A Highly Sensitive Amperometric Galactose Biosensor Based on Graphene-doped Sol-gel-derived Titania-Nafion Composite Films

A highly sensitive amperometric galactose biosensor was developed by encapsulating galactose oxidase within the graphene-doped sol-gel titania-Nafion composite film on platinized glassy carbon electrode. Due to the combined electrocatalytic activity of graphene and Pt NPs on the electrode towards hydrogen peroxide as well as the mesoporous nature of the titania-Nafion composite, the present galactose biosensor exhibited relatively fast response time under 2 s, high sensitivity of 40.6 mAM⁻¹cm⁻², and wide dynamic range over three orders of magnitude with a detection limit of 3.78×10⁻⁶ M (S/N=3). In addition, the biocompatible composite in the biosensor secures excellent long-term stability.     

Galactose Oxidase/Prussian Blue Based Biosensors

This paper describes the development of an amperometric biosensor based on galactose oxidase (GAOx) immobilization within a laponite clay film deposited on Carbon Screen‐Printed Electrodes modified by electrodeposited Prussian Blue and coated with poly‐(O‐phenylenediamine) (PPD/PB/CSPEs). Amperometric performances of GAOx@laponite/PPD/PB/CSPEs bioelectrodes were determined using several GAOx substrates. Using these modified electrodes the reduction of enzymatically generated hydrogen peroxide was performed at ?0.2 V vs. Ag‐AgCl. In an initial attempt, E.Coli transketolase activity on its immobilized form was followed using a bienzymatic GAOx‐TK biosensor.     

Multianalyte Biosensor for Simultaneous Determination of Glucose and Galactose Based on Micromachined Chamber-type Electrodes

An amperometric multianalyte biosensor for the simultaneous determination of glucose and galactose was developed based on chamber-type electrodes, which were fabricated by micromachining technology. The dual cham-ber-type enzyme electrode with glucose and galactose sensor elements was integrated onto one microchip. The experimental parameters of this biosensor were optimized. The biosensor exhibited a linearity of up to 4.0 mol/L for glucose and 4.5 mol/L for galactose, and the response time was about 30 s for glucose and 40 s for galactose. No cross-talking behavior was investigated in the course of simultaneous measurement of the two analytes. Interference from electroactive species, such as ascorbic acid and uric acid, was minimized due to the permselectivity of Nation film. In addition, the biosensor displayed a storage stability of longer than one month.     

A New Application of Carbon Nanotubes Constructing Biosensor

Carbon nanotubes used for constructing biosensor was described for the first time. Single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups were used to immobilize glucose oxidase forming a glucose biosensor. The biosensor response can be determined by amperometric method at a low applied potential (0.40V).     

Ceramic Carbon/Polypyrrole Materials for the Construction of Bienzymatic Amperometric Biosensor for Glucose

Amperometric enzymatic biosensors have high selectivity and simplicity in use. It has advantages over other analytical methods in biochemistry, pharmacology, so it evokes strong interests1,2. Generally, the detection mode involved in oxidase based biosensors is often based on the electrochemical detection of hydrogen peroxide directly3,4. However the direct oxidation of hydrogen peroxide requires a relative high working potential (exceeding ca. 0.6 V vs. SCE), at which many biological sub…     

Multianalyte Biosensors for the Simultaneous Determination of Glucose and Galactose Based on Thin Film Electrodes

A multianalyte biosensor for the simultaneous determination of glucose and galactose was developed by immobilizing glucose oxidase (GOD) and galactose oxidase (GAO) on Nation-modified thin film platinum disk electrodes. The dual Pt working electrodes with disk shape and the surrounding ring shaped counter electrode were fabricated by thin film technology,which were integrated onto the same microchip. The response of the designed biosensor for glucose and galactose were linear up to 6.0mmol/L and 3.5mmol/L with sensitivities of 0.3μA/mmol/L and 0.12μA/mmol/L, respectively. No cross-talking effect was observed.     

Development of a platinized and ferrocene-mediated cholesterol amperometric biosensor based on electropolymerization of polypyrrole in a flow system.

The preparation of a cholesterol amperometric biosensor using a platinized Pt electrode as a support for the electropolymerization of a polypyrrole film, in which cholesterol oxidase and ferrocene monocarboxylic acid (electron-transfer mediator) were co-entrapped, is described. All the biosensor preparation steps (platinization and electropolymerization) and the cholesterol determination take place in the same flow system. The presence of the mediator enhances the sensitivity and selectivity of the platinized biosensor without modifying the dynamic parameters of the response, and the platinized layer improves the operational lifetime of the mediated sensor. The sensitivity obtained was 88.51 nA mM(-1) and the limit of detection was 12.4 microM of cholesterol. The analytical properties of the biosensor for the flow-injection determination of cholesterol were studied and compared with those of other more simple amperometric biosensor configurations.     

Detection of Galactose and Lactose by a Poly(Amphiphilic Pyrrole)-Galactose Oxidase Electrode

Abstract

The entrapment of galactose oxidase (GAO) on an electrode surface by coadsorption with a cationic amphiphilic pyrrole and electropolymerization of this pyrrole monomer is described. This simple and rapid procedure for biosensor construction provides very fast responsive and sensitive GAO-based sensors to galactose and lactose. The electrode response is based on the electrochemical detection of enzymically generated hydrogen peroxide. The stability, optimum pH and selectivity of the bioelectrode as well as the characteristics of the immobilized galactose oxidase have been determined. Poly(amphiphilic pyrrole) films have been electrogenerated on the surface of the bioelectrode and the effect of such additional coatings on the biosensor selectivity have also been examined.     

Amperometric biosensor based on D-aminoacid oxidase for the R-perindopril assay

A new amperometric biosensor based on D-aminoacid oxidase is described for the assay of R-perindopril. R-perindopril can be determined in the 400-20 nmol/L concentration range; the detection limit is 10 nmol/L. The selectivity was checked with S-perindopril, D- and L-proline, and polyvinylpyrrolidone. The main interfering species was D-proline. An automated system for the assay of R-perindopril based on the concept of flow injection with an amperometric biosensor (based on D-aminoacid oxidase) as detector is also described. The system is suitable for the on-line monitoring of R-perindopril at a sampling rate of 72 samples/h, in the linear range: 100 nmol/L -20 nmol/L with an RSD better than 0.09% (n = 10).     

Rapid assay of galactose in blood serum and urine by amperometric measurement of enzyme-catalyzed oxygen consumption

An enzymatic method for the direct, rapid determination of galactose in blood serum and urine is described. The method is based on amperometric measurement of the rate of oxygen depletion when galactose is oxidized by molecular oxygen in the presence of galactose oxidase. The method does not require incubation nor deproteinization. A single sample measurement requires less than 1 min.     

Minimization of Interferences in Flow Injection Amperometric Glucose Biosensor Based on Oxidation of Enzymatically‐produced H2O2

One of the major problems in amperometric biosensors based on detection of H₂O₂ produced by enzymatic reaction between oxidase enzymes and substrate is the interference of redox active compounds such as ascorbic acid (AA), dopamine (DA) and uric acid (UA). To minimize these interferences, sodium bismuthate was used for the first time as an insoluble pre‐oxidant in the flow injection (FI) amperometric glucose biosensor at a Glucose oxidase (GOx) immobilized Pt/Pd bimetallic modified pre‐anodized pencil graphite electrode (p.PGE). In this context, these interfering compounds were injected into a flow injection analysis (FIA) system using an injector which was filled with NaBiO₃. Thus, these interferents were converted into their redox inactive oxidized forms before reaching the electrode in the flow cell. While glucose was not influenced by the pre‐oxidant in the injector, the huge oxidation peak currents of the interferents decreased significantly in the biosensor. FI amperometric current time curves showed that the AA, DA and UA were minimized by 96 %, 86 %, and 98 % respectively, in the presence of an equivalent concentration of interferences in a 1.0 mM glucose solution. The proposed FI amperometric glucose biosensor exhibits a wide linear range (0.01–10 mM, R²=0.9994) with a detection limit of 2.4×10^?3 mM. Glucose levels in the artificial serum and two real samples were successfully determined using the fabricated FI amperometric biosensor.     

Biosensor on the base of polypyrrole modified ultramicroelectrode arrays

A novel approach for the construction of a micro biosensor on the base of amperometric enzyme microelectrode arrays is described in this paper. The technique contains the electrochemical deposition of different enzymes in a conducting organic polymer, e.g. polypyrrole, on a transducer built up with the help of microfabrication technology. The electrochemical characteristics of these microelectrode arrays can be compared to conventional microelectrodes with the advantage of higher current outputs. For the first time different model enzymes like glucose oxidase, choline oxidase and lactate oxidase have been tested showing the principal possibility to construct a micro biosensor on the base of ultramicroelectrode arrays.     

Amperometric biosensor based on D-aminoacid oxidase for the R-perindopril assay

A new amperometric biosensor based on D-aminoacid oxidase is described for the assay of R-perindopril. R-perindopril can be determined in the 400–¶20 nmol/L concentration range; the detection limit is ¶10 nmol/L. The selectivity was checked with S-perindopril, D- and L-proline, and polyvinylpyrrolidone. The main interfering species was D-proline. An automated system for the assay of R-perindopril based on the concept of flow injection with an amperometric biosensor (based on D-aminoacid oxidase) as detector is also described. The system is suitable for the on-line monitoring of R-perindopril at a sampling rate of 72 samples/h, in the linear range: 100 nmol/L –20 nmol/L with an RSD better than 0.09% (n = 10).     

Amperometric Enzyme Biosensor Based on the Controlled Pore Glass

Abstract

A new amperometric biosensor based of glucose oxidase immobilized in aminopropyl-controlled pore glass (CPG) is reported. The glucose oxidase was linked to the CPG by covalent bonds with glutaraldehyde. The effect of analytical variables on the biosensor response was studied using experimental design methodology. Analytical properties such as linearity, detection limit, quantitation limit, range, and precision are reported. Interferences caused by compounds usually present in biological samples were eliminated.     

Amperometric Determination of Galactose,Lactose and Dihydroxyacetone Using Galactose Oxidase in a Flow Injection System with Immobilized Enzyme Reactors and On-Line Dialysis

Abstract

A flow injection manifold containing a dialyzer and reactors with immobilized galactose oxidase and peroxidase was used for the determination of galactose in urine, lactose in milk and dihydroxyacetone in a biotechnological reaction medium. The hydrogen peroxide which is formed by the galactose oxidase reaction was detected by amperometric reduction of a mediator. The latter had been produced from hydrogen peroxide in a peroxidase catalyzed reaction. The hydrogen peroxide detection step was studied with several mediators and hexacyanoferrate (II) was selected. An ion exchange HPLC procedure was used to purify the galactose oxidase, in particular from catalase, and the kinetics and the selectivity of a reactor containing the immobilized enzyme was investigated. Columns for removal of certain interferents such as ascorbic acid were used in the determination of galactose in urine. The response to galactose standards was linear from the detection limit of 2 μM to 60 mM. The throughput was 45 samples per hour and the relative standard deviation 0.4%.     

Simultaneous Determination of Creatine and Creatinine using Monocrystalline Diamond Paste–Based Amperometric Biosensors

Abstract

In order to determine creatine and creatinine, amperometric diamond paste biosensors were proposed. A bienzymatic biosensor based on creatinase and sarcosine oxidase was used for the assay of creatine and a trienzymatic biosensor based on creatinase, sarcosine oxidase, and creatininase was proposed for the assay of creatinine. The linear concentration ranges are of fmol/L magnitude order, with very low limits of detection. The biosensors proved to be highly reliable for determination of creatine and creatinine as raw materials in pharmaceutical formulations as well as in serum samples.     

纳米金-还原氧化石墨烯修饰葡萄糖氧化酶传感器的制备及其电流法检测饮料中的葡萄糖

利用纳米金(Au NPs)与还原氧化石墨烯(rGO)复合纳米材料制备了葡萄糖氧化酶生物传感器并用于饮料中葡萄糖含量的检测。将壳聚糖作为还原剂及稳定剂,通过一步法合成了Au NPs-rGO复合材料,并通过物理吸附固定葡萄糖氧化酶(GOx)来制作GOx生物传感器。该传感器在磷酸盐缓冲溶液(0.1 mol/L,p H6.0)中,-0.45 V(vs.Ag/Ag Cl)电位下电流法检测葡萄糖含量,线性检测范围为0.01~0.88 mmol/L,灵敏度为22.54μA·mmol-1·L·cm-2,检出限为1.01μmol/L,且表观米氏常数为0.497 mmol/L。该传感器用于多种饮料中葡萄糖含量的直接检测,结果满意。     

An electrochemical multienzymatic biosensor for determination of cholesterol

This paper describes an electrochemical biosensor for free cholesterol monitoring. The sensor is a multienzymatic electrodic system in which horseradish peroxidase and cholesterol oxidase are simultaneously immobilized within a polymeric film, on the surface of a pyrolitic graphite electrode. From voltammetric and amperometric (flow-injection) data obtained, the efficiency, reproducibility and stability of the system are discussed. Results obtained, of interest for basic and applied biochemistry, represent a first step for construction of a mediator-free biosensor with potentialities for a successful application in the biosensor area.     

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.     

TETRABUTYLAMMONIUM－TETRACYANOQUINODIMETHANE AS ELECTRON－TRANSFER MEDIATOR IN AMPEROMETRIC GLUCOSE SENSOR

ＴＥＴＲＡＢＵＴＹＬＡＭＭＯＮＩＵＭ－ＴＥＴＲＡＣＹＡＮＯＱＵＩＮＯＤＩＭＥＴＨＡＮＥＡＳＥＬＥＣＴＲＯＮ－ＴＲＡＮＳＦＥＲＭＥＤＩＡＴＯＲＩＮＡＭＰＥＲＯＭＥＴＲＩＣＧＬＵＣＯＳＥＳＥＮＳＯＲ￥ＣｈａｎｇＱｉｎｇＳＵＮ；ＷｅｎＢｅＳＯＮＧ；ＤｕｏＺ...