The interaction of fluid membranes with a scaffold, which can be a planar
surface or a more complex structure, is intrinsic to a number of systems - from
artificial supported bilayers and vesicles to cellular membranes. In principle,
these interactions can be either discrete and protein mediated, or continuous.
In the latter case, they emerge from ubiquitous intrinsic surface interaction
potentials as well as nature-designed steric contributions of the fluctuating
membrane or from the polymers of the glycocalyx. Despite the fact that these
nonspecific potentials are omnipresent, their description has been a major
challenge from experimental and theoretical points of view. Here we show that a
full understanding of the implications of the continuous interactions can be
achieved only by expanding the standard superposition models commonly used to
treat these types of systems, beyond the usual harmonic level of description.
Supported by this expanded theoretical framework, we present three independent,
yet mutually consistent, experimental approaches to measure the interaction
potential strength and the membrane tension. Upon explicitly taking into
account the nature of shot noise as well as of finite experimental resolution,
excellent agreement with the augmented theory is obtained, which finally
provides a coherent view of the behavior of the membrane in a vicinity of a
scaffold.Comment: 15 pages, 12 figures, accepted by Physical Review
