Carbon dots; the smallest photoresponsive structure of carbon in advanced drug targeting

Nowadays carbon-based materials have gained more attention in many fields including engineering, medicine, pharmaceutics, and so on. Among carbon-based nanostructures, the novel and newly reported nanodots are known as carbon dot. Carbon dots are amazing submicron carriers with a particle size of less than 10 nm which is more important for drug targeting. Due to such advantages as optical and biocompatible characteristics, these dots have received abundant requests in a variety of fields, including nanobiotechnology, nanomedicine, and pharmaceutics. Carbon dots, in combination with other materials, therapeutic agents and targeting agents, have been used in therapeutic drug distribution, photoresponsive drug release, in vitro and in vivo imaging, cancer therapy, and advanced drug targeting. In several aspects, it was necessary to modify carbon dots with functional groups for the enhancement of photoluminescence characteristics and drug loading. This review focused on carbon dots synthesis, quantum yield, and their application in photothermal therapy, pH-responsive drug delivery, cancer therapy, and cell imaging with a special look on biocompatibility and biodegradability of carbon dots.