DETECTION OF INVISIBLE BACILLI SPORES ON SURFACES USING A PORTABLE SERS-BASED ANALYZER

Abstract

Since the distribution of anthrax causing spores through the U.S. Postal System in the autumn of 2001, bioterrorism has become an ever present threat. During and following an attack it is also important to detect spores on surfaces, to assess the extent of an attack, to quantify risk of infection by contact, as well as to evaluate post-attack clean-up. To perform useful measurements, analyzers and/or methods must be capable of detecting as few as 10 spores/cm2, in under 5-minutes, with little or no sample preparation or false-positive responses, using a portable device. In an effort to develop such a device, we have been investigating the ability of surface-enhanced Raman spectroscopy (SERS) to detect dipicolinic acid (DPA) as a chemical signature of bacilli spores. In general, SERS is capable of detecting mg/L concentrations and lower, and providing unequivocal identification of chemicals based on each one's unique spectrum. However, rapid analysis requires extracting the DPA from the spores for SERS detection. Here we describe the use of a room temperature digesting agent in combination with SERS to detect 220 spores on a surface, the entire procedure which was performed in 2.5 minutes.