Immobilization Of Glucose Oxidase Research Articles

A novel effective immobilization of glucose oxidase on Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4 – Chitosan nanocomposite as an enzymatic glucose biosensor

An effectual enzymatic glucose biosensor has drawn significant attention in the natural world due to its continuous glucose monitoring systems on human beings. A need for accurate and dependable glucose biosensors is needed and has notably augmented the keen interest to synthesize new non-invasive glucose monitoring systems in the recent phase. A novel Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4 nanocomposite has been synthesized via the combustion method to develop an appreciable glucose biosensor. The glucose biosensor was fabricated by immobilization of glucose oxidase (GOx) onto chitosan (CH)-Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4 heterojunction nanocomposite on FTO glass substrate. The performance of the as-prepared enzymatic glucose biosensor was estimated using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The electrochemical studies revealed an enhanced diffusion of molecules on the electrode surface, superior charge transfer rate, high sensitivity, and fast response time. The Ni0.25Zn0.25Cu0.25Co0.25La0.06Fe1.94O4-CH bi-junction conjoining with GOx exhibits a higher sensitivity of 52.76 µAmM-1cm-2 in a comprehensive undeviating range. The catalytic properties of the electrode in the H2O2 solution were studied using cyclic voltammetry, which showed a good linear response with an increase in scan rate and peak current resulting in enriched electrostatic interaction. In addition, the fabricated biosensor with a low Michaelis-Menten constant contributes a better affinity of the electrode surface towards glucose oxide.

Electrochemical Properties Analysis of Immobilized Glucose Oxidase on Multi-Walled Carbon Nanotubes and Hydroxy-Fullerene Nanocomposites

The development of a glucose sensor that can monitor blood glucose levels is particularly important with the increasing number of diabetes patients. Here, a glucose biosensor based on Nafion (NF), glucose oxidase (GOx), multi-walled carbon nanotubes (MWCNTs), hydroxy fullerene (HFs) composite modified glassy carbon electrode (GCE) is presented. The transmission electron microscopy (TEM), field emission scanning electron microscope (FESEM), UV–visible spectroscopy (UV–vis), cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS) methods are used to study the characteristics of the modification materials and to evaluate electrochemical properties of the modified electrodes. The heterogeneous electron transfer constant (ks) is calculated to be 4.49 s−1. The response to glucose is linear in the range of 0.02–0.25 mM and 0.25–4.0 mM with a sensitivity of 80.59 μA mM−1 cm−2 and detection limit (LOD) of 9.93 μM. The NF/MWCNTs-HFs-GOx/GCE biosensor demonstrate high sensitivity to glucose with excellent storage stability and anti-interference capability.

Cascaded Nanozyme with In Situ Enhanced Photothermal Capacity for Tumor-Specific and Self-Replenishing Cancer Therapy.

Reactive oxygen species (ROS)-involved tumor therapeutic strategy, chemodynamic therapy (CDT), has attracted extensive research interest in the scientific community. However, the therapeutic effect of CDT is insufficient and unsustainable owing to the limited endogenous H2 O2 level in the tumor microenvironment. Here, peroxidase (POD)-like RuTe2 nanozyme with the immobilization of glucose oxidase (GOx) and allochroic 3,3',5,5'-tetramethylbenzidine (TMB) molecule have been synthesized to construct RuTe2 -GOx-TMB nanoreactors (RGT NRs) as cascade reaction systems for tumor-specific and self-replenishing cancer therapy. GOx in sequential nanocatalysts can effectively deplete glucose in tumor cells. Meanwhile, a sustainable supply of H2 O2 for subsequent Fenton-like reactions catalyzed by RuTe2 nanozyme is achieved in response to the mild acidic tumor microenvironment. Through this cascade reaction, highly toxic hydroxyl radicals (·OH) are produced, which can further oxidize TMB to trigger tumor-specific "turn-on" photothermal therapy (PTT). In addition, PTT and massive ROS can stimulate the tumor immune microenvironment and activate the systematic anti-tumor immune responses, exerting a notable effect on hindering tumor recurrence and metastasis. This study paves a promising paradigm for synergistic starvation therapy, PTT, and CDT cancer therapy with high efficiency.

Glucose Oxidase Captured into Electropolymerized p-Coumaric Acid towards the Development of a Glucose Biosensor

An electrochemical biosensor based on the immobilization of glucose oxidase into an electropolymerized p-coumaric acid membrane on a Pt electrode has been developed and evaluated for glucose detection in the range of 1 to 30 mM. The glucose biosensor exhibits a sensitivity of 36.96 mA/mMcm2, a LOD of 0.66 mM, and a LOQ of 2.18 mM. The biosensing membrane was electropolymerized by cyclic voltammetry in 100 mM phosphates pH 7.00 and 3% ethanol containing glucose oxidase and p-coumaric acid. The glucose biosensors’ stability, repeatability, reproducibility, and selectivity were estimated. The biosensing membrane shows permselective properties and antifouling effects. The applicability of the developed glucose biosensor was evaluated in the presence of 20 mg/mL proteins, and any signal associated with biofouling was observed. The glucose biosensors were employed for the determination of the glucose concentration in three commercial beverages.

Immobilization of GOX on PEG/fluoresence functionalized nanographene oxide to describe fluctuation of glucose level

Enzyme, produced and worked in all living things, could work as macromolecular biological catalysts in diverse biochemical processes with particular specificity, like glucose oxidase (GOX). The efficient use of enzyme properties has great importance in pharmaceutics and therapeutics. In this work, we could fabricate naive and effective electrochemical biosensors in the determination of glucose levels via utilizing GOX. Graphene oxide, as a water-soluble derivative of graphene, has shown great promise in a variety of biomedical applications including biosensors. Thus, we established a new-type special platform for GOX immobilization to perform its prosperities, in which nanographene oxide (nGO) was employed as an ideal base and poly(ethylene glycol) (PEG) was conjugated on the edge of nGO sheets to enhance its biocompatibility. Additionally, preferable functional dyes (Rhodamine B/fluorescein isothiocyanate) were also introduced to the platform. Enzyme-nanocomposites were then provided by locating GOX on the platform, i.e., GOX@nGO-PEG-RhB and GOX@nGO-PEG-FITC. The microstructure and composite of platforms and enzyme-nanocomposites were confirmed by diverse characterizations. Finally, on account of corresponding cyclic voltammetric and typical ready-state amperometric curves, it was informed that GOX@nGO-PEG-RhB and GOX@nGO-PEG-FITC could effectively respond to the fluctuation of glucose level as electrochemical biosensor. The present work presents special platforms for the immobilization of enzymes like GOX and provides new-type biosensors in the detection of glucose levels.

Langmuir-Blodgett Films with Immobilized Glucose Oxidase Enzyme Molecules for Acoustic Glucose Sensor Application.

In this work, a sensitive coating based on Langmuir-Blodgett (LB) films containing monolayers of 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) with an immobilized glucose oxidase (GOx) enzyme was created. The immobilization of the enzyme in the LB film occurred during the formation of the monolayer. The effect of the immobilization of GOx enzyme molecules on the surface properties of a Langmuir DPPE monolayer was investigated. The sensory properties of the resulting LB DPPE film with an immobilized GOx enzyme in a glucose solution of various concentrations were studied. It has shown that the immobilization of GOx enzyme molecules into the LB DPPE film leads to a rising LB film conductivity with an increasing glucose concentration. Such an effect made it possible to conclude that acoustic methods can be used to determine the concentration of glucose molecules in an aqueous solution. It was found that for an aqueous glucose solution in the concentration range from 0 to 0.8 mg/mL the phase response of the acoustic mode at a frequency of 42.7 MHz has a linear form, and its maximum change is 55°. The maximum change in the insertion loss for this mode was 18 dB for a glucose concentration in the working solution of 0.4 mg/mL. The range of glucose concentrations measured using this method, from 0 to 0.9 mg/mL, corresponds to the corresponding range in the blood. The possibility of changing the conductivity range of a glucose solution depending on the concentration of the GOx enzyme in the LB film will make it possible to develop glucose sensors for higher concentrations. Such technological sensors would be in demand in the food and pharmaceutical industries. The developed technology can become the basis for creating a new generation of acoustoelectronic biosensors in the case of using other enzymatic reactions.

Development of a Redox-Polymer-Based Electrochemical Glucose Biosensor Suitable for Integration in Microfluidic 3D Cell Culture Systems.

The inclusion of online, in situ biosensors in microfluidic cell cultures is important to monitor and characterize a physiologically mimicking environment. This work presents the performance of second-generation electrochemical enzymatic biosensors to detect glucose in cell culture media. Glutaraldehyde and ethylene glycol diglycidyl ether (EGDGE) were tested as cross-linkers to immobilize glucose oxidase and an osmium-modified redox polymer on the surface of carbon electrodes. Tests employing screen printed electrodes showed adequate performance in a Roswell Park Memorial Institute (RPMI-1640) media spiked with fetal bovine serum (FBS). Comparable first-generation sensors were shown to be heavily affected by complex biological media. This difference is explained in terms of the respective charge transfer mechanisms. Under the tested conditions, electron hopping between Os redox centers was less vulnerable than H2O2 diffusion to biofouling by the substances present in the cell culture matrix. By employing pencil leads as electrodes, the incorporation of these electrodes in a polydimethylsiloxane (PDMS) microfluidic channel was achieved simply and at a low cost. Under flow conditions, electrodes fabricated using EGDGE presented the best performance with a limit of detection of 0.5 mM, a linear range up to 10 mM, and a sensitivity of 4.69 μA mM-1 cm-2.

All-printed multiplexed electrocatalytic biosensors with rationally designed nanoparticle inks

Inkjet printing, capable of rapid and template-free fabrication with high resolution and low material waste, is a promising method to construct electrochemical biosensor devices. However, the construction of fully inkjet-printed electrochemical biosensor remains a challenge owing to the lack of appropriate inks, especially the sensing inks of bioactive materials. Herein, we demonstrate a fully inkjet-printed, integrated and multiplexed electrochemical biosensor by combining rationally designed nanoparticle Inks. The stable gold (Au) nanoparticles ink with lower sintering temperature is prepared by using L-cysteine as stabilizer, and it is used to print the interconnects, the counter electrodes, and the working electrodes. The SU-8 ink is used to serve as dielectric layer for the biosensor, whereas the silver electrode is printed on the Au electrode by using commercially silver nanoparticles ink before it is chlorinated to prepare Ag/AgCl reference electrode. Moreover, we synthesize an inkjet-printable and electroactive ink, by the ‘one-pot method’, which is composed of conductive poly 6-aminoindole (PIn-6-NH2) and gold–palladium (Au–Pd) alloy nanoparticle (Au–Pd@PIn-6-NH2) to enhance the sensing performance of gold electrode towards hydrogen peroxide (H2O2). Especially, the amino groups in PIn-6-NH2 can be further used to immobilizing glucose oxidase (GOx) and lactic acid oxidase (LOx) by glutaraldehyde to prepare printable sensing ink for the detection of glucose and lactate. The fully inkjet-printed electrochemical biosensor enabled by advanced inks can simultaneously detect glucose and lactate with good sensitivity and selectivity, as well as facile and scalable fabrication, showing great promise for metabolic monitoring.

Direct Electron Transfer of Glucose Oxidase on Pre-Anodized Paper/Carbon Electrodes Modified through Zero-Length Cross-Linkers for Glucose Biosensors.

A disposable paper-based glucose biosensor with direct electron transfer (DET) of glucose oxidase (GOX) was developed through simple covalent immobilization of GOX on a carbon electrode surface using zero-length cross-linkers. This glucose biosensor exhibited a high electron transfer rate (ks, 3.363 s-1) as well as good affinity (km, 0.03 mM) for GOX while keeping innate enzymatic activities. Furthermore, the DET-based glucose detection was accomplished by employing both square wave voltammetry and chronoamperometric techniques, and it achieved a glucose detection range from 5.4 mg/dL to 900 mg/dL, which is wider than most commercially available glucometers. This low-cost DET glucose biosensor showed remarkable selectivity, and the use of the negative operating potential avoided interference from other common electroactive compounds. It has great potential to monitor different stages of diabetes from hypoglycemic to hyperglycemic states, especially for self-monitoring of blood glucose.

A salivary glucose biosensor based on immobilization of glucose oxidase in Nafion-carbon nanotubes nanocomposites modified on screen printed electrode

Due to unhealthy lifestyles, the population of diabetics is rapidly increasing, therefore, the demand of glucose meter is also increasing. However, not all the people could overcome the fear of jabbing a needle during blood glucose tests. In this regard, we report a non-invasive glucose sensing electrode composed of conductive and bio-compatible Nafion-carbon nanotubes (Nf-CNT) nanocomposite and glucose oxidase (GOx), which are sequentially coated on screen-printed electrode (SPE). The Nf-CNT nanocomposite is prepared through ultrasonication followed by drop casting it onto the SPE. Subsequently, Nf-CNT/SPEs are subjected to plasma treatment followed by drop-casting of GOx to fabricate GOx/Nf-CNT/SPE electrodes. The plasma treatment alters the hydrophobic nature of Nf-CNT/SPE, which not only exposes the surface of Nf-CNT layer, but also enables it for uniform coating of GOx. The results confirm that the mixing ratio of Nafion and CNT as well as plasma treatment time significantly affects sensing performance. The GOx/Nf-CNT/SPE subjected to 1 min of plasma treatment prior to the coating of GOx shows the best performance with a sensitivity of 99.13 μA/mMcm2 and a linear range of 20–700 μM. Moreover, the GOx/Nf-CNT/SPE electrodes are also tested under artificial saliva, which shows their high potential in the diagnosis of diabetes.

Nano-Materials-Based Printed Glucose Sensor for Use in Incontinence Products for Health-Care Applications

Our recent development of a wireless humidity sensor system embedded in incontinence products enables new sensor applications to diagnose and supervise geriatric diseases (i.e., age-related diabetes mellitus type II). The measurement of glucose in urine, so-called glucosuria, is an early indicator for an incipient diabetes mellitus disease, whose symptoms are often age-related but misjudged. In this paper, an incontinence glucose sensor is printed with biocompatible ink and Prussian blue as an electron mediator on foil and functionalized with immobilized glucose oxidase. Inkjet printing of multiple layers of Nafion prevents large interference substances from diffusing into the measuring electrode and allows precise adjustment of the linear working range, which is significantly different from blood glucose measurement. Performance tests show the potential to detect minimum glucose values and store the sensor over a prolonged period at room temperature. The printed glucose sensor can be embedded into the absorber material of incontinence products, where capillary forces transport the urine analyte to the detection area. An attached readout module with an integrated potentiostat measures the glucose concentration in urine, which is transmitted wirelessly with incontinence events and stored in a cloud service for further analysis by medical staff and care workers.

Reducing O2 sensitivity in electrochemical nitric oxide releasing catheters: An O2-tolerant copper(II)-ligand nitrite reduction catalyst and a glucose oxidase catheter coating

Electrocatalytic nitric oxide (NO) generation from nitrite (NO2–) within a single lumen of a dual-lumen catheter using CuII-ligand (CuII-L) mediators have been successful at demonstrating NO’s potent antimicrobial and antithrombotic properties to reduce bacterial counts and mitigate clotting under low oxygen conditions (e.g., venous blood). Under more aerobic conditions, the O2 sensitivity of the Cu(II)-ligand catalysts and the reaction of O2 (highly soluble in the catheter material) with the NO diffusing through the outer walls of the catheters results in a large decreases in NO fluxes from the surfaces of the catheters, reducing the utility of this approach. Herein, we describe a new more O2-tolerant CuII-L catalyst, [Cu(BEPA-EtSO3)(OTf)], as well as a potentially useful immobilized glucose oxidase enzyme-coating approach that greatly reduces the NO reactivity with oxygen as the NO partitions and diffuses through the catheter material. Results from this work demonstrate that very effective NO fluxes (>1*10−10 mol min−1 cm−2) from a single-lumen silicone rubber catheter can be achieved in the presence of up to 10% O2 saturated solutions.

Improving self-supported nanowire arrays using response surface methodology for the synthesis of a H2O2 nanostructured sensor

In this paper, we introduce a data-driven approach for optimizing the design of highly sensitive hydrogen peroxide (H2O2) sensors based on self-supported nickel nanowire (Ni NW) arrays using response surface methodology (RSM). Our goal is to enhance the performance of the sensor by customizing the length of Ni NW while optimizing the working conditions, including the H2O2 concentration and applied potential. Focusing solely on the commercially available porous membranes, we successfully employ RSM to identify the optimal conditions for the sensor: a NW length of 2.64 μm, an optimal concentration of 3.25 mM H2O2, and a detection potential of 0.02 V. We fabricate a sensor with the optimal NW length and validate its performance through comparison to sensors with different NW lengths, such as a planar Ni sensor and a previously investigated nanostructured sensor. Our optimized sensor achieves a 50% reduction in the limit of detection (LOD) and an 18% increase in sensitivity compared with the previously investigated nanostructured sensor. Moreover, the optimized sensor is at least 35 times more sensitive for H2O2 detection than sensors with planar geometries, which are standard in commercial applications. Our results highlight the potential of RSM as a powerful, cost-effective, and theoretically agnostic tool for optimizing nanostructured sensors and accelerating the design-build-test cycle. The optimized H2O2 sensor can be applied in various fields, including the food industry, medical diagnostics, and environmental monitoring. This sensor can significantly enhance glucose detection in non-invasive samples such as tears and saliva when combined with immobilized glucose oxidase enzymes, which is crucial for continuous glucose monitoring in diabetes mellitus patients. The methodology presented in this study allows further extensions to investigate other design variables and sensing materials as well as optimize sensors for detecting different substances, fostering advancements in sensor technologies.

Conductive polymer blend based on polyaniline and galactomannan: Optical and electrical properties

Polyaniline (PAni) is a semiconductor polymer characterized by a wide conductivity range and can be used as a biosensor for glucose measurement via glucose oxidase (GOx) catalysis because PAni can immobilize GOx on its surface and allows charge transfer between GOx and its surface. However, PAni presents issues with enzyme leaching and high dielectric constant (104-105), which hinders its electrical response as a sensor. To solve both issues simultaneously, a blend of polyaniline and galactomannan (Gal) is presented. Gal is able to preserve the enzymatic activity and has insulating properties, making it suitable to enhance the immobilization of GOx on PAni and to improve the electrical response of the latter for biosensing. PAni was synthesized from the polymerization of aniline in HCl and ammonium persulfate and blended with a solution of Gal 2%, resulting in the polyaniline and galactomannan blend (PAni/Gal). Samples of Gal 2%, PAni and PAni/Gal were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and impedance spectroscopy (IS). The FTIR of the PAni/ AP blends detected the presence of the band associated to the deformation outside the binding plane (C-N) and the oxidizing agent responsible for the semiconducting property of PAni. The XRD patterns showed the crystalline structure of PAni and the amorphous structure of PAni/Gal. The IS showed that PAni/Gal exhibited a smaller dielectric constant and a higher loss tangent than PAni, indicating that PAni/Gal has better electrical behavior as a sensor compared to PAni and thus has solid potential for use in biosensors.

A Novel Large-Diameter Optical Fiber Glucose Biosensor Based on Glucose Oxidase– Graphene Oxide–Gold Nanoparticles

A novel glucose large-diameter optical fiber LSPR sensor was constructed based on chemical cross-linking and electrostatic methods of glucose oxidase-graphene oxide-gold nanoparticles (GOD-GO-AuNPs). The GOD-catalyzed oxidation of glucose reacts with oxygen to produce gluconic acid and H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> , leading to a change in its ambient refractive index, which in turn leads to a significant shift in the LSPR peak of GO-AuNPs on the fiber. The structure and morphology of GOD-GO-AuNPs were studied by FTIR, UV-vis spectroscopy, SEM, and TEM, respectively. GO improves the stability of the composite particles, reduces the biotoxicity of the metal particles, and the immobilization of glucose oxidase on the surface of the composite particles improved the enzyme activity. A fiber-optic sensor was prepared based on the optimal conditions, and the sensitivity of the sensor was 11.134 nm/(mg/mL) in the range of 0 to 1.0 mL with a response time of 55 s. It showed good anti-interference, selectivity and can be used for real detection. This method combines the advantages of GO, AuNPs, and large diameter fiber-optical which show promise for simple, stable, and cost-effective applications in the field of glucose detection.

Chitosan-based Maillard products for enzyme immobilization in multilayers structure: Its application in electrochemical sensing

In this work we demonstrate for the first time the advantages of using water-soluble chitosan polycation obtained by Maillard reaction with glucose (G-Chit) or lactose residues for the immobilization of glucose oxidase (GOx) and lactate oxidase by the layer-by-layer adsorption method onto carbon paste electrodes. Besides its solubility in enzyme-compatible media, these polymers have a suitable charge density for electrostatic adsorption and allow adequate charge transfer at the electrode-solution interface. Based on the analysis of the effect of the type of chitosan derivative on the enzymatic response; we built an efficient biosensor based on G-Chit and GOx. The multilayered structure made of three bilayers of G-Chit and GOx showed the best performance; the biosensor exhibits a sensitivity of (12.4 ± 0.3) µA mM−1 cm−2 in a glucose concentration range from 180 µM to 1.75 mM. In addition, the analytical response of this biosensor was tested in milk samples with negligible effects of the matrix. The results confirm the suitability of these chitosan derivatives for the adsorption of enzymes and the construction of supramolecular structures. The favorable environment for the enzymatic activity results in bioelectrodes with fast responses for quantification of glucose even in a complex matrix like milk.

Characterization of Enzymatic Glucose Biosensors Based on A Glassy Carbon Electrode Modified with MoS2 Nanorods

: In this work, molybdenum disulfide (MoS2) nanorods (NRs) were prepared by a simple hydrothermal method. A sensitive electrochemical glucose biosensor was developed based on the immobilization of glucose oxidase (GOx) on MoS2 NRs modified glassy carbon electrode (GCE). The SnO2 NRs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive X-ray spectroscopy (EDS). SnO2 NRs have large specific area and can load large amounts of GOx molecules. The cyclic voltammetry (CV) of GOx/MoS2 NR/GCE exhibited a linear relationship between the peak current density of CV with glucose concentration in the range of 3.0 mM to 7.0 mM with the limit of detection (LOD) of 3.0 mM and high sensitivity of mA.mM. The parameters affecting the oxidation current density such as pH, temperature, GOx concentration were also investigated. This study demonstrates the feasibility of realizing inexpensive, reliable, and highly effective performance glucose biosensors using MoS2 nanorods.&#x0D; &#x0D;

A non-invasive wearable sweat biosensor with a flexible N-GQDs/PANI nanocomposite layer for glucose monitoring

Understanding the levels change in biomarkers over time, especially glucose, is crucial for diabetics to inform early therapy. Recently, wearable sweat biosensors which operate in a non-invasive way have raised attention, providing continuous monitoring of the severity level. Nevertheless, the key challenges are that multiplexed motions may result in undesirable metal cracking by the rigid electrocatalytic layer, leading to decreased sensitivity and stability. In this work, we designed an N-GQDs anchored PANI matrix to realize flexible wearable biosensors with high detection accuracy. Upon the enhanced electron transfer by N-GQDs, N-GQDs/PANI nanocomposite offers greater sensitivity in H2O2 detection compared to pristine PANI, resulting in a sensitivity of 68.1 ± 1.11 and 44.06 ± 2.1 μA mM−1 cm−2, respectively. Moreover, after the glucose oxidase (GOx) immobilization, GOx/N-GQDs/PANI-based biosensors had shown excellent performance for glucose detection in artificial sweat. Precise glucose detection was also maintained after integrating into a flexible electrode, the sensitivity of the GOx/N-GQDs/PANI-based biosensor had retained 93.2 % with no apparent cracks in the morphology of the nanocomposite layer, compared to GOx/Pt-based one (71.3 %) toward glucose detection after a continuous bending test. Thus, the N-GQDs/PANI nanocomposite layer can provide reliable long-term monitoring with robust electrodes for non-invasive human sweat glucose monitoring on a wearable biosensor.

Fabrication of glucose bioelectrochemical sensor based on Au@Pd core-shell supported by carboxylated graphene oxide

The study presents a novel electrochemical glucose biosensor based on glucose oxidase (GOx) immobilized on Au@Pd core-shell nanoparticles supported on carboxylated graphene oxide (cGO). The immobilization of GOx was achieved by cross-linking the chitosan biopolymer (CS) including Au@Pd/cGO and glutaraldehyde (GA) on a glassy carbon electrode. The analytical performance of GCE/Au@Pd/cGO-CS/GA/GOx was investigated using amperometry. The biosensor had fast response time (5.2 ± 0.9 s), a satisfactory linear determination range between 2.0 × 10−5 and 4.2 × 10−3 M, and limit of detection of 10.4 μM. The apparent Michaelis-Menten constant (Kapp) was calculated as 3.04 mM. The fabricated biosensor also exhibited good repeatability, reproducibility, and storage stability. No interfering signals from dopamine, uric acid, ascorbic acid, paracetamol, folic acid, mannose, sucrose, and fructose were observed. The large electroactive surface area of carboxylated graphene oxide is a promising candidate for sensor preparation.

Cherry-like Pt@Fe3O4 decorated MWCNT/PANI nanohybrid based bioanode for glucose biofuel cell application

With the tremendous research in enzymatic biofuel cells, development of high-performance hybrid nanocomposites to serve as effective immobilization supports for oxido-reductive enzymes is of paramount importance. These nanocomposite based electrocatalysts are being extensively explored as low-cost solutions in enzymatic glucose biofuel cells to address the challenges of instability, short-lifetime, and poor electron transfer. Herein, a hybrid nanocomposite was synthesized by insitu polymerization of polyaniline (PANI) which is composed of multiwalled carbon nanotubes (MWCNTs) and platinum nanoparticles (Pt NPs) decorated on magnetite (Fe3O4) nanosphere with cherry like morhology. This study presents a facile and cost-effective Pt@Fe3O4/MWCNT/PANI nanoelectrocatalyst effective for the immobilization of glucose oxidase (GOx) and for exhibiting outstanding electrocatalytic activity by mediated electron transfer harvesting energy from glucose oxidation. The Pt@Fe3O4/MWCNT/PANI nanohybrid based enzymatic glucose biofuel cell demonstrated a maximum current density of 7.3 mA cm−2 with a high open circuit voltage of 0.6 V which indicates that Pt@Fe3O4/MWCNT/PANI hybrid nanocomposite is an outstanding electrocatalyst with a great potential for carrying out various electrochemical processes like energy conversion in biofuel cells.