Engineering solvent-controlled multi-color emission carbon dots in single carbon source and their application in multi-channel Ag+ detection

Multi-color carbon dots (CDs), as advanced carbon nanomaterials with exceptional features, have gained significant attention, yet the facile and rapid synthesis of CDs with tunable multi-color emission from a single carbon source remains a challenge. By simply varying the solvent (water, EtOH, or DMF), blue-, green-, and yellow-emitting CDs are obtained, with corresponding tunable emission peaks of 469, 485, and 528 nm and quantum yields of 31.2 %, 34.1 % and 35.0 %. This emission tunability attributed to variations in their carbon core and surface states. Furthermore, multi-color CDs are employed as fluorescent probes to assess their detection capabilities. The multi-color CDs enabled highly sensitive Ag + detection, achieving detection limits of 4 pM, 34 pM, and 42 pM, respectively. This strategy enabled a multichannel smartphone platform for on-site analysis, with the CDs also proving effective for bioimaging in HeLa cells and zebrafish, collectively establishing their dual potential for environmental and biomedical applications.