Bifunctional combined Au-Fe2O3 nanoparticles for induction of cancer cell-specific apoptosis and real-time imaging

We demonstrate bifunctional combined Au-Fe2O3 nanoparticles (NPs) for selectively induction of apoptosis in cancer cells and real-time imaging. The as-prepared Au-Fe2O3 NPs combine the merits of both Au and gamma-Fe2O3 NPs. maintaining excellent fluorescence quenching property and catalytic activity. Conjugated with alpha(v)beta(3) integrin-targeting peptide (RGD) and fluorescein isothiocyanate (FITC)-labeled capsase-3 recognition sequence (DEVD) on the Au surface, the resulting RGD/FITC-DEVD-Au-Fe2O3 NPs bind preferentially to integrin alpha(v)beta(3)-rich human liver cancer cells (HepG2), sequentially initiate catalytic formation of hydroxyl radicals ((OH)-O-center dot) and enable the real-time monitoring of(center dot)OH-induced caspase-3-dependent apoptosis in these cancer cells. Furthermore, the catalytic activity of RGD/FITC-DEVD- Au-Fe2O3 NPs is much higher than that of individual gamma-Fe2O3 NPs due to the polarization effect at the Au-Fe2O3 interface. Such bifunctional Au-Fe2O3 NPs exhibit simultaneous targeting, therapeutic and imaging functions and are therefore promising for future therapeutic applications in cancer. (C) 2012 Elsevier Ltd. All rights reserved.