Immunoaffinity based phosphorescent sensor platform for the detection of bacterial spores

Consideration of emergency response plans to an attack with biological weapons such as anthrax spores has spawned renewed interest in the development of inexpensive, rapid, and sensitive field portable sensors for use by non-specialists. The conceptual feasibility of such a device is demonstrated via the immunoaffinity capture of spores of the anthrax simulant B. globigii on a column followed by their washing, elution and phosphorescent detection. Spores are generically detected via the rapid extraction of dipicolinic acid (DPA) followed by its chelation with terbium to yield a phosphorescent complex. Chemical, thermal and mechanical methods of DPA extraction were evaluated. Simple extraction in HNO₃ (1.8 M) released up to 5% of the spore weight as DPA within 60 seconds. Extraction in H₂O (100°C × 10 min) liberated 7% of the spore weight as DPA. Sonication (3.5) W) with glass beads in H₂O for 45 seconds released up to 4% of the spore weight as DPA. It is estimated that implementation of these techniques will permit development of a device requiring 3-5 minutes per analysis with a limit of detection on the order of 500 ng spore/mL. This approach is not intended to replace more specific methods of analysis. However, it is proposed for consideration as an inexpensive, simple and rapid means of spore detection by non-specialists in emergency situations.