Publications (en anglais)
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Articles scientifiques
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Mémoires
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1. Articles scientifiques
 | Conformational Space of the Translocation Domain of Botulinum Toxin: Atomistic Modeling and Mesoscopic
Description of the Coiled-Coil Helix Bundle
Alexandre Delort, Grazia Cottone, Thérèse E. Malliavin, Martin Michael Müller |
Résumé
Int. J. Mol. Sci., 25: 2481, 2024.
 | Flexoelectric fluid membrane vesicles in spherical confinement
Niloufar Abtahi, Lila Bouzar, Nadia Saidi-Amroun, Martin Michael Müller |
Résumé
Plus d'infos
EPL, 131(1): 18001, 2020. Cf. aussi arXiv:2006.04475.
 | Isometric bending requires local constraints on free edges
Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo |
While the shape equations describing the equilibrium of an unstretchable thin sheet that is free
to bend are known, the boundary conditions that supplement these equations on free edges have remained elusive.
Intuitively, unstretchability is captured by a constraint on the metric within the bulk. Naïvely one would then
guess that this constraint is enough to ensure that the deformations determining the boundary conditions on these
edges respect the isometry constraint. If matters were this simple, unfortunately, it would imply unbalanced torques
(as well as forces) along the edge unless manifestly unphysical constraints are met by the boundary geometry. In this
article, we identify the source of the problem: not only the local arc-length but also the geodesic curvature need to
be constrained explicitly on all free edges. We derive the boundary conditions which follow. In contrast to conventional
wisdom, there is no need to introduce boundary layers. This framework is applied to isolated conical defects, both
with deficit as well, but more briefly, as surplus angles. Using these boundary conditions, we show that the lateral
tension within a circular cone of fixed radius is equal but opposite to the radial compression, and independent of
the deficit angle itself. We proceed to examine the effect of an oblique outer edge on this cone perturbatively
demonstrating that both the correction to the geometry as well as the stress distribution in the cone kicks in at
second order in the eccentricity of the edge.
 Fermer
Plus d'infos
Math. Mech. Solids, 24: 4051, 2019. Cf. aussi arXiv:1904.05855.
 | Helical Superstructure of Intermediate Filaments
Lila Bouzar, Martin Michael Müller, René Messina, Bernd Nöding, Sarah Köster, Hervé Mohrbach, Igor M. Kulić |
Résumé
Plus d'infos
Phys. Rev. Lett., 122: 098101, 2019. Cf. aussi arXiv:1803.04691.
 | Vesicle dynamics in confined steady and harmonically modulated Poiseuille flows
Zakaria Boujja, Chaouqi Misbah, Hamid Ez-Zahraouy, Abdelilah Benyoussef, Thomas John, Christian Wagner, Martin Michael Müller |
We present a numerical study of the time-dependent motion of a membrane vesicle in a
channel under an imposed flow. In a Poiseuille flow the shape of the vesicle depends on the flow strength,
the mechanical properties of the membrane, and the width of the channel. In a wide parameter region, the
emerging snaking shape shows an oscillatory motion like a swimmer flagella even though the flow is
stationary. We quantify this behavior by the amplitude and frequency of the oscillations of the vesicle's
center of mass. The influence of an amplitude modulation of the imposed flow on the dynamics and shape of
the snaking vesicle is also investigated. We find that this modulation---when sufficiently small---induces
a modulation in amplitude and frequency of the center of mass of the snaking vesicle. For large
modulation amplitudes transitions to static shapes are observed.
Fermer
Phys. Rev. E, 98: 043111, 2018. Cf. aussi arXiv:1810.04500.
 | Confining a fluid membrane vesicle of toroidal topology in an adhesive hard sphere
Lila Bouzar, Ferhat Menas, Martin Michael Müller |
Résumé
Plus d'infos
IOP Conf. Series: MSE, 186: 012021, 2017.
 | Squeezed helical elastica
Lila Bouzar, Martin Michael Müller, Pierre Gosselin, Igor M. Kulić, Hervé Mohrbach |
We theoretically study the conformations of a helical semi-flexible filament
confined to a two-dimensional surface. This squeezed helix exhibits a variety of unexpected shapes
resembling circles, waves or spirals depending on the material parameters. We explore the conformation
space in detail and show that the shapes can be understood as the mutual elastic interaction of
conformational quasi-particles. Our theoretical results are potentially useful to
determine the material parameters of such helical filaments in an experimental setting.
Fermer
Plus d'infos
Eur. Phys. J. E, 39: 114, 2016. Cf. aussi arXiv:1606.03611.
 | How bio-filaments twist membranes
Julien Fierling, Albert Johner, Igor M. Kulić, Hervé Mohrbach, Martin Michael Müller |
Résumé
Soft Matter, 12: 5747, 2016.
 | Toroidal membrane vesicles in spherical confinement
Lila Bouzar, Ferhat Menas, Martin Michael Müller |
We investigate the morphology of a toroidal fluid membrane vesicle confined inside a spherical container.
The equilibrium shapes are assembled in a geometrical phase diagram as a function of scaled area and
reduced volume of the membrane. For small area the vesicle can adopt its free form. When increasing
the area, the membrane cannot avoid contact and touches the confining sphere along a circular contact line,
which extends to a zone of contact for higher area. The elastic energies of the equilibrium shapes are
compared to those of their confined counterparts of spherical topology to predict under which conditions a
topology change is favored energetically.
Fermer
Plus d'infos
Phys. Rev. E, 92: 032721, 2015. Cf. aussi arXiv:1509.00765.
 | Non-linear buckling and symmetry breaking of a soft elastic sheet sliding on a cylindrical substrate
Norbert Stoop, Martin Michael Müller |
Résumé
Plus d'infos
Int. J. Non-Linear Mech., 75: 115, 2015. Cf. aussi arXiv:1503.05030.
 | Crunching Biofilament Rings
Julien Fierling, Martin Michael Müller, Hervé Mohrbach, Albert Johner, Igor M. Kulić |
We discuss a curious example for the collective mechanical behavior of coupled non-linear monomer units entrapped in a circular filament. Within a simple model we elucidate how multistability of monomer units and exponentially large degeneracy of the filament's ground state emerge as a collective feature of the closed filament. Surprisingly, increasing the monomer frustration, i.e., the bending prestrain within the circular filament, leads to a conformational softening of the system. The phenomenon, that we term polymorphic crunching, is discussed and applied to a possible scenario for membrane tube deformation by switchable dynamin or FtsZ filaments. We find an important role of cooperative inter-unit interaction for efficient ring induced membrane fission.
Fermer
Plus d'infos
Europhys. Lett., 107(6): 68002, 2014. Cf. aussi arXiv:1408.6787.
 | Confotronic dynamics of tubular filaments
Osman Kahraman, Hervé Mohrbach, Martin Michael Müller, Igor M. Kulić |
Tubular lattices are ubiquitous in nature and technology. Microtubules and nanotubes of all
kinds act as important pillars of biological cells and the man-made nano-world. We show that
when prestress is introduced in such structures, localized conformational quasiparticles emerge and
govern the collective shape dynamics of the lattice. When coupled via cooperative interactions these
quasiparticles form larger-scale quasipolymer superstructures exhibiting collective dynamic modes
and giving rise to a hallmark behavior radically different from semiflexible beams.
Fermer
Plus d'infos
Soft Matter, 10(16): pp. 2836-2847, 2014. Cf. aussi arXiv:1312.3106.
 | Whirling skirts and rotating cones
Jemal Guven, J. A. Hanna, Martin Michael Müller |
Résumé
New J. Phys., 15: 113055, 2013. Cf. aussi arXiv:1306.2619.
 | Myotubularin and PtdIns3P remodel the sarcoplasmic reticulum in muscle in vivo
Leonela Amoasii, Karim Hnia, Gaëtan Chicanne, Andreas Brech, Belinda Simone Cowling, Martin Michael Müller, Yannick Schwab, Pascale Koebel, Arnaud Ferry, Bernard Payrastre, Jocelyn Laporte |
Résumé
J. Cell Sci., 126(8): 1806, 2013.
 | Dipoles in thin sheets
Jemal Guven, J. A. Hanna, Osman Kahraman, Martin Michael Müller |
Résumé
Plus d'infos
Eur. Phys. J. E, 36: 106, 2013. Cf. aussi arXiv:1212.3262.
 | Fluid membrane vesicles in confinement
Osman Kahraman, Norbert Stoop, Martin Michael Müller |
We numerically study the morphology of fluid membrane vesicles with prescribed volume and surface area in confinement.
For spherical confinement we observe axisymmetric invaginations that transform into ellipsoidal invaginations a the area of the
vesicle is increased, followed by a transition into stomatocyte-like shapes.
We provide a detailed analysis of the axisymmetric shapes and investigate the effect of the spontaneous curvature of the membrane
as a possible mechanism for shape regulation. We show that the observed morphologies are stable under small geometric deformations
of the confinement. The results could help to understand the role of mechanics in the complex folding patterns of biological membranes.
Fermer
Plus d'infos
New J. Phys., 14: 095021, 2012.
 | Petal shapes of sympetaleous flowers: the interplay between growth, geometry and elasticity
Martine Ben Amar, Martin Michael Müller, Miguel Trejo |
Résumé
Plus d'infos
New J. Phys., 14: 085014, 2012. Choisi pour les Highlights of 2012.
 | Morphogenesis of membrane invaginations in spherical confinement
Osman Kahraman, Norbert Stoop, Martin Michael Müller |
Résumé
Plus d'infos
Europhys. Lett., 97(6): 68008, 2012. Cf. aussi arXiv:1201.2518.
 | Conical instabilities on paper
Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo |
Résumé
Plus d'infos
J. Phys. A: Math. Theor., 45(1): 015203, 2012. Cf. aussi arXiv:1107.5008.
 | Interface-mediated interactions: Entropic forces of curved membranes
Pierre Gosselin, Hervé Mohrbach, Martin Michael Müller |
Particles embedded in a fluctuating interface experience forces and torques
mediated by the deformations and by the thermal fluctuations of the medium.
Considering a system of two cylinders bound to a fluid membrane we show that
the entropic contribution enhances the curvature-mediated repulsion between
the two cylinders. This is contrary to the usual attractive Casimir force in
the absence of curvature-mediated interactions. For a large distance between
the cylinders, we retrieve the renormalization of the surface tension of a
flat membrane due to thermal fluctuations.
Fermer
Plus d'infos
Phys. Rev. E, 83(5): 051921, 2011. Cf. aussi arXiv:1011.1221.
 | Self-Contact and Instabilities in the Anisotropic Growth of Elastic Membranes
Norbert Stoop, Falk K. Wittel, Martine Ben Amar, Martin Michael Müller, Hans J. Herrmann |
We investigate the morphology of thin discs and rings growing in circumferential direction. Recent analytical results suggest that this growth produces symmetric excess cones (e-cones). We study the stability of such solutions considering self-contact and bending stress. We show that, contrary to what was assumed in previous analytical solutions, beyond a critical growth factor, no symmetric e-cone solution is energetically minimal any more. Instead, we obtain skewed e-cone solutions having lower energy, characterized by a skewness angle and repetitive spiral winding with increasing growth. These results are generalized to discs with varying thickness and rings with holes of different radii.
Fermer
Plus d'infos
Phys. Rev. Lett., 105(6): 068101, 2010. Cf. aussi arXiv:1007.1871.
 | Cell Model Approach to Membrane Mediated Protein Interactions
Martin Michael Müller, Markus Deserno |
Membrane-deforming proteins can interact through the curvature
fields they create. In the case of many such proteins a cell model
approach can be used to calculate the energy per protein and
predict, whether it would lead to phase segregation or
bud-formation. Using covariant differential geometry exact results
are derived for the lateral pressure in terms of geometric
properties at the cell boundary. Numerical solutions of the exact
shape equations in the highly nonlinear regime are found and it is
seen that both phase segregation and bud formation can occur.
Fermer
Plus d'infos
Prog. Theor. Phys. Suppl., 184: pp. 351-363, 2010.
 | Hamiltonian formulation of surfaces with constant Gaussian curvature
Miguel Trejo, Martine Ben Amar, Martin Michael Müller |
Résumé
Plus d'infos
J. Phys. A: Math. Theor., 42(42): 425204, 2009.
 | Local Membrane Mechanics of Pore-Spanning Bilayers
Ingo Mey, Milena Stephan, Eva K. Schmitt, Martin Michael Müller, Martine Ben Amar, Claudia Steinem, Andreas Janshoff |
Résumé
Plus d'infos
J. Am. Chem. Soc., 131(20): pp. 7031-7039, 2009.
 | Elasticity Mapping of Pore-Suspending Native Cell Membranes
Bärbel Lorenz, Ingo Mey, Siegfried Steltenkamp, Tamir Fine, Christina Rommel, Martin Michael Müller, Alexander Maiwald, Joachim Wegener, Claudia Steinem, Andreas Janshoff |
Résumé
Plus d'infos
Small, 5(7): pp. 832-838, 2009.
 | Conical Defects in Growing Sheets
Martin Michael Müller, Martine Ben Amar, Jemal Guven |
Résumé
Plus d'infos
Phys. Rev. Lett., 101(15): 156104, 2008. Cf. aussi arXiv:0807.1814.
 | How paper folds: bending with local constraints
Jemal Guven, Martin Michael Müller |
Résumé
Plus d'infos
J. Phys. A: Math. Theor., 41(5): 055203, 2008. Cf. aussi arXiv:0712.0978.
 | Contact lines for fluid surface adhesion
Markus Deserno, Martin Michael Müller, Jemal Guven |
When a fluid surface adheres to a substrate, the location of the
contact line adjusts in order to minimize the overall energy. This
adhesion balance implies boundary conditions which depend on the
characteristic surface deformation energies. We develop a general
geometrical framework within which these conditions can be
systematically derived.
We treat both adhesion to a rigid substrate as well as adhesion
between two fluid surfaces, and illustrate our general results for
several important Hamiltonians involving both curvature and
curvature gradients. Some of these have previously been studied
using very different techniques, others are to our knowledge new.
What becomes clear in our approach is that, except for capillary
phenomena, these boundary conditions are not the manifestation
of a local force balance, even if the concept of surface stress is
properly generalized. Hamiltonians containing higher order surface
derivatives are not just sensitive to boundary translations but also
notice changes in slope or even curvature.
Both the necessity and the functional form of the corresponding
additional contributions follow readily from our treatment.
Fermer
Plus d'infos
Phys. Rev. E, 76(1): 011605, 2007. Cf. aussi cond-mat/0703019.
Choisi pour le Virtual Journal of Biological Physics Research.
 | Balancing torques in membrane-mediated interactions: Exact results and
numerical illustrations
Martin Michael Müller, Markus Deserno, Jemal Guven |
Résumé
Plus d'infos
Phys. Rev. E, 76(1): 011921, 2007. Cf. aussi cond-mat/0702340.
Choisi pour le Virtual Journal of Biological Physics Research.
 | Aggregation and vesiculation of membrane proteins by curvature-mediated
interactions
Benedict J. Reynwar, Gregoria Illya, Vagelis A. Harmandaris, Martin Michael Müller, Kurt Kremer, Markus Deserno |
Résumé
Plus d'infos
Nature 447(7143): pp. 461-464, 2007.
 | How to determine local elastic properties of lipid bilayer membranes
from atomic-force-microscope measurements: A theoretical analysis
Davood Norouzi, Martin Michael Müller, Markus Deserno |
Résumé
Plus d'infos
Phys. Rev. E, 74(6): 061914, 2006. Cf. aussi cond-mat/0602662.
Choisi pour le Virtual Journal of Biological Physics Research.
 | Mechanical Properties of Pore-Spanning Lipid Bilayers Probed by Atomic Force Microscopy
Siegfried Steltenkamp, Martin Michael Müller, Markus Deserno, Christian Hennesthal, Claudia Steinem, Andreas Janshoff |
We measure the elastic response of a free-standing lipid membrane to a local indentation by using an atomic force microscope. Starting point is a planar
gold-coated alumina substrate with a chemisorbed 3-mercaptopropionic acid
monolayer displaying circular pores of very well defined and tunable size, over
which bilayers composed of N,N,- dimethyl- N,N,- dioctadecylammonium bromide or
1,2 - dioleoyl - 3 - trimethylammonium - propane chloride were spread.
Centrally indenting these 'nanodrums' with an atomic force microscope tip yields
force-indentation curves, which we quantitatively analyze by solving the
corresponding shape equations of continuum curvature elasticity. Since the
measured response depends in a known way on the system geometry (pore size, tip
radius) and on material parameters (bending modulus, lateral tension), this opens
the possibility to monitor local elastic properties of lipid membranes in a
well-controlled setting.
Fermer
Plus d'infos
Biophys. J., 91(1): pp. 217-226, 2006.
 | Interface mediated interactions between particles -- a geometrical approach
Martin Michael Müller, Markus Deserno, Jemal Guven |
Particles bound to an interface interact because they deform its shape.
The stresses that result are fully encoded in the geometry and described
by a divergence-free surface stress tensor. This stress tensor can be
used to express the force on a particle as a line integral along any
conveniently chosen closed contour that surrounds the particle. The
resulting expression is exact (i.e., free of any 'smallness' assumptions)
and independent of the chosen surface parametrization. Additional surface
degrees of freedom, such as vector fields describing lipid tilt, are readily
included in this formalism. As an illustration, we derive the exact force
for several important surface Hamiltonians in various symmetric two-particle
configurations in terms of the midplane geometry; its sign is evident in
certain interesting limits. Specializing to the linear regime, where the
shape can be analytically determined, these general expressions yield
force-distance relations, several of which have originally been derived
by using an energy based approach.
Fermer
Plus d'infos
Phys. Rev. E, 72(6): 061407, 2005. Cf. aussi cond-mat/0506019.
Choisi pour le Virtual Journal of Biological Physics Research.
 | Geometry of surface-mediated interactions
Martin Michael Müller, Markus Deserno, Jemal Guven |
Résumé
Plus d'infos
Europhys. Lett., 69(3): pp. 482-488, 2005. Cf. aussi cond-mat/0409043.
2. Livres
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New Trends in the Physics and Mechanics of Biological Systems
Lecture Notes of the Les Houches Summer School, vol. 92 (Oxford University Press, 2011),
éd. par Martine Ben Amar, Alain Goriely, Martin Michael Müller et Leticia Cugliandolo.
Chapitre 9 :
The physics of the cell membrane
Martin Michael Müller et Martine Ben Amar.
3. Mémoires
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Theoretical examinations of interface mediated interactions between colloidal particles,
mémoire (2004).
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Theoretical studies of fluid membrane mechanics, thèse de doctorat (2007).
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Symmetry breaking in bioelasticity, thèse d'habilitation à diriger des recherches (2015).
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