Carbon dots as a nanotool for integrated photodynamic therapy and chemotherapy

The development of combination therapy for cancer treatment has attracted considerable attention due to its enhanced therapeutic efficacy. In addition to that, the possibility of drug tracking is an extremely attractive proposition. Herein, we report a carbon dot (CD) based nanoplatform to facilitate the delivery of two distinct drugs, a photosensitizer (PS) and the chemotherapeutic drug Doxorubicin (Dox). The CD-PS-Dox nanoassembly simultaneously offers tracking due to the inherent fluorescence of the individual participants of the nanoassembly. Protoporphyrin IX (Pp IX), a well known PS has been conjugated to CDs using standard carbodiimide based chemistry. Since, the absorption spectra of the Pp IX overlaps with the emission spectra of CD, Pp LX acts as an acceptor to CD and forms a FRET pair. This nanosystem leads to ROS generation, which has the potential to damage the cancerous cells in Photodynamic Therapy (PUT) applications. Further, Dox is allowed to be electrostatically physisorbed over CDs to be released in solution at acidic pH. relevant to cancer environment. CDs are thus endowed with three responsibilities in the nanosystem: a donor for Pp IX, a site for adsorption of Dox and a fluorescent entity that could be tracked through imaging.