Development of amperometric biosensor for glucose based on a novel attractive enzyme immobilization matrix: calcium carbonate nanoparticles

Calcium carbonate nanoparticles (nano-CaCO3) may be a promising material for enzyme immobilization owing to their high biocompatibility, large specific surface area and their aggregation properties. This attractive material was exploited for the mild immobilization of glucose oxidase (GOD) in order to develop glucose amperometric biosensor. The GOD/nano-CaCO3-based sensor exhibited a marked improvement in thermal stability compared to other glucose biosensors based on inorganic host matrixes. Amperometric detection of glucose was evaluated by holding the modified electrode at 0.60 V (versus SCE) in order to oxidize the hydrogen peroxide generated by the enzymatic reaction. The biosensor exhibited a rapid response (6s), a low detection limit (0.1 microM), a wide linear range of 0.001-12 mM, a high sensitivity (58.1 mAcm-2M-1), as well as a good operational and storage stability. In addition, optimization of the biosensor construction, the effects of the applied potential as well as common interfering compounds on the amperometric response of the sensor were investigated and discussed herein.     

Studies on the electrochemical performance of glucose biosensor based on ferrocene encapsulated ORMOSIL and glucose oxidase modified graphite paste electrode

The electrochemical performance of a new glucose biosensor is reported. The glucose biosensor is developed using glucose oxidase (GOD) and ferrocene encapsulated palladium (Pd)-linked organically modified sol-gel glass (ORMOSIL) material incorporated within graphite paste electrode. The ORMOSIL material incorporated within graphite paste electrode behaves as an excellent electrocatalyst for the oxidation of enzymatically reduced GOD. The electrochemical behavior of new glucose biosensor has been examined by cyclic volammetry and amperometric measurements. The bioelectrocatalysis of ORMOSIL embedded within graphite paste as a function of storage time and varying concentration of ORMOSIL is reported. The initial amperometric response on glucose sensing is recorded to be 145 microA at 15% (w/w) concentration of the ORMOSIL which is decreased to 20 microA at 5% of the same keeping GOD concentration constant. The variation of electrochemical behavior of the ORMOSIL embedded within graphite paste as a function of time has also been studied based on cyclic voltammetry. The voltammograms showing the reversible electrochemistry of ORMOSIL encapsulated ferrocene is changed into a plateau shape as a function of time, however, the electrocatalytic behavior is still retained. The practical usability of new glucose sensor has been compared with earlier developed glucose sensor. The sensitivity, response time and linearity of the new glucose biosensor are found to be excellent over earlier reported glucose biosensor. The amperometric response, calibration curve and practical applications of new glucose sensor are reported.     

Biosensor for continuos glucose monitoring

A potentially implantable glucose biosensor for continuous monitoring of glucose levels in diabetic patients has been developed. The glucose biosensor is based on an amperometric oxygen electrode and glucose oxidase immobilized on carbon powder held in a form of a liquid suspension. The enzyme material can be replaced (the sensor recharged) without sensor disassembly. Recharging of the biosensor is achieved by injecting fresh immobilized enzyme into the sensor using a septum. Diffusion membranes made of silastic latex-rubber coatings over a microporous polycarbonate membrane are used. Calibration curves of the amperometric signal show linearity over a wide range of glucose concentrations-up to 500 mg/dL (28 mM), covering hypoglycemic, normoglycemic, and hyperglycemic conditions. Preliminary in vitro studies of the biosensor show stable performance during several recharge cycles (of 14 days each) over a period of 4 months. (c) 1994 John Wiley & Sons, Inc.     

Glucose biosensor based on multi-wall carbon nanotubes and screen printed carbon electrodes

This paper describes a disposable electrochemical biosensor for glucose monitoring. The sensor was based on multi-wall carbon nanotubes (MWCNTs) immobilized with glucose oxidase and upon screen printed carbon electrode. The effect of MWCNTs on the response of amperometric glucose oxidase electrode for glucose was examined. Results obtained, of interest for basic and applied biochemistry, represent a first step in construction of a MWCNT-enzyme electrode biosensor with potentialities for a successful application in the biosensor area.     

An amperometric glucose biosensor based on poly(o-aminophenol) and Prussian blue films at platinum electrode

Prussian blue (PB), as a good catalyst for the reduction of hydrogen peroxide, has been combined with nonconducting poly(o-aminophenol) (POAP) film to assemble glucose biosensor. Compared with PB-modified enzymatic biosensor, the biosensor based on glucose oxidase immobilized in POAP film at PB-modified electrode shows much improved stability (78% remains after 30 days) in neutral medium. Additionally, the biosensor, at an applied potential of 0.0 V, exhibits other good characteristics, such as relative low detection limit (0.01 mM), short response time (within 5s), large current density (0.28 mA/cm2), high sensitivity (24 mAM(-1)cm(-2)), and good antiinterferent ability. The apparent activation energy of enzyme-catalyzed reaction and apparent Michaelis-Menten constant are 34.2 KJmol(-1) and 10.5 mM, respectively. In addition, effects of temperature, applied potential used in the determination, pH value of the detection solution, and electroactive interferents on the amperometric response of the sensor were investigated and are discussed.     

Glucose biosensor based on electrodeposition of platinum nanoparticles onto carbon nanotubes and immobilizing enzyme with chitosan-SiO(2) sol-gel

A novel amperometric biosensor, based on electrodeposition of platinum nanoparticles onto multi-walled carbon nanotube (MWNTs) and immobilizing enzyme with chitosan-SiO(2) sol-gel, is presented in this article. MWNTs were cast on the glass carbon (GC) substrate directly. An extra Nafion coating was used to eliminate common interferents such as acetaminophen and ascorbic acids. The morphologies and electrochemical performance of the modified electrodes have been investigated by scanning electron microscopy (SEM) and amperometric methods, respectively. The synergistic action of Pt and MWNTs and the biocompatibility of chitosan-SiO(2) sol-gel made the biosensor have excellent electrocatalytic activity and high stability. The resulting biosensor exhibits good response performance to glucose with a wide linear range from 1 microM to 23 mM and a low detection limit 1 microM. The biosensor also shows a short response time (within 5s), and a high sensitivity (58.9 microAm M(-1)cm(-2)). In addition, effects of pH value, applied potential, rotating rate, electrode construction and electroactive interferents on the amperometric response of the sensor were investigated and discussed in detail.     

Amperometric phenol biosensor based on laponite clay-chitosan nanocomposite matrix

A novel strategy to fabricate an amperometric biosensor for phenol determination based on chitosan/laponite nanocomposite matrix was described. The composite film was used to immobilize PPO on the surface of a glassy carbon electrode. Chitosan was utilized to improve the analytical performance of the pure clay-modified bioelectrode. The biosensor exhibited a series of properties: good affinity to its substrate (the apparent Michaelis-Menten constant for the sensor was found to be 0.16 mM), high sensitivity (674 mA M(-1)cm(-2) for catechol) and remarkable long-term stability in storage (it retains 88% of the original activity after 60 days). In addition, optimization of the biosensor construction as well as effects of experimental variables such as pH, operating potential and temperature on the amperometric response of the sensor were discussed.     

A high-performance glucose biosensor based on monomolecular layer of glucose oxidase covalently immobilised on indium-tin oxide surface

In this paper, a mediatorless amperometric glucose biosensor based on direct covalent immobilisation of monomolecular layer of glucose oxidase (GOx) on a semiconducting indium-tin oxide (ITO) is demonstrated. The abundance of surface hydroxyl functional group of ITO allows it to be used as a suitable platform for direct covalent immobilisation of the enzyme for sensor architecture. The anodic current corresponding to electrochemical oxidation of the enzymatic product, hydrogen peroxide, at a sputtered Pt electrode at 0.500 V (vs. SCE) was obtained as the sensor signal. It was found that the biosensor based on the direct immobilisation scheme shows a fast biosensor response, minimum interference from other common metabolic species and ease of biosensor miniaturisation. A linear range of 0-10 mM of glucose was demonstrated, which exhibits a high sensitivity as far as performance per immobilised GOx molecule is concerned. A detection limit as low as 0.05 mM and long-term stability were observed. Even more important, the biosensor design allows fabrication through a dry process. These characteristics make it possible to achieve mass production of biosensor compatible with the current electronic integrated circuit manufacturing technologies.     

A porous poly(acrylonitrile-co-acrylic acid) film-based glucose biosensor constructed by electrochemical entrapment

A novel glucose biosensor was constructed by electrochemical entrapment of glucose oxidase (GOD) into porous poly(acrylonitrile-co-acrylic acid), which was synthesized via radical polymerization of acrylonitrile and acrylic acid. The obtained biosensor showed a better stability and higher sensitivity than the biosensor prepared by simple physical adsorption. Effects of some experimental variables such as immobilization time, enzyme concentration, pH, applied potential, and temperature on the amperometric response of the sensor were investigated. The biosensor exhibited a rapid response to glucose (< 30s) with a linear range of 5 x 10(-6) to 3 x 10(-3)M and a sensitivity of 6.82 mAM(-1)cm(-2). The apparent Michaelis-Menten constant (K(M)(app)) was 7.3mM.     

Application of hydrophobic palladium nanoparticles for the development of electrochemical glucose biosensor

An amperometric glucose biosensor based on an n-alkylamine-stabilized palladium nanoparticles (PdNPs)-glucose oxidase (GOx) modified glassy carbon (GC) electrode has been successfully fabricated. PdNPs were initially synthesized by a biphase mixture of water and toluene method using n-alkylamines (dodecylamine, C??-NH? and octadecylamine, C??-NH?) as stabilizing ligands. The performance of the PdNPs-GOx/GC biosensor was studied by cyclic voltammetry. The optimum working potential for amperometric measurement of glucose in pH 7.0 phosphate buffer solution is -0.02 V (vs. Ag/AgCl). The analytical performance of the biosensor prepared from C??-PdNPs-GOx is better than that of C??-PdNPs-GOx. The C??-PdNPs-GOx/GC biosensor exhibits a fast response time of ca. 3s, a detection limit of 3.0 μM (S/N=3) and a linear range of 3.0 μM-8.0 mM. The linear dependence of current density with glucose concentration is 70.8 μA cm?2 mM?1. The biosensor shows good stability, repeatability and reproducibility. It has been successfully applied to determine the glucose content in human blood serum samples.     

Amperometric glucose biosensor based on adsorption of glucose oxidase at platinum nanoparticle-modified carbon nanotube electrode

A new amperometric biosensor, based on adsorption of glucose oxidase (GOD) at the platinum nanoparticle-modified carbon nanotube (CNT) electrode, is presented in this article. CNTs were grown directly on the graphite substrate. The resulting GOD/Pt/CNT electrode was covered by a thin layer of Nafion to avoid the loss of GOD in determination and to improve the anti-interferent ability. The morphologies and electrochemical performance of the CNT, Pt/CNT, and Nafion/GOD/Pt/CNT electrodes have been investigated by scanning electron microscopy, cyclic voltammetry, and amperometric methods. The excellent electrocatalytic activity and special three-dimensional structure of the enzyme electrode result in good characteristics such as a large determination range (0.1-13.5mM), a short response time (within 5s), a large current density (1.176 mA cm(-2)), and high sensitivity (91mA M(-1)cm(-2)) and stability (73.5% remains after 22 days). In addition, effects of pH value, applied potential, electrode construction, and electroactive interferents on the amperometric response of the sensor were investigated and discussed. The reproducibility and applicability to whole blood analysis of the enzyme electrode were also evaluated.     

Amperometric glucose biosensors based on layer-by-layer assembly of chitosan and glucose oxidase on the Prussian blue-modified gold electrode

A glucose biosensor based on layer-by-layer (LBL) self-assembling of chitosan and glucose oxidase (GOD) on a Prussian blue film was developed. First, Prussian blue was deposited on a cleaned gold electrode then chitosan and GOD were assembled alternately to construct a multilayer film. The resulting amperometric glucose biosensor exhibited a fast response time (within 10 s) and a linear calibration range from 6 μM to 1.6 mM with a detection limit of 3.1 μM glucose (s/n = 3). With the low operating potential, the biosensor showed little interference to the possible interferents, including ascorbic acid, acetaminophen and uric acid, indicating an excellent selectivity.     

Mediator-free electrochemical biosensor based on buckypaper with enhanced stability and sensitivity for glucose detection

Here we report on a novel platform based on buckypaper for the design of high-performance electrochemical biosensors. Using glucose oxidase as a model enzyme, we constructed a biocompatible mediator-free biosensor and studied the potential effect of the buckypaper on the stability of the biosensor with both amperometry and FTIR spectroscopy. The results showed that the biosensor responses sensitively and selectively to glucose with a considerable functional lifetime of over 80 days. The fabricated enzymatic sensor detects glucose with a dynamic linear range of over 9 mM and a detection limit of 0.01 mM. To examine the efficiency of enzyme immobilization, the Michaelis–Menten constant was calculated to be 4.67 mM. In addition, the fabricated electrochemical biosensor shows high selectivity; no amperometric response to the common interference species such as ascorbic acid, uric acid and acetamidophenol was observed. The facile and robust buckypaper-based platform proposed in this study opens the door for the design of high-performance electrochemical biosensors for medical diagnostics and environmental monitoring.     

Development of a disposable glucose biosensor using electroless-plated Au/Ni/copper low electrical resistance electrodes

This paper presents a glucose biosensor, which was developed using a Au/Ni/copper electrode. Until now, research regarding the low electrical resistance and uniformity of this biosensor electrode has not been conducted. Glucose oxidase (GOD) immobilized on the electrode effectively plays the role of an electron shuttle, and allows glucose to be detected at 0.055 V with a dramatically reduced resistance to easily oxidizable constituents. The Au/Ni/copper electrode has a low electrical resistance, which is less than 0.01 Ω, and it may be possible to mass produce the biosensor electrode with a uniform electrical resistance. The low electrical resistance has the advantage in that the redox peak occurs at a low applied potential. Using a low operating potential (0.055 V), the GOD/Au/Ni/copper structure creates a good sensitivity to detect glucose, and efficiently excludes interferences from common coexisting substances. The GOD/Au/Ni/copper sensor exhibits a relatively short response time (about 3 s), and a sensitivity of 0.85 μA mM⁻¹ with a linear range of buffer to 33 mM of glucose. The sensor has excellent reproducibility with a correlation coefficient of 0.9989 (n = 100 times) and a total non-linearity error of 3.17%.     

Highly selective amperometric glucose microdevice derived from diffusion layer gap electrode

Although most of enzyme catalytic reactions are specific, the amperometric detection of the enzymatic reaction products is largely nonselective. How to improve the detection selectivity of the enzyme-based electrochemical biosensors has to be considered in the sensor fabrication procedures. Herein, a highly selective amperometric glucose biosensor based on the concept of diffusion layer gap electrode pair which we previously proposed was designed. In this biosensor, a gold tube coated with a conductive layer of glucose oxidase/Nafion/graphite was used to create an interference-free region in its diffusion layer by electrochemically oxidizing the interfering electroactive species at proper potentials. A Pt probe electrode was located in this diffusion layer of the tube electrode to selectively detect hydrogen peroxide generated from the enzyme catalytic oxidation of glucose in the presence of oxygen in the solution. In practical performance of the microdevice, parameters influencing the interference-removing efficiency, including the tip-tube opening distance, the tube electrode potential and the electrolyzing time had been investigated systematically. Results showed that glucose detection free from interferents could be achieved at the electrolyzing time of 30s, the tip-tube opening distance of 3mm and the tube electrode potential of 0.4V. The electrochemical response showed linear dependence on the concentration of glucose in the range of 1 x 10(-5) to 4 x 10(-3) M (the correlation coefficient: 0.9936, without interferents; 0.9995, with interferents). In addition, the effectiveness of this device was confirmed by numerical simulation using a model system of a solution containing interferents. The simulated results showed good agreement with the experimental data.     

Palladium hexacyanoferrate hydrogel as a novel and simple enzyme immobilization matrix for amperometric biosensors

An amperometric glucose biosensor with glucose oxidase (GOx) immobilized into palladium hexacyanoferrate (PdHCF) hydrogel has been prepared and evaluated. The sensor was based on a two-layer configuration with biocatalytic and electrocatalytic layers separately deposited onto the electrode. To reduce the overpotential for reduction of hydrogen peroxide liberated in the enzyme catalyzed oxidation of glucose, an inner thin layer of nickel hexacyanoferrate (NiHCF) electrodeposited onto the surface of graphite electrode was used as an electrocatalyst. As an outer layer, the hydrogel of palladium hexacyanoferrate with entrapped glucose oxidase was used. Under optimal operating conditions (pH 5.0 and E = -0.075 V versus calomel (3.0 M KCl) reference electrode), sensor showed high sensitivity to glucose (0.3-1.0 microA/mM) and a response time of less than 30s. The linear response to glucose was obtained in the concentration range between 0.05 and 1.0 mM in batch analysis mode and 0-7.0 mM in FIA. During the 32 days testing period, no significant decrease in the sensor sensitivity was observed. The sensor was applied for the determination of glucose concentration in fruit juice and yoghurt drink, and the results obtained showed good correlation with results obtained by reference spectrophotometric enzyme method.     

Controllable anchoring of gold nanoparticles to polypyrrole nanofibers by hydrogen bonding and their application in nonenzymatic glucose sensors

An enzymeless glucose biosensor based on polypyrrole nanofibers-supporting Au nanoparticles (Au/PPyNFs) was investigated in this study. The Au/PPyNFs heterogeneous composite materials were synthesized in-situ via hydrogen bonding interactions for the assembly of polyethyleneimine (PEI) on the surface of polypyrrole nanofibers (PPyNFs). By changing the molar ratio of PPy to HAuCl(4), Au/PPyNFs with different Au loadings were obtained. The morphology and composition of Au/PPyNFs were characterized using SEM, TEM, FTIR, XRD and XPS, respectively. The hybrids exhibited a high electrocatalytic activity toward glucose oxidation, which is prerequisite for the catalysts to be applied in amperometric glucose sensors. By using the nonenzymatic glucose sensor based on Au/PPyNFs, 0.2-13mM glucose can be detected with a sensitivity of 1.003μAcm(-2)mM(-1) and a good linearity (R(2)=0.9993) between current density and glucose concentration. The proposed glucose sensor provides a promising strategy to construct fast, sensitive, and anti-interfering amperometric sensors for early diagnosis and prevention of diabetes.     

Determination of D-amino acids using a D-amino acid oxidase biosensor with spectrophotometric and potentiometric detection

An amperometric and a colorimetric biosensor to detect and quantify D-amino acids selectively has been devised using D-amino acid oxidase from Rhodotorula gracilis. The sensor is characterised by a proportional response between 0.2-3 mM and 0.1-1 mM D-alanine for the amperometric (at a working potential of 1400 mV vs Ag/AgCl) and colorimetric system, respectively.     

A glucose biosensor based on microporous polyacrylonitrile synthesized by single rare-earth catalyst

A glucose biosensor was constructed by electrochemical adsorption of glucose oxidase (GOD) in microporous polyacrylonitrile (PAN), which was synthesized by single rare-earth catalyst-Y(OAr)(3.) The biosensor shows a fast response, good operational stability and reproducibility. The influences of molecular weight of polymer, pH, operating potential and temperature on the biosensor response were explored by amperometric method. The apparent activation energy and optimum pH of enzyme-catalyzed reaction are 35.9 kJ mol(-1) and 6.2, respectively.     

Amperometric glucose sensor based on coimmobilization of glucose oxidase and Poly(p-phenylenediamine) at a platinum microdisk electrode

A miniaturized glucose biosensor in which glucose oxidase (GOD) and poly(p-phenylenediamine) (poly-PPD) were coimmobilized at the surface of a platinum microdisk electrode was developed and used successfully for amperometric determination of glucose. The performance of sensors prepared at different monomer concentrations and polymerization potentials with different media was investigated in detail. It was found that similarly to poly(o-phenylenediamine) (poly-OPD), (poly-PPD) noticeably eliminated the electrochemical interference of ascorbic acid, uric acid, and l-cysteine. The amperometric response of glucose with the biosensor under optimal conditions exhibited a linear relationship in the range of 5.0 x 10(-5) to 3.0 x 10(-3) M with correlation coefficient 0.9995. According to the Michaelis-Menten equation, the apparent Michaelis constant for glucose and the maximum steady-state current density of the poly-PPD/GOD-modified microelectrode were 3.94 mM and 607.5 microA cm(-2), respectively. The current density of the sensor responding to glucose in the linear range can reach 160 microA cm(-2) mM(-1), which is far greater than that obtained using poly-OPD and poly(phenol) film. In addition, the stability of the sensor was examined over a 2-month period.