The current aggregation-induced emission luminogens (AIEgens) sometimes suffer from poor targeting selectivity due to undesirable aggregation in hydrophilic biosystem with “always-on” fluorescence or unspecific aggregation in lipophilic organelle with premature activated fluorescence. Herein, we report an unprecedented “amphiphilic AIEgen” sensor QM-SO3-ER based on the AIE building block of quinoline-malononitrile (QM). The introduced hydrophilic sulfonate group can well control the specific solubility in hydrophilic system with desirable initial “fluorescence-off” state. Moreover, the incorporated p-toluenesulfonamide group plays two roles: enhancing the lipophilic dispersity, and behaving as binding receptor to the ATP-sensitive potassium (KATP) on endoplasmic reticulum (ER) membrane to generate the docking assay confinement effect with targetable AIE signal. The amphiphilic AIEgen has for the first time well settled down the predicament of unexpected “always-on” fluorescence in aqueous system and untargetable aggregation signal in lipophilic organelle before binding to ER, thus successfully overcoming the bottleneck of AIEgen targetability.

High-fidelity monitoring of cell membrane in spatiotemporal dimensions is critically important. However, commercial fluorescence probes are stocked by aggregation-caused quenching (ACQ) effect, while the reported aggregation-induced emission (AIE)-active probes are always limited by the unspecific aggregations in biological environment. Herein, we report the rational molecular design of a state-of-the-art amphiphilic AIE luminogen (AIEgen), Membrane Tracker QMC12, using quinoline-malononitrile (QM) as the core structure to suppress ACQ effect, incorporating the positively charged pyridinium salt group to regulate the dispersity as well as strengthen the binding force to the negative charged cell membrane, and extending the alky chain to improve the anchoring ability to the cell membrane. Such membrane tracker QMC12, which disperses well in both hydrophilic and lipophilic environments, not only achieves minimal background interference and high signal-to-noise (S/N) ratio in "ultra-fast" visualizing of cell membrane, but also endows "wash-free" characteristic, even realizing the spatial view in the three dimensional (3D) multicellular spheroid model and the observation of morphology changes in temporal dimension. Moreover, QMC12 can avoid false staining and signal loss, and unprecedentedly achieve the direct observation of cell membrane's microstructure, which could better understand the 3D model to study the intercellular information exchange in spatiotemporal dimensions.

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