Sensitive Determination Of Glucose Research Articles

Non-enzymatic electrochemical sensing platform based on metal complex immobilized carbon nanotubes for glucose determination

Nickel salophen (where salophen is N,N′-bis(salicylidene)-1,2-phenylenediamine) is immobilized on multiwall carbon nanotubes. This new material is utilized for electrocatalytic oxidization and sensitive determination of glucose in human blood samples.

Sensitive determination of glucose in Dulbecco's modified Eagle medium by high-performance liquid chromatography with 1-phenyl-3-methyl-5-pyrazolone derivatization: application to gluconeogenesis studies.

A new pre-column derivative high-performance liquid chromatography (HPLC) method for determination of d-glucose with 3-O-methyl-d-glucose (3-OMG) as the internal standard was developed and validated in order to study the gluconeogenesis in HepG2 cells. Samples were derivatized with 1-phenyl-3-methy-5-pyrazolone at 70°C for 50 min. Glucose and 3-OMG were extracted by liquid-liquid extraction and separated on a YMC-Triart C18 column, with a gradient mobile phase composed of acetonitrile and 20 mm ammonium acetate solution containing 0.09% tri-ethylamine at a flow rate of 1.0 mL/min. The eluate were detected using a UV detector at 250 nm. The assay was linear over the range 0.39-25 μm (R(2) = 0.9997, n = 5) and the lower limit of quantitation was 0.39 μm (0.070 mg/mL). Intra- and inter-day precision and accuracy were <15% and within ±3%, respectively. After validation, the HPLC method was applied to investigate the gluconeogenesis in Dulbecco's modified Eagle medium (DMEM) cultured HepG2 cells. Glucose concentration was determined to be about 1-2.5 μm in this gluconeogenesis assay. In conclusion, this method has been shown to determine small amounts of glucose in DMEM successfully, with lower limit of quantitation and better sensitivity when compared with common commercial glucose assay kits.

Facile synthesis of NiCo2O4@Polyaniline core-shell nanocomposite for sensitive determination of glucose.

In this work, the core-shell structure of NiCo2O4@Polyaniline (NiCo2O4@PANI) nanocomposite is fabricated via a facile hydrothermal treatment followed by a post-Polyaniline (PANI) coating process. The synthesized materials are characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectrometer. The biosensing properties of NiCo2O4@PANI composite and NiCo2O4 nanoparticles toward glucose are studied based on glassy carbon electrode. Electrochemical studies indicate that the obtained core-shell NiCo2O4@PANI composite shows higher electrocatalytic activity toward the oxidation of glucose, compared with NiCo2O4 nanoparticles. The enhanced performance is related to the core-shell structure of NiCo2O4@PANI composite and the outstanding conductivity of the polyaniline shell. At a potential of +0.5V, the NiCo2O4@PANI nanocomposite modified glass carbon electrode demonstrates a wide linear range up to 4.7350mM with sensitivity of 4.55mAmM(-1)cm(-2) and detection limit of 0.3833μM. It also shows significant electrochemical stability, good reproducibility and excellent selectivity. The results suggest that the NiCo2O4@PANI nanocomposite is a promising electrode material for electrochemical biosensor.

Synthesis of Electrochemically Reduced Graphene Oxide Bonded to Thiodiazole-Pd and Applications to Biosensor.

A novel biosensor for the determination of hydrogen peroxide and glucose was developed based on EGN-TDZ-Pd, as an electrocatalyst. The preparation of graphene oxide (GO) nanosheets was functionalized by combining it with 5-amino-1,3,4-thiadiazole-2-thiol (TDZ) and by covalently bonding it to palladium (Pd) nanoparticles (GO-TDZ-Pd). In the electrochemical investigation, EGN-TDZ-Pd was characterized via scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry (CV) and chronoamperometry (CA) were used to characterize the performance of EGN-TDZ-Pd. The proposed H2O2 biosensor exhibited a wide linear range from 10 µM to 6.5 mM. Also, a glucose biosensor was prepared using glucose oxidase and EGN-TDZ-Pd placed onto a glassy carbon electrode (GCE). The GOx/EGN-TDZ-Pd/GCE was easily prepared using a rapid and simple procedure, and it was utilized for highly sensitive glucose determination.

Quantum dots and ionic liquid-sensitized effect as an efficient and green catalyst for the sensitive determination of glucose

A novel fluorescence (FL) method using water-soluble CdSe quantum dots (QDs) is proposed for the fluorometric determination of hydrogen peroxide and glucose. Water-soluble CdSe QDs were synthesized by using thioglycolic acid as stabilizer in aqueous solutions. The nanoparticles were structurally and optically characterized by X-ray powder diffraction (XRD), dynamic light scattering (DLS), Fourier transform infrared spectroscopy (FTIR), UV–Vis absorption spectroscopy, photoluminescence (PL) emission spectroscopy and transmission electron microscope (TEM). Ionic liquid-sensitized effect in aqueous solution was then investigated. In the presence of ionic liquid as catalyst, H2O2 was decomposed into radical that could quench the fluorescence of CdSe QDs more efficiently and rapidly. Then the oxidization of glucose by glucose oxidase was coupled with the fluorescence quenching of CdSe QDs by H2O2 producer with ionic liquid catalyst, which can be used to detect glucose. Therefore, a new FL analysis system was developed for the determination of glucose. Under the optimum conditions, there is a good linear relationship between the relative PL emission intensity and the concentration of glucose in the range of 5.0×10−7–1.0×10−4M of glucose with a correlation coefficient (R2) of 0.9973. The limit of detection of this system was found to be 1.0×10−7M. This method is not only simple, sensitive and low cost, but also reliable for practical applications.

Evaluation of luminol chemiluminescence based on simultaneous introducing of coumarin derivatives as green fluorophores and chitosan-induced Au/Ag alloy nanoparticle as catalyst for the sensitive determination of glucose.

We report herein the development of a novel chemiluminescence system based on simultaneous introducing of synthetic coumarin derivatives and chitosan-induced Au/Ag alloy NPs on the luminol CL system and suggest how it may be useful for determination of glucose. Chitosan-induced Au/Ag nanoalloys in the coumarin derivatives intensified-luminol CL system, in addition to catalyze CL reaction can make a change in the process of coumarin derivatives effect as fluorophore on the luminol CL system. This phenomenon is caused by interaction between active functional groups of coumarin derivatives and chitosan. The interaction strength depends on the coumarin derivatives' structure and their substituents. Considering the inevitable trend luminol radical and superoxide anion radical to absorption on the surface of the embedded Au/Ag nanoalloy in the chitosan matrix, it can be concluded that chitosan acts as a platform for all reagents involved in the CL reaction including coumarin derivatives, Au/Ag nanoalloy and luminol, and electron-transfer taking place on it; Placing all chemiluminescent reagents together on the chitosan network can lead to a powerful CL due to increasing rigidity of CL system. The most efficient coumarin derivative on the Au/Ag nanoalloy-fluorophore-luminol-H2O2 CL system, in relation to interaction capability with chitosan' functional groups, was selected and the CL condition in presence of it was optimized. Whereas the glucose oxidase-mediated oxidation of glucose yields gluconic acid and H2O2, under optimum condition the most efficient CL system was applied to detection of glucose due to enzymatically production of hydrogen peroxide. The linear response range of 1.5 × 10(-6)-5.0 × 10(-3)M and the detection limit (defined as the concentration that could be detected at the signal-to-noise ratio of 3) of 7.5 × 10(-7)M was found for the glucose standards. Also, the developed method was successfully applied to determination of glucose in real serum and urine samples of diabetic patients and validated against colorimetric spectroscopy method.

An Imperata Cylindrical Flowers-Shaped Porous Graphene Microelectrode for Direct Electrochemistry of Glucose Oxidase

A novel flowers-shaped porous active graphene microelectrode has been fabricated by directly electrochemical assembly and reduction of graphene oxide on platinum (Pt) wire with a diameter of 250 μm. The flowers-shaped graphene microelectrode was characterized by SEM, XRD and electrochemical techniques. Results showed that the flowers-shaped graphene microelectrode created a favorable microenvironment for the GOD. The as prepared graphene microelectrode exhibited excellent electron transfer properties for GOD with the rate constant (ks) of 2.18 s−1 and achieved the direct electrochemistry of GOD. It is notable that the glucose biosensor of GOD@flowers-shaped graphene microelectrode showed two linear ranges in 8.0–148.0 μM with the sensitivity of 267.34 μA mM−1 cm−2 and in 148.0–430.6 μM with the sensitivity of 38.15 μA mM−1 cm−2 for detecting glucose. Furthermore, the biosensor possessed strong anti-interference, remarkable stability and appreciable reproducibility for the sensitive determination of glucose. It would also be extended to other analogous enzymes and bioactive molecules for various biological and electrochemical applications.

Synthesis of graphene oxide nanosheet: A novel glucose sensor based on nickel-graphene oxide composite film

The graphene oxide (GO) nanosheets were produced by chemical conversion of graphite, and were characterized by transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FT-IR). An electrochemical sensor based on Ni/graphene (GR) composite film was developed by incorporating Ni2+ into the graphene oxide film modified glassy carbon electrode (Ni/GO/GCE) through the electrostatic interactions with negatively charged graphene oxide. The Ni2+/graphene modified glassy carbon electrode (Ni/GR/GCE) was prepared by cyclic voltammetric scanning of Ni/GO/GCE in the potential range from −1.5 to 0.2 V at 50 mV s−1 for 5 cycles. The electrochemical activity of Ni/GR/GCE was illustrated in 0.10 M NaOH using cyclic voltammetry. The Ni/GR/GCE exhibits the characteristic of improved reversibility and enhanced current responses of the Ni(III)/Ni(II) couple. The introduction of conductive graphene not only greatly facilitates the electron transfer of Ni2+, but also dramatically improves the long-term stability of the sensor by providing the electrostatic interactions. Ni/GR/GCE also shows good electrocatalytic activity toward the oxidation of glucose. The Ni/GR/GCE gives a good linear range over 10 to 2700 μM with a detection limit of 5 μM towards the determination of glucose by amperometry. This sensor keeps over 85% activity towards 0.1 mM glucose after being stored in air for a month, respectively. Furthermore, the modified sensor was successfully applied to the sensitive determination of glucose in blood samples.

The Application of Assembled Inorganic and Organic Hybrid Nanoarchitecture of Prussian Blue/Polymers/Graphene in Glucose Biosensing

By using graphene as a spacer, multilayer ultrathin films composed of Prussian blue nanoparticles and glucose oxidase have been fabricated on a glass carbon electrode via electrostatic layer-by-layer (LbL) assembly technique to construct glucose biosensors. This work demonstrated the capability of graphene as the spacer to form electrochemically functionalized inorganic and organic hybrid nanoarchitecture. The buildup and electrochemical properties of the multilayer nanoarchitecture were investigated by UV–Vis spectroscopy, atomic force microscopy technique and cyclic voltammetry, respectively. It was found that the developed glucose biosensor allowed rapid and sensitive determination of glucose. The amperometric response exhibited a linear correlation to glucose concentration over a range from 0.1 to 6.5 mM and the response time and detection limit were determined to be 2 s and 6 μM, respectively. It can be expected that the combination of useful graphene and versatile LbL technique could develop more efficient and more advanced biosensing devices.

Synthesis of zinc oxide nanoparticles on graphene–carbon nanotube hybrid for glucose biosensor applications

Synthesis of zinc oxide nanoparticles incorporated graphene–carbon nanotubes hybrid (GR–CNT–ZnO) through a simple, one-pot method is demonstrated. The as-synthesized GR–CNT–ZnO composite is applied to fabricate an enzyme based glucose biosensor. The GOx immobilized on GR–CNT–ZnO composite exhibits well-defined redox peaks with a peak potential separation (ΔEp) of about 26mV with enhanced peak currents, indicating a fast electron transfer at the modified electrode surface. The cyclic voltammetry measurements revealed that the modified film has high electrocatalytic ability towards glucose detection in the presence of oxygen. The proposed sensor has a wide linear detection range from 10μM to 6.5mM of glucose with a limit of detection (LOD) of 4.5 (±0.08)μM. In addition, the sensor possessed appreciable repeatability, reproducibility and remarkable stability for the sensitive determination of glucose. The practicality of this sensor has been demonstrated in human serum samples, with results being in good agreement with those determined using a standard photometric method.

Quantum dots and p-phenylenediamine based method for the sensitive determination of glucose

By introducing p-phenylenediamine (PPD) to the hybrid system of Mn-doped CdS/ZnS quantum dots (QDs) and glucose oxidase (GOD), a sensitive label-free method was proposed for direct detection of glucose. With glucose and PPD as substrates, 2,5-diamino-N,N′-di-(4-aminophenyl)-2,5-cyclohexadiene-1,4-diimine (DDACD) that intensively quenches the fluorescence of QDs can be produced by the catalysis of GOD. A detection limit as low as 3.2μM was obtained with the high-efficient fluorescence quencher. Two linear ranges, from 5.0μM to 1000μM and from 1.0mM to 10.0mM, were identified between time-gated fluorescence intensity and the concentration of glucose. It is shown that the newly proposed methods have high selectivity for glucose over other saccharides and coexisting biological species in serum. The method can be used directly to determine glucose in normal adult human serum without any complicated sample pretreatments. The recovery rate and repeatability of the method were also shown to be satisfactory.

Boronic acid functionalized N-doped carbon quantum dots as fluorescent probe for selective and sensitive glucose determination

Nitrogen doped carbon quantum dots (NCQDs) of about 10 nm in diameter have been obtained by hydrothermal reaction from collagen. Because of the superiority of water dispersion, low toxicity and ease of functionlization, the NCQDs were designed as a glucose sensor after covalent grafting by 3-aminophenylboronic (APBA) (APBA-NCQDs). The as-prepared APBA-NCQDs were imparted with glucose sensitivity and selectivity from other saccharides via fluorescence (FL) quenching effect at physiological pH and at room temperature, which show high sensitivity and specificity for glucose determination with a wide range from 1 mM to 14 mM. FL quenching mechanism of APBA-NCQDs was also investigated by adding an external quencher. The APBA-NCQDs-based platform is an environmentally friendly way to substitute inorganic quantum dots containing heavy metals which offer a facile and low cost detection method.

Ni(OH)2@Cu dendrite structure for highly sensitive glucose determination

Facile preparation of a nickel hydroxide-coated copper dendrite structure and excellent performance in glucose detection with sensitivity of 2082 μA mM−1cm−2.

Graphene/polyaniline/gold nanoparticles nanocomposite for the direct electron transfer of glucose oxidase and glucose biosensing

A novel glucose biosensor was developed based on the direct electrochemistry of glucose oxidase (GOD) adsorbed in graphene/polyaniline/gold nanoparticles (AuNPs) nanocomposite modified glassy carbon electrode (GCE). Compared with graphene, polyanilline (PANI) or graphene/PANI, the graphene/PANI/AuNPs nanocomposite was more biocompatible and it offered a favorable microenvironment for facilitating the direct electron transfer between GOD and electrode. The adsorbed GOD displayed a pair of well-defined quasi-reversible redox peaks with a formal potential of −0.477V (vs. SCE) and an apparent electron transfer rate constant (ks) of 4.8s−1 in 0.1M pH 7.0 PBS solution. The apparent Michaelis–Menten constant of the adsorbed GOD was 0.60mM, implying a fabulous catalytic activity and a remarkable affinity of the adsorbed GOD for glucose. The amperometric response of GOD-graphene/PANI/AuNPs modified electrode was linearly proportional to the concentration of glucose in the range of 4.0μM to 1.12mM with a low detection limit of 0.6μM at signal-to-noise of 3. The combination of the direct electron transfer character of GOD and the promising feature of graphene/PANI/AuNPs nanocomposite favors the selective and sensitive determination of glucose with improved analytical capabilities.

Boronic acid functionalized graphene quantum dots as a fluorescent probe for selective and sensitive glucose determination in microdialysate

3-Aminobenzeneboronic acid functionalized graphene quantum dots (APBA-GQDs) were synthesized and used as a selective and sensitive sensing system for glucose. Combined with microdialysis, glucose was monitored successfully in vivo in the striatum of rat.

One-pot ultrasonic-electrodeposition of copper–graphene nanoflowers in Ethaline for glucose sensing

Copper–graphene nanocomposite (Cu–GE) was one-pot prepared on a glassy carbon electrode (GCE) as a basal electrode by ultrasonic wave assisted electrodeposition with the choline chloride-based ionic liquid Ethaline as the supporting electrolyte. The proposed modified electrode was evaluated for the highly sensitive determination of glucose (Glc). Scanning electron microscopic measurement showed that the synthesized Cu–GE exhibit a flower-like shape. Energy dispersive X-ray spectroscopy confirmed that the petals were composed of C and Cu. Electrochemical methods were adopted to characterize the sensing properties of CuNPs–GE towards the electrocatalytic oxidation of Glc under alkaline conditions at 0.3 V in 0.1 mol L−1 potassium hydroxide. The sensor displayed a broad linearity of 5 to 900 μmol L−1 and 900 μmol L−1 to 11 mmol L−1 with a relatively low detection limit of 1 μmol L−1 (S/N = 3). The response time of the CuNPs–GE modified GCE was <3 s. It was tested for the determination of Glc levels in blood serum.

Graphene quantum dots as a new substrate for immobilization and direct electrochemistry of glucose oxidase: Application to sensitive glucose determination

Graphene quantum dots (GQD) were introduced as a novel and suitable substrate for enzyme immobilization. Glucose oxidase (GOx) was immobilized on GQD modified carbon ceramic electrode (CCE) and well-defined quasi-reversible redox peaks were observed. The UV–vis photoluminescence spectroscopy, transition electron microscopy, field emission scanning electron microscopy, electrochemical impedance spectroscopy, and cyclic voltammetry techniques were used for characterizing the electrochemical biosensor. The electron transfer coefficient (α) and the heterogeneous electron transfer rate constant (ks) for redox reaction of GOx were found to be 0.48 and 1.12s−1, respectively. The developed biosensor responds efficiently to glucose presence over the concentration range 5–1270μM with the detection limit 1.73μM (S/N=3) and sensitivity 0.085μAμM−1cm−2. The high value of surface coverage GOx–GQD|CCE (1.8×10−9mol/cm2) and the small value of Michaelis–Menten constant (0.76mM) confirmed an excellent loading of the enzyme and a high affinity of biosensor to glucose. High performance of the biosensor is attributed to the large surface-to-volume ratio, excellent biocompatibility of GQD, porosity of GQD|CCE, and the abundance of hydrophilic edges as well as hydrophobic plane in GQD which enhances the enzyme absorption on the electrode surface.

Inside/outside Pt nanoparticles decoration of functionalised carbon nanofibers (Pt19.2/f-CNF80.8) for sensitive non-enzymatic electrochemical glucose detection

A highly efficient and reproducible approach for effective Pt nanoparticles dispersion and excellent decoration (inside/outside) of functionalised carbon nanofibers (f-CNF) is presented. The surface morphological, compositional and structural characterisations of the synthesised Pt(19.2)/f-CNF(80.8) material were examined using transmission electron microscopy (TEM/STEM/DF-STEM), energy-dispersive X-ray spectrometry (EDS), thermogravimetric analysis (TGA/DTG), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry (CV) was employed in order to confirm the typical electrochemical response for Pt. The aim of the work was to improve the utility of both the supporting matrix (via the use of both inner/outer surfaces of nanofibers) and precious Pt, together with the sensitive glucose determination. TEM data indicated successful nanoparticle decoration with average Pt particle size 2.4 nm. The studies demonstrated that utilisation of the inner surface of the nanofibers, together with the modified outer surface characteristics using chemical treatment, enables excellent decoration, effective dispersion and efficient impregnation of Pt nanoparticles on carbon nanofibers. Pt(19.2)/f-CNF(80.8) exhibited excellent amperometric response (sensitivity = 22.7 μAmM(-1)cm(-2) and LoD = 0.42 μM) towards direct glucose sensing, over the range 0-10 mM glucose, in neutral conditions (pH 7.4). The improved carbon surface area for nanoparticle decoration, inner surface structure and morphology of nanofibers together with the presence of functional groups provided strong interactions and stability. These features together with the effective nanoparticle dispersion and decoration resulted in excellent catalytic response. The decorated nanoscaled material (Pt(19.2)/f-CNF(80.8)) is capable of large scale production, providing sensing capability in neutral conditions, while eliminating the temperature sensitivity, pH and lifetime issues associated with glucose enzymatic sensors and holds great promise in the quantification of glucose in real clinical samples.

A highly sensitive nonenzymatic glucose sensor based on CuO nanowires

We report on the sensitive determination of glucose using a glassy carbon electrode modified with CuO nanowires and a Nafion film. The structure and morphology of CuO nanowires were established by scanning electron microscopy and X-ray diffraction. The electrochemical performance of the modified electrode was investigated by cyclic voltammetry and chronoamperometry. Compared to a bare glassy carbon electrode, a substantial increase in efficiency of the electrocatalytic oxidation of glucose can be observed. The new glucose sensor displays two useful linear ranges of response towards glucose, is not affected by commonly interfering species, and displays a detection limit as small as 45 nM. The response time is <2 s towards 0.5 mM of glucose. Additional features include high electrocatalytic activity, high sensitivity, excellent selectivity, and good stability.

Sensitive and selective determination of glucose in human serum and urine based on the peroxyoxalate chemiluminescence reaction of a new Fluorophore

A novel method for simple and sensitive determination of glucose based on the peroxyoxalate chemiluminescence (PO-CL) detection of enzymatically generated H 2O 2 was investigated. Influence of various experimental parameters on glucose sensing, including the action time of the enzyme, solution pH, interferents and the concentration of CL reagents was investigated. Under the optimum condition, the linear response range of glucose was found to be 2.50 × 10 −6 to 1.75 × 10 −4 mol/L, and the detection limit (defined as the concentration that could be detected at the signal-to-noise ratio of 3) was 1.10 × 10 −6 mol/L. The present method has been used to determine the glucose concentrations in real serum and urine samples with satisfactory results.