Equilibrium behavior in phospholipid monolayers: morphology, branching curvature, and stripe width.

Phospholipid monolayers are a valuable model system to investigate the two-dimensional physics of soft thin film systems. The availability of enantiomers of Dipalmitoylphosphatidylcholine (DPPC) in purified form allows us to investigate the chiral nature of model lipid monolayers through fluorescence microscopy and traditional Langmuir thermodynamic techniques. These phospholipid monolayers are the primary lipid component of lung surfactant -necessary for proper respiration. We focus on mixtures of DPPC with cholesterol, hexadecanol (HD), and palmitic acid (PA), which have been previously studied and shown to form equilibrium morphologies over experimental time scales REF: Valtierrez et al., Sci. Adv. v:8:14, 2022. In this poster, we will assess the use of complementary image processing and analysis routines to measure the curvature of morphologies within these monolayers. The introduction of cholesterol within the monolayers stabilizes domain branches which curl and elongated over time. Previously it was shown that domain morphologies evolve to stripes of equilibrium widths. We are currently investigating the distributions of curvatures within the monolayer morphologies and their use as a signature of equilibrium behavior.