Study of the death rate of CHO cells loaded with high-Z atoms by fast atomic ions

The present report is concerned first with the study of the survival fraction of CHO-K1 cells incubated in a non cytotoxic solution 350μM auro-thio-propanol sulfonate of sodium (AuTP), a molecule containing one gold atom, and subsequently irradiated by carbon ions 290 MeV/amu (LET=13.6 keV/μm). A significant enhancement in the cell death rate is observed when molecules containing gold (AuTP) are present. Another series of experiments are concerned with irradiation by carbon ions of DNA-plasmids pBR322 loaded with heavy atoms (platinum) contained in a nano-particles (NPt) about 3 nm in size id est (i.e.) 1000 atoms. On the average, the concentration was 1 nano-particle for two plasmids in the irradiated sample. Comparison of DNA breaks induction in presence of NPt is made with previous results when the plasmids are loaded with platinum contained in a molecule: chloroterpyridine-platin (PtTC). In both situations (NPt and PtTC) the number of platinum atoms is made similar, allowing a comparison of the effects of the high-Z atoms when they are scattered in the sample (PtTC) or concentrated as clusters in the solution (NPt). (author)