Immobilization, stabilization and patterning techniques for enzyme based sensor systems.

Sandia National Laboratories has recently opened the Chemical and Radiation Detection Laboratory (CRDL) in Livermore CA to address the detection needs of a variety of government agencies (e.g., Department of Energy, Environmental Protection Agency, Department of Agriculture) as well as provide a fertile environment for the cooperative development of new industrial technologies. This laboratory consolidates a variety of existing chemical and radiation detection efforts and enables Sandia to expand into the novel area of biochemically based sensors. One aspect of this biosensor effort is further development and optimization of enzyme modified field effect transistors (EnFETs). Recent work has focused upon covalent attachment of enzymes to silicon dioxide and silicon nitride surfaces for EnFET fabrication. They are also investigating methods to pattern immobilized proteins; a critical component for development of array-based sensor systems. Novel enzyme stabilization procedures are key to patterning immobilized enzyme layers while maintaining enzyme activity. Results related to maximized enzyme loading, optimized enzyme activity and fluorescent imaging of patterned surfaces will be presented

1896 Full Paper FET-Based Biosensors for The Direct Detection of

Recent world-wide terrorist events associated with the threat of hazardous chemical agent proliferation, and outbreaks of chemical contamination in the food supply has demonstrated an urgent need for sensors that can directly detect the presence of dangerous chemical toxins.Such sensors must enable real-time detection and accurate identification of different classes of pesticides (e.g., carbamates and organophosphates) but must especially discriminate between widely used organophosphate (OP) pesticides and G- and V-type organophosphate chemical warfare nerve agents.Present field analytic sensors are bulky with limited specificity, require specially-trained personnel, and, in some cases, depend upon lengthy analysis time and specialized facilities.Most bioanalytical based systems are biomimetic.These sensors utilize sensitive enzyme recognition elements that are the in-vivo target of the neurotoxic agents which the sensor is attempting to detect.The strategy is well founded; if you want to detect cholinesterase toxins use cholinesterase receptors.However, this approach has multiple limitations.Cholinesterase receptors are sensitive to a wide range of non-related compounds and require lengthy incubation time.Cholinesterase sensors are inherently inhibition mode and therefore require baseline testing followed by sample exposure, retest and comparison to baseline.Finally, due to the irreversible nature of enzyme-ligand interactions, inhibition-mode sensors cannot be reused without regeneration of enzyme activity, which in many cases is inefficient and time-consuming.I

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