Red Carbon Dots as Theranostic Nanoplatforms for Cancer: Synthesis, Functionalization, Imaging, and Therapeutic Applications
TL;DR
Red carbon dots are an intriguing and promising family of carbon nanomaterials in precision oncology, and researchers will need to understand these structure–property–function relationships in-depth to facilitate the design of safer, reproducible, and clinically applicable theranostic systems.
Abstract
The tunable optical features, high photostability, and water-dispersibility, along with the rich surface functional groups, of red carbon dots have made them promising theranostic nanoplatforms for cancer diagnosis and therapy. The red and NIR emissive carbon dots have great potential in biomedical applications, as they have several advantages over conventional blue and green emissive carbon dots, such as reduced tissue autofluorescence, enhanced in vivo imaging contrast, deeper tissue penetration, and reduced tissue photodamage. They are excellent candidates for fluorescence imaging, image-guided therapy, and light-responsive cancer therapy. In this review, recent progress in red carbon dots as nano-platforms with multifunctionality for cancer theranostics, focusing on their synthesis, functionalization, imaging performance, and therapeutic applications, is summarized. The major synthetic strategies such as hydrothermal, solvothermal, microwave-assisted, and precursor-engineered approaches are discussed with respect to their impact on particle size, surface chemistry, quantum yield, red-shifted emission, and their photothermal and/or photodynamic efficacy. Significant emphasis is on surface functionalization strategies to enhance the properties of colloidal stability, biocompatibility, tumor targeting, cellular uptake, loading, and stimuli-responsive release. The review also emphasizes the potential applications of red carbon dots in cancer imaging, targeted drug delivery, photodynamic therapy (PDT), photothermal therapy (PTT), chemodynamic therapy (CDT), sonodynamic therapy (SDT), and synergistic cancer therapy. Although significant advances have been made, there are several challenges to address, such as the definition of emission mechanisms, batch-to-batch variability, lack of long-term biosafety data, and difficulties in clinical translation and evaluation of pharmacokinetics. In summary, red carbon dots are an intriguing and promising family of carbon nanomaterials in precision oncology. They will need to understand these structure–property–function relationships in-depth to facilitate the design of safer, reproducible, and clinically applicable theranostic systems.