Abstract: An electrochemical detection system which specifically detects selected nucleic acid segments is described. The system utilizes biological probes such as nucleic acid or peptide nucleic acid probes which are complementary to and specifically hybridize with selected nucleic acid segments in order to generate a measurable current when an amperometric potential is applied. The electrochemical signal can be quantified.

Abstract: An electrochemical detection system which specifically detects selected nucleic acid segments is described. The system utilizes biological probes such as nucleic acid or peptide nucleic acid probes which are complementary to and specifically hybridize with selected nucleic acid segments in order to generate a measurable current when an amperometric potential is applied. The electrochemical signal can be quantified.

Abstract: An apparatus is disclosed which is a microprocessor based instrument designed to conveniently and rapidly measure various analytes in environmental and biological samples. The instrument operates as a stand-alone unit powered by a battery or a DC power module and may be equipped with a communication port allowing uploading test results to a computer. Several unique electronic, microchip and software configurations were developed for the device to make it a portable, low-cost, safe, automated and simple-to-operate instrument particularly adapted for precise and accurate measurement of metal ions such as heavy metals such as lead in human blood.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Carrageenan-immobilized enzymes are prepared that are stable and retain high activity toward substrates when used in substantially water-immiscible organic solvents. The carrageenan-immobilized enzymes are preferably prepared by introducing droplets of an enzyme/carrageenan solution into a chilled alcohol saturated with a potassium salt and hardening the droplets in the alcohol. The alcohol is selected from n-butanol, benzyl alcohol, crotyl alcohol, n-propanol, isopropanol and sec-butanol. Reactions catalyzed by a .kappa.-carrageenan-immobilized esterase include steroselective transesterifications and hydrolysis reactions.