A review on carbon dots as innovative materials for advancing biomedical applications: synthesis, opportunities, and challenges

Carbon dots (CDs) have gained significant attention as innovative materials for advancing biomedical applications due to their diverse physicochemical properties and advantageous attributes. This review article comprehensively summarizes the nanostructures, surface chemistry, optical properties, and synthesis methods of CDs, including electrochemical oxidation, arc discharge, laser ablation, chemical oxidation, ultrasonic treatment, hydrothermal/solvothermal processes, microwave-assisted techniques, pyrolysis, and hybrid synthesis routes. With their low toxicity and good biocompatibility, CDs are highly desirable for biomedical applications. The review highlights recent significant advances in properties such as ultraviolet–visible absorption and band gap, quantum yield, photoluminescence, phosphorescence, photostability, photobleaching, and dispersibility. Furthermore, the article systematically explores the promising applications of CDs in biomedicine, including biosensing, bioimaging, cell labeling and tracking, drug delivery, gene delivery, antibacterial properties, antiviral activities, viral inhibition, and cancer therapy. The comprehensive overview provided in this review article offers insights into the synthesis, properties, and applications of CDs, emphasizing their potential as innovative materials for advancing biomedical research and development.