Production of monodisperse, fluorescently and radioactively labelled aerosol particles

Abstract

To compare the initial anatomic sites of particle deposition with the resultant particle clearance kinetics in the lungs, it is desirable to have particles that have both radioactive and fluorescent labels. The radioactivity allows for analysis of in vivo retention by gamma camera; the fluorescence allows for analysis of post mortem lung tissue samples by fluorescence microscopy. We made solid monodisperse carnauba wax particles labelled with 99mTc and either coumarin 1 (a fluorescent blue dye) or coumarin 6 (a fluorescent yellow dye) using an evaporation-condensation aerosol generator. Particles could be made between 1 and 4 μm and at number concentrations of 10 6 to 10 7 cm −3. The solid particles remained stable in the lungs for 3 days, and the radioactive and fluorescent labels appeared to remain with the particles. The fluorescent label was homogeneous throughout the matrix.