In vitro dissolution of curium oxide using a phagolysosomal simulant solvent system

Detailed study of actinide oxide behavior in alveolar macrophages (AM) in vitro is limited because of the short life span of these cells in culture. We created an in vitro dissolution system that could mimic the acidic phagolysosomal environment for the actinide and be maintained for an indefinite period so that dissolution of more insoluble materials could be measured. The dissolution system for this investigation, consisting of nine different solutions of HCl and the chelating agent diethylenetriamine pentaacetate (DTPA) in distilled water, is called the phagolysosomal simulant solvent (PSS). In this system, both the pH and the amount of DTPA were varied. We could observe the effect of altering pH within a range of 4.0-6.0 (similar to that of the phagolysosome) and the effect of the molar ratio of DTPA to curium at 1000:1, 100:1, or 10:1. We chose curium sequioxide (244Cm2O3) to validate the PSS for actinide dissolution versus that occurring in AM in vitro because it dissolves significantly in less than 1 week. The polydisperse 244Cm2O3) aerosol was generated, collected on filters, resuspended, and added to the PSS solutions and to cultured canine AM. By comparing dissolution in the two systems directly, we hoped to arrive at an optimum PSS for future dissolution studies. PSS and cell culture samples were taken daily for 7 days after exposure and tested for the solubilized curium. The amount of soluble material was determined by ultracentrifugation to separate the insoluble Cm2O3 from the soluble curium in the PSS solutions and filtration for the cell-containing material.(ABSTRACT TRUNCATED AT 250 WORDS)