Fluorescent carbon quantum dots: Synthesis methods, functionalization and biomedical applications

Carbon Quantum Dots (CQDs), a type of carbon material having size less than 10 nm and strong fluorescence is creating a new paradigm in the field of bioimaging and other biomedical applications. Owing to simple and low cost of synthesis, tunable and precise optical properties, high photostability and ease of surface functionalization with biological entities there is a huge potential in the field of CQDs based cell imaging applications. A thorough knowledge and understanding of synthesis methods and optical properties are crucial in translation of CQDs based bioimaging research from research lab to commercial purposes for societal benefit. Different methods of synthesis like electrochemical, laser ablation, microwave radiation, and hydrothermal and optical properties like photoluminescent (PL) property, quantum confinement effect, doping influence on optical properties of CQDs are covered in this review. Surface functionalization agents employed for different bio applications have been reviewed along with the current challenges. The applications of CQDs in bioimaging, biosensing and drug delivery along with the existing challenges and future prospects are discussed.