Unorthodox β-Cyclodextrin-Based AIE-Active Probes for Living Cell Imaging in the Absence of Fluorophore Units and Related Mechanism Exploration

Pure cyclodextrin (CD) is nonemissive in both solution and the solid state. However, herein, three beta-CD-based fluorescent bioprobes without the addition of any external fluorophores were realized by the hydrogen-bond self-assembly between diethylenetriamino-bridged beta-CD dimers for bioimaging applications. The as-prepared CD derivatives possessed the typical aggregation-induced emission property based on the abundant intermolecular hydrogen bonding between the amide proton and hydroxyl proton in aggregation states, and their strong fluorescences were observed even with the naked eye under UV light. The samples show excellent biocompatibility and low biotoxicity because the pi-aromatic building blocks such as benzene were sidestepped. However, they showed noncytotoxicity in living cells and could be utilized for targeted HeLa intracellular imaging, indicating their potential applications as sensor and imaging agents in cytology and diagnostics. This work is meaningful for both the design and development of novel nontoxic and cost-effective fluorescent bioprobes.