Bifunctional combined Au-Fe(2)O(3) nanoparticles for induction of cancer cell-specific apoptosis and real-time imaging.

We demonstrate bifunctional combined Au-Fe(2)O(3) nanoparticles (NPs) for selectively induction of apoptosis in cancer cells and real-time imaging. The as-prepared Au-Fe(2)O(3) NPs combine the merits of both Au and γ-Fe(2)O(3) NPs, maintaining excellent fluorescence quenching property and catalytic activity. Conjugated with α(Ⅴ)β(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-Fe(2)O(3) NPs bind preferentially to integrin α(Ⅴ)β(3)-rich human liver cancer cells (HepG2), sequentially initiate catalytic formation of hydroxyl radicals (·OH) and enable the real-time monitoring of·OH-induced caspase-3-dependent apoptosis in these cancer cells. Furthermore, the catalytic activity of RGD/FITC-DEVD-Au-Fe(2)O(3) NPs is much higher than that of individual γ-Fe(2)O(3) NPs due to the polarization effect at the Au-Fe(2)O(3) interface. Such bifunctional Au-Fe(2)O(3) NPs exhibit simultaneous targeting, therapeutic and imaging functions and are therefore promising for future therapeutic applications in cancer. Copyright Â