Synthesis of permeable yolk-shell structured gadolinium-doped quantum dots as a potential nanoscale multimodal-visible delivery system.

Developing a nanoscale drug delivery system with magnetic resonance imaging (MRI)/fluorescence imaging (FL) visibility to optimize the delivery efficiency and therapeutic efficacy under image guidance has attracted great attentions in the area of nanomedicine. Herein, a novel permeable yolk-shell structured gadolinium-doped quantum dots nanocomposite was synthesized as a theranostic nanocarrier via an indirectly doping method. The as-prepared permeable nanoparticles with tunable color fluorescent emission, paramagnetic and accessible mesoporous channels could be developed as a novel nanomedical platform for integrated multimodal diagnosis and therapy. The hydrophilic nanocomposites exhibited tunable fluorescence as well as high longitudinal relaxivity (r1 = 17.32mM-1s-1) in water with good colloidal stability. In vivo animal experiments further verified CSSP could achieve FL/MRI dual modality imaging. The widely used antineoplastic anthracycline drug doxorubicin (DOX) was absorbed into the permeable nanospheres with 95.3% loading efficiency and released in a pH-sensitive pattern. In vitro cancer cell cytotoxicity tests verified that the DOX-loaded nanocomposites had enhanced cytotoxicity compared with free DOX at the same concentration. The as-prepared nanocomposites present great potential as MRI/FL-visible nanoscale drug carrier to realize imaging-guided personalized therapy.