A Diimidazole-Based Amphiphilic Probe for Wash-Free Cell Plasma Membrane Imaging

The cell plasma membrane is involved in diverse cellular processes and functions. The plasma membrane imaging is an effective means of revealing its morphology and dynamics. In this work, we synthesized two amphiphilic fluorophores derived from tetraphenylimidazole (TPI), one of which is a TPI monomer (MTPI) and the other is a TPI dimer (DTPI). As fluorescent molecular rotors, both of them show negligible fluorescence in H₂O but dramatically enhanced enhanced emission in high-viscosity media. Their amphiphilic nature enables stable anchoring within anionic micelles/vesicles, accompanied by intense fluorescence activation. It's worth stressing that DTPI exhibits much more intense emission than MTPI does, whether in high-viscosity methol/glycerol mixtures or in sodium dodecyl sulfate micelles. The cell imaging experiments demonstrated that DTPI can be used as a wash-free probe for plasma membrane visualization.