Particle-mediated membrane uptake of chemical carcinogens studied by fluorescence spectroscopy.

The fluorescence emissions of chrysene, N-ethylcarbazole, and 1,6-diphenylhexatriene undergo large spectral shifts or changes in quantum yield, or both, upon their uptake from particulates by phospholipid vesicles. This membrane uptake of carcinogen and carcinogen-like molecules by model membranes does not result in any disruption of the lipid bilayers. The fluorescence emission of chrysene, when bound to silica, was found to be sensitive to the surface density of chrysene on the silica. These observations demonstrate the feasibility of using fluorescence spectroscopy to measure the rates of exchange of carcinogens from particulate matter to cell membranes and to characterize the surface distribution of chemical carcinogens on particulate matter. Comparison of the uptake rate of chrysene from the unperturbed crystal state, sonicated crystals, and the silica-adsorbed state demonstrated that the last condition results in the most rapid transport of chrysene into model membranes. This information should prove valuable in understanding the cocarcinogenic effects of particulates and polynuclear aromatic hydrocarbons.