Non-enzymatic Glucose Sensor Research Articles

Recent Advances in Enzymatic and Non-Enzymatic Electrochemical Glucose Sensing.

The detection of glucose is crucial in the management of diabetes and other medical conditions but also crucial in a wide range of industries such as food and beverages. The development of glucose sensors in the past century has allowed diabetic patients to effectively manage their disease and has saved lives. First-generation glucose sensors have considerable limitations in sensitivity and selectivity which has spurred the development of more advanced approaches for both the medical and industrial sectors. The wide range of application areas has resulted in a range of materials and fabrication techniques to produce novel glucose sensors that have higher sensitivity and selectivity, lower cost, and are simpler to use. A major focus has been on the development of enzymatic electrochemical sensors, typically using glucose oxidase. However, non-enzymatic approaches using direct electrochemistry of glucose on noble metals are now a viable approach in glucose biosensor design. This review discusses the mechanisms of electrochemical glucose sensing with a focus on the different generations of enzymatic-based sensors, their recent advances, and provides an overview of the next generation of non-enzymatic sensors. Advancements in manufacturing techniques and materials are key in propelling the field of glucose sensing, however, significant limitations remain which are highlighted in this review and requires addressing to obtain a more stable, sensitive, selective, cost efficient, and real-time glucose sensor.

Green Approach for the Synthesis of NiO Material and Their Non-Enzymatic Glucose Sensor-Based Applications at Low Potential

ABSTRACTThe study presents a novel route towards the synthesis of NiO nanostructures by using various green amino acids. The nanostructures were obtained by hydrothermal methodology assisted by threonine, arginine, aspartic acid, leucine, isoleucine and serine respectively. The characterization of the synthesized materials was studied by different techniques such as XRD, SEM and TEM. The synthesized structural features were explored for their electro-chemical properties and used for fabrication of glucose sensors based on non-enzymatic functions. The developed sensors demonstrated a promising result in terms of sensitivity, selectivity, and stability. The most important finding in the present study is the oxidation of glucose at low potentials such as 0.125, 0.23, 0.093, 0.26, 0.037, and -0.02 V respectively for the isoleucine, leucine, serine, threonine, arginine, and aspartic acid assisted NiO nanostructures. This unique finding is attributed to the morphology of different nanostructures of NiO grown with the addition of green additives. The glucose sensing ability of glucose was not affected in presence of species such as uric acid, ascorbic acid, and other carbohydrates due to their close oxidation potential compared with glucose. The sensitivities of proposed non-enzymatic glucose sensors were found to be for the isoleucine, leucine, serine, threonine, arginine, and aspartic acid assisted NiO nanostructures as 4930, 3173, 2648, 1724, 1070, and 525 µA/mM/cm2 respectively. The maximum sensing capability was recorded for isoleucine structures which showed higher sensitivity of 4930 µA/mM/cm2, greater stability and excellent anti-interference capability compared to other nanostructures. The limit LOD and LOQ were also found and remain 0.01 (S/N = 3) and 1.9 µM individually, for the newly developed method for the sensor based on NiO grown with isoleucine amino acid. The potential application of isoleucine assisted NiO nanostructures composite material for the blood sample quantities analysis which further it demonstrates the feasibility of developed based for the non-enzymatic glucose sensor.

Bifunctional three-dimensional self-supporting multistage structure CC@MOF-74(NiO)@NiCo LDH electrode for supercapacitors and non-enzymatic glucose sensors

The bifunctional electrode materials for supercapacitors and non-enzymatic glucose sensors have attracted the researchers’ great interest due to their excellent electrochemical performance. In this work, three-dimensional self-supporting multistage structure CC@MOF-74(NiO)@NiCo LDH electrode has been successfully prepared through a facile hydrothermal and electrochemical deposition method. Benefiting from the unique three-dimensional flower-like multistage structure, the optimized CC@MOF-74(NiO)@NiCo LDH electrode exhibits an excellent specific capacitance of 9.73 F cm−2 and a superior rate capability of 77.65% at a high current density of 50 mA cm−2. Besides, the material has a superior capacitance retention rate of 84.09% after 5000 cycles. Furthermore, the fabricated CC@MOF-74(NiO)@NiCo LDH//CC@NiCo2O4 @NiFe LDH ASC device exhibits a high energy density of 22.85 Wh kg−1 and the power density of 1750 W kg−1 at the current density of 10 mA cm−2. Moreover, the as-prepared CC@MOF-74(NiO)@NiCo LDH shows an outstanding electrocatalytic performance in glucose detection, including a high sensitivity of 1699 μA mM−1 cm−2, a low detection limit of 278 nM (S/N = 3) and a wide linear range of 10 μM–1.1 mM and 1.5–9 mM. The electrode also has good long-term stability and remains 93.29% of the original current density after 35 days. The unique three-dimensional flower-like structure of MOF-74 and two-dimensional layered double hydroxides (LDHs) nanosheets structure provide a larger specific surface area and improve the conductivity of the MOF-74(NiO). Furthermore, the synergistic effect of the bimetal Ni-Co provides more active sites for electrochemical reactions and shortens the ion transport path. Accordingly, the fabricated CC@MOF-74(NiO)@NiCo LDH has great potential application prospects in the field of supercapacitors and non-enzymatic glucose sensors.

NiCo-LDH nanoflake arrays-supported Au nanoparticles on copper foam as a highly sensitive electrochemical non-enzymatic glucose sensor

The detection of glucose in human blood is of great importance in the diagnosis and prevention of diabetes. In this work, we fabricated a novel electrochemical non-enzymatic glucose sensor, NiCo-LDH nanoflake arrays-supported Au nanoparticles on copper foam (NiCo-LDH@ Au/Cu) by galvanic replacement and electrodeposition methods. Owing to the synergistic effect of three-dimensional (3D) architecture of Cu foam, high electrocatalytic activity of Au nanoparticles and NiCo-LDH nanoflake arrays, the NiCo-LDH@Au/Cu electrode exhibits excellent electrocatalytic ability for glucose oxidation in NaOH solution. Under optimized conditions, the NiCo-LDH@Au/Cu electrode shows excellent activity with a linear range from 0.5 to 3000 μM at the potential of 0.50 V (vs. Ag/AgCl), a low detection limit of 0.23 μM (S/N = 3), an ultra-prompt response time of 0.5 s, and a high sensitivity of 23100 μA mM−1 cm−2, as well as good selectivity and stability. Furthermore, the as-fabricated non-enzymatic glucose sensor was successfully applied to the glucose detection in human serum as a promising candidate in the development of electrochemical non-enzymatic glucose sensor.

Developments of the Electroactive Materials for Non-Enzymatic Glucose Sensing and Their Mechanisms

A comprehensive review of the electroactive materials for non-enzymatic glucose sensing and sensing devices has been performed in this work. A general introduction for glucose sensing, a facile electrochemical technique for glucose detection, and explanations of fundamental mechanisms for the electro-oxidation of glucose via the electrochemical technique are conducted. The glucose sensing materials are classified into five major systems: (1) mono-metallic materials, (2) bi-metallic materials, (3) metallic-oxide compounds, (4) metallic-hydroxide materials, and (5) metal-metal derivatives. The performances of various systems within this decade have been compared and explained in terms of sensitivity, linear regime, the limit of detection (LOD), and detection potentials. Some promising materials and practicable methodologies for the further developments of glucose sensors have been proposed. Firstly, the atomic deposition of alloys is expected to enhance the selectivity, which is considered to be lacking in non-enzymatic glucose sensing. Secondly, by using the modification of the hydrophilicity of the metallic-oxides, a promoted current response from the electro-oxidation of glucose is expected. Lastly, by taking the advantage of the redistribution phenomenon of the oxide particles, the usage of the noble metals is foreseen to be reduced.

Elaboration and Characterization of Ni (NPs)-PANI Hybrid Material by Electrodeposition for Non-Enzymatic Glucose Sensing

Elaboration and Characterization of Ni (NPs)-PANI Hybrid Material by Electrodeposition for Non-Enzymatic Glucose Sensing

Highly Sensitive and Selective Non-Enzymatic Measurement of Glucose Using Arraying of Two Sweat Sensors Modified By Controlled Growth of Co/Cu and Functionalized Carbon Nanotubes

Due to a relation between glucose in sweat and blood, there is an opportunity to monitor patients' glucose levels non-invasively through sweat. There is a high demand for developing highly selective and sensitive biosensors in order to sense biomarkers like glucose and, therefore, the diseases based on those biomarkers. However, enzymatic sensors are selective to specific biomarkers; they are suffering from high sensitivity to the fluctuation of temperature, oxygen, pH, humidity, detergents, organic reagents, and toxic chemicals, affecting their stability and sensitivity, and reproducibility. Therefore, developing non-enzymatic glucose (or other biomarkers) sensors is getting significant attention to fulfill higher sensitivity and selectivity as well as minimized susceptibility to fouling by enzyme-ageing and adsorbed intermediates. Here we have proposed a combination of two sensors that can help us improve these non-enzymatic sensors' selectivity. Two electrochemical arrayed sensors have been developed. The first electrochemical sensor has been achieved by controlled growth of cobalt nanowire and copper nanoparticles on carbon substrate in order to measure the glucose level at low concentrations, and the second electrochemical sensor has been modified by MWCNT-CO-NH-cyanuric-NH2 and Fe3O4 in order to measure the uric acid and eliminate the interference of it in glucose measurement results. In order to show the morphology of the glucose sensor, the SEM and EDX have been conducted. Also, the FT-IR test has been shown to confirm the functionalization of MWCNT. The electrocatalytic and electrochemical performance of each sensor have been evaluated in the presence of the various contaminants of sweat. The glucose sensor showed less than 5% interference toward ascorbic acid, sodium bicarbonate, and the lactic acid at their max range of presence in the sweat. For eliminating the interference of uric acid, the second sensor has developed, which has no response to the glucose and high sensitivity to the uric acid. The calibration curve of each sensor has been provided in the 3D form, and a simple method of arraying has been applied to improve the sensors' selectivity. The arrayed sensors showed a highly glucose-selective sweat-based sensor with minimized error imposed by the uric acid interference. The glucose sensor's reproducibility and durability have also been tested, which showed less than 5% and 10% variations, respectively. In the end, the arrayed sensor's performance has been evaluated by real sweat samples of a male and a female, analyzed by Clarke’s error grid analysis showing less than 20% deviation from the glucose levels measured by the commercial glucometers.

A new approach to in-situ uniform growth of Fe3O4 nanoparticles over thermally exfoliated rGO sheet for the non-enzymatic and enzymatic detection of glucose

• One step, in-situ pyrolysis method has been approached for synthesizing uniformly decorated Fe 3 O 4 over wrinkled rGO sheet (Fe 3 O 4 /erGO). • Significant enhancement in current response and prominent redox behaviour is observed for uniformly distributed Fe 3 O 4 /erGO composite over conventional way synthesized Fe 3 O 4 /rGO. • The non-enzymatic and enzymatic glucose sensor shows wide range linearity within 0–12mM and 1–19mM, respectively. • A low detection limit of 4.1µM and 2.2µM was observed for non-enzymatic and enzymatic Fe 3 O 4 /erGO, respectively. A new strategy has been adopted to synthesis agglomeration free uniformly decorated Fe 3 O 4 nanoparticles (NPs) over reduced graphene oxide (rGO) sheets using a solid-state pyrolysis method (Fe 3 O 4 /erGO). This strategy does not require any additional capping agents. The morphology and performance of the synthesised Fe 3 O 4 /erGO were then compared with a reference catalyst prepared by the conventional chemical precipitation method (Fe 3 O 4 /rGO). It was observed that the as-prepared Fe 3 O 4 /erGO shows the presence of higher defect densities, more wrinkled nature and significantly higher reactivity towards glucose oxidation than Fe 3 O 4 /rGO. The catalyst Fe 3 O 4 /erGO modified non-enzymatic and enzymatic sensor shows about 25 and 64 times increment in current response than Fe 3 O 4 /rGO towards glucose oxidation, attributed to the higher effective electrochemical surface area (ECSA). The sensitivity of both the non-enzymatic and enzymatic sensor is calculated, taking into account both the ECSA and the geometrical surface area (GA). Both the non-enzymatic and enzymatic sensor exhibit high sensitivity, wide range linearity with a low detection limit of 4.1 µM and 2.2 µM respectively. They also show good stability over 20 cycles. It was also observed that the performance of the non-enzymatic sensor in real blood is comparable with the clinically obtained value of glucose. Additionally, the non-enzymatic sensor also shows potential for simultaneous detection of glucose and uric acid. Thus, the features of both the non-enzymatic and enzymatic Fe 3 O 4 /erGO catalyst demonstrate its potential for use as a practical electrochemical sensor.

A Redox Cu(II)-Graphene Oxide Modified Screen Printed Carbon Electrode as a Cost-Effective and Versatile Sensing Platform for Electrochemical Label-Free Immunosensor and Non-enzymatic Glucose Sensor.

A novel copper (II) ions [Cu(II)]-graphene oxide (GO) nanocomplex-modified screen-printed carbon electrode (SPCE) is successfully developed as a versatile electrochemical platform for construction of sensors without an additionally external redox probe. A simple strategy to prepare the redox GO-modified SPCE is described. Such redox GO based on adsorbed Cu(II) is prepared by incubation of GO-modified SPCE in the Cu(II) solution. This work demonstrates the fabrications of two kinds of electrochemical sensors, i.e., a new label-free electrochemical immunosensor and non-enzymatic sensor for detections of immunoglobulin G (IgG) and glucose, respectively. Our immunosensor based on square-wave voltammetry (SWV) of the redox GO-modified electrode shows the linearity in a dynamic range of 1.0–500 pg.mL−1 with a limit of detection (LOD) of 0.20 pg.mL−1 for the detection of IgG while non-enzymatic sensor reveals two dynamic ranges of 0.10–1.00 mM (sensitivity = 36.31 μA.mM−1.cm−2) and 1.00–12.50 mM (sensitivity = 3.85 μA.mM−1.cm−2) with a LOD value of 0.12 mM. The novel redox Cu(II)-GO composite electrode is a promising candidate for clinical research and diagnosis.

Non-Enzymatic Glucose Biosensor Based on Highly Pure TiO2 Nanoparticles.

This study proposes a non-enzymatic glucose sensor fabricated by synthesizing high-purity TiO2 nanoparticles in thermal plasma and depositing it directly on a substrate and then depositing chitosan–polypyrrole (CS-PPy) conductive polymer films by electrochemical method. The structural properties of the deposited TiO2 nanoparticles were analyzed by X-ray diffraction (XRD) and dynamic light scattering (DLS) system. The chemical composition and structural properties of the TiO2 nanoparticle layer and the conductive polymer films were confirmed by X-ray photoelectron spectroscopy (XPS) spectra and scanning electron microscope (SEM). The glucose detection characteristics of the fabricated biosensor were determined by cyclic voltammetry (CV). CS-PPy/TiO2 biosensor showed high sensitivity of 302.0 µA mM−1 cm−2 (R2 = 0.9957) and low detection limit of 6.7 μM. The easily manufactured CS-PPy/TiO2 biosensor showed excellent selectivity and reactivity.

Microplasma synthesis of Ni(OH)2 nanoflake array on carbon cloth as an efficient nonenzymatic sensor for glucose

In this paper, we report in situ preparation of nickel hydroxide nanoflake array on carbon cloth (Ni(OH)2 NA/CC) by a rapid and simple microplasma method. Using this technique, Ni(OH)2 nanoflake can be prepared on carbon cloth in only 1.5 h at atmospheric pressure and ambient temperature. As an electrode with highly efficient catalytic and non-enzymatic sensor for detecting glucose, such a Ni(OH)2 NA/CC electrode showed excellent electrocatalytic activity with a short response time within 5 s, low detection limit (LOD) of 62 nM (S/N=3), and response sensitivity of 2216.2 mA mM−1 cm−2, meanwhile a satisfactory reproducibility and selectivity.

Surface Selenylation Engineering for Construction of a Hierarchical NiSe2/Carbon Nanorod: A High-Performance Nonenzymatic Glucose Sensor.

As glucose (Glu) is an essential substance for metabolism as well as a symbol to diagnose diabetes, the demand of Glu sensors has increased significantly in recent decades. In this work, a hierarchical Ni-based electrochemical enzyme-free Glu sensor, namely, NiSe2/CNR (carbon nanorod), was engineered through a facile thermal treatment using dimethylglyoxime dinickel salt with selenium (Se) powder. The prepared NiSe2/CNR not only subtly introduces a hierarchical structure with rod-like carbon nanorods and rock-like NiSe2 nanoparticles, which are extremely helpful in offering a greater catalytic activity area and more catalytic active sites, but also incorporates the Se element to increase the inherent activity. The fabricated NiSe2/CNR exhibits distinguished performance for Glu detection in alkaline electrolytes with linear ranges of 0.5-411 μM and 411 μM to 6.311 mM, high sensitivities of 3636 μA mM-1 cm-2 at low concentrations, and 2121 μA mM-1 cm-2 at high concentrations, as well as a low detection limit of 380 nM (S/N = 3). It also possesses favorable reproducibility, stability, and long-term storage capacity. The practical feasibility of NiSe2/CNR was also validated by detecting Glu in human serum. Moreover, the prepared hierarchical NiSe2/CNR is of general interest for the construction of hierarchical Ni-based sensors.

Highly sensitive electrochemical non-enzymatic glucose biosensor based on squamous NiCo2O4 nanosheets decorated nitrogen-doped reduced graphene oxide

ABSTRACT Ultrathin and vertical NiCo2O4 nanosheets were grown on nitrogen-doped reduced graphene oxide (NiCo2O4 NSs@N-rGO) through a simple one-step co-precipitation procedure. The NiCo2O4 NSs@N-rGO nanocomposites were investigated through X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. And the performance of NiCo2O4NSs@N-rGO non-enzymatic glucose sensor was measured by cyclic voltammetry and amperometric method. The sensor exhibited two wide linear ranges of 0.01 mM-5.50 mM and 5.50 mM-15.50 mM with high sensitivity of 4372.9 μA·mM−1cm−2 and 1686.1 μA·mM−1cm−2, which is much better than other Co-based and Ni-based glucose sensors. In addition, the non-enzymatic glucose sensor also shows strong anti-interference and durability. Besides, it is found that this non-enzymatic glucose sensor can accurately measure the blood glucose concentration in human serum, which provides a great possibility for future application in medical treatment.

Copper/reduced graphene oxide film modified electrode for non-enzymatic glucose sensing application

Numerous studies suggest that modification with functional nanomaterials can enhance the electrode electrocatalytic activity, sensitivity, and selectivity of the electrochemical sensors. Here, a highly sensitive and cost-effective disposable non-enzymatic glucose sensor based on copper(II)/reduced graphene oxide modified screen-printed carbon electrode is demonstrated. Facile fabrication of the developed sensing electrodes is carried out by the adsorption of copper(II) onto graphene oxide modified electrode, then following the electrochemical reduction. The proposed sensor illustrates good electrocatalytic activity toward glucose oxidation with a wide linear detection range from 0.10 mM to 12.5 mM, low detection limit of 65 µM, and high sensitivity of 172 μA mM–1 cm–2 along with satisfactory anti-interference ability, reproducibility, stability, and the acceptable recoveries for the detection of glucose in a human serum sample (95.6–106.4%). The copper(II)/reduced graphene oxide based sensor with the superior performances is a great potential for the quantitation of glucose in real samples.

Nanolayers of carbon protected copper oxide nanocomposite for high performance energy storage and non-enzymatic glucose sensor

Nanolayers of carbon shell protected nanorods-like copper oxide (CuO-NC) material were prepared via a simple chemical synthesis method. A small molecule compound such as dopamine (DA) was used as carbon precursors. The prepared nanostructured materials were characterized by various techniques and used as bifunctional electrode materials for supercapacitor and non-enzymatic glucose bio-sensing. The electrochemical performance suggested that bifunctional CuO-NC materials provided a high specific capacitance of 247 F g−1 at a current density of 2.5 A g−1. Remarkably, the specific capacitance increased as a function of cycle numbers, and a maximum capacitance of 364 F g−1 was reached and sustained. Furthermore, the glucose-sensing performance was investigated and an excellent sensitivity value of 272.6 µA mM−1 cm−2 was achieved with a low limit of detection (0.14 µM). These excellent activities are mainly attributed to the presence of carbon shell, which acted as high active sites and enhanced electronic conductive paths for CuO-NC. The carbon shell also provided fast electron-transportation and effective protection of the nanorod structures under harsh redox condition, leading to excellent electrochemical activity.

Copper selenide as multifunctional non-enzymatic glucose and dopamine sensor

Cu2Se, synthesized through one-pot hydrothermal synthesis, was identified as highly efficient bifunctional sensor for co-detection of glucose and dopamine with high selectivity. As-synthesized copper selenide could electro-oxidize glucose and dopamine at different applied potentials. Glucose oxidation was observed at 0.35 V while dopamine oxidized at 0.2 V. This copper selenide-based non-enzymatic sensor showed high sensitivity for both glucose (15.341 mA mM−1 cm−2) and dopamine (12.43 μA μM−1 cm−2) with low limit of detection (0.26 μM and 84 nM). Such high sensitivity and low LOD makes this sensor attractive for possible detection of glucose/dopamine in physiological body fluids which have low concentration of these biomolecules. Extremely low applied potential for detection also makes it ideal for integrating into wearable continuous monitoring devices with low operational power requirement. This sensor showed high reproducibility, reusability and long-term operational stability along with high degree of selectivity for dopamine and glucose sensing in presence of other interferents.

Graphene oxide template based synthesis of NiCo2O4 nanosheets for high performance non-enzymatic glucose sensor

While glucose detection is ruled by enzyme-based glucose test strips, the chemically and thermally sensitive enzymes motivate the researchers to inspect chemically and thermally stable metal oxides as alternate sensing constituents for non-enzymatic glucose detection. Here, we report a synthesis of spinel nickel cobalt oxide (NiCo2O4) nanosheets-based catalyst for enzyme-free glucose sensing application via sonochemical approach using graphene oxide (GO) as nanosheets template and zeolitic imidazolate frameworks (ZIF-67) type nickel-cobalt metal-organic frameworks as oxide precursors (the catalyst named as gt-NiCo2O4 NSs). The physical characterization techniques confirmed that the as-synthesized gt-NiCo2O4 exhibited uniform porous and nanosheets morphology which can be obtained due to the ZIF-67 and GO template, respectively. Cyclic voltammetry and amperometric techniques employed for glucose oxidation at + 0.55 V using gt-NiCo2O4 NSs electrode in 0.1 M KOH. This sensor exhibited an excellent linear range (150 nM–8.86 mM), sensitivity (729.72 µA mM−1 cm−2) and lower detection level (7.35 nM; S/N ratio = 3) to glucose. Interestingly, the gt-NiCo2O4 NSs electrode displayed good recoveries to glucose in human blood serum and urine samples. Hence, the results indicates that gt-NiCo2O4 NSs is a promising electrode matrix with high sensitivity, excellent stability and good reproducibility that can enable the progress of enzyme-free glucose sensors.

Fabrication of a microdialysis-based nonenzymatic microfluidic sensor for regular glucose measurement

Microdialysis-based continuous glucose measuring systems are desirable candidates for accurate and biologically safe monitoring of glucose level in diabetic patients. However, it is necessary to improve these systems by utilizing highly reliable non-enzymatic sensors instead of enzymatic ones, while lowering the size and lessening the dialysis fluid consumption. Our purpose is to design an implantable integrated microfluidic device for regular nonenzymatic microdialysis-based glucose measurement. We report a novel nonenzymatic microfluidic glucose sensor based on Pt-Ni nanoparticles - multiwalled carbon nanotubes/screen-printed carbon electrode (Pt-Ni NPs-MWCNTs/SPE). Devised microfluidic sensor consists of a channel of a height as low as 60μm, with the modified screen-printed electrode beneath. Microfluidic tests were performed by pumping the dialysis fluid (pH=7.4) through the sensor at the flow rate of only 1 μL min−1. Fabricated microfluidic sensor exhibited satisfactory repeatability, reproducibility, and showed amperometric bisectional linear current response with sensitivities of 6.67 μA mM-1 cm-2 and 4.57 μA mM-1 cm-2 in two glucose concentration ranges of ⩽8mM and 8–12 mM, respectively. These properties, along with small channel size, low fluid consumption and high resistance to Cl- poisoning make the sensor a highly suitable candidate for our purpose. Finally, in an innovative process, a numerical simulation was utilized, showing that the sensitivity of the fabricated sensor can be theoretically increased 1.864 times the experimentally achieved value.

An Electrochemical Nonenzymatic Microsensor Modified by Nickel Cobaltate Nanospheres for Glucose Sensing in Urine

Diabetes is a common chronic disease, so it is particularly important to develop a convenient, fast, and highly sensitive non-enzymatic glucose sensor. In this work, a high sensitivity, low cost sensor was prepared on the substrate of printed circuit board. The nickel cobaltate (NiCo <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">4</sub> ) spherical nanomaterials were synthesized by facile hydrothermal and calcining methods. The working electrode was modified by NiCo <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">4</sub> nanospheres and the cation exchange resin in turn. Nafion cation exchange film can help to reduce the interference caused by surface-active compounds cyclic voltammetry- amperometric method was used to study the electrocatalytic performance of the sensor at room temperature. The sensor modified by NiCo <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">4</sub> nanospheres showed good sensor performance for glucose, including excellent sensitivity (3449.14 μA mM <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1 </sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ), wide linear range ( 1 μM to 100 mM), and low detection limit ( 0.376 μM). In addition, it has high selectivity, repeatability and stability. The sensor proposed in this work has been successfully applied to the detection of glucose in urine, and the results are consistent with the actual glucose concentration in urine.

Highly sensitive non-enzymatic glucose sensor with copper oxide nanoparticle impregnated mesoporous silica

Cuprous oxide (Cu2O) nanoparticles at a loading of 33.5 wt.% were impregnated in amine-functionalized mesoporous silica (NH2-SBA-15) particles, by an in situ chemical reduction method. Subsequently, Cu2O-NH2-SBA-15 hybrid was used as a modifier of glassy carbon electrode (GCE) for making a non-enzymatic glucose sensor. The optimum composition of the modifier on the GCE surface (0.47 mg Cu in Cu2O-NH2-SBA-15/cm2 surface area of GCE) resulted in a wide linearity range (0.2–15 mM glucose) and a high sensitivity of 438.3 µAcm−2 mM−1, due to the high loading of Cu2O in NH2-SBA-15 host. Furthermore, glucose was detected both in normal range (5 mM) and in hypoglycaemic range (2 mM), selectively in presence of concentrations of interfering species typically found in the normal blood, such as sodium chloride (142 mM), potassium chloride (3.7 mM), urea (4.7 mM) and ascorbic acid (0.05 mM). The response time was also less than 5 s. Therefore, it achieved the desirable sensor characteristics, like linearity, sensitivity, selectivity, and speed of response. This better performance of the sensor is mainly attributed to a high electrocatalytic activity of Cu2O nanoparticles towards glucose.