Study of calix[4]resorcinarene-dopamine complexation in mixed phospholipid monolayers formed at the air-water interface

We have studied the physical properties of monolayers formed by calix4]resorcinarene and in mixtures with dipalmitoyl phosphatidylcholine (DPPC) in various molar ratios formed at the air-water interface and at presence of dopamine in water subphase by means of measurements of surface pressure and dipole potential. We showed that both calix4]resorcinarene as well as its mixture with DPPC form stable monolayers at the water subphase. The presence of dopamine resulted in an increase of the mean molecular area and in a decrease of the compressibility modulus of the monolayers. For mixed monolayers at higher content of calix4]resorcinarene (> 0.2 molar fraction) a deviation from ideal miscibility took place especially for monolayers in a solid state. This can be connected with formation of aggregates of calix4] resorcinarene. Lowest miscibility and weakest interaction of dopamine with a monolayer was observed for calix4]resorcinarene molar fraction of 0.33 in the monolayer.