Abstract: The invention is a novel fluorescently labeled microparticle, where the microparticle internally incorporates at least one dipyrrometheneboron difluoride dye. Appropriate selection of substituents results in dipyrrometheneboron difluoride derivatives that, when incorporated into polymer microparticles, give the desired excitation and emission wavelengths. The spectral characteristics of the labeling dyes in liquid are not greatly changed when the dye is incorporated into the particles, and the spectral excitation and emission wavelengths are compatible with commonly used filter sets. Other embodiments of the fluorescent microparticles include additional dyes and/or bioreactive substances.

Abstract: The invention relates to a method of analyzing a sample thought to contain bacteria using an aqueous solution comprising one or more fluorescent dyes: a fluorescent dye of formula I, a fluorescent dye of formula II, a fluorescent dye of formula III, and a fluorescent dye of formula IV. Each of the dyes differ each from the other in their affinity for nucleic acids and in their spectral response to different types of bacteria in the sample. The first three dyes are nucleic acid stains and the fourth dye is a fluorescent reagent that binds selectively to cell surface components. The fluorescent dyes of formula I are highly membrane-permeant cyanine dye derivatives and label all bacteria, whether live or dead, whether Gram positive or Gram negative. The dyes of formula II label only live Gram positive bacteria and label all dead bacteria, whether Gram positive or negative. The dyes of formula II bind to nucleic acids preferentially with respect to the dyes of formula I.