3D Modeling of Silver Doped ZrO2 Coupled Graphene-Based Mesoporous Silica Quaternary Nanocomposite for a Nonenzymatic Glucose Sensing Effects

Zirconium copper oxide microflowers based non-enzymatic screen-printed electrochemical sensor for the detection of glucose in saliva, urine, and blood serum

Zirconium copper oxide microflowers (Zr/CuO MF) based non-enzymatic sensor was developed for glucose detection in saliva, urine, and blood. An easy urea hydrolysis method was employed for the synthesis of the metal oxide and further calcined to improve the catalytic property. The flower-like morphology of the Zr/CuO was confirmed by SEM analysis and the presence of copper and zirconium was examined using energy dispersive X-ray analysis (EDAX). The Zr/CuO MF modified screen-printed electrodes exhibited excellent glucose sensing performance in 0.15 M NaOH medium and could quantify glucose in the range from 10 µM to 27 mM. A high sensitivity of 1.815 ± 0.003 mA mM-1 cm-2 was obtained for lower glucose concentration from 15 µM to 3 mM and 1.250 ± 0.006 mA mM-1 cm-2 for higher concentration glucose from 3 to 27 mM. The limit of detection of the fabricated sensor was found to be 0.8 µM. The sensor displayed high selectivity and stability towards glucose in different body fluids like saliva, urine, and blood serum at a working potential of 0.6 V (vs. Ag/AgCl). In saliva, urine, and serum samples, the sensor exhibited excellent recovery of 95-108, 92-108, and 93-101% in saliva, urine, and serum, respectively, with a relative standard deviation of less than 10%, demonstrating high accuracy and reliability of the sensor. The developed sensor is promising for developing an invasive and non-invasive point-of-care testing device for glucose detection.

Focus Review on Nanomaterial-Based Electrochemical Sensing of Glucose for Health Applications

Diabetes management can be considered the first paradigm of modern personalized medicine. An overview of the most relevant advancements in glucose sensing achieved in the last 5 years is presented. In particular, devices exploiting both consolidated and innovative electrochemical sensing strategies, based on nanomaterials, have been described, taking into account their performances, advantages and limitations, when applied for the glucose analysis in blood and serum samples, urine, as well as in less conventional biological fluids. The routine measurement is still largely based on the finger-pricking method, which is usually considered unpleasant. In alternative, glucose continuous monitoring relies on electrochemical sensing in the interstitial fluid, using implanted electrodes. Due to the invasive nature of such devices, further investigations have been carried out in order to develop less invasive sensors that can operate in sweat, tears or wound exudates. Thanks to their unique features, nanomaterials have been successfully applied for the development of both enzymatic and non-enzymatic glucose sensors, which are compliant with the specific needs of the most advanced applications, such as flexible and deformable systems capable of conforming to skin or eyes, in order to produce reliable medical devices operating at the point of care.

Sensor to Electronics Applications of Graphene Oxide through AZO Grafting

Graphene is a two-dimensional (2D) material with a single atomic crystal structure of carbon that has the potential to create next-generation devices for photonic, optoelectronic, thermoelectric, sensing, wearable electronics, etc., owing to its excellent electron mobility, large surface-to-volume ratio, adjustable optics, and high mechanical strength. In contrast, owing to their light-induced conformations, fast response, photochemical stability, and surface-relief structures, azobenzene (AZO) polymers have been used as temperature sensors and photo-switchable molecules and are recognized as excellent candidates for a new generation of light-controllable molecular electronics. They can withstand trans-cis isomerization by conducting light irradiation or heating but have poor photon lifetime and energy density and are prone to agglomeration even at mild doping levels, reducing their optical sensitivity. Graphene derivatives, including graphene oxide (GO) and reduced graphene oxide (RGO), are an excellent platform that, combined with AZO-based polymers, could generate a new type of hybrid structure with interesting properties of ordered molecules. AZO derivatives may modify the energy density, optical responsiveness, and photon storage capacity, potentially preventing aggregation and strengthening the AZO complexes. They are potential candidates for sensors, photocatalysts, photodetectors, photocurrent switching, and other optical applications. This review aimed to provide an overview of the recent progress in graphene-related 2D materials (Gr2MS) and AZO polymer AZO-GO/RGO hybrid structures and their synthesis and applications. The review concludes with remarks based on the findings of this study.

Methanol and Ethanol Electrooxidation on ZrO2/NiO/rGO

Recently, transition metal oxides have been considered for various applications due to their unique properties. We present the synthesis of a three-component catalyst consisting of zirconium oxide (ZrO₂), nickel oxide (NiO), and reduced graphene oxide (rGO) in the form of ZrO₂/NiO/rGO by a simple one-step hydrothermal method. X-ray powder diffraction (XRD), scanning electron microscope (SEM), and bright-field transmission electron microscopy (BF-TEM) analyses were performed to accurately characterize the catalysts. Cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV) analyses were also carried out to investigate the methanol and ethanol alcohol electrooxidation ability of the synthesized nanocatalysts. Inspired by the good potential of metal oxides in the field of catalysts, especially in fuel-cell anodes, we investigated the capability of this catalyst in the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). After proving the successful synthesis and examining the surface morphology of these materials, detailed electrochemical tests were performed to show the outstanding capability of this new nanocatalyst for use in the anode of alcohol fuel cells. ZrO₂/NiO/rGO indicated a current density of 26.6 mA/cm² at a peak potential of 0.52 V and 99.5% cyclic stability in the MOR and a current density of 17.3 mA/cm² at a peak potential of 0.52 V and 98.5% cyclic stability in the EOR (at optimal concentration/scan rate 20 mV/s), representing an attractive option for use in the anode of alcoholic fuel cells.

A flexible mesoporous Cu doped FeSn–G–SiO2 composite based biosensor for microalbumin detection

A new mesoporous Cu-doped FeSn–G–SiO₂ (CFSGS) based biosensor was developed for the detection of microalbumin in urine samples. The mechanically flexible FeSn modified sensor was fabricated at room temperature. These demonstrations highlight the unexplored potential of FeSn for developing novel biosensing devices. It is extremely sensitive and selective. Surfactant-aided self-assembly was used to synthesise the mesoporous CFSGS. The large surface area due to the mesopore presence in the CFSG surface that has been composited inside the mesoporous SiO₂ boosted the electrochemical detection. The linear range and detection limit of microalbumin under optimum circumstances were 0.42 and 1 to 10 μL, respectively. This easily fabricated mesoporous CFSGS provided a fast response with high sensitivity, and good selectivity. The sensor's reusability and repeatability were also quite high, with just a 90 percent drop after 4 weeks of storage at ambient temperature. The biosensor also demonstrated high selectivity against typical potential interfering chemicals found in urine (ascorbic acid, urea, and sodium chloride). The good performance of the mesoporous CFSGS biosensor was validated by measuring microalbumin, and the findings indicated that this sensing device performed very well.

Microalbumin sensing mechanism with electrochemical performance system.