Normalizing polydiacetylene colorimetric assays of vesicle binding across lipid systems.

Mixed polydiacetylene (PDA) lipid vesicles mimic cell membranes and exhibit a colorimetric response induced by mechanical stress, which can be used to determine the affinity of proteins or molecules for lipid membranes. Due to a simple spectroscopic readout, PDA assays are amenable to high-throughput screens; however, these assays exhibit batch-to-batch variability. Sensitivity of the assay is also influenced by physicochemical properties associated with different lipids. Here, a method of normalizing PDA assays to reduce variability and enable direct comparison across lipid systems is described.