Binding-Directed Energy Transfer of Conjugated Polymer Materials for Dual-Color Imaging of Cell Membrane

Binding of biomolecules or probes to the plasma membrane is of great importance for investigations of cell morphology and various biological processes. Herein, a water-soluble conjugated polymer is designed as a membrane probe. The probe shows a strong affinity toward lipid membranes owing to the high charge density from abundant imidazolium moieties together with the moderate rigidity and hydrophobicity derived from the conjugated backbone. Upon binding with a membrane, the interchain FRET of the probe was substantially enhanced, which resulted in the emission of both blue and red fluorescence. This is favorable for dual-color imaging. Finally, cellular experiments demonstrate the excellent performance of this macromolecular probe on stable binding with cell membranes without the appearance of cell endocytocysis even after a long retention time.