Publications
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Articles in scientific journals
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Books
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Theses
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1. Articles in scientific journals
| Flexoelectric fluid membrane vesicles in spherical confinement
Niloufar Abtahi, Lila Bouzar, Nadia Saidi-Amroun, Martin Michael Müller |
The morphology of spherically confined flexoelectric fluid membrane vesicles in an ex-
ternal uniform electric field is studied numerically. Due to the deformations induced by
the confinement, the membrane becomes polarized resulting in an interaction with the
external field. The equilibrium shapes of the vesicle without electric field can be clas-
sified in a geometrical phase diagram as a function of scaled area and reduced volume
[1, 2]. When the area of the membrane is only slightly larger than the area of the con-
fining sphere, a single axisymmetric invagination appears. A non-vanishing electric field
induces an additional elongation of the confined vesicle which is either perpendicular or
parallel depending on the sign of the electric field parameter. Higher values of the surface
area or the electric field parameter can reduce the symmetry of the system leading to
more complex folding. We present the resulting shapes and show that transition lines
are shifted in the presence of an electric field. The obtained folding patterns could be of
interest for biophysical and technological applications alike.
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EPL, 131(1): 18001, 2020. See also arXiv:2006.04475.
| Isometric bending requires local constraints on free edges
Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo |
Abstract
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Math. Mech. Solids, 24: 4051, 2019. See also arXiv:1904.05855.
| Helical Superstructure of Intermediate Filaments
Lila Bouzar, Martin Michael Müller, René Messina, Bernd Nöding, Sarah Köster, Hervé Mohrbach, Igor M. Kulić |
Abstract
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Phys. Rev. Lett., 122: 098101, 2019. See also 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 |
Abstract
Phys. Rev. E, 98: 043111, 2018. See also arXiv:1810.04500.
| Confining a fluid membrane vesicle of toroidal topology in an adhesive hard sphere
Lila Bouzar, Ferhat Menas, Martin Michael Müller |
We discuss how the equilibrium shapes of a confined toroidal fluid membrane vesicle
change when an adhesion between membrane and confining sphere is taken into account. The case without adhesion
was studied in Ref. [1]. Different types of solution were found and assembled in a phase diagram as a function of area
and reduced volume of the membrane. Depending on the degree of confinement the vesicle is either free, in contact along
a circle (contact-circle solutions) or on a surface (contact-area solutions). All solutions without adhesion are up-down symmetric.
When the container is adhesive, the phase diagram is altered and new kinds of solution without up-down symmetry are found.
For increasing values of adhesion the region of contact-circle solutions shrinks until it vanishes completely from the phase diagram.
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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.
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Eur. Phys. J. E, 39: 114, 2016. See also arXiv:1606.03611.
| How bio-filaments twist membranes
Julien Fierling, Albert Johner, Igor M. Kulić, Hervé Mohrbach, Martin Michael Müller |
Abstract
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.
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Phys. Rev. E, 92: 032721, 2015. See also arXiv:1509.00765.
| Non-linear buckling and symmetry breaking of a soft elastic sheet sliding on a cylindrical substrate
Norbert Stoop, Martin Michael Müller |
Abstract
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Int. J. Non-Linear Mech., 75: 115, 2015. See also 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.
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Europhys. Lett., 107(6): 68002, 2014. See also arXiv:1408.6787.
| Confotronic dynamics of tubular filaments
Osman Kahraman, Hervé Mohrbach, Martin Michael Müller, Igor M. Kulić |
Abstract
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Soft Matter, 10(16): pp. 2836-2847, 2014. See also arXiv:1312.3106.
| Whirling skirts and rotating cones
Jemal Guven, J. A. Hanna, Martin Michael Müller |
Steady, dihedrally symmetric patterns with sharp peaks may be observed on a spinning skirt, lagging behind the material flow of the fabric. These qualitative features are captured with a minimal model of traveling waves on an inextensible, flexible, generalized-conical sheet rotating about a fixed axis. Conservation laws are used to reduce the dynamics to a quadrature describing a particle in a three-parameter family of potentials. One parameter is associated with the stress in the sheet, aNoether is the current associated with rotational invariance, and the third is a Rossby number which indicates the relative strength of Coriolis forces. Solutions are quantized by enforcing a topology appropriate to a skirt and a particular choice of dihedral symmetry. A perturbative analysis of nearly axisymmetric cones shows that Coriolis effects are essential in establishing skirt-like solutions. Fully non-linear solutions with three-fold symmetry are presented which bear a suggestive resemblance to the observed patterns.
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New J. Phys., 15: 113055, 2013. See also 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 |
Abstract
J. Cell Sci., 126(8): 1806, 2013.
| Dipoles in thin sheets
Jemal Guven, J. A. Hanna, Osman Kahraman, Martin Michael Müller |
Abstract
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Eur. Phys. J. E, 36: 106, 2013. See also arXiv:1212.3262.
| Fluid membrane vesicles in confinement
Osman Kahraman, Norbert Stoop, Martin Michael Müller |
Abstract
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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 |
Abstract
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New J. Phys., 14: 085014, 2012. Also featured in the Highlights of 2012.
| Morphogenesis of membrane invaginations in spherical confinement
Osman Kahraman, Norbert Stoop, Martin Michael Müller |
Abstract
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Europhys. Lett., 97(6): 68008, 2012. See also arXiv:1201.2518.
| Conical instabilities on paper
Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo |
Abstract
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J. Phys. A: Math. Theor., 45(1): 015203, 2012. See also 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.
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Phys. Rev. E, 83(5): 051921, 2011. See also 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.
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Phys. Rev. Lett., 105(6): 068101, 2010. See also arXiv:1007.1871.
| Cell Model Approach to Membrane Mediated Protein Interactions
Martin Michael Müller, Markus Deserno |
Abstract
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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 |
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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 |
The mechanical behavior of lipid bilayers spanning the pores of highly ordered porous silicon substrates was studied by local indentation experiments as a function of surface functionalization, lipid composition, solvent content, indentation velocity, and pore radius. Solvent-containing nanoblack lipid membranes (nano-BLMs) as well as solvent-free pore-spanning bilayers were imaged by fluorescence and atomic force microscopy prior to force curve acquisition, which allows distinguishing between membrane-covered and uncovered pores. Force indentation curves on pore-spanning bilayers attached to functionalized hydrophobic porous silicon substrates reveal a predominately linear response that is mainly attributed to prestress in the membranes. This is in agreement with the observation that indentation leads to membrane lysis well below 5% area dilatation. However, membrane bending and lateral tension dominates over
prestress and stretching if solvent-free supported membranes obtained from spreading giant liposomes on hydrophilic porous silicon are indented.
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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 |
Abstract
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Small, 5(7): pp. 832-838, 2009.
| Conical Defects in Growing Sheets
Martin Michael Müller, Martine Ben Amar, Jemal Guven |
A growing or shrinking disc will adopt a conical shape, its intrinsic geometry characterized by a surplus angle φe at the apex. If growth is slow, the cone will find its equilibrium. Whereas this is trivial if φe≤0, the disc can fold into one of a discrete infinite number of states if φe is positive. We construct these states in the regime where bending dominates, determine their energies and how stress is distributed in them. For each state a critical value of φe is identified beyond which the cone touches itself. Before this occurs, all states are stable; the ground state has twofold symmetry.
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Phys. Rev. Lett., 101(15): 156104, 2008. See also arXiv:0807.1814.
| How paper folds: bending with local constraints
Jemal Guven, Martin Michael Müller |
Abstract
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J. Phys. A: Math. Theor., 41(5): 055203, 2008. See also arXiv:0712.0978.
| Contact lines for fluid surface adhesion
Markus Deserno, Martin Michael Müller, Jemal Guven |
Abstract
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Phys. Rev. E, 76(1): 011605, 2007. See also cond-mat/0703019. Also featured in the Virtual Journal of Biological Physics Research.
| Balancing torques in membrane-mediated interactions: Exact results and
numerical illustrations
Martin Michael Müller, Markus Deserno, Jemal Guven |
Abstract
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Phys. Rev. E, 76(1): 011921, 2007. See also cond-mat/0702340. Also featured in the 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 |
Membrane remodelling plays an important role in cellular tasks such as endocytosis, vesiculation and protein sorting, and in the biogenesis of organelles such as the endoplasmic reticulum or the Golgi apparatus. It is well established that the remodelling process is aided by specialized proteins that can sense as well as create membrane curvature, and trigger tubulation when added to synthetic liposomes. Because the energy needed for such large-scale changes in membrane geometry significantly exceeds the binding energy between individual proteins and between protein and membrane, cooperative action is essential. It has recently been suggested that curvature-mediated attractive interactions could aid cooperation and complement the effects of specific binding events on membrane remodelling. But it is difficult to experimentally isolate curvature-mediated interactions from direct attractions between proteins. Moreover, approximate theories predict repulsion between isotropically curving proteins. Here we use coarse-grained membrane simulations to show that curvature-inducing model proteins adsorbed on lipid bilayer membranes can experience attractive interactions that arise purely as a result of membrane curvature. We find that once a minimal local bending is realized, the effect robustly drives protein cluster formation and subsequent transformation into vesicles with radii that correlate with the local curvature imprint. Owing to its universal nature, curvature-mediated attraction can operate even between proteins lacking any specific interactions, such as newly synthesized and still immature membrane proteins in the endoplasmic reticulum.
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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 |
Abstract
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Phys. Rev. E, 74(6): 061914, 2006. See also cond-mat/0602662. Also featured in the 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 |
Abstract
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Biophys. J., 91(1): pp. 217-226, 2006.
| Interface mediated interactions between particles -- a geometrical approach
Martin Michael Müller, Markus Deserno, Jemal Guven |
Abstract
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Phys. Rev. E, 72(6): 061407, 2005. See also cond-mat/0506019. Also featured in the Virtual Journal of Biological Physics Research.
| Geometry of surface-mediated interactions
Martin Michael Müller, Markus Deserno, Jemal Guven |
Abstract
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Europhys. Lett., 69(3): pp. 482-488, 2005. See also cond-mat/0409043.
2. Books
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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),
edited by Martine Ben Amar, Alain Goriely, Martin Michael Müller and Leticia Cugliandolo.
Chapter 9:
The physics of the cell membrane
Martin Michael Müller and Martine Ben Amar.
3. Theses
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Theoretical examinations of interface mediated interactions between colloidal particles,
diploma thesis (2004).
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Theoretical studies of fluid membrane mechanics, dissertation (2007).
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Symmetry breaking in bioelasticity, habilitation thesis (2015).
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