ in the body fluid in a robust, reliable, and cost-effective way. Here, stainless steel microneedle (SS-MN) is used as an ideal candidate for multiplex sensing due to its great chemical stability as well as the rigidity for accurate and painless puncture. The device is fabricated with ion selective electrode (ISM) coating on each needle for their corresponding electrolyte and enzyme for glucose detection. In vitro experiments performed in artificial ISF samples yielded excellent sensitivity and a good linear response. The sensor is successfully applied for in vivo detection of glucose and these ions in SD rats for validating their feasibility as a real-time sensing device. Overall, this developed concept comprises of significant progress in the sensing of glucose and other ions in relation to an electrolyte imbalance in the humans that holds relevance in controlling several diseases.

Electrochemical Fabrication of 2D CuO Nanosheets on Pt Foil as a Highly Sensitive Non‐Enzymatic Glucose Sensor

AbstractA simple and environmentally‐friendly approach was developed to synthesize 2D CuO nanosheets using electrochemical deposition. The formed 2D CuO nanosheets (NSs) exhibit numerous advantageous properties such as no toxicity, high electrical conductivity, large active surface area, and a p‐type semiconducting nature with a band gap of 1.2 eV. A sensitive electrochemical sensor was constructed for the amperometric detection of glucose to take advantage of these characteristics. The fabricated sensor displayed an excellent sensitivity of 2710 μA mM−1 cm−2 along with a wide linear range of 0.001–1.0 mM and a lower limit of detection of 0.8 μM (S/N=3). Additionally, the modified electrode possesses high selectivity and good stability. The outstanding electrocatalytic performance of the electrode is attributed to a large active surface area, unique structural morphology, and the high conductivity of the 2D CuO nanosheets.

Portable Amperometric Glucose Detection based on NiS/CuS Nanorods Integrated with a Smartphone Device

Glucose detection is particularly important for clinical diagnosis and personal prevention and control. Herein, the smartphone-based amperometric glucose sensors were constructed using the NiS/CuS nanorods (NRs) as sensing electrodes. The NiS/CuS NRs were prepared through a facile hydrothermal process accompanied by the subsequent vulcanization treatment. The morphological and structural properties of NiS/CuS NRs were characterized with SEM, EDS, XRD, and XPS. Electrochemical measurements including cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy display that NiS/CuS NRs can act as highly efficient electrocatalyst for glucose detection. The NiS/CuS NRs electrodes present a wide detection range of 1–8000 μM for glucose sensing with the sensitivity of 956.38 μA·mM<sup>−1</sup>·cm<sup>−2</sup>. The detection limit was 0.35 μM (S/N=3). When employed in smartphone-based glucose sensing device, they also display a high sensitivity of 738.09 μA·mM<sup>−1</sup>·cm<sup>−2</sup> and low detection limit of 1.67 μM. Moreover, the smartphone-based glucose sensing device also presents favorable feasibility in determination of glucose in serum samples with the recoveries ranging between 99.5 and 105.8%. The results may provide a promising viewpoint to design other new portable glucose sensors.

Non-enzymatic glucose sensing using a nickel hydroxide/chitosan modified screen-printed electrode incorporated into a flow injection analysis system.

This works presents a novel screen-printed carbon electrode modified with nickel hydroxide nanoparticles and chitosan (Ni(OH)2/CS/SPCE) for the non-enzymatic flow injection amperometric detection of glucose. The electrode was modified by drop-casting a suspension of the synthesised nanocomposite onto the screen-printed electrode and dried for 1 hour at room temperature. EDX analysis was used to investigate the chemical composition of the electrode before and after modifying. The electrochemical response of the unmodified SPCE and modified electrode was initially investigated by cyclic voltammetry (CV) using 0.1 M NaOH as the supporting electrolyte. CVs showed catalytic activity for glucose oxidation using the Ni(OH)2/CS/SPCE at 0.55 V. During flow injection analysis (FIA), 0.60 V and 1.5 mL min-1 were identified as the optimal potential and flow rate, respectively. A wide linear range of detection was observed (0.2 to 10.0 mM) with a sensitivity and limit of detection of 913 μA mM-1 cm-2 and 0.0174 mM, respectively. The modified electrode also displayed excellent repeatability (RSD = 0.47%, n = 20) and good reproducibility (RSD = 2.52%, n = 6). The modified electrode was shown to be very selectivity for glucose over other interferences commonly found in human blood samples. The practicality of the developed flow injection-amperometric system (FIA-Amp) was validated by the quantification of glucose in real serum samples, where results were in close agreement with those obtained from the local hospital.

Çok Duvarlı Karbon Nanotüpler/Politiyofen Kompozit Kullanılarak Hazırlanan Amperometrik Glikoz Biyosensörü

In this study, multi-walled carbon nanotubes/polythiophene composite (MWCNTs/PTh) modified glassy carbon electrode was used for the amperometric detection of glucose. Glucose oxidase (GOx) was entrapped by a crosslinking agent on the MWCNTs/PTh composite film synthesized by electrochemical polymerization of thiophene onto MWCNTs. Characterization of composite film was achieved by cyclic voltammetry (CV), fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) techniques. The amperometric measurements of electrode was performed at +0.70V vs. SCE, which was the electrooxidation potential of enzymatically produced H2O2. The effects of thiophene amount in the composite, pH, temperature and substrate concentration were investigated on the response of enzyme electrode. Optimum pH was 7.0 at room temperature and the response time of enzyme electrode was 25 s. The upper limit of the linear working range was 4.85 mM glucose concentration. The limit of detection of sensor was calculated as 148 µM. The sensitivity of glucose biosensor was determined as 4.39 µA mM-1 cm-2. The value of apparent Michaelis-Menten constant (KMapp) was 1.68 mM according to the Lineweaver-Burk equation. The activation energy of this immobilized enzyme system was 88.92 kJ mol-1.

Facile fabrication of hierarchically nanostructured gold electrode for bio-electrochemical applications

Nanoporous gold (NPG) is one of the most extensively investigated nanomaterials owing to its tunable pore size, ease of surface modification, and range of applications from catalysis, actuation, and molecular release to the development of electrochemical sensors. In an effort to improve the usefulness of NPG, a simple and robust method for the fabrication of hierarchical and bimodal nanoporous gold electrodes (hb-NPG) containing both macro-and mesopores is reported using electrochemical alloying and dealloying processes to engineer a bicontinuous solid/void morphology. Scanning electron microscopy (color SEM) images depict the hierarchical pore structure created after the multistep synthesis with an ensemble of tiny pores below 100 nm in size located in ligaments spanning larger pores of several hundred nanometers. Smaller-sized pores are exploited for surface modification, and the network of larger pores aids in molecular transport. Cyclic voltammetry (CV) was used to compare the electrochemically active surface area of the hierarchical bimodal structure with that of the regular unimodal NPG with an emphasis on the critical role of both dealloying and annealing in creating the desired structure. The adsorption of different proteins was followed using UV-vis absorbance measurements of solution depletion revealing the high loading capacity of hb-NPG. The surface coverage of lipoic acid on the hb-NPG was analyzed using thermogravimetric analysis (TGA) and reductive desorption. The roughness factor determinations suggest that the fabricated hb-NPG electrode has tremendous potential for biosensor development by changing the scaling relations between volume and surface area which may lead to improved analytical performance. We have chosen to take advantage of the surface architectures of hb-NPG due to the presence of a large specific surface area for functionalization and rapid transport pathways for faster response. It is shown that the hb-NPG electrode has a higher sensitivity for the amperometric detection of glucose than does an NPG electrode of the same geometric surface area.

(Invited) Homo- and Heteromatallic Cyanide Bridged Networks and Derived Materials for Selected Electrochemical Applications Involving Enhanced Charge Transport and Storage

Hexacyanoferrates and related cyanometallates exhibit model electron transfer properties that are of importance to many electrochemical and related applications. In particular homo- and heterometallic cyanide bridged networks and derived materials have proven to exhibit very rich and diverse electrochemical properties. Their redox properties can be tuned by adjusting stoichiometry and oxidation state of the constituent metal centers, incorporation of interstitial ions, or preparation methods. Polynuclear cyanometallates are promising open-framework systems for low-cost electrochemical energy storage applications. Both soluble and insoluble analogues of Prussian blue have been explored as cathode materials with lithium, sodium, potassium, magnesium, calcium, and even zinc intercalated ionic carriers. Electrochromic devices are another promising area for employing the unique properties of cyanometallates. Prussian blue itself exhibits electrocatalytic properties toward hydrogen peroxide, and it has been used for biosensing and amperometric detection of glucose, L-cysteine, and glutamate. Also removal of radioactive cesium ions from contaminated water has been successfully achieved with Prussian blue and its metal substituted analogues.It is well-established that the choice of redox-active charge-storage material has a significant impact on the performance of a redox flow battery. The concentration of redox centers and their reaction kinetics have an influence on the available current densities and, thus, the power of the device. Remembering the requirement of good solubility of redox species, the semi-solid slurry approach (provided that the dispersion is homogeneous) represents another effective way to improve the volumetric capacity of the redox electrolyte (i.e. of the electrolyte with dissolved redox couples). An interesting approach to improve current densities involves application of circulating suspensions of electroactive materials. Prussian blue and its metal (Fe, Co, Ni, etc.) substituted analogues, which are electroactive mixed-valence inorganic systems, exhibit very rich and diverse electrochemistry. Their electrochemical properties that can be tuned through the variation of the material composition. Special attention will be paid to the formation of stable colloidal suspensions of truly mixed-valence fast-conducting Berlin Green, iron(III) hexacyanoferrate(III,II), together with multi-layered clay-like nickel(II) hexacyanoferrate(III) structures characterized by fast potassium counter-cation motion. It can be hypothesized that the proposed system could serve as the catholyte redox suspension containing large population of mixed-valence redox centers and capable of fast charge propagation and, consequently, yielding fairly large current densities. The materials can also be explored for sorption of large concentrations of Zn2+ ions and for the improvement of the Zn2+/Zn chemistry. While the application of Zn2+/Zn as the anode active system is well established in redox flow batteries, we are going to address and minimize limitations that include the efficiency of zinc deposition and the hydrogen evolution reaction taking place at the potentials where Zn is electrodeposited. The increase of current density could be achieved not only by reducing the viscosity of the electrolyte, thus accelerating charge-carrier transport, but also – by referencing to our experience with mixed-valent nickel hexacyanoferrate system as charge relay for dye-sensitized solar cells – through improvement of the dynamics of charge propagation by improving mobility of charge compensating counter-ions.

Fabrication of Cu(II) oxide-hydroxide nanostructures onto graphene paper by laser and thermal processes for sensitive nano-electrochemical sensing of glucose

Glucose electrochemical sensors based on nanostructures of CuO/Cu(OH)2 onto graphene paper were prepared by thermal (solid) and nanosecond pulsed laser (molten phase) dewetting of a CuO layer 6 nm thin deposited by sputtering. Dewetted systems, obtained without the use of any binder, act as array of nanoelectrodes. Solid state and molten phase dewetting produce nanostructures of copper oxide-hydroxide with different average size, shape and surface composition. Molten phase dewetting originates particles with size below 100 nm, while solid state dewetting produces particles with average size of about 200 nm. Moreover, molten phase dewetting produce drop-shaped nanostructures, conversely nanostructures derived from solid state dewetting are multifaceted. X-ray photoelectron spectroscopy (XPS) characterization revealed that the surface of nanostructures is formed by a copper(II) species CuO and Cu(OH)2. Shape of anodic branch of the cyclic voltammograms of glucose in alkali solution evidenced a convergent diffusion mechanism. Analytical performances in amperometric mode are as good as or better than other sensors based on copper oxide. Amperometric detection of glucose was done at potential as low as 0.4 V versus saturated calomel electrode by both types of electrodes. Linear range from 50 μM to 10 mM, sensitivity ranging from 7 to 43 μA cm−2 mM−1 and detection limit of 7 μM was obtained. Good analytical performances were obtained by laser dewetted electrodes with a low copper content up to 1.2 by atoms percentage of the surface. Analytical performance of the proposed electrodes is compliant for the determination of glucose both in blood serum, saliva or tear.

Laser-Induced Graphene-Based Enzymatic Biosensor for Glucose Detection.

Laser-induced graphene (LIG) has recently been receiving increasing attention due to its simple fabrication and low cost. This study reports a flexible laser-induced graphene-based electrochemical biosensor fabricated on a polymer substrate by the laser direct engraving process. For this purpose, a 450 nm UV laser was employed to produce a laser-induced graphene electrode (LIGE) on a polyimide substrate. After the laser engraving of LIGE, the chitosan–glucose oxidase (GOx) composite was immobilized on the LIGE surface to develop the biosensor for glucose detection. It was observed that the developed LIGE biosensor exhibited good amperometric responses toward glucose detection over a wide linear range up to 8 mM. The GOx/chitosan-modified LIGE biosensor showed high sensitivity of 43.15 µA mM−1 cm−2 with a detection limit of 0.431 mM. The interference studies performed with some possible interfering compounds such as ascorbic acid, uric acid, and urea exhibited no interference as there was no difference observed in the amperometric glucose detection. It was suggested that the LIGE-based biosensor proposed herein was easy to prepare and could be used for low-cost, rapid, and sensitive/selective glucose detection.

Efficient electrocatalytic oxidation of water and glucose on dendritic-shaped multicomponent transition metals/spongy graphene composites

To improve the efficiency of electrochemical processes for environmental remediation, we present a new type of hybrid nanomaterials based on leaf-like copper-based quaternary transition metals and spongy monolayer graphene. To demonstrate the functionality of the hybrid electrocatalyst, fast and competent electrooxidation of water and glucose is shown. The mechanism of improved catalysis is ascribed to the synergetic catalytic effect of quaternary Cu-Ni-Fe-Co alloy with dendritic morphology along with the highly conductive and spongy structure of the graphene monolayer. It is shown that water oxidation can be performed at a low overpotential of 315 mV to reach a current denisty of 100 mA cm-2 and a low Tafel slope of 63.06 mV dec−1. Fast and sensitive amperometric detection of glucose at low concentrations (≥1.3 μM; 4153 μA mM−1 cm−2) in alkaline solutions is also presented. The compelling performance of the hybrid catalyst as compared with many noble-metal and non-precious metal electrocatalysts for water oxidation and electrochemical sensing is reported.

2D metal azolate framework as nanozyme for amperometric detection of glucose at physiological pH and alkaline medium.

Thesynthesis of Co-based two-dimensional (2D) metal azolate framework nanosheets (MAF-5-CoII NS) is described usinga simple hydrothermal method. The product was isostructural to MAF-5 (Zn). The as-prepared MAF-5-CoII NS exhibited high surface area (1155m2/g), purity, and crystallinity. The MAF-5-CoII NS-modified screen-printed electrode (MAF-5-CoII NS/SPE) was used for nonenzymatic detection of glucose in diluted human blood plasma (BP) samples with phosphate buffer saline (PBS, pH7.4) and NaOH (0.1M, pH13.0) solutions. The MAF-5-CoII NS nanozyme displayed good redox activity in both neutral and alkaline media with the formation of CoII/CoIII redox pair, which induced the catalytic oxidation of glucose. Under the optimized detection potential, the sensor presented a chronoamperometric current response for the oxidation of glucose with two wide concentration ranges in PBS-diluted (62.80 to 180μM and 305 to 8055μM) and NaOH-diluted (58.90 to 117.6μM and 180 to 10,055μM) BP samples, which were within the limit of blood glucose levels of diabetic patients before (4.4-7.2mM) and after (10mM) meals (recommended by the American Diabetes Association). The sensor has a limit of detection of ca. 0.25 and 0.05μM, respectively, and maximum sensitivity of ca. 36.55 and 1361.65mA/cm2/mM, respectively, in PBS- and NaOH-diluted BP samples. The sensor also displayed excellent stability in the neutral and alkaline media due to the existence of hydrophobic linkers (2-ethyl imidazole) in the MAF-5-CoII NS, good repeatability and reproducibility, and interference-free signals. Thus, MAF-5-CoII NS is a promising nanozyme for the development of the disposable type of sensor for glucose detection in human body fluids. Graphical abstract.

Single Potential Scan Methods for Nanoporous Gold Formation on Ultramicroelectrode Surfaces

AbstractNanoporous gold (NPG) has been extensively investigated because of their applications. Here, we report a straightforward method for the preparation of NPG on micrometer‐scale electrodes. Well‐defined NPG structures were formed on Au surfaces by a single potential scan within 100 seconds. This method is applied to Au surfaces with small dimensions regardless of the electrode geometry, whereas it is not applicable to conventional millimeter‐scale electrodes. The effects of electrode sizes and scan rates on NPG formation were systematically examined, and the amperometric glucose detection with 20‐μL sample volumes using an ultramicroelectrode (UME) with NPG surfaces was demonstrated.

Au (111)-like electrode in highly ordered SiO2-cavity: a novel nonenzymatic amperometric detection of glucose

Au (111)-like electrode in highly ordered SiO2-cavity: a novel nonenzymatic amperometric detection of glucose

Amperometric detection of glucose and H2O2 using peroxide selective electrode based on carboxymethylcellulose/polypyrrole and Prussian Blue nanocomposite

Carboxymethylcellulose (CMC), which is obtained from one of the most abundant biomass materials in the world, could have a major role in many practical applications thanks to its promising properties. In this work, electrochemical synthesis of polypyrrole (PPy) with simultaneous incorporation of CMC as dopant/plasticizing agent and Prussian Blue nanoparticles (PBNPs) as a peroxidase mimetic catalyst have been performed to design biocompatible sensor platform. CMC displays an effective mission in every stage of sensor platform formation. It increases the dispersibility of pyrrole (Py) in water with its template effect, and it enhances the conductivity of polypyrrole chains after electropolymerization by acting as a dopant and a plasticizer. Moreover, CMC in the composite structure increases the hydrophilicity of the sensor platform that may cause a significant improvement in the operational stability of the sensor. Such a 3D interwoven structure produced on the indium tin oxide electrode by a smart combination of materials used exhibited high-performance sensor responses to hydrogen peroxide (H2O2) and glucose. Sensor optimization resulted in a limit of detection (LOD) of 0.59 μM, a linear range from 5 to 470 μM and a sensitivity of 456.8 μA mM−1 cm-2 for H2O2 detection. When the same sensor platform used in glucose detection after GOx immobilization resulted in 5.23 μM LOD with a linear range from 20 and 1100 μM and a sensitivity of 456.8 μA mM−1 cm-2. Moreover, the interference of the most common interfering compounds would exist in real samples was also featured to set the ground for further sensor studies based on CMC, PPy, and PBNPs.

Metal–Organic Framework‐Derived Nickel/Cobalt‐Based Nanohybrids for Sensing Non‐Enzymatic Glucose

AbstractThe daily detection of blood glucose levels has become a major concern globally because blood glucose levels are related to human health. Composites comprising non‐noble metal nanomaterials and highly conductive carbon materials are active and selective catalysts for glucose detection in non‐enzyme sensors, and are therefore particularly attractive. In the present study, we prepared nickel/cobalt (NiCo) alloy nano‐particles encapsulated in graphitized carbon by pyrolyzing a bimetallic (Ni and Co) metal organic framework (NiCo‐MOF) at 800 °C under a nitrogen atmosphere (denoted NiCo/C). In the linear range 0.5 μM–4.38 mM, a non‐enzymatic glucose sensor comprising SPE/NiCo/C (SPE=screen‐printed electrode) exhibited a high sensitivity of 265.53 μA mM−1 cm−2, with a low detection limit of 0.2 μM (S/N=3). The NiCo/C sensor had good selectivity for the amperometric detection of glucose. Glucose levels were measured with acceptable reliability and accuracy in human serum samples. The current work offers an alternative tool for diagnosing diabetes and monitoring daily blood glucose levels.

Copper-molybdenum sulfide/reduced graphene oxide hybrid with three-dimensional wrinkles and pores for enhanced amperometric detection of glucose

A new transitional metal sulfide-reduced graphene oxide hybrid CuxS-MoS2-rGO was developed for enhanced electrocatalytic oxidation and amperometric sensing of glucose. The hybrid was prepared by a facile one-pot hydrothermal approach. The component and structure of the hybrid were characterized by SEM, EDS, XPS, XRD, and Raman spectrum. The MoS2-rGO forms a three-dimensional (3D) wrinkled porous matrix, and element Cu in the form of CuxS (x = 1 or 2) is well dispersed in it. The introduction of Cu greatly elevates the catalysis, while MoS2 plays a key role in forming 3D wrinkled and porous structure, while rGO obviously accelerates the electron transfer. Due to their synergy effect, the hybrid CuxS-MoS2-rGO displays significantly enhanced catalysis towards glucose oxidation (40-fold enhanced oxidation current compared with that of MoS2 or MoS2-rGO or nearly 40% increase than that of CuxS-rGO). Based on this, a nonenzymatic amperometric sensor for glucose was developed, which shows a wide linear range of 2-6330 μM, a low detection limit of 0.6 μM, a high stability and adequate selectivity. For glucose sensing in human serum, the developed sensor shows recoveries between 97.2% and 101.2%. Such facile and high-yield approach can be used to prepare other multi-transitional metal sulfide hybrid with promising application in electrochemical sensor and electrocatalysis.