Research

Self-assembly of spherical interpolyelectrolyte complexes from oppositely charged polymers

V. A. Baulin and E. Trizac
Soft Matter, 8 (25), 6755 – 6766 (2012)
The formation of inter-polyelectrolyte complexes from the association of oppositely charged polymers in an electrolyte is studied. The charged polymers are linear oppositely charged polyelectrolytes, with possibly a neutral block. This leads to complexes with a charged core, and a more dilute corona […]

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Critical adsorption controls translocation of polymer chain through lipid bilayers and permeation of solvent

J.-U. Sommer, M. Werner and V. A. Baulin

Europhysics Letters, 98, 18003 (2012)

Monte Carlo simulations using an explicit solvent model indicate a new pathway for translocation of a polymer chain through a lipid bilayer. We consider a polymer chain composed of repeat units with a given hydrophobicity and a coarse-grained model of a lipid bilayer in […]

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Degradation versus self-assembly of block copolymer micelles

A. Muratov and V. A. Baulin

Langmuir, 28, 3071-3076 (2012)

The stability of micelles self-assembled from block co-polymers can be altered by the degradation of the blocks. Slow degradation shifts the equilibrium size distribution of block co-polymer micelles and changes their properties. The quasi-equilibrium scaling theory shows that the degradation of hydrophobic blocks in the core of […]

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Biomolecule Surface Patterning May Enhance Membrane Association

S. Pogodin, N. K. H. Slater and V. A. Baulin

ACS Nano, 6(2), 1308-1313 (2012)

Under dehydration conditions, amphipathic late embryogenesis abundant proteins fold spontaneously from a random conformation into α-helical structures, and this transition is promoted by the presence of membranes. To gain insight into the thermodynamics of membrane association, we model the resulting α-helical structures […]

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Differential attraction and repulsion of Staphylococcus aureus and Pseudomonas aeruginosa on molecularly smooth titanium films

E. Ivanova, V. Khanh Truong , H. Webb , V.A. Baulin, J. Wang , N. Mohammodi, F. Wang, C. Fluke, R. Crawford

Langmuir, 27(18), 11710-11721 (2011)

Magnetron sputtering techniques were used to prepare molecularly smooth titanium thin films possessing an average roughness between 0.18 nm and 0.52 nm over 5 μm × 5 μm AFM scanning areas. Films […]

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Coupled concentration polarization and electroosmotic circulation near micro/nanointerfaces: Taylor–Aris model of hydrodynamic dispersion and limits of its applicability

A. Yaroshchuk, E. Zholkovskiy, S. Pogodin and V.A. Baulin
Langmuir, 27(18), 11710-11721 (2011)

Mismatches in electrokinetic properties between micro- and nanochannels give rise to superposition of electroosmotic and pressure-driven flows in the microchannels. Parabolic or similar flow profiles are known to cause the so-called hydrodynamic dispersion, which under certain conditions can be formally assimilated to an […]

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Equilibrium insertion of nanoscale objects into phospholipid bilayers

S. Pogodin and V.A. Baulin
Current Nanoscience, 7 (5), 721-726 (2011)

Certain membrane proteins, peptides, nanoparticles and nanotubes have rigid structure and fixed shape. They are often viewed as spheres and cylinders with certain surface properties. Single Chain Mean Field theory is used to model the equilibrium insertion of nanoscale spheres and rods into the phospholipid bilayer. […]

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Accurate critical micelle concentrations from a single chain mean field theory

A. Gezae Daful, V.A. Baulin, J. Bonet i Avalos and A.D. Mackie
J. Phys. Chem. B, 115, 3434–3443 (2011)
A single chain mean field theory is used to quantitatively describe the micellization process of the nonionic polyethylene oxide alkyl ether, CnEm class of surfactants at 25 °C. An explicit but simple microscopic model with only three […]

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Surface patterning of carbon nanotubes can enhance their penetration through a phospholipid bilayer

S. Pogodin, N.K.H. Slater and V.A. Baulin
ACS Nano, 5 (2), 1141–1146 (2011)

Nanotube patterning may occur naturally upon the spontaneous self-assembly of biomolecules onto the surface of single-walled carbon nanotubes (SWNTs). It results in periodically alternating bands of surface properties, ranging from relatively hydrophilic to hydrophobic, along the axis of the nanotube. Single-chain mean field (SCMF) […]

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Aggregation of amphiphilic polymers in the presence of adhesive small colloidal particles

V.A. Baulin, A. Johner and J. Bonet Avalos
J. Chem. Phys., 133, 174905 (2010)
The interaction of amphiphilic polymers with small colloids, capable to reversibly stick onto the chains, is studied. Adhesive small colloids in solution are able to dynamically bind two polymer segments. This association leads to topological changes in the polymer network configurations, such as […]

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Coarse-grained models of phospholipid membranes within the single chain mean field theory

S. Pogodin and V.A. Baulin
Soft Matter, 6, 2216 – 2226 (2010)
The single chain mean field theory is used to simulate the equilibrium structure of phospholipid membranes at the molecular level. Three levels of coarse-graining of DMPC phospholipid surfactants are present: the detailed 44-beads double tails model, the 10-beads double tails model and the minimal 3-beads […]

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Can a carbon nanotube pierce through a phospholipid bilayer?

S. Pogodin and V.A. Baulin
ACS Nano, 4 (9), 5293–5300 (2010)
Great efficiency to penetrate into living cells is attributed to carbon nanotubes due to a number of direct and indirect observations of carbon nanotubes inside the cells. However, a direct evidence of physical translocation of nanotubes through phospholipid bilayers and the exact microscopic mechanism of their […]

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Collision induced spatial organization of microtubules

V.A. Baulin, C.M. Marques, F. Thalmann
Biophysical Chemistry, 128(2-3), 231 – 244 (2007)
The dynamic behavior of microtubules in solution can be strongly modified by interactions with walls or other structures. We examine here a microtubule growth model where the increase in size of the plus-end is perturbed by collisions with other microtubules. We show that […]

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Micellization of Sliding Polymer Surfactants

V.A. Baulin, N.-K. Lee, A. Johner, C.M. Marques
Macromolecules, 39(2), 871 – 876 (2006)
Following up a recent paper on grafted sliding polymer layers [Macromolecules 2005, 38, 1434−1441], we investigated the influence of the sliding degree of freedom on the self-assembly of sliding polymeric surfactants that can be obtained by complexation of polymers with cyclodextrins. In contrast […]

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Sliding grafted polymer layers

V.A. Baulin, A. Johner, C.M. Marques
Macromolecules, 38(4), 1434 – 1441 (2005)
We study theoretically the structure of sliding grafted polymer layers, or SGP layers. These interfacial structures are built by attaching each polymer to the substrate with a ringlike molecule such as cyclodextrins. Such a topological grafting mode allows the chains to freely slide along the […]

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Self-assembled aggregates in the gravitational field: Growth and nematic order

V. A. Baulin
J. Chem. Phys., 119, 2874 (2003)
The influence of the gravitational field on the reversible process of assembly and disassembly of linear aggregates is the focus of this paper. Even the earth gravitational field can affect the equilibrium properties of heavy biological aggregates such as microtubules or actin filaments. The gravity gives rise to […]

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Self-consistent field theory of brushes of neutral water-soluble polymers

V.A. Baulin, E.B. Zhulina, A. Halperin
J. Chem. Phys., 119, 2874 (2003)
The self-consistent field theory of brushes of neutral water-soluble polymers described by two-state models is formulated in terms of the effective Flory interaction parameter χeff(T,ϕ) that depends on both temperature, T, and the monomer volume fraction, ϕ. The concentration profiles, distribution of free ends and […]

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Signatures of a concentration dependent Flory chi parameter: swelling and collapse of coils and brushes

V. A. Baulin and A. Halperin
Macromolecules, 35, 6432 – 6438 (2002)
The quality of solvents of polymers is often described in terms of the Flory χ parameter typically assumed to depend only on the temperature, T. In certain polymer-solvent systems fitting the experimental data enforces the replacement of (χT) by a concentration-dependent χeff. In turn, this modifies […]

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Concentration dependence of the Flory (X) parameter within two-state models

V. A. Baulin and A. Halperin
Macromolecules, 35, 6432 – 6438 (2002)
The Flory χ parameter is typically assumed to depend only on the temperature, T. Experimental results often require the replacement of this χ(T) by χeff, which depends also on the monomer volume fraction, φ, χeff(φ,T). Such χeff(φ,T) can arise from two-state models, proposed for polyetheleneoxide (PEO) and […]

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Nematic ordering of rigid rods in a gravitational field

V.A. Baulin, A.R. Khokhlov
Phys. Rev. E, 60(3), 2973 – 2977 (1999)
The isotropic-to-nematic transition in an athermal solution of long rigid rods subject to a gravitational (or centrifugal) field is theoretically considered in the Onsager approximation. The new feature emerging in the presence of gravity is a concentration gradient that coupled with the nematic ordering. For rodlike […]

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