Non-enzymatic Glucose Sensor Research Articles

Non-enzymatic Glucose Sensor Based on CuO Nanoplates

We have successfully fabricated an electrochemical sensor for non-enzymatic glucose measurement based on copper oxide (CuO) nanoplates. CuO nanoplates were synthesized by a facile hydrothermal method at 180 oC for 23 h without using any surfactants. Filed-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) were used to characterize morphologies and crystal structures of synthesized CuO nanoplates. A mixture of CuO nanoplates and polytetrafluoroethylene with mass ratio 0.15:1 was compressed at 9800 kPa onto platinum (Pt) to form Pt/CuO disk and it has been used as a working electrode for glucose measurement following non-enzymatic approach. Glucose concentration was evaluated by cyclic voltammetry in 0.1M NaOH solution. This enzyme-free electrochemical method was able to detect glucose with a concentration as low as 0.1 mM. These results show that CuO nanoplates are a promising candidate for non-enzymatic glucose detection.

A dual-template defective 3DOMM-TiO2-x for enhanced non-enzymatic electrochemical glucose determination

A defective three dimensionally ordered macro-mesoporous TiO2-X (3DOMM-TiO2-X) was successfully prepared through dual-template method and applied as non-enzymatic electrochemical glucose sensor. The introduced oxygen vacancies and Ti3+ defects through defect engineering, as well as the macro-mesoporous structure induced by dual template, synergistically improve the performance of glucose determination. The Nafion/3DOMM-TiO2-X/FTO electrode shows better current response to glucose than commercial P25 and 3DOM-TiO2. A two-stage wide detection linear range of 1 μM ~ 2.32 mM and 2.32 mM ~ 14.72 mM was observed, with the sensitivity of 14.11 μA mM−1 cm−2 and 3.44 μA mM−1 cm−2, detection limits of 0.15 μM and 0.63 μM (S/N = 3), respectively. The electrode also exhibits superior reproducibility, stability, and selectivity performance. Furthermore, a reactive oxygen species oxidation mechanism was proposed and investigated. The Nafion/3DOMM-TiO2-X/FTO electrode also exhibits the potential as a photoelectrochemical electrode. Our results indicate the feasibility of the strategies to enhance the sensing ability by improving electronic conductivity through constructing 3DOMM porous structure and defect engineering.

A Review on the Development of Non-Enzymatic Glucose Sensor Based on Graphene-Based Nanocomposites

In this 21th century, the demand for glucose sensors in monitoring diabetes reaches a year-on-year peak due to the unhealthy lifestyle of society. Therefore, it is the utmost important task for scientists and researchers to develop a highly efficient and effective glucose sensor. However, conventional enzymatic glucose sensors have showed some drawbacks and the underlying issues faced by enzymatic glucose sensors are outlined in this paper. With the tremendous advancement of science and technology, the field of diabetes monitoring has evolved from enzymatic to nonenzymatic glucose sensor that heavily emphasized on the usage of nanomaterial. This transformation is supported by various justifications such as a better stability of nonenzymatic sensors towards the surrounding, higher sensitivity and ease of fabrication. Numerous materials including graphene, noble metals, (transition) metal oxides and composites have been explored for its potential in the development and performance improvement of nonenzymatic glucose sensors. This paper reviewed nonenzymatic glucose sensors, their mechanism of glucose oxidation and various promising graphene-based nanocomposite systems as well as the challenges and future perspectives of glucose biosensors.

In situ formation of reduced graphene oxide@Co3O4-N-doped carbon and its structure-function relationship for glucose sensing

The coordination of multiple materials is an effective strategy to develop high-performance sensing material, which requires a profound understanding of the structure-function relationship between multiple materials. Herein, a novel electrode material that reduced graphene oxide@Co3O4-N-doped carbon (rGO@Co3O4-NC) jungle has been formed on the surface of indium tin oxide (ITO) by the proposed in-situ preparation method. The template-directed growth of zeolitic imidazolate framework-67 (ZIF-67) is performed in a confined preparation process. The rGO@Co3O4-NC/ITO electrode with a unique structure based on two-dimensional nanosheets is eventually fabricated by a pyrolysis process of precursor. Such rGO@Co3O4-NC/ITO electrode can be directly used as a working electrode to establish an electrochemical sensor. The non-enzymatic glucose sensor based on rGO@Co3O4-NC/ITO exhibits good performances including the sensitivity of 2563 μA mM−1 cm−2, the detection limit of 50.4 nM, and the linear detection range of 0.5 μM–20.0 μM (R = 0.9992). The performance benefits of rGO@Co3O4-NC have been considered to be attributed to the structural and compositional advantages of ternary materials. This work represents the structure-function relationship of rGO, Co3O4 and NC, which is helpful for the design of multiple materials.

Facile Synthesis of Au/Ni(OH)2 Nanocomposites and its Application in Nonenzymatic Glucose Sensing

A simple and environment-friendly autocatalytic reduction process was developed for synthesis of Au/Ni(OH)2 nanocomposites. The nanocomposites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It is found the nanocomposites are composed of ultrathin Ni(OH)2 nanosheets and gold nanoparticles (AuNPs), and the AuNPs disperse evenly on the Ni(OH)2 nanosheets. The electrochemical and electrocatalytic properties of the Au/Ni(OH)2 modified glassy carbon electrode (Au/Ni(OH)2/GCE) were investigated by electrochemical experiments. Furthermore, through optimizing Au loading of the nanocomposites, the 5%-Au/Ni(OH)2/GCE displays the best electrocatalytic activity towards glucose oxidization in alkaline medium. Under optimal conditions, the 5%-Au/Ni(OH)2/GCE displays a wide linear range of 0.01 to 3.15 mM (R2 = 0.998) to glucose. Besides, the sensor has a low detection limit of 0.10 μM (S/N = 3) and a high sensitivity of 342.1 μA·mM−1·cm−2. It also displays satisfying stability, good reproducibility and selectivity.

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.

Facile synthesis of CuCo2O4@NiCo2O4 hybrid nanowire arrays on carbon cloth for a multicomponent non-enzymatic glucose sensor

The design of hierarchical heterogeneous structures with rational components is considered as a promising method to enhance the properties of electrocatalyst. Binary metal oxides, with high electrochemical activity, have attracted considerable interest in glucose determination. In this work, we synthesized the CuCo2O4@NiCo2O4 hybrid structure on conductive carbon cloth (CC) via a simple two-step hydrothermal process and investigated its catalytic ability toward glucose. The two individual components that make up this hybrid electrode have good electrical conductivity and excellent catalytic properties for glucose, so the smart combination of these two active materials can provide more catalytic sites and sufficient redox couples for the glucose oxidation. As a result, the CuCo2O4@NiCo2O4 modified CC presented superior glucose sensing properties, including ultrahigh sensitivity, fast response time, wide linear range and acceptable detection limit. Besides, the sample also exhibited good selectivity for substances in human blood that interfere with glucose detection, such as UA, AA, fructose, sucrose and KCl. The potential of the CuCo2O4@NiCo2O4/CC electrode for practical application was investigated by measuring the glucose concentration in real serum samples. These results prove that the construction of hierarchical ordered structure is conducive to the improvement of glucose sensor.

Flame synthesis of NiO nanoparticles on carbon cloth: An efficient non-enzymatic sensor for glucose and formaldehyde

Flame synthesis is one of the important methods for the synthesis of nanomaterials. In this work, NiO nanoparticles on carbon cloth (NiO/CC) were synthesized via a flame method, and the synthesized NiO/CC was used as a non-enzymatic sensor for the detection of glucose and formaldehyde. NiO/CC shows an excellent analytical performance for glucose sensing with a satisfactory reproducibility and selectivity, providing a response time as short as 3 s, a wide detection ranging from 5 μM to 2 mM, a LOD with 7.45 nM (S/N = 3), and a sensitive response with 4025 μA mM−1cm−2. Furthermore, the sensor also has a sensitive response to formaldehyde, a LOD of 6.8 nM (S/N = 3), a sensitivity of 5752 μA mM−1cm−2 and a response time of 3 s were obtained.

Preparation and comparison of colloid based Ni50Co50(OH)2/BOX electrocatalyst for catalysis and high performance nonenzymatic glucose sensor

A novel nonenzymatic glucose sensor based on Ni50Co50(OH)2/BOX/FTO was constructed with high sensitivity and excellent selectivity when compared with Ni(OH)2/FTO and Co(OH)2/FTO. Ni50Co50(OH)2/BOX/FTO glucose sensor with nanometric size was made by using a simple colloidal method. The morphological demonstration of nanomaterials/nanoparticles were characterized by using TEM (transmission electron microscopy), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), XRD and Raman, showing homogenously immersed particles with a size of less than 50 nm. Electrochemical measurements showed that colloidal based Ni50Co50(OH)2/BOX/FTO electrocatalyst possessed good catalysis capacity with low onset potential and excellent catalytic activity toward glucose. Nanocomposite has excellent sensitivity of 927.3 μA mM−1 cm−2, a wide linear range of 0.005 mM to 10.83 mM and LOD (low detection limit) of 0.017 μM (S/N = 3). Nanocomposites were applied for glucose determination in blood serum samples with standard addition; promising results were obtained with a standard deviation of ±1 to 2.5%. Nanocomposite show good reproducibility or recovery towards glucose. Ni50Co50(OH)2/BOX/FTO provide a new easy platform for electrochemical determination of glucose as nonenzymatic sensor.

A novel non-enzymatic glucose sensor based on gold-nickel bimetallic nanoparticles doped aluminosilicate framework prepared from agro-waste material

Functionalizedporous nanomaterials have been introduced as novel substrates with high surface area and large porosity for the construction of efficient catalysts in sensors. In this regard, nano X zeolite (NX), as a kind of aluminosilicate framework material, can be used as a hosting material for nanocatalysts in the design and fabrication of electrochemical sensors. Herein, a sensor based on multi-walled carbon nanotube (MWCNT) and NX material as a substrate for AuNi bimetallic nanoparticles obtained from agro-waste stem sweep was fabricated to detect nanomolar concenteration of glucose. The catalyst has provided a desired analytical performance for the glucose sensor with low limit of detection (0.063 µM) in the linear range of 1–1900 µM and sensitivity of 662.93 µA mM−1. The results depend on the presence of NX in the sensor and confirm the preference of a porous host existence for the AuNi catalyst in the sensing process. In AuNi/NX/MWCNT electrocatalyst, the disaggregation of Au nanoparticles by decorating on sacrificial Ni and the creation of abundant active sites through NX make the acceptable results for non-enzymatic detection of glucose in the human serum samples.

New Bi2MoO6 nano-shapes toward ultrasensitive enzymeless glucose tracing: Synergetic effect of the Bi-Mo association

In a novel approach, an efficient non-enzymatic glucose sensor based on pure phase of aurivillius bismuth molybdate (BM or γ-Bi2MoO6) mixed metal oxides is reported. Three BM samples were synthesized, with/without l-cysteine (Cys) and dodecylamine (DDA) as additives, leading to different shapes: bullet (BM-C), confetti (BM-2Cys) and candy (BM-2DDA). The morphology and purity of the structures were confirmed by FE-SEM images and XRD. In order to investigate the sensor application, the samples were integrated on reduced graphene oxide and incorporated into simple and inexpensive glassy carbon electrode (GCE) without using any polyvinylpyrrolidone (PVP) or Nafion. To perform cyclic voltammetry experiments, all three biosensors were measured in PBS solution (pH = 7) in ±1.5 voltage range and 50 mV s−1 scan rate. Glucose identification by the synthesized composites is an obvious sign of their high efficiency. According to chronoamperomograms, the best sensitivity of 3050 μA L mmol−1 cm−2 with linear range of 0.02–0.14 mmol L−1, low detection limit (LOD) of 0.004 mmol L−1 and the signal/noise equal to 3 was achieved by BM-2DDA/rGO/GCE biosensor and its speedy amperometric response is less than 5 s. This biosensor showed impressive selectivity, repeatability and reproducibility results besides it maintains its stability considerably in great percentage of 98.5% after eight weeks. Also it showed prolonged stability after 50 min.

Platinum and zinc oxide modified carbon nitride electrode as non-enzymatic highly selective and reusable electrochemical diabetic sensor in human blood

Development of non-enzymatic glucose sensor is essential to reduce the cost of diabetes regular monitoring. Here, graphitic carbon nitride (g-C3N4) is modified with platinum and zinc oxide for non-enzymatic electrochemical glucose sensing in physiological conditions for the first time in the literature. The interactions between Pt, g-C3N4 and the ZnO are studied using different physicochemical characterization techniques. The Electrochemical glucose sensing at the ZnO-Pt-gC3N4 occurs at low applied potential of +0.20 V (vs. Ag/AgCl) with high sensitivity 3.34 μA/mM/cm2 and fast response (5 s) time. This sensor exhibited a wide linear range 0.25–110 mM with lower limit of detection of 0.1 µM. The architectured sensor was evaluated in human blood, serum and urine samples. The sensor is 4 time reusable in whole blood without activity deterioration. This reusable surface helps to reduce the cost of strip.

Comparative study of enzymatic and non-enzymatic detection of glucose using manganese ferrite nanoparticles

The use of metal oxide nanoparticles for the development of cost-effective glucose biosensors has been receiving increased attention. Enzymatic and non-enzymatic glucose sensor using polyethylene glycol (PEG) grafted manganese ferrite (PEG-MnFe2O4) nanoparticles (NPs) modified onto a glassy carbon electrode (GCE) is reported in the present study. XRD and Raman studies confirmed the cubic spinel structure of MnFe2O4. The immobilization of glucose oxidase (GOx) on PEG-MnFe2O4 (GOx@PEG-MnFe2O4) was validated using FTIR and TGA. Sensing electrodes exhibited well-defined redox peaks in 0.1 M phosphate buffered saline (PBS) solution at pH 7.4 against the reference electrode Ag/AgCl. GOx@PEG-MnFe2O4/GCE displayed a sensitivity of 1.985 μA mM−1 cm−2 in the linear range of 1 to 20 mM with a limit of detection (LOD) of 0.132 mM whereas non-enzymatic sensor exhibited a sensitivity of 1.044 μA mM−1 cm−2 in the linear range of 1 to 10 mM with a LOD of 0.099 mM. The lower Michaelis constant () value indicates greater affinity towards glucose for the enzymatic sensor. GOx@PEG-MnFe2O4 revealed selectivity specifically for glucose over various interferants such as fructose, lactic acid, sucrose, uric acid and ascorbic acid. In addition, this enzymatic sensor demonstrated better reproducibility and lifetime.

Metal oxide-based composite for non-enzymatic glucose sensors

The increasing demand for monitoring the glucose concentration in the blood of diabetic patients has aroused the attention of researchers to prepare high-performance glucose biosensors. After decades of development, enzyme-based biosensors have gradually matured and commercialized, but they still suffer from insufficient stability due to the inherent defects of the enzyme. Non-enzymatic glucose sensor was proposed to address this issue. The introduction of nanotechnology has provided more possibilities for the preparation of highly efficient catalytic materials. Among the synthesized electrocatalysts, metal oxides are one of the most important components owing to their outstanding properties. Recent studies have integrated metal oxides with other materials to further improve sensor performance. This review focuses on the application of metal oxide-based hybrid structure in the glucose sensor, mainly including metal oxide/metal oxide, metal/metal oxide, and carbon material/metal oxide. The preparation method, electrochemical properties, and catalytic mechanism of the sensors are discussed in detail. Finally, we present some of the existing challenges and make personal predictions for the future development of non-enzymatic glucose sensors.

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.

Poly(9H-carbazole) as a Organic Semiconductor for Enzymatic and Non-Enzymatic Glucose Sensors.

Organic semiconductors and conducting polymers are the most promising next-generation conducting materials for electrochemical biosensors as the greener and cheaper alternative for electrodes based on transition metals or their oxides. Therefore, polycarbazole as the organic semiconducting polymer was electrochemically synthesized and deposited on working electrode. Structure and semiconducting properties of polycarbazole have theoretically and experimentally been analyzed and proved. For these electrochemical systems, a maximal sensitivity of 14 μA·cm−2·mM−1, a wide linear range of detection up to 5 mM, and a minimal limit of detection of around 0.2 mM were achieved. Moreover, Michaelis’s constant of these sensors depends not only on the enzyme but on the material of electrode and applied potential. The electrocatalytic mechanism and performance of the non- and enzymatic sensors based on this material as a conducting layer have been discussed by estimating pseudocapacitive and faradaic currents and by adding glucose as an analyte at the different applied potentials. In this work, the attention was focused on the electrochemical origin and mechanism involved in the non- and enzymatic oxidation and reduction of glucose.

Electrochemical system designed on a copper tape platform as a nonenzymatic glucose sensor

The electrochemical glucose sensors have an essential role in the control of diabetes since they bring a simple, economic, accurate, rapid response, and reliable method for the detection of glucose and act as a useful diagnostic tool in the various real samples. This work describes the use of economic and prototyping technique based on copper tape as a cost-effective platform to develop flexible and straightforward glucose sensors. In this technique, the galvanic replacement reaction that is a cheap, instrument-free, and reproducible technique, was applied to provide the nanostructural silver coat on copper tape (Ag-CuT) for preparation of working electrode, silver-counter electrode, and Ag/AgCl reference electrode. Three-electrode configuration was patterned on a hydrophobic self-adhesive glossy paper using a laser cutter; then, copper-based electrodes were stuck on the patterned glossy paper. This electrochemical system was used in developing an enzyme-free sensor for glucose detection. The flexible sensing platform shows excellent electro-catalytic activity toward the oxidation of glucose. The proposed flexible electrochemical sensor (f-ES) offers a wide linear range from 3 μM to 3300 μM with a high sensitivity of 4610 μA mM−1 cm−2 and acceptable reproducibility. Given the facile, economical, reliability, and prototype nature of the technique, it has the potentials for application in wearable or portable glucose sensors.

Ligand-to-metal charge transfer (LMCT) complex: New approach to non-enzymatic glucose sensors based on TiO2

Titanium metal covered with titanium dioxide (Ti/TiO2) was used as a promising non-enzymatic glucose sensor demonstrating a new approach to electrochemical glucose determination. A Ti/TiO2 nanotubes-glucose complex formation on an electrode surface was demonstrated by infrared, Raman, and X-ray photoelectron spectroscopy. The main electrochemical method used for glucose detection was electrochemical impedance spectroscopy as a promising method for an easy electrochemical determination. To the best of our knowledge, this kind of sensor has never been studied especially in case of non-enzymatic glucose detection. Ti/TiO2 glucose sensor displays a wide practical linear range (1–15 mM) in a pH neutral condition, which cover the typical range in diabetic patients. The selectivity and the limit of detection were 8.3 kΩ·mM−1 and 1.2 mM, respectively. Therefore this kind of a system is very promising candidate for blood glucose sensing which should be able to replace enzymatic glucose sensors. Based on the properties of the prepared sensors, TiO2 is an unrivalled material for glucose sensing comparable with the enzymatic sensors.

Mesoporous ZnCo2O4 nanowire arrays with oxygen vacancies and N-dopants for significant improvement of non-enzymatic glucose detection

An efficient electrode for use in a sensitive, nonenzymatic catalyst for electro-oxidation of glucose is urgently needed to reduce the cost of regular diabetic monitoring. Finding a way to improve sensitivity while reserving the catalytic activity for glucose monitoring presents a big challenge. Replacing oxygen defects with nitrogen atoms in a nanostructured transition metal oxide can expose more catalytic active sites with improved electrical conductivity. Herein, a simple and scalable technique has been demonstrated to fabricate N-doped mesoporous ZnCo2O4 nanowire arrays (N-doped ZnCo2O4 electrode) through NH3-plasma treatment toward high-performance nonenzymatic glucose sensors. As a result, an N-doped ZnCo2O4 electrode exhibits ultra-sensitivity of 14,000 μA·mM−1 cm−2, a detection limit of 0.54 μM (S/N = 3), and a short response time of about 7.9 s. The impressive electrocatalytic performance originates from the filling of oxygen vacancies with nitrogen atoms in the mesoporous ZnCo2O4 nanowire arrays, which helps to accelerate the kinetics by increasing the pre-oxidation state of Co3+ and improving the electrical conductivity. Therefore, this study provides new insights into investigating the rational design of nanostructured transition metal oxides/hydroxides with tunable active sites and electrical conductivities for high-performance non-enzymatic glucose sensors.

A disposable and sensitive non-enzymatic glucose sensor based on 3D graphene/Cu2O modified carbon paper electrode

Herein, a three-dimensional graphene wall (GWs) and nano-Cu2O modified carbon fiber paper (CFP) electrode were used to develop a disposable and sensitive non-enzymatic glucose sensor. This sensing interface of GWs/Cu2O consists of an interlaced CFP on which intercrossed graphene walls (GWs) were vertically tethered in situ by radio frequency plasma enhanced chemical vapor deposition (RF-PECVD), and Cu2O nanoparticles (NPs) were evenly grew on the 3D GWs layer and skeleton through the complete thermal decomposition of copper acetate (Cu (CH3COO)2) at high temperature. The CFP/GWs/Cu2O shows a large specific surface area and rich solution diffusion channels, which can expose more catalytic active sites without Nafion fixation film, thus greatly improving the electrocatalytic performance of this glucose sensor. The CFP/GWs/Cu2O sensor shows excellent catalytic performance to glucose with a linear detection range of 0.5 μM–5166 μM, LOD of 0.21 μM, and response time <4 s. This kind of disposable and sensitive electrode can capable of controlling uniform growth and accurate quantification, and has great development potential in the field of medical detection and the commercialization of wearable sensors.