Morphology-Dependent Cell Imaging by Using a Self-Assembled Diacetylene Peptide Amphiphile

Herein, a novel cationic peptide gemini amphiphile containing diacetylene motifs (DA(2)P) is presented, which self-assembles into novel tadpole-and bola-shaped nanostructures at low concentrations and nanofibers at higher concentrations. Interestingly, the DA(2)P assemblies can be polymerized into a fluorescent red phase but only during incubation with HeLa cells, most likely owing to the reorganization of the diacetylene chains of DA(2)P upon interaction with the cell membrane. The red-fluorescent polymerized DA(2)P assemblies can serve as a novel cell imaging probe. However, only vesicles, tadpole- and bola-shaped DA(2)P assemblies can be translocated into HeLa cells, whereas the nanofiber-like DA(2)P assemblies are trapped by the cell membranes and do not enter the cells. Hence, morphology-dependent cell imaging is observed.