Element release and cytotoxicity of Pd-Cu binary alloys

The release of elements from a series of palladium-copper alloys into cell-culture medium was measured using atomic absorption spectroscopy. The effect of the alloys on the succinyl dehydrogenase activity of Balb/c 3T3 fibroblasts was also measured. Palladium inhibited the release of Cu in alloys up to 70 atomic weight percent Cu. Below 70 at. % Cu, Cu release was < 0.8 micrograms/cm2 at 72 hours. Palladium release was lower from pure Pd (0.08 micrograms/cm2) at 72 hours than from Pd-Cu alloys containing > 70 at. % Cu, where it increased to 1.2 micrograms/cm2. The cytotoxicity of the alloys correlated closely with the release of Cu, becoming markedly cytotoxic above 70 at. % Cu, when Cu release was greater than 2.2 micrograms/cm2.