Mesoporous silica microparticles enhance the cytotoxicity of anticancer platinum drugs.

We report on the endocytosis and the time-dependent enhanced cytotoxicity of anticancer platinum drugs when the drugs are combined with (or loaded into) one of the two most common types of mesoporous silica materials, MCM-41 or SBA-15. The anticancer drug cisplatin and its isomer transplatin, when loaded on MCM-41 and SBA-15 microparticles, were less cytotoxic to leukemia cells than the drugs alone after 12 h exposure. However, the drug-loaded microparticles exhibited unprecedented enhanced cytotoxicity to the cancerous cells after 24 h of exposure. This cytotoxicity of the drug-loaded microparticles was even higher than of the pure drugs in solutions, suggesting that mesoporous silica microparticles loaded with cisplatin or transplatin enabled a localized intracellular release of the platinum compounds and possibly also facilitated the drug's hydrolysis, enhancing the desired cytotoxic effect.