Electrochemical biosensors: recommended definitions and classification.

Rotating ring-disk enzyme electrode for biocatalysis kinetic studies and characterization of the immobilized enzyme layer

The present invention relates generally to systems and methods for measuring an analyte in a host. More particularly, the present invention relates to systems and methods for transcutaneous measurement of glucose in a host.

Transcutaneous analyte sensor

Systems and methods for dynamically and intelligently estimating analyte data from a continuous analyte sensor, including receiving a data stream, selecting one of a plurality of algorithms, and employing the selected algorithm to estimate analyte values. Additional data processing includes evaluating the selected estimative algorithms, analyzing a variation of the estimated analyte values based on statistical, clinical, or physiological parameters, comparing the estimated analyte values with corresponding measure analyte values, and providing output to a user. Estimation can be used to compensate for time lag, match sensor data with corresponding reference data, warn of upcoming clinical risk, replace erroneous sensor data signals, and provide more timely analyte information encourage proactive behavior and preempt clinical risk.

Signal processing for continuous analyte sensor

The growth of membrane technology

A new trace glucose analyzer has been designed using electrochemical sensors. The differential device includes (a) a glucose sensor consisting of a modified gas electrode in which ihe pH detector was replaced by a platinum disk and the porous film by a collagen membrane on which beta-D-glucose oxidase has been covalently bound after an acyl-azide activation process; (b) a compensating electrode mounted with a nonenzymatic collagen membrane. After injection of a glucose containing sample into the reaction vessel, where the probes are immersed, an anodic current is detected at the enzyme working electrode. Current outputs of both electrodes are subtracted and twice differentiated; a steady state is reached and the stationary and dynamic responses are recorded. Both responses are proportional to glucose concentration in the 0.1 µM-2 mM range, and the reproducibility was found to be better than 2% using these conditions. The extreme sensitivity exhibited by our system, i.e., 10 nM, is better than previously reported data by 3 orders of magnitude, and is very favorable for trace glucose assays in food and biological samples.

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Enzyme collagen membrane for electrochemical determination of glucose

Multipurpose electrode with different enzyme systems bound to collagen films

A novel type of biosensors involving immobilized bioluminescence enzymes and a fiber-optic probe has been developed. The enzymes were immobilized on preactivated Nylon membranes placed in close contact with the tip of a bundle of optical glass fibers. The fiber-optic sensor was immersed in a stirred and thermostated cell protected from ambient light by a PVC jacket. The light emitted by the luminescence reactions was conducted through the fiber bundle to the photomultiplier tube of a luminometer. With immobilized firefly luciferase from Photinus pyralis, light emission could be linearly related to ATP concentration in the range 2.8 × 10−10 − 1.4 × 10−6 M. When co-immobilizing bacterial luciferase and oxidoreductase from Vibrio fischeri, NADH measurements could be performed from 3 × 10−10 M to 3 × 10−6 M. The luminol chemiluminescence reaction catalyzed by immobilized horseradish peroxidase has also been used for hydrogen peroxide determination. The standard curve was linear from 2 × 10−8 M to 2 ×...

Luminescence Fiber-Optic Biosensor

Commercially available polyamide preactivated membranes for immunodiagnostic use were found suitable for the preparation of immobilized enzyme membranes adaptable to biosensors. Membranes with immobilized glucose oxidese as model enzyme, tested with a microprocessor-based device involving an enzymatic electrode, gave excellent results. The extremely simple and fast procedure allows anyone to prepare such bioactive membranes easily, possibly from his own enzyme preparation and within a few minutes set up a specific probe from commercially available sensors.

New Immobilized Enzyme Membranes for Tailor-Made Biosensors

An original method of preparation of enzyme collagen membranes has been developed which enables the asymmetrical coupling of multienzymatic systems working in sequence. One or several enzymes are immobilized on one face of the acyl-azide activated membranes, another enzyme being bound on the other face. When the first enzymatic face is exposed to the adequate reaction mixture, the products diffuse through the collagen membrane and act as substrates for the enzyme present on the other side. This possibility has been applied to the design of new and polyvalent multienzyme electrodes.

P. R. Coulet

Papers

Enzyme collagen membrane for electrochemical determination of glucose

Multipurpose electrode with different enzyme systems bound to collagen films

Luminescence Fiber-Optic Biosensor

New Immobilized Enzyme Membranes for Tailor-Made Biosensors

Asymmetrical Coupling of Enzymatic Systems on Collagen Membranes Application to Multienzyme Electrodes