Multifunctional Metallo-Organic Vesicles Displaying Aggregation-Induced Emission: Two-Photon Cell-Imaging, Drug Delivery, and Specific Detection of Zinc Ion

Molecules displaying aggregation-induced emission (AIE) property can hardly self-assemble into vesicles desired in design of theranostics. We report the formation of metallo-organic AIE vesicles with triarylamine carboxylate (TPA-1) and Zn2+ ions. TPA-1 shows a great binding affinity to Zn2+ as a fluorescence turn-on sensor. The vesicles exhibited high fluorescence-emission property under two-photon mode which endows them very good cell imaging ability. Drug-loading experiments suggest a loading capacity for the model anticancer drug 5-fluorouracil (5-Fu) can reach up to 53.4%, and sustained release of the drug is possible in biological environment. This is the first report of supramolecular coordination fluorescent vesicles based on AIE molecule. Further study reveals the fluorescence enhancement of TPA-1 can only be triggered by Zn2+, suggesting the ability of specific detection of Zn2+. This study indicates that the formation of metallo-organic vesicles can be a multiplatform for cell-imaging, drug carrier, and metal ions detection.