Pt–Pb nanowire array electrode for enzyme-free glucose detection

Manganese Carbonate/Laser-Induced Graphene Composite for Glucose Sensing

Laser-induced graphene (LIG) has received great interest as a potential candidate for electronic and sensing applications. In the present study, we report the enhanced performance of a manganese carbonate-decorated LIG (MnCO3/LIG) composite electrode material employed for electrochemical glucose detection. Initially, the porous LIG was fabricated by directly lasing poly(ether sulfone) membrane substrate. Then, the MnCO3/LIG composite was synthesized via a hydrothermal method. Later, MnCO3/LIG was immobilized onto a glassy carbon electrode surface and employed for glucose detection. The structure of the MnCO3/LIG composite was carefully characterized. The influence of the MnCO3/LIG composite on the performance of the electrode was investigated using cyclic voltammetry curves. The MnCO3/LIG composite exhibited an excellent sensitivity of 2731.2 μA mM-1 cm-2, and a limit of detection of 2.2 μM was obtained for the detection of glucose. Overall, the performance of the MnCO3/LIG composite was found to be superior to that of most of the MnCO3-based composites.

Green synthesized gold nanoparticles and CuO-based nonenzymatic sensor for saliva glucose monitoring

Glucose, essential for brain and muscle functions, requires careful monitoring in diabetes and other chronic disease management. While blood glucose monitoring provides precise information about these diseases, it remains an invasive method. Saliva glucose monitoring could offer an alternative approach, but the glucose concentration in saliva is very low. In this work, we report a simple, low-cost, highly sensitive nonenzymatic electrochemical glucose sensor. We developed this sensor using green synthesized gold nanoparticles (AuNPs) and wet chemical synthesized copper oxide (CuO) nanoparticles on a screen-printed carbon electrode (Au/CuO/SPCE). The sensor's high sensitivity results from dual amplification strategies using AuNPs and CuO nanomaterials, each demonstrating catalytic activity towards glucose. This shows promising potential for saliva glucose monitoring. The AuNPs were synthesized using an Au precursor and orange peel extract (OPE), yielding stable colloidal AuNPs with a mean diameter of about 37 nm, thus eliminating the need for additional capping agents. Under optimal conditions, amperometric tests revealed that the sensor responded linearly to glucose concentrations ranging from 2 μM to 397 μM with a sensitivity of 236.70 μA mM-1 cm-2. Furthermore, the sensor demonstrated excellent reproducibility, stability and high selectivity for glucose in the presence of different biomolecules. We validated the sensor's efficacy by measuring glucose in human saliva, showing its potential for noninvasive glucose monitoring. This research advances the development of point-of-care devices, positioning the sensor as a promising tool for noninvasive glucose monitoring and improved diabetes management.

A highly electrocatalytic, stretchable, and breathable enzyme-free electrochemical patch based on electrospun fibers decorated with platinum nano pine needles for continuous glucose sensing in neutral conditions

Given the worldwide increase in diabetes, there is an urgent need for glucose sensors that can achieve the on-body detection of glucose concentration. With the development of nanomaterials and flexible electronics, wearable electrochemical enzyme-free glucose biosensors that can conveniently, continuously and stably monitor the glucose concentrations of diabetes patients without invasion and risk of infection are coming into focus. However, despite the enormous efforts toward wearable electrochemical enzyme-free glucose sensors, there have been limited achievements in developing a stretchable and breathable glucose sensor with high sensitivity, low detection limit, and excellent catalytic activity towards glucose oxidation in neutral media, to meet the need for continuous wearable glucose monitoring in scenarios such as the on-body detection of glucose in human sweat. Herein, we demonstrate a novel electrochemical enzyme-free glucose-sensing patch on the foundation of electrospun polyurethane (PU) fibrous mats to address some of the aforementioned challenges. The sensing patch was fabricated through a facile technology of electrospinning, followed by magnetron sputtering of gold (Au) to enable high conductivity. After that, ultrasonic-assisted electrodeposition was utilized to in situ introduce well-dispersed platinum nano pine needles along each fiber. Due to the good stretchability of PU materials, porous structure, and large specific surface area of electrochemical sites, the glucose-sensing patch promises merits such as good stretchability (performs well under 10% strain), high sensitivity (203.13 μA mM-1 cm-1), prominently low detection limit (14.77 μM), excellent selectivity, and efficient vapor permeability. Notably, the advanced hierarchical nanostructures with excellent catalytic activity towards glucose oxidation could be capable of detecting glucose in neutral conditions (pH = 7.4) without the assistance of enzymes. Given the facile fabrication methods and the integrated superior performances, this enzyme-free glucose-sensing patch could play a vital role in wearable glucose sensors.

Disposable biosensors based on metal nanoparticles

The coronavirus disease2019 (COVID-19) pandemic has highlighted the need for disposable biosensors that can detect viruses in infected patients quickly due to fast response and also at a low cost.The present review provides an overview of the applications of disposable biosensors based on metal nanoparticles in enzymatic and non-enzymatic sensors with special reference to glucose and H₂O₂, immunosensors as well as genosensors (DNA biosensors in which the recognized event consists of the hybridization reaction)for point-of-care diagnostics. The disposable biosensors for COVID19 have also been discussed.

Nanowire-based sensor electronics for chemical and biological applications

Detection and recognition of chemical and biological species via sensor electronics are important not only for various sensing applications but also for fundamental scientific understanding. In the past two decades, sensor devices using one-dimensional (1D) nanowires have emerged as promising and powerful platforms for electrical detection of chemical species and biologically relevant molecules due to their superior sensing performance, long-term stability, and ultra-low power consumption. This paper presents a comprehensive overview of the recent progress and achievements in 1D nanowire synthesis, working principles of nanowire-based sensors, and the applications of nanowire-based sensor electronics in chemical and biological analytes detection and recognition. In addition, some critical issues that hinder the practical applications of 1D nanowire-based sensor electronics, including device reproducibility and selectivity, stability, and power consumption, will be highlighted. Finally, challenges, perspectives, and opportunities for developing advanced and innovative nanowire-based sensor electronics in chemical and biological applications are featured.

The impact of chemical engineering and technological advances on managing diabetes: present and future concepts

Monitoring blood glucose levels for diabetic patients is critical to achieve tight glycaemic control. As none of the current antidiabetic treatments restore lost functional β-cell mass in diabetic patients, insulin injections and the use of insulin pumps are most widely used in the management of glycaemia. The use of advanced and intelligent chemical engineering, together with the incorporation of micro- and nanotechnological-based processes have lately revolutionized diabetic management. The start of this concept goes back to 1974 with the description of an electrode that repeatedly measures the level of blood glucose and triggers insulin release from an infusion pump to enter the blood stream from a small reservoir upon need. Next to the insulin pumps, other drug delivery routes, including nasal, transdermal and buccal, are currently investigated. These processes necessitate competences from chemists, engineers-alike and innovative views of pharmacologists and diabetologists. Engineered micro and nanostructures hold a unique potential when it comes to drug delivery applications required for the treatment of diabetic patients. As the technical aspects of chemistry, biology and informatics on medicine are expanding fast, time has come to step back and to evaluate the impact of technology-driven chemistry on diabetics and how the bridges from research laboratories to market products are established. In this review, the large variety of therapeutic approaches proposed in the last five years for diabetic patients are discussed in an applied context. A survey of the state of the art of closed-loop insulin delivery strategies in response to blood glucose level fluctuation is provided together with insights into the emerging key technologies for diagnosis and drug development. Chemical engineering strategies centered on preserving and regenerating functional pancreatic β-cell mass are evoked in addition as they represent a permanent solution for diabetic patients.

A Non-enzymatic Electrochemical Sensor for Glucose Detection Based on Ag@TiO2@ Metal-Organic Framework (ZIF-67) Nanocomposite

This work presents the preparation of an efficient and sensitive glucose sensor for the detection of glucose in an alkaline media. The glucose sensor is composed of a metal organic framework (MOF) composite comprising Ag@TiO₂ nanoparticles. The hybrid of Ag@TiO₂ encapsulated in ZIF-67 was synthesized by the solvothermal method and applied onto a glassy carbon electrode (GCE) for the non-enzymatic sensing of glucose. The porosity of ZIF-67 was favorable for the unhindered diffusion and entrapment of glucose and its cavities served as reaction vessels. The electrochemical behavior of Ag@TiO₂@ZIF-67 showed amplified results when compared with that of Ag@TiO₂ and ZIF-67. Cyclic tests toward the oxidation of glucose has demonstrated excellent stability of a MOF-based hybrid sensor. The sensor based on Ag@TiO₂@ZIF-67 showed high sensitivity of 0.788 μAμM⁻¹cm⁻² with a linear concentration range of 48 μM⁻¹ mM and a response time of 5 s with an excellent detection limit of 0.99 μM (S/N = 3).

Solvothermal synthesis of Fe3O4 nanospheres for high-performance electrochemical non-enzymatic glucose sensor

Ferroferric oxide (Fe3O4) nanospheres have been synthesized via a facile solvothermal procedure to serve as an electrode material for high performance non-enzymatic glucose sensor. The as-synthesized Fe3O4 nanospheres with a uniform size from 16 to 18 nm, which can increase the reaction contact area and the active sites in the process of glucose detection. Benefiting from the particular nanoscale structure, the Fe3O4 nanospheres obviously enhanced the activity of electrocatalytic oxidation towards glucose. When the Fe3O4 nanospheres material was used for non-enzymatic glucose sensor, several electrochemical properties including the high sensitivity 6560 μA mM-1 cm-2 (0.1-1.1 mM), limit of detection 33 μM (S/N = 3) and good long-term stability were well demonstrated. Furthermore, Fe3O4 nanospheres electrode confirmed the excellent performance of selectivity in glucose detection with the interfering substances existed such as urea, citric acid, ascorbic acid, and NaCl. Due to the excellent electrocatalytic activity in alkaline solution, the Fe3O4 nanospheres material can be considered as a promising candidate in blood glucose monitoring.

Electrochemical non-enzymatic glucose sensors: recent progress and perspectives

This review summarizes recent advances in the development of electrocatalysts for non-enzymatic glucose detection. The sensing mechanism and influencing factors are discussed, and the perspectives and challenges are also addressed.

Sol-Gel Template Synthesis and Characterization of Lu₂O₃:Eu3+ Nanowire Arrays

Uniform Lu₂O₃:Eu³⁺ nanowire arrays were successfully prepared by the sol-gel process using anodic aluminum oxide (AAO) templates. The as-synthesized nanowires are homogeneous, highly ordered, and dense and have a uniform diameter of ~300 nm defined by the AAO templates. The X-ray diffraction and selected area electron diffraction results show that the Lu₂O₃:Eu³⁺ nanowires have a polycrystalline cubic structure, and the crystallite size of the Lu₂O₃:Eu³⁺ nanowires is confined by the AAO template. The nanowires within the AAO template showed good photoluminescence and X-ray-excited optical luminescence performances for Lu₂O₃:Eu³⁺. The emission peaks were attributed to the ⁵D₀ → ⁷F_J transitions of Eu³⁺ (J = 0, 1, 2, 3).

"Non-Naked" Gold with Glucose Oxidase-Like Activity: A Nanozyme for Tandem Catalysis

It has been widely reported that "naked" gold nanoparticles (Au NPs) without protectors have glucose oxidase (GOx)-like activity, and the use of protectors can inhibit the GOx-like activity. Here, "non-naked" Au NPs with GOx-like activity are synthesized by using protein as protector. Although "naked" Au NPs have peroxidase-like activity and GOx-like activity, the optimal pH ranges of the both activities are obviously different. Fortunately, as-synthesized "non-naked" Au NPs show the dual enzyme-like activities at the same pH. So, "non-naked" Au NPs can be described as "tandem nanozyme." As another bonus, the participation of protein protector can stabilize the GOx-like activity and make Au NPs modifiable. Even though Au NPs are connected with graphene oxide (GO), the GOx-like activity is still not changed. Further, Au NPs-GO nanocomposites are applied on the one-pot nonenzymatic glucose colorimetric detection. The "non-naked" gold not only broadens the species of tandem nanozymes, but also facilitates the functionalization of nanozymes, which is promising for immunoassay, biosensor, and medical treatment.

Recent advances in electrochemical non-enzymatic glucose sensors - A review

This review encompasses the mechanisms of electrochemical glucose detection and recent advances in non-enzymatic glucose sensors based on a variety of materials ranging from platinum, gold, metal alloys/adatom, non-precious transition metal/metal oxides to glucose-specific organic materials. It shows that the discovery of new materials based on unique nanostructures have not only provided the detailed insight into non-enzymatic glucose oxidation, but also demonstrated the possibility of direct detection in whole blood or interstitial fluids. We critically evaluate various aspects of non-enzymatic electrochemical glucose sensors in terms of significance as well as performance. Beyond laboratory tests, the prospect of commercialization of non-enzymatic glucose sensors is discussed.

MoS2–Au@Pt nanohybrids as a sensing platform for electrochemical nonenzymatic glucose detection

A MoS₂–Au@Pt nanohybrid was used as a sensing platform for electrochemical nonenzymatic glucose detection with high sensitivity, selectivity and stability.

Electrochemical nonenzymatic sensing of glucose using advanced nanomaterials

An overview (with 376 refs.) is given here on the current state of methods for electrochemical sensing of glucose based on the use of advanced nanomaterials. An introduction into the field covers aspects of enzyme based sensing versus nonenzymatic sensing using nanomaterials. The next chapter cover the most commonly used nanomaterials for use in such sensors, with sections on uses of noble metals, transition metals, metal oxides, metal hydroxides, and metal sulfides, on bimetallic nanoparticles and alloys, and on other composites. A further section treats electrodes based on the use of carbon nanomaterials (with subsections on carbon nanotubes, on graphene, graphene oxide and carbon dots, and on other carbonaceous nanomaterials. The mechanisms for electro-catalysis are also discussed, and several Tables are given where the performance of sensors is being compared. Finally, the review addresses merits and limitations (such as the frequent need for working in strongly etching alkaline solutions and the need for diluting samples because sensors often have analytical ranges that are far below the glucose levels found in blood). We also address market/technology gaps in comparison to commercially available enzymatic sensors. Graphical Abstract Schematic representation of electrochemical nonenzymatic glucose sensing on the nanomaterials modified electrodes. At an applied potential, the nanomaterial-modified electrodes exhibit excellent electrocatalytic activity for direct oxidation of glucose oxidation.

Rational design of porous binary Pt-based nanodendrites as efficient catalysts for direct glucose fuel cells over a wide pH range

Porous binary PtPd, AuPt, PtCu, and PtNi nanodendrites prepared by a facile one-step reduction under ultrasonic irradiation at room temperature, exhibited a substantial catalytic activity towards glucose oxidation reaction at different pH values relative to a commercial Pt/C catalyst.

Fabrication of bimetallic Cu/Au nanotubes and their sensitive, selective, reproducible and reusable electrochemical sensing of glucose

Herein, we report a facile two-step approach to produce gold-incorporated copper (Cu/Au) nanostructures through controlled disproportionation of the Cu(+)-oleylamine complex at 220 °C to form copper nanowires and the subsequent reaction with Au(3+) at different temperatures of 140, 220 and 300 °C. In comparison with copper nanowires, these bimetallic Cu/Au nanostructures exhibit their synergistic effect to greatly enhance glucose oxidation. Among them, the shape-controlled Cu/Au nanotubes prepared at 140 °C show the highest electrocatalytic activity for non-enzymatic glucose sensing in alkaline solution. In addition to high sensitivity and fast response, the Cu/Au nanotubes possess high selectivity against interferences from other potential interfering species and excellent reproducibility with long-term stability. By introducing gold into copper nanostructures at a low level of 3, 1 and 0.1 mol% relative to the initial copper precursor, a significant electrocatalytic enhancement of the resulting bimetallic Cu/Au nanostructures starts to occur at 1 mol%. Overall, the present fabrication of stable Cu/Au nanostructures offers a promising low-cost platform for sensitive, selective, reproducible and reusable electrochemical sensing of glucose.

A novel non-enzymatic amperometric glucose sensor based on a hollow Pt–Ni alloy nanotube array electrode with enhanced sensitivity

A non-enzymatic electrode is proposed as a glucose sensor based on Pt-replaced Ni nanowires which are prepared by constant current electro-deposition within the anodic alumina membrane and galvanic replacement reaction.

A feasible approach to synthesize Cu2O microcrystals and their enhanced non-enzymatic sensor performance

This work provides a green and feasible approach to obtain a “clean surface” Cu₂O with enhanced glucose sensor performance.

Nanoflower-like CoS-decorated 3D porous carbon skeleton derived from rose for a high performance nonenzymatic glucose sensor

A nanoflower-like CoS-decorated 3D porous carbon skeleton from rose has been synthesised and firstly applied in the detection of glucose.

A novel Ni–WC/AC catalyst with enhanced electroactivity for glucose oxidation

A novel Ni–WC/AC catalyst possessed enhanced electroactivity for glucose oxidation due to the synergistic effect between Ni and WC.