Synergy of CO2-Response and Aggregation Induced Emission in A Block Copolymer: A Facile Way to "See" Cancer Cells.

Carbon dioxide (CO2), an important gas molecule metabolite produced by the tricarboxylic acid cycle, is a direct signal for identifying cancers in cells and tissues. Herein, design and synthesis of a novel "breathable" block polymer supramolecular assemblies probe consisting of hydrophilic block, amidine-containing CO2-responsive block, and aggregation-induced emission (AIE) luminescence block to detect CO2 metabolized by cancer cells is reported. The triblock copolymer poly-(4-undecoxy tetraphenyl ethylene methacrylate)-b-poly-((N-amidino)-(2, 3- dihydro- 1H-1, 4- methyl-1, 2, 3- triazole)-(ethenylbenzene))-b-poly(ethylene oxide) (PTPE-b-PAD-b-PEO) was successfully synthesized and characterized. This triblock copolymer could be self-assembled into "breathable" aqueous solution vesicles. In the presence of CO2, the amidine-containing CO2-responsive block (PAD block) of the vesicle "inhales" an amount of CO2 and this causes the volume of the vesicle to expand. The expansion of the vesicle induces the aggregation of the AIE luminescence block (PTPE block), which resulted in the fluorescence intensity enhancement. The supramolecular vesicles "exhale" the CO2, and the volume and AIE phenomenon of the vesicles decreases when N2 is passed into the solution. Based on this reversible change of fluorescence intensity, HeLa cervical cancer cells, CNE1 nasopharynx cancer cells, 5-8F nasopharynx cancer cells, 16HBE human bronchial epithelial cells and GES-1 human gastric mucosa epithelial cells have all been successfully detected and identified.