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

Abstract

Pure cyclodextrin (CD) is nonemissive in both solution and the solid state. However, herein, three β-CD-based fluorescent bioprobes without the addition of any external fluorophores were realized by the hydrogen-bond selfassembly between diethylenetriamino-bridged β-CD dimers for bioimaging applications. The as-prepared CD derivatives possessed the typical aggregationinduced 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 π-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.

Polypseudorotaxanes Derived from Tetraphenylethylene: Preparation and Tandem-Activated Aggregation-Induced Emission

“…The reversible process of assembly and disassembly through host–guest interactions ,− has emerged as a powerful and flexible strategy to assemble supramolecular structures and attracted interest in optical sensing and imaging, drug and gene delivery, and so on. ,, Cyclodextrins (CDs), a class of cyclic oligosaccharides, are extensively employed as host building blocks owing to their hydrophobic cavities and hydrophilic exteriors, facilitating the formation of inclusion complexes with some hydrophobic guest molecules (for example, adamantine derivatives) in aqueous media . Therefore, the hydrophobic molecules could become more hydrophilic or disperse once the host–guest complexes with CDs in aqueous solutions are formed, which may be used to tune the aggregation and fluorescence of AIE molecules. ,− For example, Tang et al engineered a γ-CD-TPE host–guest inclusion complex, resulting in the disaggregation of TPE and no fluorescence in water . Multiple host–guest inclusion complexes linked by spacers with or without bulky end-caps could form stable polyrotaxanes (PRs) and polypseudorotaxanes (PPRs).…”