Measuring Critical Micelle Concentration as a Function of Cavitand Additives Using Surface Tension and Dye Micellization

摘要

In the presences of additives it has been demonstrated that the critical micelle concentration of amphiphiles can be modified in two ways: through specific interactions with the amphiphile and/or by changing the nature of the solvent. This project focused on the attempt to determine the effects on the critical micelle concentration of hexadecylphospholcholine brought upon by the addition of cavitands (vase-shaped molecular receptors). These effects were measured using various methods for measuring the critical micelle concentration of a surfactant. These methods include: measurements via surface tension using a surface tensiometer, surface tension measurements via the micropipette method, and dye micellization via fluorescent spectrophotometer. Consistent with literature values, the CMC of HePC occurred at 17.8 µM for the Wilhelmy plate method, the capillary height method and the filter paper method. The addition of 50 µM of cavitand caused the CMC to increase to 31.6 µM in the Wilhelmy plate method, the filter paper method and the capillary height method. The CMC of HePC using the dye micellization method occurred around 17.8 µM, however, experiments performed with the addition of cavitands proved to be inconclusive at determining the CMC value. We envision that cavitands may serve as small molecule membrane receptors, our efforts towards studying their effect on critical micelle concentration is a cornerstone of predicting cavitand behavior in more complex lipid bilayer systems, including mammalian cells.