University of Maryland

Fischell Bioengineering Department

3135 Kim Engineering Building

College Park, MD 20742

P: (301) 405 8250

F: (301) 314 6868

E: helim@umd.edu

 

 

CELLS

VESICLES

BIOPOLYMERS

Shapes of Mixed Phospholipid Vesicles. With G. Paredes and A. Maldonado Arce.  J. Biol. Phys. Description of the morphology of vesicles as a function of the membrane lipid mixture. Cylindrical vesicles form coils when an external perturbation is imposed.

Interplay Between Shear Stress and Adhesion Ligands on the Locomotion of Human Neutrophils.  With Lee Smith, J. Haun, and D. Hammer. Biophys. J. (In Press). The effect of flow and adhesive substrates on neutrophil motility is explored in this paper.

Neutrophil Spreading: From Touchdown to First Steps.. With K. Sengupta, Lee Smith, P. Janmey, and D. Hammer.  Biophys. J. (In Press). Spreading of neutrophils is explored using interference microscopy.  Neutrophils show anisotropic spreading with adhesion dependent growth.

Cholesterol Depletion Increases Membrane Stiffness of Aortic Endothelial Cells. With F. Byfield, V. Romanenko, G. Rothblat, and I. Levitan. Biophys. J. 87 (2004) 3344. Is cholesterol good for you?

Pore Stability and Dynamics in Polymer Membranes. With H. Bermudez, D. A. Hammer, and D. E. Discher.  Europhys. Lett. 64 (2003) 550. Membrane thickness allows to control the dynamics of pores, from slow growing kinetically trapped holes.

Electromechanical Limits of Polymersomes. With H. Bermudez, F. S. Bates, and D. E. Discher, Phys. Rev. Lett. 87 (2001) 208301. A study on the stability of vesicles as a function of membrane thickness. Thicker is tougher  but thinner is more functional.

Flexibility Transitions and Looped Adsorption of Worm-like Chains. With P. Dalhaimer, O. I. Wagner, J.-F. Leterrier, P. A. Janmey, and D. E. Discher. J. of Polymer Sci. B 43 (2005) 280. Polymer adsorption to 2D substrates modifies the persistence length.

Elongation and Fluctuations of Semi-flexible Polymers in a Nematic Solvent. With Z. Dogic, J. Zhang, A.W.C. Lau, P. Dalhaimer, D. Discher, P. A. Janmey, R.D. Kamien, T.C. Lubensky, and A. Yodh. Phys. Rev. Lett. 92 (2004) 125503. Aligning the tracks!

Domain Unfolding in Neurofilament Sidearms: Effects of Phosphorylation and ATP. With P. Carl, P. Janmey, J. F. Leterrier, and D. E. Discher, FEBS Letters 531 (2002) 397. An electrostatic bridge is responsible for the large force required to fold a charged polymer.

THEORY (The old times!)

Electrostatically Induced Undulations of Lamellar DNA-Lipid Complexes. With H. Schiessel. European Phys. J. E 5 (2001) 499.

Interaction Between Inclusions Embedded in Membranes. With A. Berman, N. Dan, P. Pincus, and S. Safran, Biophys. J. 71 (1996) 648.

Static Structure of the Two-Dimensional Hard-Disk Plus Yukawa Fluid. With M. Medina Noyola and J.L. Arauz Lara, J. Chem. Phys. 99 (1993) 5462.

Other stuff

Cholesterol Depletion Constrains Mechanical Deformation of Aortic Endothelial Cells. With F. Byfield, V. Romanenko, G. Rothblat, and I. Levitan. Proceedings of the IASTED International Conference on Biomechanics. (2003) 86.

 

Hydrodynamics of Polymer Membranes. With P. Dalhaimer, F. S. Bates,  and D. E. Discher.  Comptes Rendus de l’Academie des Sciences – Series IV Physics-Astrophysics 4 (2003) 251.

 

Electrostatic Repulsion of Positively Charged Vesicles and Negatively Charged Objects. With Yi Chen, N. Dan, T. C. Lubensky, P. Nelson, L. Ramos, and D.A. Weitz, Science 285 (1999) 394.

 

Structure Factor of Flexible Membranes. With D. Lavallee, Europhys. Lett. 43 (1998) 355.

 

Virus Cell-Fusion. With S. Aranda. II Mexican Symposium on Medical Physics. American Institute of Physics Conference Proceedings 440, 211 (1998).

 

Structure and Self-diffusion in a Model Two-dimensional Brownian Liquid. With M. Carbajal-Tinoco, E. Urrutia-Banuelos, J.L.Arauz-Lara, M. Medina-Noyola, and J. Alejandre, J. of Chem. Phys. 101 (1994) 10925.

NJC