Calibration of glucose biosensors by using pre-steady state kinetic data (original) (raw)

Analytical Characteristics of Electrochemical Biosensors

Portugaliae Electrochimica Acta, 2009

The goal of this work is the evaluation of the analytical characteristics of the determinations performed using glucose oxidase and acetylcholinesterase based electrochemical sensors, developed applying original or optimized conventional methods of enzyme immobilization. It was found that the sensitivity of glucose determination, for example, varies from 0.048 to 3.36 mA L mol -1 cm -2 and the response time of the glucose oxidase based sensors -from 5 to 30 s, according to the method of the bioreceptor immobilization. The sensitivity of the analysis is affected from the activity of the immobilized biocomponent, from the composition of the solution (concentration of the substrate, of the mediator and of the inhibitor), and from the experimental conditions (pH, temperature, agitation), as well as from the kinetic parameters of the studied process. It was found that the immobilized glucose oxidase conserves its substrate specificity in the presence of a number of glucides (galactose, maltose, fructose, and saccharose) in 100 fold higher concentrations. The selectivity of glucose analysis is ensured applying a suitable potential. Interferences free glucose amperometric determination was performed at 0.00 V/SCE, in the presence of ascorbates and urates. The electrochemical quantification of enzyme inhibitors allows reaching particularly low limits of detection (

Measurement of glucose concentrations in human plasma using a glucose biosensor

Analytical Biochemistry, 2005

Glucose is a major component of animal and plant carbohydrates. Quantitative determination of glucose in human blood is of paramount importance for the diagnosis and eVective treatment of diabetes. Therefore, considerable eVort has been focused on developing eVective diagnostic tools for the beneWt of diabetic patients. In recent years, research in the development of chemosensors and biosensors has been very fast growing and many glucose biosensors have been presented . However, many of the experimental setups are complicated and require a bulky and expensive electrochemical system for cyclic voltammetric studies, electropolymerization, and electrodeposition or spectroXuorimeter for optical sensing. Thus, it is obvious that there is still a niche for improving glucose biosensors with simpler design and relatively low cost.

Evaluation of chrono-impedance technique as transduction method for a carbon paste/glucose oxidase (CP/GOx) based glucose biosensor

Biosensors and Bioelectronics, 2010

The chrono-impedance technique (CIT) for real time determination of glucose concentration in a first generation glucose oxidase/carbon paste electrode was implemented. The biosensor was polarized with a signal composed of 900 mV DC potential and 50 mV RMS AC signal at 0.4 Hz. A frequency response analyzer was used to measure the complex impedance (magnitude |Z| and phase (˚)) of the biosensorbulk interface. Real time measurements were performed while glucose was added to the bulk within a concentration range of 0-40 mM. The cumulative impedance dose-response curves were used to construct calibration curves, both for magnitude and phase. The best fitting was obtained with a hyperbolic equation. Four biosensors were built obtaining five calibration curves for each of them. A single test measurement (unknown glucose concentration) was also obtained after each calibration procedure. Glucose concentrations were estimated with the calibration curves and also measured by colorimetry, the latter being the reference method. Besides, one-way ANOVA test evaluated repeatability. Difference between means was not statistically significant (p > 0.01) for both magnitudes (|Z| and˚). The Student's t-test assessed the differences significance, which produced in all cases p levels lower or equal than 0.44. Thus, CIT was proved to be a reliable method to measure glucose concentration in real time. Moreover, it showed high repeatability and compared well against colorimetry (r 2 = 0.98).

Mathematical Modelling of Amperometric Glucose Biosensor Based on Immobilized Enzymes: New Approach of Taylors Series Method

International Journal of Electrochemical Science

An amperometric glucose biosensor's theoretical model is discussed. The glucose oxidase enzyme in this model is immobilized in conducting polypyrrole.This model includes a nonlinear term that corresponds with the kinetics of enzyme reactions. The solution of coupled nonlinear reaction diffusion equations is obtained using new approach of Taylor method. Additionally, a comparison of numerical simulation and analytical approximation is provided. There is an agreement between numerical results and analytical expressions.

A glucose biosensor operating under non-isothermal conditions: the dynamic response

Biosensors and Bioelectronics, 1999

The results obtained with a glucose biosensor operating under non-isothermal conditions are presented and discussed. Glucose oxidase, immobilized onto Nylon membranes, was used as biological element. An amperometric two electrodes system was employed to measure the anodic current produced by oxidation of hydrogen peroxide. Non-isothermal conditions were characterised in terms of the temperature difference, DT= T w − T c , and of the average temperature of the system, T av = (T w +T c )/ 2, T w and T c being the temperature in the warm and cold half-cells constituting the biosensor. Comparison between the functioning of the biosensor under isothermal and non-isothermal conditions was performed. It was found that, under non-isothermal conditions, the dynamic response and sensitivity increased, while the response times and the detection limit decreased, if comparison was done with the same parameters measured under isothermal conditions. The increase of the dynamic response was found to be proportional to the applied temperature gradient.

Electrochemical Evaluation of the Properties of the Immobilized Enzyme Glucose Oxidase

ECS Transactions, 2008

The enzyme glucose oxidase was evaluated as a recognition element in electrochemical biosensors. Immobilization techniques as physical adsorption, entrapment in electrogenerated polymer film, affinity and covalent binding are discussed based in the involved physicochemical and kinetic phenomena. This includes the determination of the main kinetic parameters: apparent Michaelis-Menten constant K m app and maximal rate I max of the heterogeneous enzyme reactions of glucose oxidation in the absence and in the presence of inhibitors. Parameters as pH, optimal temperature and stability of the biocatalyst were established analyzing the transfer function of the developed amperometric glucose oxidase sensors of first and second generation I=I max [S] / (K m app + [S]).

Real-time measurement of glucose using chrono-impedance technique on a second generation biosensor

Biosensors and Bioelectronics, 2011

Chrono-impedance technique (CIT) was implemented as a new transduction method for real time measurement of glucose in a biosensor system based in carbon paste (CP)/Ferrocene (FC)/glucose oxidase (GOx). The system presents high selectivity because the optimal stimulation signal composed by a 165 mV DC potential and 50 mV RMS AC signal at 0.4 Hz was used. The low DC potential used decreased the interfering species effect and the biosensor showed a linear impedance response toward glucose detection at concentrations from 0 mM to 20 mM,with 0.9853 and 0.9945 correlation coefficient for impedance module (|Z|) and phase (˚), respectively. The results of quadruplicate sets reveal the high repeatability and reproducibility of the measurements with a relative standard deviation (RSD) less than 10%. CIT presented good accuracy (within 10% of the actual value) and precision did not exceed 15% of RSD for high concentration values and 20% for the low concentration ones. In addition, a high correlation coefficient (R 2 = 0.9954) between chrono-impedance and colorimetric methods was obtained. On the other hand, when two samples prepared at the same conditions were measured in parallel with both methods (the measurement was repeated four times), it should be noticed that student's t-test produced no difference between the two mentioned methods (p = 1). The biosensor system hereby presented is highly specific to glucose detection and shows a better linear range than the one reported on the previous article.

Miniature glucose biosensor with extended linearity

Sensors and Actuators B: Chemical, 1992

A rapid and simple method for the preparation of a miniature glucose sensor (enzyme electrode) has been developed. Glucose oxidase is immobilized by glutaraldehyde in albumin gel on a cellulose diacetate membyane. This membrane is directly attached to an H,Oz detecting electrode and covered with an external polyvinyl chloride membrane. The response time of the glucose electrode thus prepared is about 2 min, the calibration graph is linear for O-30 mM glucose, and the sensor can be used repeatedly at room temperature for at least IO days with small deterioration in response.