Organization and Structural Properties of Langmuir Films Composed of Conjugated Polydiacetylene and Phospholipids

Abstract

Molecular assemblies containing phospholipids and conjugated polydiacetylene lipids exhibit unique biochromatic properties and have attracted increasing interest in recent years as potential bio-and chemosensors. We present a detailed study of the properties of mixed films formed at the air-water interface, which consist of phospholipid molecules and diacetylene lipids. The organization of the films has been characterized by surface pressure-area isotherms. Application of atomic force microscopy, polarized optical microscopy, and UV-vis spectroscopy provides further insight into the structures and interactions of the film components. The data indicate that the two constituents in the film are miscible at low surface pressure, while segregation of phospholipid and polymer domains occurs at higher surface pressures. The distribution and interactions between the diacetylene and phospholipid domains additionally depends on the molar fraction of phospholipid in the film. Characterization of the structural properties of the polydiacetylene domains in the films points to a formation of organized trilayer and multilayer phases at high surface pressures and high diacetylene concentrations.

Temperature dependence of the organization and molecular interactions within phospholipid/diacetylene Langmuir films

“…1). In particular, the surface pressure-area isotherms of TRCDA are strongly affected by the propensity of the single-alkyl-chain diacetylene molecules to organize in multilayer films [19,20]. At low surface pressures and low temperatures (5 • C), only a condensed phase with a limiting area of 26 Å 2 molecule −1 was observed, which collapsed around 13 mN m −1 .…”

“…Mixed films of DMPC and TRCDA have been previously investigated using varied spectroscopic, microscopic, and surfaceanalysis techniques [19,20]. Here we compare the thermodynamic properties of mixed DMPC/TRCDA films in different compositions and at three temperatures.…”

Glass-supported lipid/polydiacetylene films for colour sensing of membrane-active compounds

“…As depicted in Fig. 1, the lipids and PDA molecules form distinct domains within the film rather than dispersed homogeneously (Gaboriaud et al, 2001;Volinsky et al, 2002). The AFM image and height profile in Fig.…”

Colorimetric Polymer Films for Predicting Lipid Interactions and Percutaneous Adsorption of Pharmaceutical Formulations

“…All diacetylene/DMPC films were prepared at 20°C in a computerized Langmuir trough manufactured by NIMA (model Nima 312D (7×50 cm 2 ), Nima Technology Ltd, Coventry, U.K.) (19,20). The surface pressure was monitored using a 1-cm-wide filter paper as a Wilhelmy plate.…”