Andcare, Inc.

Enzyme Technology Research Group, Inc.

Junguo Zhao

Robert W Henkens

John P O'Daly

Marek Wojciechowski

Susan E Morris

Honghua Zhang

Steven E Wegner

Najih Naser

Zhi-Wei Liang

Michael A Harpold

Terence M McCaffrey

The present invention provides a new device for use in measuring lead levels in biological and environmental samples. Using square wave coulometry and colloidal gold particles impregnated on carbon electrodes, the present invention provides a rapid, reliable, portable and inexpensive means of detecting low lead levels. The colloidal gold modified electrodes have microelectrode array characteristics and produce significantly higher stripping detection signals for lead than are produced at bulk gold electrode surfaces. The method is effective in determining levels of lead down to at least 5 .mu.g/dL in blood samples as small as 10 .mu.L.

Colloidal-gold electrosensor measuring device

An electro-immunosensor which can be used to determine the presence of a wide range of analytes in solution is described. Also described are methods of determining subnanogram levels of analytes in a one-step procedure. This novel immunosensor comprises an analyte binding agent bound to an electrode and a analyte/enzyme conjugate bound to the analyte binding agent as part of a catalytic electrical circuit. Displacement of the conjugate by analyte causes a proportional decrease in current. The immunosensor may also be adapted to detect two analytes in a single step by using different enzymes conjugated to the analyte binding agents.

Electrochemical immunoassay methods

The invention relates to methods of determining micromolar levels of lead ion in various fluids, including blood. Detection of lead or other heavy metal ion concentrations as low as 1 .mu.g/dL is achieved. The methods are adaptable to the detection of low levels of lead in whole blood, employing a novel separation and release of lead ion from lead chelating agents. The disclosed methods employ isocitrate dehydrogenase-based electrodes which are particularly suited for detecting nanomolar levels of lead.

Convenient determination of trace lead in whole blood and other fluids

Horseradish peroxidase (HRP) immobilized on colloidal gold and then deposited on an electrode surface can be reduced at a convenient rate at low voltage (Ag/AgCl) without an electron transfer mediator. Bioelectrodes combining both a colloidal gold-adsorbed oxidase and colloidal gold-adsorbed HRP located on an electrode surface are efficient biodetectors, particularly for the measurement of low glucose levels in samples when glucose oxidase is employed as the sensing enzyme. The biodetectors may be employed for mediatorless detection of a wide variety of analytyes depending on the oxidase employed.

Peroxidase colloidal gold oxidase biosensors for mediatorless glucose

Horseradish peroxidase (HRP) immobilized on colloidal gold and then deposited on an electrode surface can be reduced at a convenient rate at low voltage (Ag/AgCl) without an electron transfer mediator. Bioelectrodes combining both a colloidal gold-adsorbed oxidase and colloidal gold-adsorbed HRP located on an electrode surface are efficient biodetectors, particularly for the measurement of low glucose levels in samples when glucose oxidase is employed as the sensing enzyme. The biodetectors may be employed for mediatorless detection of a wide variety of analytes depending on the oxidase employed.

The invention relates to novel b of detecting metal ion concentrations less than about 10 .mu.g/dl fluid. Biosensors based on the enzyme isocitrate dehydrogenase are particularly suited for detecting trace lead ion concentrations in water and in blood. Bioelectrodes are fabricated from surface deposited colloidal gold adsorbed enzyme that retains high catalytic activity Other aspects of the invention include detection devices for convenient and rapid measurement of metal ions.

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Chapel Hill, NC, United States of America

Junguo Zhao