Non-enzymatic Glucose Detection Research Articles

Development of hyaluronic acid-based electroconductive hydrogel as a sensitive non-enzymatic glucose sensor

Herein, a novel hyaluronic acid (HA)-based electroconductive hydrogel with enhanced mechanical properties was developed for the non-enzymatic glucose detection. As the main component of the polymeric network, HA was modified through methacrylation to integrate photocrosslinkable groups into its backbone. Electrical conductivity was provided to hydrogel by using two different conductivity sources as the introduction of reduced graphene oxide (rGO) and polyaniline (PANI) to HA-based hydrogel structure. The combination of these conductivity sources not only provided the sufficient electrical conductivity (1.58 ×10−5 S/cm) to hydrogels, but also ensured superior mechanical performance in terms of compressive strength (992.1 kPa) and elastic modulus (23.4 kPa) due to the synergistic effect of the rGO and PANI, that are the significant parameters for sensor applications. The electrochemical activity and sensor performance of the HA-based hydrogel were investigated via cyclic voltammetry (CV) and choronoamperometry (CA) methods. The fabricated HA-based hydrogel sensor exhibited high sensitivity as 421.42 µAmM−1cm−2 and selectivity for glucose with a low detection limit (0.3 µM). Moreover, it showed excellent long-term stability, reproducibility and anti-interference feature towards uric acid, ascorbic acid and sorbitol. Based on these results it could be stated that the developed HA-based hydrogel sensor containing ternary HA-rGO-PANI formulation for the first time in the literature might be served as a promising potential for the non-enzymatic glucose detection and it also offers a new perspective for fabricating efficient hydrogel-based biosensing systems for future studies.

Copper(II)-Incorporated Porphyrin-Based Porous Organic Polymer for a Nonenzymatic Electrochemical Glucose Sensor.

To date, the fabrication of multifunctional nanoplatforms based on a porous organic polymer for electrochemical sensing of biorelevant molecules has received considerable attention in the search for a more active, robust, and sensitive electrocatalyst. Here, in this report, we have developed a new porous organic polymer based on porphyrin (TEG-POR) from a polycondensation reaction between a triethylene glycol-linked dialdehyde and pyrrole. The Cu(II) complex of the polymer Cu-TEG-POR shows high sensitivity and a low detection limit for glucose electro-oxidation in an alkaline medium. The characterization of the as-synthesized polymer was done by thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and 13C CP-MAS solid-state NMR. The N2 adsorption/desorption isotherm was carried out at 77 K to analyze the porous property. TEG-POR and Cu-TEG-POR both show excellent thermal stability. The Cu-TEG-POR-modified GC electrode shows a low detection limit (LOD) value of 0.9 μM and a wide linear range (0.001-1.3 mM) with a sensitivity of 415.8 μA mM-1 cm-2 toward electrochemical glucose sensing. The interference of the modified electrode from ascorbic acid, dopamine, NaCl, uric acid, fructose, sucrose, and cysteine was insignificant. Cu-TEG-POR exhibits acceptable recovery for blood glucose detection (97.25-104%), suggesting its scope in the future for selective and sensitive nonenzymatic glucose detection in human blood.

Synthesis, Characterization, and Electrochemical Evaluation of Copper Sulfide Nanoparticles and Their Application for Non-Enzymatic Glucose Detection in Blood Samples.

Glutathione-capped copper sulfide (CuxSy) nanoparticles with two different average sizes were successfully achieved by using a simple reduction process that involves only changing the reaction temperature. Temperature-induced changes in the size of CuxSy nanoparticles resulted in particles with different optical, morphological, and electrochemical properties. The dependence of electrochemical sensing properties on the sizes of CuxSy nanoparticles was studied by using voltammetric and amperometric techniques. The spherical CuxSy nanoparticles with the average particle size of 25 ± 0.6 nm were found to be highly conductive as compared to CuxSy nanoparticles with the average particle size of 4.5 ± 0.2 nm. The spherical CuxSy nanoparticles exhibited a low bandgap energy (Eg) of 1.87 eV, resulting in superior electrochemical properties and improved electron transfer during glucose detection. The sensor showed a very good electrocatalytic activity toward glucose molecules in the presence of interference species such as uric acid (UA), ascorbic acid (AA), fructose, sodium chloride, and sucrose. These species are often present in low concentrations in the blood. The sensor demonstrated an excellent dynamic linear range between 0.2 to 16 mM, detection limit of 0.2 mM, and sensitivity of 0.013 mA/mM. The applicability of the developed sensor for real field determination of glucose was demonstrated by use of spiked blood samples, which confirmed that the developed sensor had great potential for real analysis of blood glucose levels.

Corrosion-assisted in situ growth of NiCoFe-layered double hydroxides on Fe foam for sensitive non-enzymatic glucose detection.

Because of their remarkable qualities including changeable chemical composition, good redox characteristics, and ease of manufacture, non-enzymatic glucose sensors based on metallic hydroxides have attracted much interest. However, enhancement of their peroxidase-like catalytic activity is challenging due to their poor substrate affinity and low electrical conductivity, affecting electron transfer. Herein, a three-dimensional hierarchical architecture of Ni/Co-decorated-Fe layered double hydroxide (NiCoFe-LDH) was straightforwardly constructed on Fe foam (FF) via a feasible corrosion strategy, and the non-enzymatic glucose sensing properties of the NiCoFe-LDH/FF electrode were investigated. In the linear detection range of 0.010-0.1 mM, the electrode exhibits an extreme sensitivity of 5717 μA mM-1 cm-2 with a low threshold for glucose determination of 2.61 μM (S/N = 3) and a short reaction time (∼2 s), which is ascribed to its specific intertwined nanosheet-like morphology with rich electron transfer passages that enhance conductivity and improve the accessibility to more active catalytic sites for glucose oxidation. Moreover, the electrode shows excellent selectivity, good stability, and promising practicality for glucose detection in actual serum samples. These results indicate that the feasible corrosion approach towards the simple synthesis of trimetallic layered double hydroxide electrodes results in improved affinity and stability, holding new prospects for achieving reliable, cost-efficient, and eco-friendly non-enzymatic glucose detection.

CeO2/CuO/NiO hybrid nanostructures loaded on N-doped reduced graphene oxide nanosheets as an efficient electrocatalyst for water oxidation and non-enzymatic glucose detection.

In this work, the three-component heterostructure of CeO2/CuO/NiO was synthesized by a co-precipitation procedure and heating at a temperature of 750 °C. Then, CeO2/CuO/NiO nanoparticles were successfully supported on N-doped reduced graphene oxide (N-rGO) by a hydrothermal method. The obtained nanomaterials were used as effective electrocatalysts for the oxygen evolution reaction and glucose sensing in an alkaline medium. The results indicated that when CeO2/CuO/NiO is anchored on N-rGO nanosheets, active catalytic sites increase. On the other hand, N-doped rGO enhances electrical conductivity and electron transfer for water or glucose oxidation. CeO2/CuO/NiO@N-rGO has a large electrochemically active surface area and more active catalytic positions, and thus exhibits high activity for the OER with a low overpotential of 290 mV, a suitable Tafel slope of 110 mV dec-1, and superior stability and durability for at least 10 hours. CeO2/CuO/NiO@N-rGO can also detect glucose with a high sensitivity of 912.7 μA mM-1 cm-2, a low detection limit of 0.053 μM, a wide linear range between 0.001 and 24 mM, and a short response time of about 2.9 s. Moreover, the high selectivity and stability of this electrode for glucose sensing show its potential for clinical applications.

A facile synthesis of CuZrO2 nanoparticle functionalized chitosan for capable and stable non-enzymatic electrochemical detection of glucose and H2O2

Mixed transition metal oxides and organic polymers are receiving a lot of interest because of their positive characteristics, such as high permeability, large specific surface area, and ion dispersion paths.

Non-enzymatic glucose sensing using a nickel hydroxide/chitosan modified screen-printed electrode incorporated into a flow injection analysis system.

This works presents a novel screen-printed carbon electrode modified with nickel hydroxide nanoparticles and chitosan (Ni(OH)2/CS/SPCE) for the non-enzymatic flow injection amperometric detection of glucose. The electrode was modified by drop-casting a suspension of the synthesised nanocomposite onto the screen-printed electrode and dried for 1 hour at room temperature. EDX analysis was used to investigate the chemical composition of the electrode before and after modifying. The electrochemical response of the unmodified SPCE and modified electrode was initially investigated by cyclic voltammetry (CV) using 0.1 M NaOH as the supporting electrolyte. CVs showed catalytic activity for glucose oxidation using the Ni(OH)2/CS/SPCE at 0.55 V. During flow injection analysis (FIA), 0.60 V and 1.5 mL min-1 were identified as the optimal potential and flow rate, respectively. A wide linear range of detection was observed (0.2 to 10.0 mM) with a sensitivity and limit of detection of 913 μA mM-1 cm-2 and 0.0174 mM, respectively. The modified electrode also displayed excellent repeatability (RSD = 0.47%, n = 20) and good reproducibility (RSD = 2.52%, n = 6). The modified electrode was shown to be very selectivity for glucose over other interferences commonly found in human blood samples. The practicality of the developed flow injection-amperometric system (FIA-Amp) was validated by the quantification of glucose in real serum samples, where results were in close agreement with those obtained from the local hospital.

Band gap and defect engineering of bismuth vanadate using La, Ce, Zr dopants to obtain a photoelectrochemical system for ultra-sensitive detection of glucose in blood serum.

Bismuth vanadate (BiVO4) is a promising photoactive material for the design of photoelectrochemical (PEC) analytical devices for the non-enzymatic detection of glucose. In this work, un-doped and La/Ce/Zr doped BiVO4 photo anodes were developed by spray pyrolysis coating to generate unique 2D hierarchical architectures using the facile ultrasonic spray coating technique without any complex pre or post-treatment. The influence of different dopants on the morphology and photoelectrochemical activity of BiVO4 coatings was investigated. X-ray diffraction, scanning electron microscopy, UV-vis optical absorbance, and positron annihilation techniques were used to evaluate the structure, defects, and optical properties of BiVO4 films. DFT simulation confirmed the Zr doping induced band gap reduction in the BiVO4 lattice. The Zr doping on the Bi site in BiVO4 lattice provided significantly low Bi and V-based defect density and a higher bulk diffusion length of charge pairs (4 times that of pristine) as well as charge transfer efficiency and this led to the foremost photocurrent for water splitting. The Zr-doped BiVO4 photo anode showed remarkable sensitivity in glucose sensing. The sensitivity and limit of detection of the Zr-doped BiVO4 PEC device towards glucose were 0.14 mA cm-2 mM-1 and 1.22 μM, respectively, in the concentration range of 1-7 mM. The system showed sensitive detection of glucose in blood serum. This is the first time that a 2D morphology electrode design consisting of Zr-doped BiVO4, which leads to exceptionally high sensitivity for glucose sensing, has been reported.

Development of glucose sensor based on cobalt and nickel doped ceria nanostructures

In this study, we report the development of a novel and effective electrochemical sensor for non-enzymatic glucose enhanced detection through Ni/Co doped ceria electrocatalysts instead of pristine ceria. The synthesized pristine and doped ceria nanostructures were characterized through X-ray diffraction, scanning electron microscopy and diffused reflectance spectroscopy (DRS). The electrochemical response of the ceria modified glassy carbon electrodes for the non-enzymatic detection of glucose was monitored through cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and chronoamperometry. Results indicate that Ni doped CeO2 and Co doped CeO2 show high sensitivity towards glucose in basic medium with sensitivity values of 11.1 µA/mM cm2 and 184 µA/mM cm2 respectively. The Ni/CeO2 and Co/CeO2 based sensor can detect glucose in a sample up to limits of 80 µM and 16 µM. The efficacy of the fabricated sensors is further demonstrated by EIS, where Co/CeO2 modified electrode shows much lower charge transfer resistance (Rct = 1107 Ω) compared to Ni/CeO2 modified GCE (Rct = 4337 Ω). Amperometric studies indicate a rapid response time (<10 s). The developed biosensors are also highly selective towards glucose amid various interfering species, including uric acid and ascorbic acid. Overall, the Co doped ceria nanostructures serve as efficient electrocatalyst for glucose due to greater electroactivity, high selectivity and sensitivity, low detection limit, and long-term stability.

In-situ synthesis of metasequoia-leaf-like Cu/Cu2O/Ni(OH)2 on a glassy carbon electrode for efficient non-enzymatic glucose sensing

Novel metasequoia-leaf-like Cu/Cu2O/Ni(OH)2 on a glassy carbon electrode (GCE) was used for non-enzymatic glucose detection using an easy, one-step electrodeposition technique. The direct electrodeposition method is conducive to shifting electrons in a binder-free electrode, and increasing the appropriate deposition voltage can obtain material in 15 s. Furthermore, the metasequoia-leaf-like construction has many dynamic locales for synergistic glucose oxidation, which may advance the dispersion rate of glucose. The research shows that the glucose detection sensitivity of the Cu/Cu2O/Ni(OH)2 electrode is 5737.5 μA mM−1 cm−2 and 4676.0 μA mM−1 cm−2, corresponding to the dynamic linear ranges 1 μM–1 mM and 1 mM–5 mM. In addition, the electrode shows good repeatability, reproducibility, stability, and selectivity. Furthermore, the electrode has been successfully utilized to detect glucose in human serum, confirming that the Cu/Cu2O/Ni(OH)2 electrode can identify glucose.

Synthesis and characterization of CuO nanostructures on ZnO nanotubes for non-enzymatic detection of glucose

A non-enzymatic glucose sensing material is investigated on the basis of nanocomposites. Etched zinc oxide (ZnO) nanotubes have been synthesized as base and then dip-coated with various cupric oxide (CuO) nanostructures. Different concentrations of CuO precursor solution formed several sizes and shapes of nanostructures, including nanoparticles and nanoleaves. The fabricated CuO/ZnO nanotubes electrode has high sensitivity of 3.2 mAmM−1cm−2 and superior anti-interference ability towards glucose sensing. It also has good linearity in the range of human pre-meal blood glucose level, which has potential for diabetes monitoring.

One-step synthesis of copper-platinum nanoparticles modified electrode for non-enzymatic salivary glucose detection

In this work, copper-platinum nanoparticles (Cu-Pt NPs) were successfully modified on a glassy carbon electrode (GCE) by a facile electrodeposition process for non-enzymatic glucose detection. The composition and morphology of Cu-Pt NPs were characterized by scanning electron microscopy, transmission electron microscopy and X-ray photoelectron spectroscopy. The electrochemical properties were evaluated through cyclic voltammetry, electrochemical impedance spectroscopy and amperometric methods. The as-obtained Cu-Pt NPs/GCE displayed a high sensitivity of 2209 µA mM−1 cm−2 toward glucose detection in a linear range of 10–750 µM with a low limit of detection (LOD) of 1.8 µM (S/N = 3). Overall, Cu-Pt NPs/GCE was advantageous in terms of selectivity, reproducibility, long-term stability and rapid response time. The detection of glucose by Cu-Pt NPs/GCE was able to be renewed to satisfactory levels through an unsophisticated reduction processing program. Additionally, Cu-Pt NPs/GCE was able of detecting glucose in artificial saliva and human serum samples. In sum, these findings look promising for future.

A Review on Non-Enzymatic Electrochemical Biosensors of Glucose Using Carbon Nanofiber Nanocomposites.

Diabetes mellitus has become a worldwide epidemic, and it is expected to become the seventh leading cause of death by 2030. In response to the increasing number of diabetes patients worldwide, glucose biosensors with high sensitivity and selectivity have been developed for rapid detection. The selectivity, high sensitivity, simplicity, and quick response of electrochemical biosensors have made them a popular choice in recent years. This review summarizes the recent developments in electrodes for non-enzymatic glucose detection using carbon nanofiber (CNF)-based nanocomposites. The electrochemical performance and limitations of enzymatic and non-enzymatic glucose biosensors are reviewed. Then, the recent developments in non-enzymatic glucose biosensors using CNF composites are discussed. The final section of the review provides a summary of the challenges and perspectives, for progress in non-enzymatic glucose biosensors.

Stable, reproducible, and binder-free gold/copper core–shell nanostructures for high-sensitive non-enzymatic glucose detection

The core–shell non-enzymatic glucose sensors are generally fabricated by chemical synthesis approaches followed by a binder-based immobilization process. Here, we have introduced a new approach to directly synthesis the core–shell of Au@Cu and its Au@CuxO oxides on an FTO electrode for non-enzymatic glucose detection. Physical vapor deposition of Au thin film followed by thermal annealing has been used to fabricate Au nanocores on the electrode. The Cu shells have been deposited selectively on the Au cores using an electrodeposition method. Additionally, Au@Cu2O and Au@CuO have been synthesized via post thermal annealing of the Au@Cu electrode. This binder-free and selective-growing approach has the merit of high electrooxidation activity owing to improving electron transfer ability and providing more active sites on the surface. Electrochemical measurements indicate the superior activity of the Au@Cu2O electrode for glucose oxidation. The high sensitivity of 1601 μAcm−2 mM−1 and a low detection limit of 0.6 μM are achieved for the superior electrode. Additionally, the sensor indicates remarkable reproducibility and supplies accurate results for glucose detection in human serums. Moreover, this synthesis approach can be used for fast, highly controllable and precise fabrication of many core–shell structures by adjusting the electrochemical deposition and thermal treatment parameters.

Room-temperature fabrication of a heterostructure Cu2O@CuO nanosheet electrocatalyst for non-enzymatic detection of glucose and H2O2

• Binder-free Cu 2 O@CuO nanosheets were deposited on FTO using vacuum kinetic spray at room temperature. • Cu 2 O@CuO nanosheets exhibited high sensitivity toward detection of glucose at 818.5 μA·mM −1 ·cm −2 . • Cu 2 O@CuO nanosheets exhibited wide linear detection range of glucose from 0.02 to 5 mM. Heterostructure Cu 2 O@CuO nanosheets are spontaneously formed during the kinetic-spraying of nanostructured CuO thin film on the fluorine-doped tin oxide (FTO) substrate at room temperature under low vacuum conditions by the NPDS technique. The Cu 2 O@CuO nanosheets fabricated as a heterogeneous electrocatalyst are utilized for free enzyme detection of glucose and H 2 O 2 in 0.1 M NaOH, whereby the synergy between the multivalent copper species (I and II) results in an overall improvement of electrocatalytic performance. The in-situ formation of interfacial Cu 2 O@CuO heterostructure is verified using a high-resolution transmission microscope and X-ray photon electron spectroscopy. The fabricated electrocatalysts exhibit high sensitivity toward glucose oxidation of 818.5 μA·mM −1 ·cm −2 with a wide linear detection range extending from 0.02 to 5 mM and a limit of detection (LOD) of 5.8 μM. Also, the heterostructure Cu 2 O@CuO nanosheets show a very wide linear detection range of H 2 O 2 oxidation from 0.02 to 11 mM with a good detection sensitivity of 168 μA·mM −1 ·cm −2 and a LOD of 8.75 μM. The long-term stability for around 30 min and high oxidation selectivity with other interfering species are verified. Furthermore, Cu 2 O@CuO nanosheets exhibit higher catalytic rate constant and diffusion coefficient toward glucose species compared with H 2 O 2 .

Co3O4 and CuBi2O4 Hybrid Nanostructures for Efficient Nonenzymatic Glucose Detection in Human Blood and Serum Samples with Mechanistic Insights

AbstractIn this report, CuBi2O4/Co3O4 has been used for the electrochemical detection of glucose. Herein, CuBi2O4 nanorods and Co3O4 has been hybridized with CuBi2O4 to form CuBi2O4/Co3O4 nanocomposite hydrothermally. CuBi2O4 and CuBi2O4/Co3O4 electrodes are fabricated by using drop casting method. Structural, morphological studies of CuBi2O4/Co3O4 and electrochemical characterizations pertaining to its performance in comparison to CuBi2O4 for electrochemical detection of glucose are performed and discussed elaborately. The detailed mechanism involved in the electrochemical detection of glucose is proposed. The electrode has shown the sensitivity of 49 μA mM−1 cm−2 with a limit of detection (LOD) of 0.136 μM. DFT calculations are performed on the optimized molecules involved in the electrochemical detection of glucose confirming CuBi2O4/Co3O4 acting as electron donor while glucose as electron acceptor. Further, natural bond orbital (NBO) for charge distribution calculations and ESP mappings for the optimized molecules are performed to understand nucleophilic/electrophilic positions. This study reveals that CuBi2O4 and its modifications are promising materials for the electrochemical detection of glucose. Further, the role of Co3O4 in improving the sensitivity and electrochemical performance for detection of glucose has been discussed.

Constructing heterointerface of crystalline Au nanoparticles and amorphous porous CoSnO3 nanocubes for sensitive electrochemical detection of glucose

Au/CoSnO3 was explored as a novel electrocatalyst for highly sensitive nonenzymatic detection of glucose. Au/CoSnO3 was synthesized by a galvanic replacement strategy. The obtained nanomaterials were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffractometry (XRD) and electrochemical techniques. The results display that a small amount of crystalline Au nanoparticles are decorated on the surface of amorphous porous CoSnO3 nanocubes. The formation of such unique amorphous/crystalline heterogeneous interface makes Au/CoSnO3 exhibit excellent electrocatalytic activity for the electrochemical oxidation of glucose. The sensor based on Au/CoSnO3 can detect glucose with a wide linear detection range of 0.2 µM–0.11 mM, a high sensitivity of 2317.1 µA·mM−1·cm−2 and a low detection limit of 0.078 µM. This study demonstrates CoSnO3 as an effective sensing material and also provides a way to improve electrocatalytic properties of nanomaterials through interfacial engineering.

High entropy alloy nanoparticle - graphene (HEA:G) composite for non-enzymatic glucose oxidation : optimization for enhanced catalytic performance

High entropy alloy (HEA) metal nanoparticles engineered graphene composites (HEA:G) were produced via green approach involving mechanical milling and sonication assisted exfoliation. Mixture of metal powders and graphite (metal-to-graphite weight ratio: 20%, 50%, 70%, 90%) were ball milled and exfoliated. As produced 20:80, 50:50, 70:30, 90:10 - HEA:G composites electrochemical activity was explored using the redox probe potassium ferricyanide [K3Fe(CN)6] and for the non-enzymatic detection of glucose. From cyclic voltammetry(CV) response, the significant electron transfer kinetics for K3Fe(CN)6 was found for 20:80, 50:50, 70:30 composites, whereas reduced activity was observed with 90:10. Also, 20:80, 50:50, 70:30 composites exhibited notable oxidation of glucose in 0.1 M PBS compared to 90:10. The anodic current indicating oxidation of glucose was found to be increasing linearly with HEA:G composite - 20:80<50:50<70:30. However, DPV measurements indicate better working potential from 0.45 V to 0.4 V followed by saturation in the oxidation currents for 50:50 and 70:30 composites. The sensitivity obtained for HEA:G composites 20:80, 50:50, 70:30 were 12.09 μAmM−1cm−2, 22.99 μAmM−1cm−2, 18.2 μAmM−1cm−2 respectively. Hence, 50:50 and 70:30 are the efficient composites exhibiting excellent catalytic activity indicating the prominence of HEA:Graphene composites and their synergism.

Free-standing hybrid material of Cu/Cu2O/CuO modified by graphene with commercial Cu foil using for non-enzymatic glucose detection

Free-standing Cu/Cu2O/CuO modified by graphene was formed through two steps: Firstly, the commercial Cu foil was thermal annealed to form Cu/Cu2O/CuO; Secondly, the Cu/Cu2O/CuO was modified by graphene through electrochemical exfoliated method. The SEM, XRD, TEM and XPS have been used to characterize the morphology, the crystalline phase, and the surface composition of the hybrid electrode as-prepared. The effects of Cu and its oxides on graphene has been uncovered by the Raman results. The sensitivity of the glucose sensor in 0.1 M NaOH by using the as-prepared hybrid material reaches 3102 μA·mM−1 cm−2 within a linear range of 0.002–2.88 mM, which is better than that of the Cu/graphene and the Cu/Cu2O/CuO prepared at the same conditions. The sensor also shows excellent anti-interference ability, good cycling stability and time stability. The advantage of the sensor is caused by the strengthened synergistic effects between the graphene and the Cu/Cu2O/CuO due to the alleviated detrimental effects of the metal on the property of the graphene through using oxides middle layer as well as the large active area that obtained. This work provides a new way to study the effects of graphene in improving the property of the metal oxide especially in using for glucose sensor.

Electrochemical fabrication of Co(OH)2 nanoparticles decorated carbon cloth for non-enzymatic glucose and uric acid detection.

Cobalt hydroxide nanoparticles (Co(OH)2 NPs) were uniformly deposited on flexible carbon cloth substrate (Co(OH)2@CC) rapidly by a facile one-step electrodeposition, which can act as an enzyme-free glucose and uric acid sensor in an alkaline electrolyte. Compositional and morphological characterization were examined by X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS), which confirmed the deposited nanospheres were Co(OH)2 nanoparticles (NPs). The electrochemical oxidation of glucose and uric acid at Co(OH)2@CC electrode was investigated by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and chronoamperometry methods. The results revealed a remarkable electrocatalytic activity toward the single and simultaneous determination of glucose and uric acid at about 0.6 V and 0.3V (vs. Ag/AgCl), respectively, which isattributed to a noticeable synergy effect between Co(OH)2 NPs and CC with good repeatability, satisfactory reproducibility, considerable long-term stability, superior selectivity, outstanding sensitivity, and wide linear detection range from 1 uM to 2mM and 25nM to 1.5 uM for glucose and UA, respectively. The detection limits were 0.36nM for UA and 0.24μM for glucose (S/N = 3). Finally, theCo(OH)2@CC electrode was utilized for glucose and uric acid determination in human blood samples and satisfying results were obtained. The relative standard derivations (RSDs) for glucose and UA were in the range 6 to 14% and 0 to 3%, respectively. The recovery ranges for glucose an UA were 97 to 103% and 95 and 101%, respectively. These features make the novel Co(OH)2@CC sensor developed by a low-cost, efficient, and eco-friendly preparation method apotentially practical candidate for application to biosensors.