Highly biocompatible carbon nanodots for simultaneous bioimaging and targeted photodynamic therapy in vitro and in vivo

Photosensitizers (PSs) are light-sensitive molecules that are highly hydrophobic, which poses a challenge to their use for targeted photodynamic therapy. Hence, considerable efforts have been made to develop carriers for the delivery of PSs. Herein, a novel design is described of highly biocompatible, fluorescent, folic acid (FA)-functionalized carbon nanodots (CDs) as carriers for the PS zinc phthalocyanine (ZnPc) to achieve simultaneous biological imaging and targeted photodynamic therapy. FA is modified on PEG-passivated CDs (CD-PEG) for targeted delivery to FA-positive cancer cells, and ZnPc is loaded onto CD-PEG-FA via π-π stacking interactions. CD-PEG-FA/ZnPc exhibits excellent targeted delivery of the PS, leading to simultaneous imaging and significant targeted photodynamic therapy after irradiation in vitro and in vivo. The present CD-based targeted delivery of PSs is anticipated to offer a convenient and effective platform for enhanced photodynamic therapy to treat cancers in the near future.