The motivation for using response to physical perturbation to classify microparticles came from our previous experiments with Dipicolinic Acid (DPA). DPA as a calcium complex is a major component of bacterial spores, constituting more than 5% of their dry weight. It is not commonly found in other natural products and therefore its presence is indicative of the presence of bacterial spores. Previous schemes utilizing the presence of DPA to detect these spores have relied on fluorescence which occurs when lanthanide metals (e.g., terbium) are added to a solution where the presence of DPA is to be determined. We have recently demonstrated that changes in the fluorescence of DPA can be stimulated without the addition of such reagents. Thus after exposure to UV light, a substantial increase of fluorescence emitted by DPA solutions with a peak at 410 nm occurs for excitation light with wavelength less than approximately 305 nm.

Date Published: 28 July 2000
PDF: 12 pages
Proc. SPIE 4036, Chemical and Biological Sensing, (28 July 2000); doi: 10.1117/12.394077

Published in SPIE Proceedings Vol. 4036:
Chemical and Biological Sensing
Patrick J. Gardner, Editor(s)