PHOTOREACTIVE GOLD SURFACE--STREPTAVIDIN BASED BIOSENSOR

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This project is designed for the development of reagents and coating technology for cost-effective and functionally superior thin film coating of noble metal surfaces on biosensors and diagnostic particles (e.g., colloidal gold). Photoaffinity immobilization of a monolayer of the "universal binding protein" streptavidin from its crude source material without prior purification, will be accomplished with hydrophilic photogroups on amphophilic spacers with a short hydrophilic segment joined to a hydrophobic alkyldithiol segment. The model biosensor system to be used is Surface Plasmon Resonance, a sensitive optical system requiring no sample processing, and using disposable gold-coated optical plastic cartridges for rapid myocardial infarct diagnosis on site in the emergency room. Specific aims of the Phase I effort include a reagent for coating a gold surface to stably immobilize from crude source solution a load of streptavidin with biotin-binding capacity of at least 1 pmole per square centimeter, which is stable to storage at ambient lab conditions for at least 3 months and which has a specific analyte binding signal at least four times that of its nonspecific binding signal from blood. Subsequent development goals include-a five-fold improvement in these functional characteristics and a multianalyte assay capability through patterned immobilization of biomolecules on passivated noble metal biosensor surfaces. PROPOSED COMMERCIAL APPLICATIONS Commercial applications include the noble metal-based biosensors such as Surface Plasmon Resonance (SPR) and Surface Acoustic Wave (SAW) systems now on the market or under development/FDA approval for rapid, on-site diagnosis of thrombotic and infectious diseases. The cardiac marker market alone may be estimated from the 4-5 million patient admissions each year for chest pains.