Multifunctional upconversion nanostructure for in vivo dual-modal imaging guidedmagnetically targeted photothermal therapy

摘要

Lanthanide-based upconversion nanoparticles (UCNPs) have shown great potential as unique optical nano-probes in biomedical sensing and imaging. Herein, utilizing a layer-by-layer (LBL) assembly approach, we synthesize a novel class of multifunctional nanoparticles (MFNPs) by adsorbing of superparamagnetic iron oxide nanoparticles (IONPs) on UCNPs, forming a UCNP-IONP nanocomposite, on top of which a thin gold shell is grown. The obtained UCNP-IONP-Au MFNPs are then coated with polyethylene glycol and used for in vitro targeted upconversion luminescence (UCL), magnetic resonance (MR), and dark-field scattering multimodal imaging of cells. The NIR optical absorption offered by the gold shell of MFNPs also enables photothermal destruction of cancer cells. In vivo dual-model UCL and MR imaging of tumors. MFNPs is further demonstrated in mice, uncovering that by placing a magnet nearby the tumor, MFNPs tend to migrate towards the tumor after intravenous injection and show high tumor accumulation, which is 8 folds higher than that without magnetic targeting. NIR laser irradiation is then applied to the tumors grown on MFNP-injected mice under magnetic tumor-targeting, obtaining an outstanding photothermal therapeutic efficacy with 100% of tumor elimination in a murine breast cancer model. Our work presents a unique strategy for multi-modal imaging guided, magnetically targeted physical cancer therapy and highlights the promise of using multifunctional nanostructures for novel cancer theranostics.