Multifunctional yolk-shell nanoparticles: A potential MRI contrast and anticancer agent

Abstract

We report a new type of multifunctional nanomaterials, FePt@Fe 2O 3 yolk-shell nanoparticles, that exhibit high cytotoxicity originated from the FePt yolks and strong MR contrast enhancement resulting from the Fe 2O 3 shells. Encouraged by the recently observed high cytotoxicity of FePt@CoS 2 yolk-shell nanoparticles, we used Fe 2O 3 to replace CoS 2 as the shells to further explore the applications of the yolk-shell nanostructures. The ultralow IC 50 value (238 ± 9 ng of Pt/mL) of FePt@Fe 2O 3 yolk-shell nanoparticles likely originates from the fact that the slow oxidation and release of FePt yolks increases the cytotoxicity. Moreover, compared with two commercial magnetic resonance imaging (MRI) contrast agents, MION and Sinerem, the FePt@Fe 2O 3 yolk-shell nanoparticle showed stronger contrast enhancement according to their apparent transverse relaxivity values (r 2* = 3.462 (μg/mL) -1 s -1). The bifunctional FePt@Fe 2O 3 yolk-shell nanoparticles may serve both as an MRI contrast agent and as a potent anticancer drug. This work indicates that these unique yolk-shell nanoparticles may ultimately lead to new designs of multifunctional nanostructures for nanomedicine. © 2008 American Chemical Society.