A unique self-assembly-driven probe for sensing a lipid bilayer: ratiometric probing of vesicle to micelle transition.

An amphiphilic pyrene-terpyridine (Pytpy) probe forms novel, fluorescent nanoaggregates in phospholipid membranes. This unique membrane-driven self-assembly of Pytpy shows large Stokes shifts and long-lived fluorescent states and efficiently reports on vesicle-micelle transition through ratiometric changes. Strikingly, Pytpy can even distinguish between bilayer-like domains and more-dynamic micelle-like 'rim' phases that co-exist in mixed assemblies (bicelles).