Effect of stigmasterol-based mesogen and phytosphingosine on the Langmuir monolayer of DPPC

Abstract

We have studied the effect of a novel stigmasterol-based mesogen (4-mercaptoalkyl benzoate of stigmasterol or 4MBS) and phytosphingosine (PHS molecules) on the Langmuir monolayer of 1, 2 dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) using the surface manometry technique. The mixed monolayers of 4MBS/DPPC and PHS/DPPC in different compositions are investigated using surface manometry. The surface pressure–area per molecule isotherms were analysed to determine the mechanical and thermodynamical aspects like phase transitions and stability of the mixed Langmuir monolayer. The Brewster angle microscope (BAM) was used for visualising the monolayer morphology. Our studies show that PHS and 4MBS molecules stabilise the liquid expanded (LE)–liquid condensed (LC) phase coexistence region of the DPPC monolayer.