The loading and release of the anti-
cancer drug platinum cis-dichlorodiamine (
cisplatin) from mesoporous
silicon (pSi) microparticles is studied. The pSi microparticles are modified with 1-dodecene or with 1,12-undecylenic
acid by hydrosilylation, and each modified pSi material acts as a
reducing agent, forming a deposit of Pt on its surface that nucleates further deposition, capping the mesoporous structure and trapping free (unreduced)
cisplatin within. Slow oxidation and hydrolytic dissolution of the Si/SiO(2) matrix in
buffer solution or in culture medium leads to the release of drugs from the microparticles. The
drug-loaded particles show significantly greater toxicity toward human
ovarian cancer cells (in vitro), relative to an equivalent quantity of free
cisplatin. This result is consistent with the mechanism of drug release, which generates locally high concentrations of the
drug in the vicinity of the degrading particles. Control assays with pSi particles loaded in a similar manner with the therapeutically inactive trans isomer of the
platinum drug, and with pSi particles containing no
drug, result in low cellular toxicity. A hydrophobic
pro-drug, cis,trans,cis-[Pt(NH(3))(2)(O(2)C(CH(2))(8)CH(3))(2)Cl(2)], is loaded into the pSi films from
chloroform without concomitant reduction of the pSi carrier.