SBIR-STTR Award

We have developed highly specific, sensitive devices for the monitoring of glucose, primary alcohols, ketones and other products. Our technology uses a mediator to transfer electrons derived from enzymic oxidation of the substance being measured, to an electrode held at constant potential. Numerous researchers have investigated the transfer of electrons from an oxidase enzyme to an electrode. However, none have achieved the current densities required to make a realistic device. We have already achieved (a) high density electron transfer between a range of enzymes and electrodes, and (b) incorporation of enzymes onto electrodes to make realistic monitoring devices. The hydrogen peroxide monitor will use a cheap carbon electrode, horse heart cytochrome c (a commercially available enzyme) as a mediator of electron transport, and cytochrome c peroxidase as the active enzymic agent. Electrons from the oxidation of hydrogen peroxide at the cytochrome c peroxidase will be passed via the mediator, to the carbon electrode. The resulting current in the external circuit can be used to measure the concentration of hydrogen peroxide.The potential applications as described by the company:We propose the development of a highly specific monitor for hydrogen peroxide using our novel enzyme technology. This sensor will detect hydrogen peroxide at parts per billion levels in cloud water and in precipitation. Moreover, it will be suitable for real time field use. Commercial applications of this device include environmental monitoring of pollution, monitoring of water supplies and the production of hydrogen peroxide in processes industry. Extensions of this technology would allow development of monitors for other pollutants (polychlorinated biphenyls, alkanes, ketones, aldehydes for example).

The H202 monitor will use yeast cytochronie c peroxidase linked to a suitable mediator of electron transport. Research in Phase I has demonstrated that horse heart cytochronie c together with yeast cytochrome c peroxidase will provide sufficient sensitivity to measure H202 concentrations in the parts per billion range. Alternative mediators to cytochrome c are also under investigation. During Phase 11, the optimal electrochemical system will be developed into a prototype device. Particular emphasis will be placed on the following: (1) The design and construction of a robust working electrode. This will entail selection of an appropriate material for electrode construction, examination of surface chemical modifications, and investigation of suitable techniques for immobilizing the enzymes on the surface. (2) The design and construction of a monitor configuration. This will entail a choice of either a two or three electrode configuration, integration of a reference and working electrode, and construction of sample handling and presentation equipment. (3) Design and construction of appropriate microprocessor-based electronics and data output devices including operating software.Anticipated Results/Potential Commercial Applications as described by the awardee: The aim of this program is to demonstrate the commercial feasibility of producing a H202 monitor capable of measuring H202 at parts per billion levels. It is expected that this technology will have two broad areas of commercial applications: (1) Environmental monitoring - An ability to measure oxidizing agents, such as H202, in environmental samples, will allow an analysis of the critical role of H202 in the problem of sulphur dioxide emissions and the associated issue of "acid rain" (2) Health Care Monitoring-There is a requirement for the analysis of H202 in many assays of clinical importance, such as cholesterol assayed by cholesterol oxidase. Existing polarographic techniques are too insensitive and not specific enough for many of these applications.