7 research outputs found
Axisymmetric Drop Shape Analysis−Constrained Sessile Drop (ADSA-CSD): A Film Balance Technique for High Collapse Pressures
Failure of ergotamine to act as an amplifier of sulfonylurea-stimulated insulin secretion
Phase Transitions in Dipalmitoylphosphatidylcholine Monolayers
A self-assembled
phospholipid monolayer at an air–water
interface is a well-defined model system for studying surface thermodynamics,
membrane biophysics, thin-film materials, and colloidal soft matter.
Here we report a study of two-dimensional phase transitions in the
dipalmitoylphosphatidylcholine (DPPC) monolayer at the air–water
interface using a newly developed methodology called constrained drop
surfactometry (CDS). CDS is superior to the classical Langmuir balance
in its capacity for rigorous temperature control and leak-proof environments,
thus making it an ideal alternative to the Langmuir balance for studying
lipid polymorphism. In addition, we have developed a novel Langmuir–Blodgett
(LB) transfer technique that allows the direct transfer of lipid monolayers
from the droplet surface under well-controlled conditions. This LB
transfer technique permits the direct visualization of phase coexistence
in the DPPC monolayer. With these technological advances, we found
that the two-dimensional phase behavior of the DPPC monolayer is analogous
to the three-dimensional phase transition of a pure substance. This
study has implications in the fundamental understanding of surface
thermodynamics as well as applications such as self-assembled monolayers
and pulmonary surfactant biophysics