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1.
Molecules ; 28(15)2023 Jul 31.
Article in English | MEDLINE | ID: mdl-37570760

ABSTRACT

The interaction between macromolecular chains and phospholipid membranes in aqueous solution was investigated using dissipative particle dynamics simulations. Two cases were considered, one in which the macromolecular chains were pulled along parallel to the membrane surfaces and another in which they were pulled vertical to the membrane surfaces. Several parameters, including the radius of gyration, shape factor, particle number, and order parameter, were used to investigate the interaction mechanisms during the dynamics processes by adjusting the pulling force strength of the chains. In both cases, the results showed that the macromolecular chains undergo conformational transitions from a coiled to a rod-like structure. Furthermore, the simulations revealed that the membranes can be damaged and repaired during the dynamic processes. The role of the pulling forces and the adsorption interactions between the chains and membranes differed in the parallel and perpendicular pulling cases. These findings contribute to our understanding of the interaction mechanisms between macromolecules and membranes, and they may have potential applications in biology and medicine.


Subject(s)
Mechanical Phenomena , Phospholipids , Macromolecular Substances , Membranes , Molecular Conformation
2.
Membranes (Basel) ; 11(9)2021 Aug 26.
Article in English | MEDLINE | ID: mdl-34564472

ABSTRACT

We investigate the phase behavior of the asymmetric lipid membranes under shear flows, using the dissipative particle dynamics simulation. Two cases, the weak and strong shear flows, are considered for the asymmetric lipid microstructures. Three typical asymmetric structures, the membranes, tubes, and vesicle, are included in the phase diagrams, where the effect of two different types of lipid chain length on the formation of asymmetric membranes is evaluated. The dynamic processes are demonstrated for the asymmetric membranes by calculating the average radius of gyration and shape factor. The result indicates that different shear flows will affect the shape of the second type of lipid molecules; the shape of the first type of lipid molecules is more stable than that of the second type of lipid molecules. The mechanical properties are investigated for the asymmetric membranes by analyzing the interface tension. The results reveal an absolute pressure at the junctions of different types of particles under the weak shear flow; the other positions are almost in a state of no pressure; there is almost no pressure inside the asymmetric lipid membrane structure under the strong shear flow. The findings will help us to understand the potential applications of asymmetric lipid microstructures in the biological and medical fields.

3.
Polymers (Basel) ; 12(12)2020 Dec 17.
Article in English | MEDLINE | ID: mdl-33348889

ABSTRACT

In this work, the interactions between bottlebrush polymers and phospholipid membranes were investigated using dissipative particle dynamics simulations. The weak and strong adsorption phenomena between the polymers and membranes were examined by calculating the system parameters. A spring model was introduced to explain the variances in the shape factors and the radius of gyration of the bottlebrush polymers, as well as the order parameters of the phospholipid membrane in the pulling processes. This work provides further understanding for the application of bottlebrush polymers in biological processes.

4.
RSC Adv ; 10(41): 24521-24532, 2020 Jun 24.
Article in English | MEDLINE | ID: mdl-35516199

ABSTRACT

Asymmetric phospholipid microstructures, such as asymmetric phospholipid membranes, have potential applications in biological and medicinal processes. Here, we used the dissipative particle dynamics simulation method to predict the asymmetric phospholipid microstructures in aqueous solutions. The asymmetric phospholipid membranes, tubes and vesicles are determined and characterized by the chain density distributions and order parameters. The phase diagrams are constructed to evaluate the effects of the chain length on the asymmetric structure formations at equilibrium states, while the average radius of gyration and shape factors are calculated to analyze the asymmetric structure formations in the non-equilibrium processes. Meanwhile, we predicted the mechanical properties of the asymmetric membranes by analyzing the spatial distributions of the interface tensions and osmotic pressures in solutions.

5.
J Chem Phys ; 149(24): 244901, 2018 Dec 28.
Article in English | MEDLINE | ID: mdl-30599738

ABSTRACT

Shear-induced microstructures and their phase diagrams were investigated for phospholipid molecules in aqueous solution by dissipative particle dynamic simulation. Self-assembled microstructures, including spherical and cylindrical micelles, spherical vesicles, lamellae, undulated lamellae, perforated lamellae, and continuous networks, were observed under various shear flows and phospholipid concentrations, where the spatial inhomogeneity and symmetry were analysed. A series of phase diagrams were constructed based on the chain lengths under various phospholipid concentrations. The phase distributions showed that the structures with spherical symmetry could be shear-induced to structures with cylindrical symmetry in the dilute solutions. In the semi-concentrated solutions, the lamellae were located in most spaces under zero shear flows, which could be shear-induced into undulated lamellae and then into cylindrical micelles. For the concentrated solutions, the strong shear flows oriented the directions of multilayer lamellae and phase transitions appeared between several cylindrical network structures. These observations on shear-induced microstructures and their distributions revealed a promising approach that could be used to design bio-microstructures based on phospholipid molecules under shear flows.


Subject(s)
Phase Transition , Phospholipids/chemistry , Micelles , Models, Chemical , Molecular Dynamics Simulation , Molecular Structure
6.
Polymers (Basel) ; 10(6)2018 May 28.
Article in English | MEDLINE | ID: mdl-30966624

ABSTRACT

The effect of the polymer chain topology structure on the adsorption behavior in the polymer-nanoparticle (NP) interface is investigated by employing coarse-grained molecular dynamics simulations in various polymer-NP interaction and chain stiffness. At a weak polymer-NP interaction, ring chain with a closed topology structure has a slight priority to occupy the interfacial region than linear chain. At a strong polymer-NP interaction, the "middle" adsorption mechanism dominates the polymer local packing in the interface. As the increase of chain stiffness, an interesting transition from ring to linear chain preferential adsorption behavior occurs. The semiflexible linear chain squeezes ring chain out of the interfacial region by forming a helical structure and wrapping tightly the surface of NP. In particular, this selective adsorption behavior becomes more dramatic for the case of rigid-like chain, in which 3D tangent conformation of linear chain is absolutely prior to the 2D plane orbital structure of ring chain. The local packing and competitive adsorption behavior of bidisperse matrix in polymer-NP interface can be explained based on the adsorption mechanism of monodisperse (pure ring or linear) case. These investigations may provide some insights into polymer-NP interfacial adsorption behavior and guide the design of high-performance nanocomposites.

7.
Phys Chem Chem Phys ; 18(15): 10309-19, 2016 Apr 21.
Article in English | MEDLINE | ID: mdl-27020849

ABSTRACT

We investigated the phase diagrams of diblock copolymers in external electrostatic fields by using real-space self-consistent field theory. The lamella, cylinder, sphere, and ellipsoid structures were observed and analyzed by their segment distributions, which were arranged to two types of phase diagrams to examine the phase behavior in weak and strong electric fields. One type was constructed on the basis of Flory-Huggins interaction parameter and volume fraction. We identified an ellipsoid structure with a body-centered cuboid arrangement as a stable phase and discussed the shift of phase boundaries in the electric fields. The other type of phase diagrams was established on the basis of the dielectric constants of two blocks in the electric fields. We then determined the regions of ellipsoid phase in the phase diagrams to examine the influence of dielectric constants on the phase transition between ellipsoidal and hexagonally packed cylinder phases. A general agreement was obtained by comparing our results with those described in previous experimental and theoretical studies.

8.
Eur Phys J E Soft Matter ; 32(1): 103-7, 2010 May.
Article in English | MEDLINE | ID: mdl-20524028

ABSTRACT

The presence of highly regular secondary structure motifs in protein structure is a fascinating area of study. The secondary structures play important roles in protein structure and protein folding. We investigate the folding properties of protein by introducing the effect of secondary structure elements. We observed the emergence of several structures with both large average energy gap and high designability. The dynamic study indicates that these structures are more foldable than those without the effect of secondary structures.


Subject(s)
Protein Folding , Proteins/chemistry , Models, Molecular , Protein Structure, Secondary , Temperature , Thermodynamics
9.
Phys Rev E Stat Nonlin Soft Matter Phys ; 72(4 Pt 1): 041912, 2005 Oct.
Article in English | MEDLINE | ID: mdl-16383425

ABSTRACT

We investigate the folding behavior of protein sequences by numerically studying all sequences with a maximally compact lattice model through exhaustive enumeration. We get the prionlike behavior of protein folding. Individual proteins remaining stable in the isolated native state may change their conformations when they aggregate. We observe the folding properties as the interfacial interaction strength changes and find that the strength must be strong enough before the propagation of the most stable structures happens.


Subject(s)
Models, Chemical , Models, Molecular , Multiprotein Complexes/chemistry , Prions/chemistry , Amino Acid Sequence , Binding Sites , Computer Simulation , Dimerization , Molecular Sequence Data , Multiprotein Complexes/ultrastructure , Prions/analysis , Protein Binding , Protein Conformation , Protein Folding , Sequence Analysis, Protein
10.
Phys Rev E Stat Nonlin Soft Matter Phys ; 72(2 Pt 1): 021904, 2005 Aug.
Article in English | MEDLINE | ID: mdl-16196601

ABSTRACT

We study the medium effects on the selection of sequences in protein folding by taking into account surface potential in hydrophobic-polar model. Our numerical calculation demonstrates that the surface potential enhances the average gap for the highly designable structures. It also shows that the most stable structure may be no longer the most stable one if the medium is changed.


Subject(s)
Culture Media/chemistry , Models, Chemical , Models, Molecular , Sequence Analysis, Protein/methods , Solvents/chemistry , Amino Acid Sequence , Computer Simulation , Molecular Sequence Data , Protein Conformation , Protein Folding , Solutions , Structure-Activity Relationship
11.
Phys Rev E Stat Nonlin Soft Matter Phys ; 71(6 Pt 1): 061202, 2005 Jun.
Article in English | MEDLINE | ID: mdl-16089726

ABSTRACT

We investigate the heat conduction in a quasi-one-dimensional gas model with various degrees of chaos. Our calculations indicate that the heat conductivity kappa is independent of system size when the chaos of the channel is strong enough. The different diffusion behaviors for the cases of chaotic and nonchaotic channels are also studied. The numerical results of divergent exponent alpha of heat conduction and diffusion exponent beta are consistent with the formula alpha = 2 - 2/beta. We explore the temperature profiles numerically and analytically, which show that the temperature jump is primarily attributed to superdiffusion for both nonchaotic and chaotic cases, and for the latter case of superdiffusion the finite size affects the value of beta remarkably.

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