Multifunctional Carbon Nanodots: Enhanced Near-Infrared Photosensitizing, Photothermal Activity, and Body Clearance

The emergence of quasispherical carbon nanodots (CNDs) has broadened the family of carbon-based materials and their applications in many fields. However, the rational design of near-infrared (NIR) CNDs and their specific applications in theranostic biomedicine are still challenging. Herein, the design and characterization of multifunctional CNDs (MCNDs) as NIR laser-triggered nanoagents are reported. These MCNDs are constructed by covalent functionalization of CNDs with folic acid and a hydrophobic photosensitizer, chlorin e6 (Ce6), based on a double amidation approach. The resulting MCNDs show high colloidal stability in different physiological environments. They are endowed with NIR fluorescence emission, an enhanced NIR photosensitizing, and a high photothermal activity. The in vitro test indicates that MCNDs own an efficient targeting capacity to penetrate into cancer cells, leading to cell killing at a low dose under NIR laser irradiation. Finally, MCNDs display a long blood circulation time in mice and effective body clearance through a dual hepatobiliary and renal elimination pathway. These features are encouraging for their use as NIR laser-triggered nanoagents for personalized medicine. This work not only paves a new way for the multifunctionalization of CNDs, simply by integrating other functional components, but also broadens their versatile applications in targeted cancer theranostic nanomedicine.