Carbon dots embedded metal organic framework @ chitosan core-shell nanoparticles for vitro dual mode imaging and pH-responsive drug delivery

In this study, a novel core-shell MOFs/[email protected] nanoparticles were synthesized and validated for in vitro diagnosis and treatment of cancer. MIL-100 (Fe-BTC) is a potential drug platform because of its large specific surface area. Importantly it can be used for magnetic resonance imaging as it contains large amount of Fe3+. To demonstrate the optical imaging properties, carbon dots (CDs) were encapsulated into the synthesized MOFs, thereby endowing fluorescence features to the nanoparticles. The composite was further coated with O-carboxymethyl chitosan (OCMC) to form MOFs/[email protected] to improve biocompability and endow pH responsive property. The structure and morphology of the composite were characterized by XRD, IR, SEM and TEM. Moreover, the composite exhibited excellent performance in fluorescence imaging (FOI) and magnetic resonance imaging (MRI), which proved that MOFs/[email protected] could be used for FOI/MRI dual mode imaging. Cytotoxicity assays indicated that MOFs/[email protected] particles were highly biocompatible and suitable to be used to transport drugs in human bodies. Doxorubicin (DOX) was selected as a model drug and the drug delivery was discussed. The drug loading was 50 mg/g. It was found that the DOX was released rapidly at pH 3.8 but at pH 7.4, the rate and extent of release were greatly attenuated. The particles therefore demonstrated an excellent pH-triggered drug release performance.