Probing Cell Membrane\nTension Using DNA Framework-Encoded\nVibration-Induced Emission Molecular Assemblies

Mechanosensitive fluorescent probes are valuable tools\nfor detecting\nchanges in cellular mechanics and viscosity. While numerous mechanosensitive\nprobes have been developed, the construction of molecular assemblies\nfor probing cellular mechanics remains largely unexplored, possibly\ndue to the challenges of designing assemblies with synergistic and\nintegrated functionalities. Here, we report the design and synthesis\nof mechanosensitive molecular assemblies by integrating DNA frameworks\nwith vibration-induced emission (VIE) probes to enable live-cell membrane\ntension imaging. The molecular assemblies consist of a rigid tetrahedral\nDNA framework anchored with prescribed numbers of VIE probes. We find\nthat VIE probes on the DNA framework retain their ratiometric fluorescence\nresponse characteristics in aqueous systems and on lipidic model membranes.\nImportantly, VIE assemblies exhibit distinct cell membrane targeting\nbehaviors depending on the number of contact points between the molecular\nassemblies and the cell membrane. Especially, trivalent molecular\nassemblies can inhibit the internalization of the probes by the cells,\na property absent in free VIE and mono/divalent molecular assemblies,\nthereby achieving targeted and prolonged retention on the cell membrane.\nUsing the trivalent molecular assemblies, we successfully achieve\nratiometric fluorescence imaging of cell membrane tension using confocal\nlaser scanning microscopy, revealing the potential of such multifunctional\nmechanical-sensitive probes for live-cell applications.