Acid-Controlled Fabrication of Multicolor Carbon Dots with Switchable Organelle-Targeting Capability for Visualizing Organelle Interactions

Synchronous regulation of the photoluminescence and physicochemical characteristics of multicolor carbon dots (CDs) can fully realize their application potential in multicomponent imaging. Herein, by utilizing an acid-regulated synthetic strategy, green-emissive and orange-emissive CDs that target lipid droplets (LDs) and mitochondria (Mito) have been developed for fluorescence visualization of LD–Mito interactions. The finding of different molecular fluorophores reveals that the precursor undergoes different reaction pathways in neutral and acidic conditions, which alters the size of sp2-conjugated domain and surface properties for the successful regulation of photoluminescence properties and organelle-targeting ability. Moreover, the one-step fabrication of these two CDs was also realized by lowering the dosage of acid. Therefore, the multicolor imaging of LDs and Mito has been achieved with one-step staining, disclosing that their interaction frequency decreases during the lipotoxicity process. This work successfully demonstrates the high coupling potential between multicolor CDs and organelle-interaction visualization, which would provide guidance on the correlation between photoluminescence features and other properties of multicolor CDs for extending application space.