V. V. Vasilevskaya

Russian Academy of Sciences, Moskva, Moscow, Russia

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Publications (65)149.55 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: We performed monomolecular observations on linear and circular giant DNAs (208 kbp) in an aqueous solution by the use of fluorescence microscopy. The results showed that the degree of conformational fluctuation in circular DNA was ca. 40% less than that in linear DNA, although the long-axis length of circular DNA was only 10% smaller than that of linear DNA. Additionally, the relaxation time of a circular chain was shorter than that of a linear chain by at least one order of magnitude. The essential features of this marked difference between linear and circular DNAs were reproduced by numerical simulations on a ribbon-like macromolecule as a coarse-grained model of a long semiflexible, double-helical DNA molecule. In addition, we calculated the radius of gyration of an interacting chain in a circular form on the basis of the mean field model, which provides a better understanding of the present experimental trend than a traditional theoretical equation.
    The Journal of Chemical Physics 04/2015; 142(14):145101. DOI:10.1063/1.4916309 · 3.12 Impact Factor
  • Mikhail K. Glagolev, Alexei А. Lazutin, Valentina V. Vasilevskaya
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    ABSTRACT: The influence of the cross-linking agent concentration on the macroscopic properties of hypercrosslinked polystyrene networks was studied by means of computer experiment. The computer experiment includes the 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, the determination of properties of samples (elastic modulus and specific surface). The measurements of elastic modulus and specific surface were performed in frameworks of coarse-grained and atomistic presentation. It was shown that for both models the elastic modulus increases while the specific surface decreases with increase of the number of crosslinks. Both models give very close values for specific surface whereas the elastic moduli determined from atomistic simulations could be an order of magnitude greater than the values calculated using the coarse-grained representation of the same sample. The calculated values of the elastic modulus and specific surface are in reasonable quantitative correspondence with experimental data.
    Macromolecular Symposia 02/2015; 348(1). DOI:10.1002/masy.201400148
  • 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. DOI:10.1021/ma500447k · 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. DOI:10.1063/1.4869695 · 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. DOI:10.1063/1.4839795 · 3.12 Impact Factor
  • Source
    Anna Glagoleva, Igor Erukhimovich, Valentina Vasilevskaya
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    ABSTRACT: The free volume (voids) distribution in the lamellae of the conventional symmetric and amphiphilic diblock copolymers is studied via Monte–Carlo simulation based on the standard bond fluctuation model. Both in the conventional and amphiphilic block copolymers the voids are found to concentrate on the interfaces between the incompatible units, the magnitude of the effect being unexpectedly significant. A crystalline‐like ordering of voids with increase of the incompatibility between the different repeated units in amphiphilic copolymers is first reported and implications of this peculiarity for the morphology and mechanical properties of the amphiphilic copolymers are discussed.
    Macromolecular Theory and Simulations 01/2013; 22(1). DOI:10.1002/mats.201200056 · 1.79 Impact Factor
  • M. K. Krotova, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: The theory of DNA compaction in solutions of highly charged proteins carrying charge of the same sign as DNA is developed. It is shown that the introduction of a negatively charged protein may induce the collapse of DNA that occurs as a first-order phase transition. The concentration of protein in the vicinity of DNA practically coincides with the concentration of protein in solution on the whole, and the introduction of protein into a solution is equivalent to the effective worsening of solvent quality. The higher the absolute value of the protein charge, the more pronounced this worsening. The higher the charge of the protein, the smaller its content that causes the compaction of DNA. The properties of the transition depend on the effective charge of DNA and on the concentration of a low-molecular-mass salt. An increase in the concentration of the salt may weaken the action of protein as a compaction agent and cause the reverse transition of a DNA macromolecule to the coiled state.
    Polymer Science Series C 09/2012; 54(1). DOI:10.1134/S1811238212020014 · 0.65 Impact Factor
  • M. K. Glagolev, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: The Monte Carlo method is used to study macromolecule layers with mobile grafting points during deterioration in the solvent quality. If the chains are rigidly grafted onto the surface, the micelle core is bonded to the surface through chain fragments that are strongly extended along the surface, but if the points are fairly mobile, the micelles are dense aggregates maximally segregated from the surface. In addition, an increase in the mobility of the chains leads to increase in the mean aggregation number of the micelles, its dispersion, and height of the aggregate.
    Polymer Science Series A 09/2012; 54(9). DOI:10.1134/S0965545X12090027 · 0.88 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. DOI:10.1063/1.4745480 · 3.12 Impact Factor
  • Alexei A. Lazutin, Alexander N. Semenov, Valentina V. Vasilevskaya
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    ABSTRACT: Monte Carlo simulations are employed in order to analyze the structure of polyelectrolyte complexes consisting of two identical but oppositely charged macroions with varying chain stiffness. It is shown that two complex structures can arise depending on the stiffness of the constituent chains. Stiff chains are organized into a ladder structure in which chains are located parallel to each other and monomeric units are arranged into ionic pairs according to their position in the chain. Flexible chains form a globular scrambled-egg structure with a disordered position of monomer units. The conformational transition between the two structures proceeds as a phase transition.
    Macromolecular Theory and Simulations 06/2012; 21(5). DOI:10.1002/mats.201100097 · 1.79 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 09/2011; 53(9):846-866. DOI:10.1134/S0965545X11090148 · 0.88 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 08/2011; 53(8):733-743. DOI:10.1134/S0965545X11080037 · 0.88 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 04/2011; 53(4):344-353. DOI:10.1134/S0965545X11040031 · 0.88 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. DOI:10.1103/PhysRevLett.105.128302 · 7.73 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 07/2010; 52(7):761-774. DOI:10.1134/S0965545X10070102 · 0.88 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 03/2010; 52(3):317-327. DOI:10.1134/S0965545X10030144 · 0.88 Impact Factor
  • 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 02/2010; 52(2):182-190. DOI:10.1134/S0965545X10020124 · 0.88 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; 42(19). DOI:10.1021/ma900204u · 5.93 Impact Factor
  • M. K. Krotova, V. V. Vasilevskaya, A. R. Khokhlov
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    ABSTRACT: The effect of a low-molecular-mass salt on the thermodynamic stability of stoichiometric interpolymer complexes composed of oppositely charged macromolecules with different solvent affinities has been theoretically studied. It has been shown that the dissociation of such complexes with an increase in the concentration of the salt proceeds via several stages. At a low concentration of the salt, complexes retain their structure and dimensions. When a certain critical concentration of the salt n scr is achieved, the dimensions of the complex increase abruptly. At this concentration, macromolecules involved in the complex begin to separate, and at concentration n s*, they fully move apart but remain soluble owing to the polyelectrolyte effect. Upon a further increase in the concentration of the salt, the polyelectrolyte effect is shielded and the dimensions of macromolecules decrease. The critical concentration of the low-molecular-mass salt, n scr, increases with an increase in the degree of ionization of macromolecules and a decrease in the affinity of the hydrophilic component for water and diminishes with the degree of polymerization of macromolecules and the degree of hydrophobicity of a polycation. Because of the easy formation of soluble complexes from oppositely charged macromolecules differing in solvent affinities and their high stability in solutions of a low-molecularmass salt, such complexes are promising for wide use in medicine and pharmaceutical practice.
    Polymer Science Series A 10/2009; 51(10):1075-1082. DOI:10.1134/S0965545X09100046 · 0.88 Impact Factor
  • 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 04/2009; 51(4):424-429. DOI:10.1134/S0965545X09040087 · 0.88 Impact Factor

Publication Stats

922 Citations
149.55 Total Impact Points

Institutions

  • 1994–2013
    • Russian Academy of Sciences
      • Institute of Organoelement Compounds
      Moskva, Moscow, Russia
  • 2005
    • Russian Academy of Medical Sciences
      Moskva, Moscow, Russia
  • 2002
    • Karpov Institute of Physical Chemistry
      Moskva, Moscow, Russia
  • 2001
    • University of Groningen
      Groningen, Groningen, Netherlands
  • 1989–2000
    • Lomonosov Moscow State University
      • • Division of Physics
      • • Faculty of Physics
      Moskva, Moscow, Russia
  • 1995–1997
    • Nagoya University
      • School of Informatics and Sciences
      Nagoya, Aichi, Japan