Curvature is a fundamental lipid
membrane property that influences
many membrane-mediated biological processes and dynamic soft materials.
One of the key parameters that determines the energetics of curvature
change is the membrane bending rigidity. Understanding the intrinsic
effect of pressure on membrane bending is critical to understanding
the adaptation and structural behavior of biomembranes in deep-sea
organisms as well as soft material processing. However, it has not
previously been possible to measure the influence of high hydrostatic
pressure on membrane bending energetics, and this bottleneck has primarily
been due to a lack of technology platforms for performing such measurements.
We have developed a new high-pressure microscopy cell which, combined
with vesicle fluctuation analysis, has allowed us to make the first
measurements of membrane bending rigidity as a function of pressure.
Our results show a significant increase in bending rigidity at pressures
up to 40 MPa. Above 40 MPa, the membrane mechanics become more complex.
Corresponding small and wide-angle X-ray diffraction shows an increase
in density and thickness of the bilayer with increasing pressure which
correlates with the micromechanical measurements. These results are
consistent with recent theoretical predictions of the bending rigidity
as a function of hydrocarbon chain density. This technology has the
potential to transform our quantitative understanding of the role
of pressure in soft material processing, the structural behavior of
biomembranes, and the adaptation mechanisms employed by deep-sea organisms
