Single, dual and multi-emission carbon dots based optosensing for food safety

Background: In recent years, carbon dots (CDs) have been increasingly studied owing to their excellent physical and optical properties. Conventional fluorescent sensing detection based on CDs usually relies on the intensity changes of a single fluorescent emission centre, which are often susceptible to interference due to changes in the concentration of sensor, uneven distribution, or the changes in instrument efficiency. Compared with a single fluorescent emission centre, dual-, triple-, and multi-fluorescent emission centres can overcome these obstacles and improve the robustness and accuracy of sensing by simultaneously exploiting multi-dimensional signal outputs. Scope and approach: This study focuses on the single-, dual-and multi-fluorescent emission centres of fabricated CDs and their emerging application in food safety detection. Furthermore, the multi-luminescence properties and photoluminescence mechanism will be discussed in depth. Particularly the applications of these materials are elaborated in regard to food quality and safety detection, including the detection of hazards due to food processing, pesticides, veterinary drug residues, toxins and metal ion. Finally, the current challenges and future perspectives will be presented in terms of fabricating CDs that enhance multi-dimensional optical properties for use in emerging biosensor applications. Key findings and conclusions: The dual-, and multi-fluorescent-emission centres of CDs coupled with ratiometric fluorescence, and multi-dimensional analysis, can effectively improve the sensitivity and accuracy of detection methods. Compared with the method of functionalizing the surface of CDs, and then connecting them with a corresponding fluorescent emitting material, the direct use of dual-and multi-fluorescent-emission CDs as the fluorescent material combined with chemometric analyses is a better choice for detecting substances in food matrices.