V. V. Vasilevskaya

Russian Academy of Sciences, Moskva, Moscow, Russia

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Publications (58)89.76 Total impact

  • Mahfoud Boustta, Laurent Leclercq, Michel Vert, Valentina V. Vasilevskaya
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    ABSTRACT: Positively and negatively charged molecules, endothelia, and cells play important roles in biological salted aqueous media. This work aimed at studying artificial polyelectrolyte complexes in terms of formation and stability in the context of the increasing interest for the use of polyelectrolyte systems in drug delivery or as polyelectrolyte complexes or polyplexes for gene transfection. The effect of salt concentration on model polyelectrolyte complexes was studied both experimentally and from a theoretical viewpoint. The critical salt concentration at which phase separation appeared when multifunctional polyanions, namely poly(l-lysine citramide) and poly(l-lysine citramide imide) were mixed with poly(l-lysine) showed that salt concentration, degree of polymerization and charge density conditioned the formation and the stability of corresponding polyelectrolyte complexes. Data agreed well with the trends indicated by the theoretical approach and they are discussed in comparison with the case of nonviral transfection using polyplexes.
    Macromolecules 05/2014; 47(11):3574–3581. · 5.93 Impact Factor
  • A A Lazutin, M K Glagolev, V V Vasilevskaya, A R Khokhlov
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    ABSTRACT: An algorithm involving classical molecular dynamics simulations with mapping and reverse mapping procedure is here suggested to simulate the crosslinking of the polystyrene dissolved in dichloroethane by monochlorodimethyl ether. The algorithm comprises consecutive stages: molecular dynamics atomistic simulation of a polystyrene solution, the mapping of atomistic structure onto coarse-grained model, the crosslink formation, the reverse mapping, and finally relaxation of the structure dissolved in dichloroethane and in dry state. The calculated values of the specific volume and the elastic modulus are in reasonable quantitative correspondence with experimental data.
    The Journal of Chemical Physics 04/2014; 140(13):134903. · 3.12 Impact Factor
  • A A Glagoleva, V V Vasilevskaya, K Yoshikawa, A R Khokhlov
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    ABSTRACT: In general, bio-macromolecules are composed of hydrophilic and hydrophobic moieties and are confined within small cavities, such as cell membranes and intracellular organelles. Here, we studied the self-organization of macromolecules having groups with different affinities to solvents under spherical nano-scale confinement by means of computer modeling. It is shown that depending on the interaction parameters of monomer units composed of side- and main-chain monomer groups along a single linear macromolecule and on cavity size, such amphiphilic polymers undergo the conformational transitions between hollow nanospheres, rod-like and folded cylindrical structures, and a necklace conformation with and without a particular ordering of beads. The diagram of the conformations in the variables the incompatibility parameter of monomer units and the cavity radius is constructed.
    The Journal of Chemical Physics 12/2013; 139(24):244901. · 3.12 Impact Factor
  • M K Glagolev, V V Vasilevskaya, A R Khokhlov
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    ABSTRACT: Concentrated solutions of amphiphilic macromolecules with local helical structure were studied by means of molecular dynamic simulations. It is shown that in poor solvent the macromolecules are assembled into wire-like aggregates having complex core-shell structure. The core consists of a hydrophobic backbone of the chains which intertwine around each other. It is protected by the shell of hydrophilic side groups. In racemic mixture of right-hand and left-hand helix macromolecules the wire-like complex is a chain of braid bundles of macromolecules with the same chirality stacking at their ends. The average number of macromolecules in the wire cross-section is close to that of separate bundles observed in dilute solutions of such macromolecules. The effects described here could serve as a simple model of self-organization in solutions of macromolecules with local helical structure.
    The Journal of Chemical Physics 08/2012; 137(8):084901. · 3.12 Impact Factor
  • Alexei A. Lazutin, Alexander N. Semenov, Valentina V. Vasilevskaya
    Macromolecular Theory and Simulations 06/2012; 21(5). · 1.61 Impact Factor
  • V. V. Vasilevskaya, V. A. Ermilov
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    ABSTRACT: The review presents the basic models used to analyze the self-assembly of protein macromolecules and the main results of studying the self-organization of macromolecules in terms of the concepts of amphiphilicity of an individual monomer unit. The features of the coil-globule transition of these macro-molecules in solutions with different concentrations are described in terms of the statistics of the distribution of monomer units and chain rigidity. It is shown that this model is efficient for interpreting and analyzing experimental data for the study of synthetic and biological macromolecules.
    Polymer Science Series A 01/2011; 53(9):846-866. · 0.67 Impact Factor
  • A. A. Glagoleva, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: The molecular-dynamics method is used to study the adsorption of A-graft-B macromolecules on patterned planar surfaces consisting of regions a and b that specifically interact with chain units. Surfaces with patterns in the form of circles of different radii and a spiral stripe are discussed. Effective recognition occurs during the adsorption of an A-graft-B macromolecule on these patterned surfaces. Recognition means that, for a proper combination of the architecture of a macromolecule and the energy parameters of its interaction with the plane regions, the macromolecule can be located along the boundary of a circle with a given radius or can stay in a given location of the spiral stripe.
    Polymer Science Series A 01/2011; 53(4):344-353. · 0.67 Impact Factor
  • M. K. Glagolev, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: The molecular-dynamics method is used to study solutions of amphiphilic macromolecules with a local helical structure. A deterioration in the solvent quality in concentrated solutions of these macromolecules leads to the formation of intermolecular fibrillar helix bundles with approximately the same lengths and aggregation numbers. The number of chains in a bundle is determined by parameters that characterize the local structure and is weakly dependent on the length of the macromolecule and the volume fraction of the polymer in the solution. In racemic mixtures of these macromolecules, a deterioration in the solvent quality leads to effective demixing; that is, the resultant fibrillar bundles generally contain macromolecules of exclusively the same chirality.
    Polymer Science Series A 01/2011; 53(8):733-743. · 0.67 Impact Factor
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    ABSTRACT: We studied the conformational properties of DNA in a salt solution of the strongly charged protein bovine serum albumin. DNA is compacted when a suitable amount of bovine serum albumin is added to the solution due to a crowding effect and strong electrostatic repulsion between DNA and bovine serum albumin, both of which carry negative charges. However, DNA undergoes an unfolding transition with an increase in the salt concentration. This observation contradicts the current understanding of polymer- and salt-induced condensation, ψ condensation. We propose a simple theoretical model by taking into account the competition between the translational entropy of ions and electrostatic interaction.
    Physical Review Letters 09/2010; 105(12):128302. · 7.73 Impact Factor
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    ABSTRACT: From the study of single molecular observation of individual DNA chains by use of fluorescence microscopy, it has become clear that the transition between elongated coil state and compacted globule state is highly discrete on the level of individual chains. On the other hand, the transition appears continuous on the level of the ensemble of DNAs. We report the experimental evidence on this unique property of the DNA chain, using T4 DNA, 166 kilo base pairs (kbp), with the addition of Co(NH3)3+6. Theoretical consideration has been performed on the bimodality in the free energy of single DNA chains, indicating that the character of the coil-globule transition changes largely depending on the valency of the coexistence cationic species.
    Berichte der Bunsengesellschaft für physikalische Chemie. 05/2010; 100(6):876 - 880.
  • A. A. Glagoleva, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: Computer-aided simulation performed via two independent methods (the Monte Carlo method and method of dissipative particle dynamics) is performed for studying the effect of microphase separation in concentrated solutions of diblock copolymers composed of linear blocks A and amphiphilic blocks A-graft-B. The type of microstructures generated by strong incompatibility between units A and B is shown to be controlled by the ratio of block lengths. For example, in the case of short amphiphilic blocks, elongated micelles with correlated mutual alignment are formed. In the case of longer amphiphilic blocks, lamellar structures are produced; with an increase in the length of this block, these structures are transformed into sequences of lamellas containing parallel layers, lamellas with intersecting layers, and perforated lamellas. When the system contains long amphiphilic blocks, bicontinuous structures arise.
    Polymer Science Series A 01/2010; 52(2):182-190. · 0.67 Impact Factor
  • V. A. Ermilov, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: The relation of the coil-globule transition in macromolecules consisting of amphiphilic and hydrophilic monomer units to the radius of action of the interaction potential is investigated by the method of computer-assisted experiments. The internal structure of globules formed by such macromolecules is significantly dependent on the radius of action of the potential. In the case of the long-range potential, the globule is characterized by the blob structure, while in the case of the short-range potential, a quasi-helical structure forms. In this structure, the skeleton of a macromolecule forms a helical turn, and the direction of twisting may vary from one turn to another. The coil-globule transition in such macromolecules proceeds through formation of the necklace conformation from quasi-helical micelle beads. For sufficiently long macromolecules, the dimensions of such globules are linearly dependent on the degree of polymerization.
    Polymer Science Series A 01/2010; 52(3):317-327. · 0.67 Impact Factor
  • M. K. Glagolev, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: Conformational characteristics of amphiphilic macromolecules with secondary local helical structuring are studied by the method of molecular dynamics for different properties of a helix (bending angles between neighboring vectors of the bond and internal rotation angle) and different rigidities of its fixation. Extended helices with high distances between helical turns and dense helices in which neighboring turns directly adjoin each other are studied. As the quality of a solvent deteriorates, extended helices experience a well-pronounced coil-globule transition, whose amplitude increases with an increase in chain rigidity, while the dimensions of dense helices gradually change. In a poor solvent, extended helices formed “collagen-like” structures, flexible chains of dense helices produce hairpin structures, and rigid macromolecules of dense helices form rodlike globules with an almost ideal local helical order. Independently of helix parameters, a deterioration in solvent quality leads to stabilization of the local secondary structure.
    Polymer Science Series A 01/2010; 52(7):761-774. · 0.67 Impact Factor
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    ABSTRACT: The influence of salt concentration on the size and on the thermodynamic stability of interpolymer complexes composed of oppositely charged macroions having different affinity to solvent was studied from a theoretical viewpoint. It was shown that increasing salt concentration causes changes in the structure of complex particles. At low salt concentration, the particles preserve their structure and size. At a critical salt concentration, nScr, the particle size rises sharply to a slightly larger dimension. From this concentration, the macroions forming the interpolymer complex start to separate, and the complex is fully destroyed at a salt concentration nS*. After separation, the macroions coexist in solution and with further increase in salt concentration reduce their sizes according to the screening of polyion charges by salt ions. nScr and nS* depend on physical parameters such as the degree of polymerization of macroions, their degree of ionization, and macroion−solvent interaction parameters. Experimental data collected in the particular cases of PLL-PLCA and PLL-PLCAI complexes with polylysine qualitatively agree with the trends indicated by the theoretical approach.
    Macromolecules. 10/2009;
  • P. N. Ablyazov, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: The destruction of a globule in the presence of a dimeric substrate composed of a hydrophilic group OP and a hydrophobic group H with a high affinity to hydrophobic H units of a macromolecule has been studied. Globules of the homopolymer H macromolecule and the macromolecule of the HP copolymer with proteinlike statistics of monomer unit distribution along a chain have been investigated. The destruction of a globule in such systems begins with the transformation of the globule’s shape from spherical to disklike. At high substrate concentrations, the globule of the proteinlike copolymer is completely destroyed; under the same conditions, the homopolymer macromolecule forms a structure composed of two beads having a shape close to that of the oblate ellipsoid that are located symmetrically about a string connecting them.
    Polymer Science Series A 01/2009; 51(4):424-429. · 0.67 Impact Factor
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    V.V. Vasilevskaya, V.A. Markov, G. ten Brinke, A R Khokhlov
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    ABSTRACT: Conformational properties of amphiphilic stiff-chain macromolecules in concentrated solutions in poor solvent have been studied via computer modeling. We have found that the conformational state of macromolecules in such systems depends on the macromolecular stiffness and on the way the solution has been prepared. Thus, if the concentration of globules increased from a very diluted solution, the globules remain stable, independent of the macromolecular stiffness, and do not aggregate even in concentrated solutions. On the other hand, if the solvent quality is gradually decreased in a solution with a concentration much larger than that of a semidilute solution, then relatively flexible chains form separate globules, whereas semirigid macromolecules tend to aggregate and form braid-like conformations. The results obtained agree with the published experimental data and can be used for directed synthesis of macromolecules modeling the behavior of biopolymers.
    09/2008;
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    ABSTRACT: The influence of the distribution statistics of side-chain grafting sites on the conformational properties of amphiphilic comblike macromolecules immersed in a solvent that is poor for the main chain and good for the side chains was studied. It was shown that the coil-globule transition for macromolecules with the protein-like distribution of side-chain grafting sites occurs at higher temperatures, wherein the size of the proteinlike macromolecules is generally smaller than that of the corresponding regular macromolecules. Regardless of distribution statistics of side-chain grafting sites, the coil-globule transition of comb macromolecules passes through the step of the formation of the beads-on-a-string conformation composed of micelle-like beads. The temperature dependence curves of the heat capacity exhibit at least two maximums associated with the coil-globule transition per se and the coalescence of the beads into a single globule. The coil-globule transition temperature is slightly dependent upon the degree of polymerization of the main chain and drops with a decrease in the degree of polymerization of the side chains. It was found that comb macromolecules can form spherical, disklike, or cylindrical globules, depending on the structural parameters.
    Polymer Science Series A 08/2008; 50(9):1008-1017. · 0.67 Impact Factor
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    ABSTRACT: The coil-globule transition in rigid-chain amphiphilic macromolecules was studied by means of computer simulation, and the phase diagrams for such molecules in the solvent quality-persistence length coordinates were constructed. It was shown that the type of phase diagram depends to a substantial extent on the degree of polymerization of a macromolecule. Relatively short amphiphilic macromolecules in the poor-solvent region always form a spherical globule, with the transition to this globule involving one or two intermediate conformations. These are the disk globule if the Kuhn segment is relatively large and the string of spherical micelles or the disk globule in the case of relative flexible chains. The phase diagram of a long rodlike amphiphilic chain turned out to be even more complex. Namely, three characteristic regions were distinguished in the region of a poor solvent, depending on the chain rigidity: the region of a cylindrical globule without certain order in the main chain, the region of the cylindrical globule with blobs having the collagen ordering of the chain, and the region of coexistence of collagen-like and toroidal globules. In the intermediate transitional region, not only conformations of strings of spherical micelle beads but also the necklace conformations in which the polymer chain in each bead has collagen ordering can occur in this case.
    Polymer Science Series A 01/2008; 50(6):621-629. · 0.67 Impact Factor
  • V. V. Vasilevskaya, L. Leclercq, M. Boustta, M. Vert, A. R. Khokhlov
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    ABSTRACT: We consider the new type of water-soluble stoichiometric interpolymer polyelectrolyte complexes (IPEC) consisting of macromolecules having different affinities to solvent and different densities of ionic groups along the chain. It was proposed that complexes of such macromolecules have a core−shell structure. The inner part of complex with a radius r contains monomer units of both macromolecules, while exterior part with a radius R consists exclusively of monomer units of hydrophilic macromolecules. With such complex organization, the external charged hydrophilic shell effectively protects the complex from precipitation and fusion with other complex assemblies. These theoretical conclusions allow to explain the experimental data on the stability of IPECs containing poly(l-lysine), poly(l-lysine citramide), poly(l-lysine citramide imide), and poly(acrylic acid), and can be of interest in the field of DNA−polycation complexes aimed at transfecting genes to cell nuclei.
    Macromolecules. 07/2007; 40(16).
  • P. N. Ablyazov, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: Chemical transformations of surface-active substrate in the presence of surface-active catalyst are studied by the methods of computer simulation. Reactions occur in emulsion, at whose interfaces reactants are concentrated. It is established that there is an optimal size of emulsion droplets at which the reaction rate is the highest. It is shown that the kinetics of reactions substantially depends on the surface activity of reactants and the potential barrier of reaction. Under specific conditions, the rate of reaction notably increases during the initial time interval.
    Colloid Journal 05/2007; 69(3):265-271. · 0.63 Impact Factor

Publication Stats

439 Citations
89.76 Total Impact Points

Institutions

  • 1998–2012
    • Russian Academy of Sciences
      • Institute of Organoelement Compounds
      Moskva, Moscow, Russia
  • 2006–2010
    • Lomonosov Moscow State University
      • • Division of Physics
      • • Faculty of Physics
      Moscow, Moscow, Russia
  • 2003–2004
    • Universität Ulm
      • Institute of Theoretical Physics
      Ulm, Baden-Wuerttemberg, Germany
  • 1995
    • Nagoya University
      • School of Informatics and Sciences
      Nagoya-shi, Aichi-ken, Japan