Stable Glucose Biosensor Research Articles

Biomimetic magnetite/polydopamine/β-cyclodextrins nanocomposite for long-term glucose measurements

A highly selective, sensitive, and long-term stable glucose biosensor was developed, based on β-cyclodextrins (β-CDs) grafted onto magnetite/polydopamine (Fe3O4/PDA) with adsorbed glucose oxidase (GOx) from Aspergillus niger. The properties of the nanoplatform were determined by transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FT-IR), Bradford assay, electrokinetic analysis (zeta potential), non-invasive light scattering (NIBS) and measurement of the polydispersity index (PdI). The biosensor’s operating conditions were optimized, and the optimal conditions were used in tests on model and real glucose solution. Results for the biosensor showed a broad linear range (1–26 mM glucose), with sensitivity as high as 115.74 μA mM−1 cm−2 and a limit of detection (LOD) of 1.55 μM. The results show the biosensor to be an interesting potential tool for use in many areas where glucose measurement is essential. Moreover, the proposed system demonstrated long-term stability, up to 9 months. Furthermore, excellent selectivity against ascorbic acid, uric acid, L-cysteine and sugars such as saccharose, maltose and fructose was confirmed.

Highly selective and stable glucose biosensor based on incorporation of platinum nanoparticles into polyaniline-montmorillonite hybrid composites

The selectivity and stability of biosensor are still challenging goal. Herein, a glucose biosensor was developed by anchoring glucose oxidase (GOD) within the polyaniline (PANI)-montmorillonite (MMT)-platinum nanoparticles (PtNPs) nanocomposite through the electrodeposition of PtNPs on the PANI-MMT hybrid composites, which had been prepared on the surface of platinum plate electrode by in situ electrochemical suspension polymerization. Scanning electron spectroscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and amperometry measurements were employed to characterize the morphology and electrochemical properties of the as-prepared biosensor. No current response was monitored from the possible interferents such as glycine (Gly), urea (Urea), L-phenylalanine (L-Phe), ascorbic acid (AA), L-tyrosine (L-Tyr) and D-galactose (D-Gal). The signal intensity towards glucose detection kept almost no change after storage for 40 days, and still remained above 91.7% of original value even after two months. The developed biosensor revealed a quick response to glucose over a wide linear range from 10 μM to 1.94 mM and a low detection limit of 0.1 μM. The biosensor was successfully applied for glucose detection in human blood serum. The results demonstrate the possible control of nanocomposite microenvironment by using electrochemical synthesis to obtain molecular level dispersion for immobilizing glucose oxidase, and enhance electron transfer and electrocatalytic effect.

Self-assembly of glucose oxidase on reduced graphene oxide-magnetic nanoparticles nanocomposite-based direct electrochemistry for reagentless glucose biosensor

A novel approach of the immobilization of a highly selective and stable glucose biosensor based on direct electrochemistry was fabricated by a self-assembly of glucose oxidase (GOD) on reduced graphene oxide (RGO) covalently conjugated to magnetic nanoparticles (Fe3O4 NPs) modified on a magnetic screen-printed electrode (MSPE). The RGO-Fe3O4 nanocomposite has remarkable enhancement in large surface areas, is favorable environment for enzyme immobilization, facilitates electron transfer between enzymes and electrode surfaces and possesses superparamagnetism property. The morphology and electrochemical properties of RGO-Fe3O4/GOD were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, cyclic voltammetry (CV) and amperometry. The modified electrode was a fast, direct electron transfer with an apparent electron transfer rate constant (ks) of 13.78s−1. The proposed biosensor showed fast amperometric response (3s) to glucose with a wide linear range from 0.05 to 1mM, a low detection limit of 0.1μM at a signal to noise ratio of 3 (S/N=3) and good sensitivity (5.9μA/mM). The resulting biosensor has high stability, good reproducibility, excellent selectivity and successfully applied detection potential at −0.45V. This mediatorless glucose sensing used the advantages of covalent bonding and self-assembly as a new approach for immobilizing enzymes without any binder. It would be worth noting that it opens a new avenue for fabricating excellent electrochemical biosensors. Novelty statementThis is a new approach that reporting the immobilization of glucose oxidase on reduced graphene oxide (RGO) covalently conjugated to magnetic nanoparticles (Fe3O4 NPs) by electrostatic interaction and modified screen printed electrode. We propose the reagentless with fabrication method without binder and adhesive agents for immobilized enzyme. Fe3O4 NPs increasing surface area to enhance the immobilization and prevent the leaching of enzymes at electrode surfaces by magnetic stickers which is improve the stability of the biosensor. Based on this synthesis technique, it is a good new strategy and simple used to fabrication of third-generation glucose biosensor and this nanocomposite could be used as a platform for disposable biosensor and biofuel cell applications.

Fabrication of a liquid-gated enzyme field effect device for sensitive glucose detection

This study presents fabrication of a liquid-gated enzyme field effect device and its implementation as a glucose biosensor. The device consisted of four electrodes on a glass substrate with a channel functionalized by carboxylated multi-walled carbon nanotubes-polyaniline nanocomposite (MWCNTCOOH/PAn) and glucose oxidase. The resistance of functionalized channel increased with increasing the concentration of glucose when an electric field was applied to the liquid gate. The most effective and stable performance was obtained at the applied electric field of 100 mV. The device resistance, R, exhibited a linear relationship with the logarithm of glucose concentration in the range between 0.005 and 500 mM glucose. The detection limit (S/N = 3) for glucose was about 0.5 μM. Large effective area and good conductivity properties of MWCNTCOOH/PAn nanocomposite were the key features of the fabricated sensitive and stable glucose biosensor.

A highly sensitive and stable glucose biosensor using thymine-based polycations into laponite hydrogel films

A series of glucose bioelectrodes were prepared by glucose oxidase (GOx) immobilization into laponite hydrogel films containing DNA bioinspired polycations made of vinylbenzyl thymine (VBT) and vinylbenzyl triethylammonium chloride (VBA) with general formulae [(VBT)m(VBA)n]≈25n+ with m=0, 1 and n=2, 4, 8, deposited onto glassy carbon electrode. The bioelectrodes were characterized by chronoamperometry, cyclic voltammetry and electrochemical impedance spectroscopy. Results indicated that the electrochemical properties of the laponite hydrogel films were largely improved by the incorporation of thymine-based polycations, being proportional to the positive charge density of the polycation molecule. After incorporation of glucose oxidase, the sensitivity of the bioelectrode to glucose increased with the positive charge density of the polycation. Additionally, the presence of the vinylbenzyl thymine moiety played a role in the long-term stability and reproducibility of the bioelectrode signal. As a consequence, the [(VBT)(VBA)8]≈258+ was the most appropriate polycation for bioelectrode preparation and glucose sensing, with a specific sensitivity of se=176mAmmol−1Lcm−2U−1, almost two-order of magnitude larger than other laponite immobilized GOx bioelectrodes reported elsewhere. These features were confirmed by testing the bioelectrode for a selective determination of glucose in powder milk and blood serum samples without interference of either ascorbic or uric acids under the experimental conditions.The present study demonstrates the suitability of DNA bioinspired water-soluble polycations [(VBT)m(VBA)n]≈25n+ for enzyme immobilization like GOx into laponite hydrogels, and the preparation of highly sensitive and stable bioelectrodes on glassy carbon surface.

A glucose biosensor based on direct electron transfer of glucose oxidase immobilized onto glassy carbon electrode modified with nitrophenyl diazonium salt

This study reports a novel, simple and fast approach for construction of a highly stable glucose biosensor based on the immobilization of glucose oxidase (GOx) onto a glassy carbon electrode (GCE) electrografted with 4-aminophenyl (AP) by diazonium chemistry. Aminophenyl was used as cross-linker for covalent attachment of glucose oxidase to the electrode surface. Cyclic voltammograms of the GOx-modified GCE in phosphate buffer solution exhibited a pair of well-defined redox peaks, attesting the direct electron transfer (DET) of GOx with the underlying electrode. The proposed biosensor could be used to detect glucose based on the consumption of O2 with the oxidation of glucose catalyzed by GOx and exhibited a wide linear range of glucose from 0.05mM to 4.5mM and low detection limit of 10μM. The surface coverage of active GOx, heterogeneous electron transfer rate constant (ks) and Michaelis–Menten constant (KM) of immobilized GOx were 1.23×10−12molcm−2, 4.25s−1 and 2.95mM, respectively. The great stability of this biosensor, technically simple and possibility of preparation at short period of time make this method suitable for fabrication of low-cost glucose biosensors.

A highly stable oxygen-independent glucose biosensor based on a chitosan-albumin cryogel incorporated with carbon nanotubes and ferrocene

A novel, excellently stable glucose biosensor was fabricated based on a chitosan-bovine serum albumin (Chi-BSA) cryogel with incorporated multiwalled carbon nanotubes (MWCNTs), ferrocene (Fc), and glucose oxidase (GOD). A porous Chi-BSA cryogel was prepared by freezing and thawing of the chitosan-albumin hydrogel, synthesized by crosslinking with glutaraldehyde. The electron transfer of the Chi-BSA cryogel was enhanced using MWCNTs mediated by the Fc trapped within the cryogel. The glucose response of this biosensor was amperometrically measured at an applied potential of 0.175V versus Ag/AgCl in a flow injection system. The MWCNTs/Chi-BSA-Fc/GOD biosensor demonstrated high operational stability after more than 350 injections (RSD=3.6%), with a wide linear range from 0.010 to 30mM and a low Michaelis–Menten constant (1.5mM). The fabricated biosensor response to glucose was not affected by dissolved oxygen and showed no response to the common interferences in blood samples such as, ascorbic acid and uric acid, in physiological levels. In comparison with the standard hexokinase-spectrophotometric method employed by the hospital, the glucose concentrations in blood plasma samples measured by the modified electrode were in good agreement (P>0.05). This chitosan based cryogel would be an excellent enzyme supporting material for other biosensor applications.

Proteins from Thermophiles for the Design of Advanced Fluorescence Biosensors. Glucose sensing as Model

Glucose sensing is used as a model to explore the advantages deriving from the use of sugar binding proteins isolated from thermophilic organisms to develop stable fluorescence biosensors. The gene of a putative thermostable sugar-binding protein was cloned and expressed in E. coli. The recombinant protein was purified to homogeneity and used as a probe for the development of a fluorescence biosensor for the detection of glucose. Fluorescence spectroscopy experiments demonstrated that the recombinant protein binds glucose with a dissociation constant of about 10 mM, a concentration of sugar close to the concentration of glucose present in the human blood. A docking simulation on the modeled structure of the protein confirmed its ability to bind glucose and proposed possible modifications to improve the affinity for glucose and/or its detection. The obtained results suggest the use of this thermostable protein as a probe for a stable glucose biosensor.

A thermostable sugar-binding protein from the Archaeon Pyrococcus horikoshii as a probe for the development of a stable fluorescence biosensor for diabetic patients.

In this work is presented the first attempt to develop an innovative ultrastable protein-based biosensor for blood glucose detections. The gene of a putative thermostable sugar-binding protein has been cloned and expressed in E. coli. The recombinant protein has been purified to homogeneity by thermoprecipitation and affinity chromatography steps. The recombinant protein is a monomer with an apparent molecular weight of 55,000 as judged by gel filtration and sodium dodecyl sulfate polyacrylamide gel eletrophoresis. Circular dichroism experiments showed that the protein possesses a secondary structure content rich in alpha-helices and beta-structures and that the protein is highly stable as investigated in the range of temperature between 20 and 95 degrees C. Fluorescence spectroscopy experiments demonstrated that the recombinant protein binds glucose with a dissociation constant of about 10 mM, a concentration of sugar very close to the concentration of glucose present in the human blood. A docking simulation on the modeled structure of the protein confirms its ability to bind glucose and proposes possible modifications to improve the affinity for glucose and/or its detection. The obtained results suggest the use of the protein as a probe for a stable glucose biosensor.

Continuous glucose monitoring using enzyme-immobilized platinized diamond microfiber electrodes

A sensitive and stable glucose biosensor for in vivo monitoring has been developed using boron-doped diamond microfiber (BDDMF) electrodes. The electrodes were modified with platinum nano-particles to detect H 2O 2, which was enzymatically produced by glucose oxidase (GOx) immobilized on the electrode surface. The platinum-modified BDDMF (Pt-BDDMF) electrodes exhibited much higher sensitivity compared to Pt-microfiber electrodes, Pt electrodes and Pt-modified diamond thin film electrodes. Deposition conditions for Pt nano-particles on the BDDMF electrodes and immobilization of GOx were optimized. GOx/overoxidized polypyrrole (OPPy)/Pt-modified BDDMF electrodes were applied for continuous interference-free glucose monitoring. Amperometric measurements of glucose showed a linear response in the range of 1–70 mM, with an R.S.D. of 3.7% for five injections of 100 μM glucose. The electrodes exhibited good stability over 3 months with no detected anodic current for ascorbic acid (AA), which is an interfering compound.

Polyelectrolyte-stabilized glucose biosensor based on woodceramics as electrode

Objective: Different biosensors for early diagnosis of diabetes have been discussed increasingly. We demonstrate the applicability of a glucose biosensor for rapid and quantitative determination of glucose in experimental sample solutions. Design and Methods: Polyethylenimine (PEI)-stabilized glucose oxidase (GOD) was used for the construction of stable glucose biosensor utilizing a simple manufacture procedure. The stabilized glucose oxidase was immobilized by physical adsorption into activated porous and conductive carbonaceous material—woodceramics that served as the immobilization matrix and the electrochemical transducer. The optimum parameters for the construction of the biosensor and the influences of pH and temperature on the biosensor response were explored. Results: Optimum results were obtained using soaking solutions of 2300 U/ml GOD, 10 mg/ml mediator toluidine blue O (TBO), and 2.0%, w/v PEI. The sensitivity of the resulting biosensor for glucose was 1.22 μA/mM, with a linear response in the concentration range of 0.5–7 mM. The sensor-to-sensor reproducibility was good, the relative standard deviation (R.S.D.) being less than 8.0%. The storage and operational stabilities of the glucose biosensor were good. Conclusions: The glucose biosensor provides reproducible and quantitative information on glucose within minutes and is applicable for the detection of glucose in experimental samples.

Polyelectrolyte-stabilized glucose biosensor based on woodceramics as electrode

Objective: Different biosensors for early diagnosis of diabetes have been discussed increasingly. We demonstrate the applicability of a glucose biosensor for rapid and quantitative determination of glucose in experimental sample solutions. Design and Methods: Polyethylenimine (PEI)-stabilized glucose oxidase (GOD) was used for the construction of stable glucose biosensor utilizing a simple manufacture procedure. The stabilized glucose oxidase was immobilized by physical adsorption into activated porous and conductive carbonaceous material—woodceramics that served as the immobilization matrix and the electrochemical transducer. The optimum parameters for the construction of the biosensor and the influences of pH and temperature on the biosensor response were explored. Results: Optimum results were obtained using soaking solutions of 2300 U/ml GOD, 10 mg/ml mediator toluidine blue O (TBO), and 2.0%, w/v PEI. The sensitivity of the resulting biosensor for glucose was 1.22 μA/mM, with a linear response in the concentration range of 0.5–7 mM. The sensor-to-sensor reproducibility was good, the relative standard deviation (R.S.D.) being less than 8.0%. The storage and operational stabilities of the glucose biosensor were good. Conclusions: The glucose biosensor provides reproducible and quantitative information on glucose within minutes and is applicable for the detection of glucose in experimental samples.

A stable glucose biosensor prepared by co-immobilizing glucose oxidase into poly(p-chlorophenol) at a platinum electrode.

An amperometric glucose biosensor was successfully developed by electrochemical polymerization of p-chlorophenol (4-CP) at a Pt electrode in the presence of glucose oxidase. The amperometric response of this biosensor to hydrogen peroxide, formed as the product of enzymatic reaction, was measured at a potential of 0.6 V (vs. SCE) in phosphate buffer solution. The performances of sensors, prepared at different monomer concentrations and polymerization potentials, were investigated in detail. The biosensor prepared under optimal conditions had a linear response to glucose ranging from 2.5 x 10(-4) to 1.5 x 10(-2) mol L(-1) with a correlation coefficient of 0.997 and a response time of less than 2 s. Substrate selectivity of the polymer-based enzyme electrode was tested for coexisting interferents such as uric acid and ascorbic acid, and no discernible response was observed. After 90 days, the response of the biosensor remained almost unchanged, indicating very good stability.

Glucose biosensors based on dendrimer monolayers.

The peculiarities of glucose biosensors based on different generation of dendrimers (G0, G1 and G4) have been studied by amperometry and QCM techniques. It is shown that stable glucose biosensor can be obtained with low generation of dendrimers. The sensor sensitivity, however considerable, increased with increasing number of generation of dendrimers. This can be due to the increased volume of the dendrimer interior as well as with increased number of binding sites for glucose oxidase (GOX). QCM experiments showed that immobilization of GOX resulted in formation of enzyme multilayers on a dendrimer surface. The enzyme turnover for this system (0.1-0.01 s(-1)) was lower then that for immobilization of GOX onto a supported lipid films by means of avidin-biotin technology (1.1 s(-1)). However, dendrimer based biosensors are more stable in comparison with sBLM based sensors and could be stored in a refrigerator in dry conditions over 15 days without substantial loss of sensitivity.