Peptide-functionalized NaGdF(4) nanoparticles for tumor-targeted magnetic resonance imaging and effective therapy

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 NaGdF(4) nanoparticles (termed as, NaGdF(4)@bp-peptide NPs) have been synthesized through the Gd–phosphate coordination reaction of the spherical NaGdF(4) 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 NaGdF(4)@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 NaGdF(4) nanoparticles (termed as, NaGdF(4)@CPP NPs). Using mouse-bearing MCF-7 breast cancer as a model system, the in vivo experimental results demonstrate that NaGdF(4)@bp-peptide NPs have integration of T(1)-weighted magnetic resonance imaging (MRI) contrast and tumor-targeting functionalities, and are able to suppress tumor growth without causing systemic toxicity.