Development of Biological Obscurants

SPEC and Dr. James P. Chambers of the University of Texas at San Antonio propose to develop biological obscurants for battlefield applications based on the use of bacteriochlorophylls. In this Phase I program, SPEC and Dr. Chambers will conduct spectroscopic investigations of bacteria containing bacteriochlorophyll b with tetrapyrrole pigments to demonstrate the feasibility of using chlorophyll compounds as obscurants. Also in the Phase I, we will investigate the use of combinatorial techniques to alter the protein microenvironment near the tetrapyrrole ring and thus tune the absorption spectra to provide multi-spectral capabilities. The rational for use of chlorophyll compounds as an obscurant is based on the broad range of spectral absorption possible using chlorophyll derivatives. Observed absorption peaks coincide well with specific areas of military interest including: (1) the visible range; (2) night vision ranges including 700 to 800 for older systems and 900 for 3rd generation image tube technology; and (3) the 1064 nm range for most smart bomb and missile laser guidance systems. Based on these absorption spectra, bacteriochlorophyll compounds are excellent candidate compounds to investigate as replacements for obscurants currently in use which have a number of shortcomings including: limited spectral ranges, cleanup requirements, and toxic effects. BENEFITS: Biological obscurants could provide multi-spectral capabilities, environmental-friendly biodegradation, and non-pathogenic constituents and by-products. Other advantages could come in the manufacturing process by providing low-cost, rapid production and simplified storage and transport. It is conceivable that production of large quantities of obscurant could take place in forward locations from only small quantities biologically active cells.