Principles, mechanisms, and application of carbon quantum dots in sensors: a review

摘要： The Carbon quantum dots (CQDs) as an emerging class of quantum dots (QDs) with advantages such as good photoluminescence (PL) properties, easy synthesis routes, economical synthesis, cheap starting materials, water-solubility, low level of toxicity, chemical stability, and easy functionalization have received great attention during recent years. The CQDs have been used in versatile sensor applications. The CQDs sensors could be ultimately sensitive, and the limit of detection (LOD) for these sensors can reach the nanomolar, picomolar or even femtomolar ranges. The CQDs-based sensors and biosensors work with different mechanisms including fluorescence quenching, static quenching, dynamic quenching, energy transfer, inner filter effect (IFE), photo-induced electron transfer (PET), and fluorescence resonance energy transfer (FRET). The CQDs-based sensors and biosensors have been applied for detection of different species such as metal ions, acids, proteins, biothiols, polypeptides, DNA and miRNA, water pollutants, hematin, drugs, vitamins, and other chemicals. It seems that the CQDs-based sensors and biosensors are promising candidates for high performance and yet accurate sensors in different areas. In this review, the CQDs are introduced, and the synthesis methods and optical properties of the CQDs are discussed. Different types of CQDs-based sensors and biosensors and their working mechanisms are clarified.