AIE-Active and Thermoresponsive Alternating Polyurethanes of Bile Acid and PEG for Cell Imaging AITranslate

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DOI：https://doi.org/10.1021/acsapm.9b00676

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Alternating polyurethanes (PUs) of poly(ethylene glycol) (PEG) and bile acids were synthesized through a single step condensation and then conjugated with a tetraphenylethene (TPE) derivative, a typical aggregation-induced emission (AIE) molecule, as chain ends. These degradable PUs showed thermo-sensitivity in water, and the phase transition temperatures can be adjusted through varying the ratios of hydrophilicity–hydrophobicity and the concentrations of the polymers. In aqueous solutions, these PUs emitted strong fluorescence, which gradually declined in intensity with increasing temperature. In the presence of γ-cyclodextrins, due to host–guest complexation of TPE units with γ-cyclodextrins, fluorescence exhibited a small decrease and then a significant increase upon heating. These PUs exhibited excellent cytocompatibility and were used for A375 cells imaging. Gradual enhancement of the green fluorescence was found mainly in the cytoplasm with increasing temperature assisted by γ-cyclodextrin. These alternating PUs provide a design for photofunctional biomaterials, such as injectable in situ drug carriers. The in vivo biocompatibility will be further evaluated.