Metallic nanoparticles showed potent efficacy for diagnosis and therapy of cancer, but their clinical applications are limited by their poor tumor-targeting ability. Herein, peptide-functionalized 9 nm NaGdF4 nanoparticles (termed as, NaGdF4@bp-peptide NPs) have been synthesized through the Gd-phosphate coordination reaction of the spherical NaGdF4 nanoparticles with phosphopeptides (sequence: KLAKLAKKLAKLAKG(p-S)GAKRGARSTA, p-S means phosphorylated serine) including a p32 protein binding motif incorporating a cell-penetrating function, and a proapoptotic domain. The NaGdF4@bp-peptide NPs are ready to be efficiently internalized by cancer cells; they show a much higher cytotoxicity in MCF-7 breast cancer cells than the casein phosphopeptide (CPP) modified NaGdF4 nanoparticles (termed as, NaGdF4@CPP NPs). Using mouse-bearing MCF-7 breast cancer as a model system, the in vivo experimental results demonstrate that NaGdF4@bp-peptide NPs have integration of T1-weighted magnetic resonance imaging (MRI) contrast and tumor-targeting functionalities, and are able to suppress tumor growth without causing systemic toxicity.
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