Coating 5μ Particles With Carbon and Metals for Lung Clearance Studies

Abstract

By an evaporation in vacuum technique, 5μ Teflon particles (density, 2 gm/cu cm) were coated with aluminum, beryllium, carbon, chromium, lead, manganese, silver, and uranium. After retention for one week in 0.9% sodium chloride (NaCI) solution at 37 C, most of the particles were coated more than 50% with all elements. The coatings remained after one month, except for lead and uranium. Aerosols of the coated particles were produced, and about 90% of the particles occurred in single form. The thickness of the coats was calculated to be a few hundredths of one micron and the increase in aerodynamic diameter a few tenths of one micron. As the particles coated with different elements are similar in size and in aerodynamic diameter, they should be useful in the study of the elimination mechanisms for inhaled particles. Phagocytosis in vitro by alveolar macrophages during 1.5 hours of exposure to particles coated with lead, silver, and carbon was studied. The carbon-coated particles were phagocytized at a significantly higher rate than silver- and lead-coated particles.