Precious metal carborane polymer nanoparticles: characterisation of micellar formulations and anticancer activity

Abstract

We report the encapsulation of highly hydrophobic 16-electron organometallic ruthenium and osmium carborane complexes [Ru/Os(p-cymene)(1,2-dicarba-closo-dodecarborane-1,2-dithiolate)] (1 and 2) in Pluronic® triblock copolymer P123 core–shell micelles. The spherical nanoparticles RuMs and OsMs, dispersed in water, were characterized by dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), and synchrotron small-angle X-ray scattering (SAXS; diameter ca. 15 and 19 nm, respectively). Complexes 1 and 2 were highly active towards A2780 human ovarian cancer cells (IC₅₀ 0.17 and 2.50 μM, respectively) and the encapsulated complexes, as RuMs and OsMs nanoparticles, were less potent (IC₅₀ 6.69 μM and 117.5 μM, respectively), but more selective towards cancer cells compared to normal cells.