- We describe applications of a colorimetric assay based on supramolecular assemblies of lipid–polydiacetylene vesicles for analysis and screening of membrane interactions of lipophilic enzymes, peptides, and ions and for study of the effects of lipid composition upon membrane properties. The lipid–polymer aggregates undergo visible and quantifiable blue-to-red transitions following interfacial interactions and perturbation by varied biochemical processes. Specifically, we show that the colorimetric assay can be tuned for selective detection of enzymes reacting with different lipid species. The experiments also demonstrate that the lipid/polymer platform facilitates screening of peptide–membrane interactions in multicomponent mixtures. The colorimetric vesicles can incorporate lipid species from different cellular sources facilitating analysis of the contribution of molecular components to membrane properties and lipid interactions.