Research

Direct proof of spontaneous translocation of lipid-covered hydrophobic nanoparticles through a phospholipid bilayer

Science Advances 2 (11), e1600261 (2016)
Yachong Guo, Emmanuel Terazzi, Ralf Seemann, Jean Baptiste Fleury and Vladimir A. Baulin

Hydrophobic nanoparticles introduced into living systems may lead to increased toxicity, can activate immune cells, or can be used as nanocarriers for drug or gene delivery. It is generally accepted that small hydrophobic nanoparticles are blocked by lipid bilayers and accumulate in the […]

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Adsorption of Human Plasma Albumin and Fibronectin onto Nanostructured Black Silicon Surfaces

Langmuir: 10.1021/acs.langmuir.6b02601 (2016)
Duy H. K. Nguyen, Vy T. H. Pham, Mohammad Al Kobaisi, Chris M. Bhadra, Anna Orlowska, Shahram Ghanaati, Berardo Mario Manzi, Vladimir A Baulin, Saulius Juodkazis, Peter Kingshott, Russell J Crawford, and Elena P. Ivanova

The protein adsorption of two human plasma proteins, albumin (Alb) and fibronectin (Fn) onto synthetic nanostructured bactericidal material, black silicon […]

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“Race for the surface”: eukaryotic cells can win

ACS Appl. Mater. Interfaces: 8(34) 22025-22031 (2016)
Vy T. H. Pham, Vi Khanh Truong, Anna Orlowska, Shahram Ghanaati, Mike Barbeck, Patrick Booms, Alex James Fulcher, Chris M. Bhadra, Ricardas Buividas, Vladimir A Baulin, Charles James Kirkpatrick, Pauline Doran, David E. Mainwaring, Saulius Juodkazis, Russell J Crawford, and Elena P. Ivanova

With an aging population and the consequent […]

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The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field

PLoS ONE 11(7): e0158135 (2016)
The Hong Phong Nguyen , Vy T. H. Pham , Song Ha Nguyen , Vladimir A. Baulin, Rodney J. Croft, Brian Phillips, Russell J. Crawford, Elena P. Ivanova

The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject […]

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Peroxidised phospholipid bilayers: insight from Coarse-Grained Molecular Dynamics simulations

Soft Matter, 12, 263-271 (2016)
Yachong Guo, Vladimir Baulin and Fabrice Thalmann

An original coarse-grained model for peroxidised phospholipids is presented, based on the MARTINI lipid force field. This model results from a combination of thermodynamic modelling and structural information on the area per lipid, which have been made available recently. The resulting coarse-grained lipid molecules form stable bilayers, […]

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Self-organised nanoarchitecture of titanium surfaces influences the attachment of Staphylococcus aureus and Pseudomonas aeruginosa bacteria

Applied Microbiology and Biotechnology (2015) 99 (16), 6831-6840 DOI: 10.1007/s00253-015-6572-7
Vi K. Truong, Vy T. H. Pham, A. Medvedev, R. Lapovok, Y. Estrin, T. C. Lowe, V. Baulin, V. Boshkovikj, C. J. Fluke, R. J. Crawford, E. P. Ivanova

The surface nanotopography and architecture of medical implant devices are important factors that can control the extent of bacterial attachment. The ability to prevent bacterial attachment […]

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Efficient and Stable Method to Solve Poisson–Boltzmann Equation with Steep Gradients

Computational Electrostatics for Biological Applications
2015, pp 111-119 DOI: 10.1007/978-3-319-12211-3_5
Beibei Huang and Vladimir A. Baulin

This work describes a method to solve Poisson–Boltzmann Equation (PBE) with steep gradients when common methods of solving non-linear equations do not converge or work inefficiently. This is particularly the case for relatively large boundary conditions leading to rapid changes of the solution in a narrow […]

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Mechanism of dynamic reorientation of cortical microtubules due to mechanical stress

Biophysical Chemistry, (2015) 207, 82–89 DOI: 10.1016/j.bpc.2015.09.004
Alexander Muratov and Vladimir A. Baulin
Directional growth caused by gravitropism and corresponding bending of plant cells has been explored since 19th century, however, many aspects of mechanisms underlying the perception of gravity at the molecular level are still not well known. Perception of gravity in root and shoot gravitropisms is usually attributed to gravisensitive […]

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Graphene Induces Formation of Pores That Kill Spherical and Rod-Shaped Bacteria

ACS Nano, DOI: 10.1021/acsnano.5b03368 (2015)
Vy T. H. Pham, Vi Khanh Truong, Matthew D. J. Quinn, Shannon M. Notley, Yachong Guo, Vladimir A. Baulin, Mohammad Al Kobaisi, Russell J. Crawford, and Elena P. Ivanova

Pristine graphene, its derivatives, and composites have been widely reported to possess antibacterial properties. Most of the studies simulating the interaction between bacterial cell […]

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General model of phospholipid bilayers in fluid phase within the single chain mean field theory

J. Chem. Phys. 140, 174903 (2014)
Yachong Guo, Sergey Pogodin and Vladimir A. Baulin

Coarse-grained model for saturated phospholipids: 1,2-didecanoyl-sn-glycero-3-phosphocholine (DCPC), 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC), 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC), 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC) and unsaturated phospholipids: 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 1,2- dioleoyl-sn-glycero-3-phosphocholine (DOPC) is introduced within the single chain mean field theory. A single set of parameters adjusted for DMPC bilayers gives an adequate description […]

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Nanotopography as a trigger for the microscale, autogenous and passive lysis of erythrocytes

J. Mater. Chem. B, 2 (19), 2785-2948 (2014)
Vy T. H. Pham, Vi Khanh Truong, David E. Mainwaring, Yachong Guo, Vladimir Baulin, Mohammad Al Kobaisi,   Gediminas Gervinskas, Saulius Juodkazis, Wendy R. Zeng, Pauline Doran, Russell J Crawford and Elena P. Ivanova

Microscale devices are increasingly being developed for diagnostic analysis although conventional lysis as an initial step presents […]

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Lipid oxidation induces structural changes in biomimetic membranes

Soft Matter, 10, 4241-4247 (2014)
G. Weber, T. Charitat, M. S. Baptista, A. F. Uchoa, C. Pavani, H. C. Junqueira, Y. Guo, V. A. Baulin, R. Itri, C. M. Marques, A. P. Schroder

Oxidation can intimately influence and structurally compromise the levels of biological self-assembly embodied by intracellular and plasma membranes. Lipid peroxidation, a natural metabolic outcome of […]

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Selective bactericidal activity of nanopatterned superhydrophobic cicada Psaltoda claripennis wing surfaces

Appl Microbiol Biotechnol., 97 (20), 9257-9262 (2013)
Jafar Hasan, Hayden K. Webb, Vi Khanh Truong, Sergey Pogodin, Vladimir A. Baulin, Gregory S. Watson, Jolanta A. Watson, Russell J. Crawford, Elena P. Ivanova
The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria on contact […]

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IPEC Solver: Numerical simulation tool to study inter-polyelectrolyte complexation

Comp. Phys. Comm., 184 (9), 2221–2229 (2013)
B. Huang and V.A. Baulin

IPEC Solver is a Windows program designed to analyze the stability of core–shell inter-polyelectrolyte complexes formed by complexation of oppositely charged block copolymers. The two-dimensional size distribution of the complexes composed by different numbers of positively or negatively charged polyelectrolytes is calculated based on the […]

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Bacterial attachment on sub-nanometrically smooth titanium substrata

Biofouling, 29 (2), 163-170 (2013)
H.K. Webb, V. Boshkovikj, C.J. Fluke, V.K. Truong, J. Hasan, V.A. Baulin, R. Lapovok, Y. Estrin, R.J. Crawford and E.P. Ivanova
Despite the volume of work that has been conducted on the topic, the role of surface topography in mediating bacterial cell adhesion is not well understood. The primary reason for this lack of […]

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Biophysical Model of Bacterial Cell Interactions with Nanopatterned Cicada Wing Surfaces

S. Pogodin, J. Hasan, V.A. Baulin, H.K. Webb, V.K. Truong, T.H.P. Nguyen, V. Boshkovikj, C.J. Fluke, G.S. Watson, J.A. Watson, R.J. Crawford and E.P. Ivanova

Biophys. J., 104 (4), 835-840 (2013)

The nanopattern on the surface of Clanger cicada (Psaltoda claripennis) wings represents the first example of a new class of biomaterials that can kill bacteria […]

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Nanoparticle-Induced Permeability of Lipid Membranes

Sergey Pogodin, Marco Werner, Jens-Uwe Sommer, Vladimir A. Baulin

ACS Nano, DOI: 10.1021/nn3028858 (2012)

Monte Carlo simulations using the bond fluctuation method with explicit solvent reveal the mechanism of enhanced permeability of lipid bilayers induced by the adsorption of nanoparticles with controlled hydrophobicity. Simulation results indicate an adsorption transition of nanoparticles on the bilayer in a […]

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Homo-polymers with balanced hydrophobicity translocate through lipid bilayers and enhance local solvent permeability

Marco Werner, Jens-Uwe Sommer and Vladimir A. Baulin

Soft Matter, 8, 11708-11716 (2012)

Recent experimental studies indicate that polymeric structures with a well-adjusted balance of amphiphilic parts may translocate through self-assembled phospholipid bilayers and enhance the passive trans-membrane transport of smaller molecules. Using a coarse grained lattice Monte Carlo model with explicit solvent we investigate self-assembled lipid […]

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Natural Bactericidal Surfaces: Mechanical Rupture of Pseudomonas aeruginosa Cells by Cicada Wings

Elena P. Ivanova, Jafar Hasan, Hayden K. Webb, Vi Khanh Truong, Gregory S. Watson, Jolanta A. Watson, Vladimir A. Baulin, Sergey Pogodin, James Y. Wang, Mark J. Tobin, Christian Löbbe, Russell J. Crawford

Small, 8 (16), 2489 – 2494 (2012)

Natural superhydrophobic surfaces are often thought to have antibiofouling potential due to their self-cleaning properties. However, when […]

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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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