- We present the construction of microscopic vesicular particles comprising phospholipids and polydiacetylene (PDA), a polymer with unique color and fluorescence properties. We show that the vesicle-embedded PDA domains function as chromatic reporters of membrane events, undergoing dramatic colorimetric and fluorescence transformations induced by interactions with membrane-active species. In particular, the micrometer sizes of the giant vesicles facilitate their utilization for visual inspection of membrane events by conventional microscopy techniques. The morphology, size, and chromatic properties of the vesicular aggregates depend upon the type of phospholipids and the molecular ratio between the phospholipids and diacetylene, indicating that the lipids and polymer form interdependent domains within the vesicles. The giant chromatic aggregates have been employed for detection and microscopic visualization of varied membrane processes, including lipid interactions of lipophilic drugs, binding of antimicrobial peptides, and membrane attachment by virus particles.