Soluble single-walled carbon nanotubes as longboat delivery systems for Platinum(IV) anticancer drug design

Amine-functionalized soluble single-walled carbon nanotubes (SWNTs) were derivatized with cisplatin prodrug conjugates as a delivery system by which to internalize multiple prodrug centers. The platinum(IV) complex, c,c,t-[Pt(NH3)(2)Cl-2(OEt)(O2CCH2CH2CO2H)], was tethered to the surface of the carbon nanotubes through peptide linkages formed by the reaction of the SWNT-tethered amines with the carboxylate moiety. The SWNTs were taken into testicular cancer cells by endocytosis, where the drop in pH facilitates reductive release of the platinum(II) core complex, which then readily diffuses throughout the cell, as determined by platinum atomic absorption spectroscopy. The entrapment of the SWNTs within the endosomes was confirmed by fluorescence microscopy of SWNTs containing both tethered fluorescein and platinum units. The cytotoxicity of the free platinum(IV) complex increases by > 100-fold when the complex is attached to the surface of the functionalized SWNTs.