Peptide Based Assays for Homeland Security

Accacia International has produced a potentially powerful system for the detection of a wide variety of biothreat agents. Accacia International proposes to design and prototype a compact, handheld fluorescence polarization based sensor capable of detecting biowarfare agents. Accacia International, with the aid of Dr. Andrew Ellington¿s laboratory, will develop assays for a variety of biothreat agents and a device that can detect a signal created by the transduction of high-affinity peptide binding into fluorescently labeled nucleic acid signal. Multiple peptide ligands selected for by peptide phage display will be immobilized on phycoerythrin (PE) in order to create multivalent conjugates that can bind with high affinity for the surfaces of biothreat agents including Bacillus anthracis and Escherichia coli. These multivalent conjugates, so-called ¿burrs¿, will also contain nucleic acid tags that can be amplified by rolling circle amplification (RCA). Peptide-mediated RCA will be detected by observing the substantive changes in fluorescence polarization (FP) that will result from the incorporation of fluorescent nucleotides into long, concatameric polymers. The assays will be optimized and adapted to a MEMS-FP device designed by Accacia International. Anticipated Benefits / Potential Commercial Applications of the Reasearch and Development: There is a great demand for ultrasensitive assays and instrumentation in the clinical diagnostic, water monitoring, agricultural and food industries. The Accacia Team will couple proximity ligation with the ultrasensitivity and speed of a fluorescence sensor by incorporating ¿burrs¿ into fluorescence polarization assays adapted to a MEMS-FP device to be used initially by the Homeland Defense and adapted for commercial use in detection of foodborne pathogens and marketed to food and agricultural industries.