Adsorption of the Pt-II Anticancer Drug Carboplatin by Mesoporous Silica

MCM-41, a mesoporous silica nanomaterial with a high surface area for adsorption of small molecules, is a potential new type of delivery vehicle for therapeutic and diagnostic agents. In this report, we show that MCM-41 adsorbs the front-line anticancer drug carboplatin, [Pt(CBDCA-O,O')(NH3)(2)] (CBDCA = cyclobutane-1,1-dicarboxylate; 1), which is used to treat ovarian, lung, and other types of cancer. UV/Visible difference absorption spectroscopy shows that MCM-41 adsorbs 1.8 +/- 0.2% of its own weight of carboplatin after a 24 h exposure to 26.9 mM drug in H2O. The pseudo-first-order rate constant for adsorption of carboplatin by MCM-41, measured using [H-1,N-15] heteronuclear single quantum coherence (HSQC) NMR, and N-15-labeled carboplatin is k(1) = 2.92 +/- 2.17 x 10(-6) s(-1) at ca. 25 degrees.