We describe a fully automated and autonomous air-borne biothreat detection system for biosurveillance applications.
The system, including the nucleic-acid-based detection assay, was designed, built and shipped by Microfluidic Systems
Inc (MFSI), a new subsidiary of PositiveID Corporation (PSID). Our findings demonstrate that the system and assay
unequivocally identify pathogenic strains of Bacillus anthracis, Yersinia pestis, Francisella tularensis, Burkholderia
mallei, and Burkholderia pseudomallei. In order to assess the assay's ability to detect unknown samples, our team also
challenged it against a series of blind samples provided by the Department of Homeland Security (DHS). These samples
included natural occurring isolated strains, near-neighbor isolates, and environmental samples. Our results indicate that
the multiplex assay was specific and produced no false positives when challenged with in house gDNA collections and
DHS provided panels. Here we present another analytical tool for the rapid identification of nine Centers for Disease
Control and Prevention category A and B biothreat organisms.
A ratiometric pH-sensitive fluorescent dye (hydroxypyrenetrisulfonic acid) was
covalently attached to an acrylamide polymer. These pH-sensitive copolymers were
either covalently bonded to the end of an optical fiber or polymerized into separate gels.
Long-term, accelerated aging studies were performed on the fibers and gels in 43°C
distilled H20. The fiber-immobilized optrodes gave good pH responses for up to
2 months. The pH-sensitive gels were physically attached to optical fibers and gave
very good pH responses for over one year. These physically immobilized, one-year-old,
pH-sensitive copolymers provided optrodes with linear pH responses between pH 6 and
8 and resolution greater than 0.25 pH unit. A simple photostability experiment on these
optrodes showed that they were very photostable. The results of this study indicate that
pH-sensitive copolymers in a simple optrode design can be employed as pH sensors with
useful lifetimes exceeding one year.