Highly responsive fluorescent assemblies allow unique, multiparametric sensing of phospholipid membrane environment.

Despite decades-long extensive research, probes that provide a comprehensive description of the lipid membrane microenvironment are still lacking. We report here a 'smart' pyrene-terpyridine probe for multiparametric sensing of lipid membranes; wherein the complexity of the local microenvironment can be described by distinct features of the probe fluorescence. The self-assembly of the probe molecules in phospholipid bilayers is sensitive to membrane order and phase state. The self-assembled probes show a unique emission, influenced by dye-dye interactions and excited state charge transfer. Moreover, this emission is sensitive to interfacial hydration, with very specific changes in emission wavelengths and fluorescence lifetimes as lipid compositions and properties are varied. In parallel, changes in lipid order along with hydration affect the ground state interactions in dye-aggregates and thus can be measured through ratiometric changes in excitation and emission readouts. In addition, fluorescence anisotropy measurements provide another way to study the nature of dye-aggregates in lipid bilayers. Overall, here we demonstrate how multiple aspects of membrane microenvironment can be sensed through unique fluorescence signatures of this ҆smart҆ probe in lipid membranes, and establish a new paradigm in lipid membrane sensing.