Non-enzymatic Glucose Detection Research Articles

A novel contemporary molecular imprinting technique for non-enzymatic selective glucose detection

In this article we have reported highly selective detection of glucose using molecular imprinting technique (MIP), where unclad portion of a fiber is used as a substrate. The sensor works on non-enzymatic approach which makes it more promising. Employing unclad fiber with large core diameter not only eased the coupling but also provided enough evanescent field to interact with ambient medium. The presence of MIP in sensing region (unclad fiber) provides binding sites sensitive only to the size and shape specific target molecules that notably improved the selectivity. In addition, we have added carbon nano particles (CNPs) with high specific surface area to the polymer matrix, which provides numerous microcavities that worked as active sites. This enabled efficient penetration of analyte to the coated fiber surface. Herein, exponentially decaying evanescent field was elicited for establishing intensity modulated optical fiber sensors. Our experimental measurements showed that adding 0.0025 g CNPs to polymer matrix not only preserved the size of micro holes in MIP but also rendered high linear response in the clinical range of glucose concentration that is 2–10 mM. The present device introduced several advantages such as low-cost, online monitoring, fast response time (∼7 s), high stability and selectivity that makes it promising candidate for integrated sensors and biological medicine measurements.

Screen-printed Ga2O3 thin film derived from liquid metal employed in highly sensitive pH and non-enzymatic glucose recognition

A new scaffold was introduced prefacing a screen-printed native gallium oxide (Ga2O3) layer derived from galinstan and pure metallic gallium, employed in Extended Gate Field Effect Transistor (EGFET) along with electrochemical measurement for pH and non-enzymatic glucose detection. Screen-printed Ga2O3 from galinstan exhibited a better pH sensitivity (79. 46 mV/pH) with 99% linearity and improved reliability compared to Ga2O3 derived from pure gallium. The highly selective Ga2O3 (from galistan) based glucose sensor exhibited high sensitivity (22.01 mV/mM) in EGFET and a minimum limit of detection (20 μM) in electrochemical measurement. The commercial applicability of the galinstan-based EGFET glucose sensor was examined by detecting glucose in human serum. Material characterization supported the electrical results. This approach is an innovative state-of-the-art for a stable, inexpensive, and reliable pH and glucose detection method at room temperature.

Electrochemical Characterization of Modified Glassy Carbon Electrodes for Non-Enzymatic Glucose Sensors.

The diversity of materials proposed for non-enzymatic glucose detection and the lack of standardized protocols for assessing sensor performance have caused considerable confusion in the field. Therefore, methods for pre-evaluation of working electrodes, which will enable their conscious design, are currently intensively sought. Our approach involved comprehensive morphologic and structural characterization of copper sulfides as well as drop-casted suspensions based on three different polymers—cationic chitosan, anionic Nafion, and nonionic polyvinylpyrrolidone (PVP). For this purpose, scanning electron microscopy (SEM), X-ray diffraction (XRD), and Raman spectroscopy were applied. Subsequently, comparative studies of electrochemical properties of bare glassy carbon electrode (GCE), polymer- and copper sulfides/polymer-modified GCEs were performed using electrochemical impedance spectroscopy (EIS) and voltammetry. The results from EIS provided an explanation for the enhanced analytical performance of Cu-PVP/GCE over chitosan- and Nafion-based electrodes. Moreover, it was found that the pH of the electrolyte significantly affects the electrocatalytic behavior of copper sulfides, indicating the importance of OHads in the detection mechanism. Additionally, diffusion was denoted as a limiting step in the irreversible electrooxidation process that occurs in the proposed system.

Preparation of electrochemical sensor based on the novel NiO quantum dots modified Cu/Cu2O 3D hybrid electrode and its application for non-enzymatic detection of glucose in serums and beverages

Herein, 3D Cu/Cu2O/NiO hybrid electrodes were successfully synthesized via a seed-medium process combined with electrodeposition. The NiO was deposited on the surface of Cu2O stacked octahedrons as NiO quantum dots (NiO QDS), whereas, Cu was obtained by the reduction of Cu2O during the electrodeposition process. These 3D hybrid electrodes were first proposed and applied to non-enzymatic glucose detection. The effect of electrodeposition time on structure and performance was further investigated. The single Cu2O electrode showed the highest sensitivity (1763 μA m M−1 cm−2), whereas, the 3D hybrid electrodes that being electrodeposited for 2 min exhibited the widest linear range (up to 21.65 mM). In addition, the obtained 3D Cu/Cu2O/NiO QDs hybrid electrode was applied to detect glucose in real serum and beverages. The acceptable sensing performance in real serum and beverages proves our obtained 3D Cu/Cu2O/NiO QDs hybrid electrode a potential for monitoring of glucose in biological and food samples.

Nickel-gold bimetallic nanostructures with the improved electrochemical performance for non-enzymatic glucose determination

Bimetallic nanostructured electrodes are promising candidates for non-enzymatic glucose detection due to their excellent selectivity and high sensitivity. In this work, a bimetallic Ni/Au non-enzymatic glucose sensor was developed by the electrodeposition of nickel nanostructures on Au nanoparticles (NP). Physical vapor deposition followed by thermal annealing was used for the growth of seeding Au (NP) on fluorine doped tin oxide (FTO) substrates. The electrochemical growth of Ni nanostructures on the Au-seeded substrates led to enhanced electrochemical responses from the modified electrodes. Cyclic voltammetry results showed considerable improvement of the electrocatalytic activity of the Ni/Au bimetallic structure in comparison to monolithic Ni and Au structures due to the synergistic effect. The sensor showed two linear ranges of 5 μM–3.5 mM and 3.5–7 mM for glucose detection with the sensitivity of 893 (μA mM−1 cm−2). The low detection limit of 0.7 μM and the fast response time of 5 s was achieved. The selectivity, reproducibility and accuracy of the fabricated sensor in determination of human serum glucose suggest its potential for large-scale production as commercial non-enzymatic glucose detection.

Non-Enzymatic Detection of Glucose in Neutral Solution Using PBS-Treated Electrodeposited Copper-Nickel Electrodes.

Transition metals have been explored extensively for non-enzymatic electrochemical detection of glucose. However, to enable glucose oxidation, the majority of reports require highly alkaline electrolytes which can be damaging to the sensors and hazardous to handle. In this work, we developed a non-enzymatic sensor for detection of glucose in near-neutral solution based on copper-nickel electrodes which are electrochemically modified in phosphate-buffered saline (PBS). Nickel and copper were deposited using chronopotentiometry, followed by a two-step annealing process in air (Step 1: at room temperature and Step 2: at 150 °C) and electrochemical stabilization in PBS. Morphology and chemical composition of the electrodes were characterized using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Cyclic voltammetry was used to measure oxidation reaction of glucose in sodium sulfate (100 mM, pH 6.4). The PBS-Cu-Ni working electrodes enabled detection of glucose with a limit of detection (LOD) of 4.2 nM, a dynamic response from 5 nM to 20 mM, and sensitivity of 5.47 0.45 at an applied potential of 0.2 V. In addition to the ultralow LOD, the sensors are selective toward glucose in the presence of physiologically relevant concentrations of ascorbic acid and uric acid spiked in artificial saliva. The optimized PBS-Cu-Ni electrodes demonstrate better stability after seven days storage in ambient compared to the Cu-Ni electrodes without PBS treatment.

Surfactant‐free synthesis of self-assembled CuO spheres composited with MnO2 nanorods for non-enzymatic glucose detection

Cupric oxide (CuO) spheres and manganese dioxide (MnO 2 ) nanorods by hydrothermal synthesis are investigated for non-enzymatic glucose sensors. Self-assembled CuO spheres were first synthesized on ITO/glass substrate without surfactant. MnO 2 nanorods were then composited on the exterior of CuO spheres by using a drop-coating method. The MnO 2 nanorods/CuO sphere/ITO working electrode was used to analyze the catalytic ability to glucose. Large surface-to-volume ratio of the material enhances the glucose sensing performances. MnO 2 improves the sensitivity and the linearity of the glucose detection. The working electrode has high sensitivity of 2360.81 μA mM −1 cm −2 to glucose. Good linear range between 0.5 and 2.5 mM glucose concentration can also be found. It also has great anti-interference ability. Excellent performances of the MnO 2 nanorods/CuO sphere to glucose can help more accurately and quickly detecting the blood sugar concentration. • Cupric oxide sphere and manganese dioxide nanorods were synthesized by low-temperature hydrothermal method. • Cupric oxide can self-assembled into a spherical structure without surfactant. • Manganese dioxide nanorods/cupric oxide sphere has high sensitivity of 2360.81 μA mM −1 cm −2 to glucose.

Cu2O nanowires with exposed {111} facet for nonenzymatic detection of glucose in complex biological fluids

Accurate glucose sensing in complex biological fluids could enable diagnostics for home healthcare. However, glucose oxidase (GOx) has been suffered from poor reproducibility and chemical instability due to intrinsic nature of enzymes. Here, we report a free-standing and robust reduced graphene oxide wrapped Cu foam (rGO/CuF)-supported Cu2O nanowires (Cu2O NWs) with exposed {111} facet via facile electrodeposition route. When being used as an electrode for nonenzymic glucose detection, Cu2O NWs@rGO/CuF exhibited the distinguished performances with powerful reliability for analyzing human plasma and even whole blood samples. These unprecedented performances could be ascribed to nanoscale hydrophilic structure of Cu2O NWs, which could control the fouling level especially for protein. Moreover, taking into account the Cu2O NWs with exposed {111} facet, Cu2O NWs {111} could reduce ion diffusion distance and couple with improved electronic conductivity, thus leading to high glucose sensitivity. Through the theoretical calculations, a reliable interpretation of the catalytic mechanism with Cu2O NWs {111} has been provided. This study deepens the understanding of hydrophilic nanostructure and facet-dependent activity of Cu2O NWs and points out a strategy to improve their sensitivity and stability.

Facile synthesis of Cu/Co-ZIF nanoarrays for non-enzymatic glucose detection

Cu/Co-ZIF nanoflake arrays on carbon cloth are fabricated by controlling the introducing of Cu2+ ions during the growth of Co-ZIF. The Cu/Co-ZIF-20 electrode prepared with 20 mM Cu2+ possesses large electrochemically active surface area and bimetallic active sites, which can be revealed by cyclic voltammetry tests. The amperometric i–t measurements demonstrate that the Cu/Co-ZIF-20 electrode displays a wide linear range from 0.05 mM to 6.0 mM, and a high sensitivity of 1.03 mA mM−1 cm−2. Good selectivity, repeatability and practical applicability indicate its promising application in enzyme-free glucose sensing.

The dependence of Cu2O morphology on different surfactants and its application for non-enzymatic glucose detection

Herein, the Cu2O yolk-shell nanospheres, nanocubes and microcubes were successfully prepared by a simple seed-medium process. The formation of the Cu2O yolk-shell nanospheres can be attributed to the self-assembly process caused by the introduction of the seed medium. The formation mechanism of our obtained Cu2O yolk-shell nanospheres and the dependence of Cu2O morphology on different surfactants have been studied. The obtained samples were applied in the field of non-enzymatic glucose detection. The electrochemical response characteristics of the modified electrodes toward glucose were investigated by cyclic voltammetry (CV) and chronoamperometry (CA). The electrode modified with C-Cu2O (obtained by using CTAB as surfactant) shared the highest sensitivity of 3123 μAmM−1 cm-2, whereas, the electrode modified with S-Cu2O (obtained by using SDBS as surfactant) exhibited the lowest LOD of 0.87 μM and the widest linear range of 0.05–10.65 mM. All obtained sensors showed fast response to the addition of glucose. The obtained electrodes showed better responses to glucose than other coexisting interferences, indicating that the obtained electrodes had the acceptable selectivity to glucose. In addition, the stability for 5 consecutive weeks had also been studied and exhibited satisfactory results. The obtained electrode was also used to detect the glucose content in real serum. The acceptable selectivity, stability together with the excellent sensing ability in real serum make the obtained electrodes a potential for practical applications.

RGO@Cu2O@Cu Ternary Nanocomposite for High-Performance Non-Enzymatic Glucose Detection

Fast, reliable, and low-cost glucose detection methods are of great importance for the control of diabetes. In this study, Cu2O combined with Cu nanoparticles anchored on reduced graphene oxide (RGO), was synthesized to function as the electrode in a non-enzymatic glucose sensor. The synergistic effect between Cu nanoparticles and Cu2O, together with the high conductivity of RGO enabled considerably lower resistivity with greater glucose oxidation activity than pure Cu2O. The RGO@Cu2O@Cu electrode exhibited a high sensitivity of 1.112 mA mM−1 cm−2 with a detection limit of 0.019 μM, and the linear range is up to 4 mM. Additionally, the RGO@Cu2O@Cu electrode displayed good anti-interference performance within human blood and high stability while operating for a long duration. Significantly, the glucose detection capability of the as-designed electrode was comparable to commercial sensors, representing a valuable design for future non-enzymatic glucose sensing.

Non-enzymatic andrapid detection of glucose on PVA-CuO thin film using ARDUINO UNO based capacitance measurement unit.

Glucose measurement is one of the essential health monitoring practices for maintaining blood sugar levels. Here, we have fabricated a highly specific capacitive nano-sensor for non-enzymatic glucose detection. Capacitance measurements were carried out on polyvinyl alcohol capped copper oxide (PVA-CuO) thin films on indium tin oxide (ITO) coated glass using ARDUINO UNO. The capacitance study shows a decrease in capacitance with an increase in glucose concentrations. The applicability in real samples was performed by studying the glucose in the presence of fetal bovine serum. Most commonly found interfering agents were used for interference studies, which confirmed the capacitive nano-sensor specificity. The system was further checked for repeatability up to six readings and reproducibility up to 5 chips. The shelf-life study showed stability forfour weeks of a chip. These studies indicate that this capacitance-based measurement unit can be used for reliable, rapid, and non-enzymatic detection of glucose in real sample.

Laser-Assisted Surface Modification of Ni Microstructures with Au and Pt toward Cell Biocompatibility and High Enzyme-Free Glucose Sensing.

We investigated the influence of morphology of Ni microstructures modified with Au and Pt on their cell biocompatibility and electrocatalytic activity toward non-enzymatic glucose detection. Synthesis and modification were carried out using a simple and inexpensive approach based on the method of laser-induced deposition of metal microstructures from a solution on the surface of various dielectrics. Morphological analysis of the fabricated materials demonstrated that the surface of the Ni electrode has a hierarchical structure with large-scale 10 μm pores and small-scale 10 nm irregularities. In turn, the Ni-Pt surface has large-scale cavities, small-scale pores (1–1.5 μm), and a few tens of nanometer particles opposite to Ni-Au that reveals no obvious hierarchical structure. These observations were supported by impedance spectroscopy confirming the hierarchy of the surface topography of Ni and Ni-Pt structures. We tested the biocompatibility of the fabricated Ni-based electrodes with the HeLa cells. It was shown that the Ni-Au electrode has a much better cell adhesion than Ni-Pt with a more complex morphology. On the contrary, porous Ni and Ni-Pt electrodes with a more developed surface area than that of Ni-Au have better catalytic performance toward enzymeless glucose sensing, revealing greater sensitivity, selectivity, and stability. In this regard, modification of Ni with Pt led to the most prominent results providing rather good glucose detection limits (0.14 and 0.19 μA) and linear ranges (10–300 and 300–1500 μA) as well as the highest sensitivities of 18,570 and 2929 μA mM–1 cm–2. We also proposed some ideas to clarify the observed behavior and explain the influence of morphology of the fabricated electrodes on their electrocatalytic activity and biocompatibility.

Simultaneous Detection of Glucose and Fructose in Synthetic Musts by Multivariate Analysis of Silica-Based Amperometric Sensor Signals.

Silica-based electrodes which permanently include a graphite/Au nanoparticles composite were tested for non-enzymatic detection of glucose and fructose. The composite material showed an effective electrocatalytic activity, to achieve the oxidation of the two analytes at quite low potential values and with good linearity. Reduced surface passivation was observed even in presence of organic species normally constituting real samples. Electrochemical responses were systematically recorded in cyclic voltammetry and differential pulse voltammetry by analysing 99 solutions containing glucose and fructose at different concentration values. The analysed samples consisted both in glucose and fructose aqueous solutions at pH 12 and in solutions of synthetic musts of red grapes, to test the feasibility of the approach in a real frame. Multivariate exploratory analyses of the electrochemical signals were performed using the Principal Component Analysis (PCA). This gave evidence of the effectiveness of the chemometric approach to study the electrochemical sensor responses. Thanks to PCA, it was possible to highlight the different contributions of glucose and fructose to the voltammetric signal, allowing their selective determination.

Dendritic core-shell copper-nickel alloy@metal oxide for efficient non-enzymatic glucose detection

The synergy effect of bimetallic oxide shell and high electrically conductive metallic core enables the dendritic Cu-Ni/ nickel foam (NF) for detecting non-enzymatic glucose. • Binder-free Cu-Ni alloys@metal oxide was prepared by facile electrodeposition method. • The dendritic structure promotes glucose diffusion and provides rich active sites. • The bimetallic oxide shell and metallic core enable highly effective glucose sensing. A success has been achieved in the synthesis of dendritic core-shell copper-nickel alloy@metal oxide on nickel foam (Cu-Ni/NF) electrode for non-enzymatic glucose detection by going through a facile electrodeposition process followed by oxidation in NaOH solution. The direct electrodeposition approach facilitates the transfer of electrons in the binder-free electrode, and the dendritic structure promotes glucose diffusion while providing sufficient active sites required for the process of glucose electrocatlysis. Moreover, the unique core-shell structure promotes the catalytic activity towards glucose oxidation due to the synergistic effect caused by the bimetallic oxide shell and the metallic core that is conductive to electron transport. Accordingly, the Cu-Ni/NF electrode exhibits a high sensitivity of 11.34 mA mM −1 cm -2 , a low detection limit of 2 μM (S/N = 3), and a wide linear range of 1–600 μM for glucose detection. In addition, the electrode demonstrates such advantages as high selectivity, fast response time, and long duration stability. The designed Cu-Ni/NF electrode shows its massive potential of application for non-enzymatic glucose detection.

Mn2O3 porous microsheets prepared by a chemical precipitation method as an effective electrochemical sensor for non-enzymatic glucose detection

Mn2O3 porous microsheets prepared by a chemical precipitation method as an effective electrochemical sensor for non-enzymatic glucose detection

Enhancing the non-enzymatic glucose detection performance of Ni(OH)2 nanosheets via defect engineering

Electrochemical non-enzymatic glucose detection technology has been widely used in glucose sensors because of its simple operation and outstanding detection efficiency. Electrocatalysts that are earth-abundant and highly active are still to be explored to meet practical detection requirements. In this work, we report a strongly enhanced glucose detection performance of Ni(OH)2 by defect engineering. Ni(OH)2 nanosheets are synthesized by the electrochemical deposition method. Defects with various concentrations are introduced into Ni(OH)2 nanosheets by Ar plasma treatment. The defective Ni(OH)2 exhibits strongly enhanced glucose detection performance with higher sensitivity and wider linear response range. In-situ Raman spectra results suggest that defects can promote the deprotonation reaction of defective Ni(OH)2 to form NiOOH intermediates. In consequence, the oxidization of the glucose by the formed NiOOH is strongly facilitated, leading to the enhanced detection performance. The results in this work clarify the essential role of defects in determining the glucose detection performance of transition metal hydroxides and demonstrate defect engineering can be used for improving the performance of electrochemical non-enzymic sensors.

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.

Development of Ag–Ni NPs loaded on MWCNTs for highly sensitive, selective and reproducible non-enzymatic electrochemical detection of glucose

Development of Ag–Ni NPs loaded on MWCNTs for highly sensitive, selective and reproducible non-enzymatic electrochemical detection of glucose

Copper and Nickel Microsensors Produced by Selective Laser Reductive Sintering for Non-Enzymatic Glucose Detection.

In this work, the method of selective laser reductive sintering was used to fabricate the sensor-active copper and nickel microstructures on the surface of glass-ceramics suitable for non-enzymatic detection of glucose. The calculated sensitivities for these microsensors are 1110 and 2080 μA mM−1·cm−2 for copper and nickel, respectively. Linear regime of enzymeless glucose sensing is provided between 0.003 and 3 mM for copper and between 0.01 and 3 mM for nickel. Limits of glucose detection for these manufactured micropatterns are equal to 0.91 and 2.1 µM for copper and nickel, respectively. In addition, the fabricated materials demonstrate rather good selectivity, long-term stability and reproducibility.