Geometry in Nature
 
 
 
Home
Research
Vita
Publications
Links
Contact
 


 
 

Publications

  1. Articles in scientific journals
  2. Books
  3. Theses

 

See also profiles on Publons, Orcid or Google Scholar.

 

 

1. Articles in scientific journals

  •  

    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

    Abstract     

    Int. J. Mol. Sci., 25: 2481, 2024.

     


  •  

    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.

     Reduce     Read more

    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
    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

    Intermediate filaments are the least explored among the large cytoskeletal elements. We show here that they display conformational anomalies in narrow microfluidic channels. Their unusual behavior can be understood as the consequence of a previously undetected, large scale helically curved superstructure. Confinement in a channel orders the otherwise soft, strongly fluctuating helical filaments and enhances their structural correlations, giving rise to experimentally detectable, strongly oscillating tangent correlation functions. We propose an explanation for the detected intrinsic curving phenomenon - an elastic shape instability that we call autocoiling. The mechanism involves self-induced filament buckling via a surface stress located at the outside of the cross-section. The results agree with ultrastructural findings and rationalize for the commonly observed looped intermediate filament shapes. Beyond curvature, explaining the molecular origin of the detected helical torsion remains an interesting challenge.

     Reduce     Read more

    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

    Abstract     Read more

    IOP Conf. Series: MSE, 186: 012021, 2017.

     


  •  

    Squeezed helical elastica

    Lila Bouzar, Martin Michael Müller, Pierre Gosselin, Igor M. Kulić, Hervé Mohrbach

    Abstract     Read more

    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.

     Reduce     Read more

    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     Read more

    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

    Abstract     Read more

    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     Read more

    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

    Abstract     

    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     Read more

    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     Read more

    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

    The growth of a thin elastic sheet imposes constraints on its geometry such as its Gaussian curvature KG. In this paper, we construct the shapes of sympetalous bell-shaped flowers with a constant Gaussian curvature. Minimizing the bending energies of both the petal and the veins, we are able to predict quantitatively the global shape of these flowers. We discuss two toy problems where the Gaussian curvature is either negative or positive. In the former case the axisymmetric pseudosphere turns out to mimic the correct shape before edge curling; in the latter case, singularities of the mathematical surface coincide with strong veins. Using a variational minimization of the elastic energy, we find that the optimal number for the veins is either four, five or six, a number which is deceptively close to the statistics on real flowers in nature.

     Reduce     Read more

    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     Read more

    Europhys. Lett., 97(6): 68008, 2012. See also arXiv:1201.2518.

     


  •  

    Conical instabilities on paper

    Jemal Guven, Martin Michael Müller, Pablo Vázquez-Montejo

    The stability of the fundamental defects of an unstretchable flat sheet is examined. This involves expanding the bending energy to second order in deformations about the defect. The modes of deformation occur as eigenstates of a fourth-order linear differential operator. Unstretchability places a global linear constraint on these modes. Conical defects with a surplus angle exhibit an infinite number of states. If this angle is below a critical value, these states possess an n-fold symmetry labeled by an integer, n ≥ 2. A nonlinear stability analysis shows that the 2-fold ground state is stable, whereas excited states possess 2(n - 2) unstable modes which come in even and odd pairs.

     Reduce     Read more

    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.

     Reduce     Read more

    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.

     Reduce     Read more

    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     Read more

    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

    Abstract     Read more

    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.

     Reduce     Read more

    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     Read more

    Small, 5(7): pp. 832-838, 2009.

     


  •  

    Conical Defects in Growing Sheets

    Martin Michael Müller, Martine Ben Amar, Jemal Guven

    Abstract     Read more

    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     Read more

    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     Read more

    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     Read more

    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

    Abstract     Read more

    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     Read more

    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     Read more

    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.

     Reduce     Read more

    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

    Soft interfaces can mediate interactions between particles bound to them. The force transmitted through the surface geometry on a particle may be expressed as a closed line integral of the surface stress tensor around that particle. This contour may be deformed to exploit the symmetries present; for two identical particles, one obtains an exact expression for the force between them in terms of the local surface geometry of their mid-plane; in the case of a fluid membrane the sign of the interaction is often evident. The approach, by construction, is adapted directly to the surface and is independent of its parameterization. Furthermore, it is applicable for arbitrarily large deformations; in particular, it remains valid beyond the linear small-gradient regime.

     Reduce     Read more

    Europhys. Lett., 69(3): pp. 482-488, 2005. See also cond-mat/0409043.

     


 

 

2. Books

 

  • 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

  • Theoretical examinations of interface mediated interactions between colloidal particles, diploma thesis (2004).


  • Theoretical studies of fluid membrane mechanics, dissertation (2007).


  • Symmetry breaking in bioelasticity, habilitation thesis (2015).

 

 

 
     

 

     © Martin Michael Müller