Abstract
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.
Highlights
Phospholipid membranes in cellular and biomimetic systems exhibit significant fluctuations [1,2,3,4,5,6], which may be of thermal origin or may arise as a result of active processes in the environment [7,8,9,10]
We develop three approaches to simultaneously determine the membrane tension σ and the strength γ of the membrane-substrate interaction potential
We presented three independent methods to determine the strength of the nonspecific potential and the tension of membranes that weakly adhere in homogeneous potentials
Summary
Phospholipid membranes in cellular and biomimetic systems exhibit significant fluctuations [1,2,3,4,5,6], which may be of thermal origin or may arise as a result of active processes in the environment [7,8,9,10]. Fluctuations play an important role in the regulation of the cell recognition process [6] and regulate the adhesiveness of membranes [11]. In the context of protein-mediated interactions, an important role of the fluctuations is to rescale the binding affinity for the macromolecular complexation [12] and to promote correlations between the binders, both in the plane of the membrane and while binding to surrounding scaffolds [13,14].
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