Janus or homogeneous nanoparticle mediated self-assembly of polymer electrolyte fuel cell membranes

Adhesion dynamics of Janus nanocarriers to endothelial cells: A dissipative particle dynamics study

Janus nanocarriers (NCs) provide promising features in interfacial applications such as targeted drug delivery. Herein, we use dissipative particle dynamics simulations to study the adhesion dynamics of NCs with Janus ligand compositions to the endothelial cell as a function of a series of effects, such as the initial orientation, ligand density, shape, and size of Janus NCs. The Janus NCs, with its long axis parallel to the endothelial glycocalyx (EG) layer, has the best penetration depth due to its lower potential energy and the lowest shell entropy loss. Among different shapes of Janus NCs, both the potential energy and the EG entropy loss control the penetration. In fact, at the parallel orientations, Janus shapes with a robust mechanical strength and larger surface area at the EG/water interface can rotate and penetrate more efficiently. An increase in the ligand density of Janus NCs increases entropy losses of both the hydrophilic and the hydrophobic ligands and decreases the potential energy. Thus, for a specific Janus NCs, functionalizing with an appropriate ligand density would help driving forces prevail over barriers of penetration into the EG layer. For a particular ligand density, once the radius of the Janus NCs exceeds the appropriate size, barriers such as hydrophobic ligands and shell entropy losses are also reinforced significantly and surpass driving forces. Our observations reveal that entropy losses for hydrophobic ligands of Janus NCs and for the shell of NCs are decisive for the adhesion and penetration of Janus NCs to endothelial cells.

Adhesion dynamics of functionalized nanocarriers to endothelial cells: a dissipative particle dynamics study

Targeted drug delivery to endothelial cells utilizing functionalized nanocarriers (NCs) is an essential procedure in therapeutic and diagnosis therapies. Using dissipative particle dynamics simulation, NCs have been designed and combined with an endothelial environment, such as the endothelial glycocalyx (EG) layer, receptors, water, and cell wall. Furthermore, the energy landscapes of the functionalized NC with the endothelial cell have been analyzed as a function of properties such as the shape, size, initial orientation, and ligand density of NCs. Our results show that an appropriate higher ligand density for each particular NC provides more driving forces than barriers for the penetration of the NCs. Herein we report the importance of shell entropy loss for the NC shape effect on the adhesion and penetration into the EG layer. Moreover, the rotation of the disc shape NC as a wheel during the penetration is an extra driving force for its further inclusion. By increasing the NCs' size larger than the appropriate size for each particular ligand density, due to an increase in the NCs' shell entropy loss, the barriers surpass the driving forces for NC penetration. Furthermore, the parallel orientation provides the NCs with the best penetration capabilities. However, the rotation of the disc shape NCs enhances their diffusion in the perpendicular orientation too. Overall, our findings highlight the crucial role of the shell entropy loss in governing the penetration of NCs. Besides, studying NCs with a homogeneous ligand composition enabled us to cross barriers and probe energetics after the complete inclusion of the NCs.

DPD Modelling of the Self- and Co-Assembly of Polymers and Polyelectrolytes in Aqueous Media: Impact on Polymer Science

This review article is addressed to a broad community of polymer scientists. We outline and analyse the fundamentals of the dissipative particle dynamics (DPD) simulation method from the point of view of polymer physics and review the articles on polymer systems published in approximately the last two decades, focusing on their impact on macromolecular science. Special attention is devoted to polymer and polyelectrolyte self- and co-assembly and self-organisation and to the problems connected with the implementation of explicit electrostatics in DPD numerical machinery. Critical analysis of the results of a number of successful DPD studies of complex polymer systems published recently documents the importance and suitability of this coarse-grained method for studying polymer systems.

Dissipative particle dynamics simulations in colloid and Interface science: a review

Dissipative particle dynamics (DPD) is one of the most efficient mesoscale coarse-grained methodologies for modeling soft matter systems. Here, we comprehensively review the progress in theoretical formulations, parametrization strategies, and applications of DPD over the last two decades. DPD bridges the gap between the microscopic atomistic and macroscopic continuum length and time scales. Numerous efforts have been performed to improve the computational efficiency and to develop advanced versions and modifications of the original DPD framework. The progress in the parametrization techniques that can reproduce the engineering properties of experimental systems attracted a lot of interest from the industrial community longing to use DPD to characterize, help design and optimize the practical products. While there are still areas for improvements, DPD has been efficiently applied to numerous colloidal and interfacial phenomena involving phase separations, self-assembly, and transport in polymeric, surfactant, nanoparticle, and biomolecules systems.

Replica exchange dissipative particle dynamics method on threadlike micellar aqueous solutions

The self-assembly of surfactant molecules can spontaneously result in a variety of micelle morphologies, such as spherical micelles, threadlike micelles, and vesicles, and it is therefore crucial to predict and control the self-assembly to achieve a helpful process in the fields of materials chemistry and engineering. A dissipative particle dynamics (DPD) method used in a coarse-grained molecular simulation is applied to simulate various self-assembling soft matter systems because it can handle greater length and time scales than a typical molecular dynamics simulation (MD). It should be noted that the thorough sampling of a system is not assured at low temperatures because of large complex systems with coarse-grained representations. In this article, we demonstrate that the replica exchange method (REM) is very effective for even a DPD in which the energy barrier is comparatively lower than that of a MD. A replica exchange on DPD (REDPD) simulation for threadlike micellar aqueous solutions was conducted, and the values of the potential energy and the mean aggregation number were compared. As a result, the correct values and a self-assembled structure within a low-temperature range can only be obtained through the REDPD.

Mesoscopic simulation study on the structural transition of comb-shaped block copolymer lamellae on chemically patterned substrates: from vertical to lateral

Directed self-assembly of polymers on chemically homogeneous and heterogeneous patterns is of considerable interest for nanolithography and nanofluidic devices. By employing dissipative particle dynamics (DPD) technology, we explore the nanoscale phase separation of comb-like block copolymers (CBCPs) confined at chemically homogeneous and heterogeneous substrates. Herein, the geometric and energetic influences of striped substrates on the microphases are firstly studied using various geometries of annular stripes for the heterogeneous substrates. Different parameters including the stripe geometry, substrate selectivity, and film thickness are studied systematically. T-Junction lamellae and acclivitous alignment are achieved on the heterogeneous substrates because of the synergy of geometrical effects of the striped pattern from heterogeneous substrates together with weak preference of the substrates toward one of the CBCP components. In this study, we provide a detailed understanding of microphase separation of CBCPs on the heterogeneous substrates, and the approach outlined in the present study offers a crucial tool for experimentalists to design CBCP thin films with complex device-oriented structures.

Self-assembly of peptide amphiphiles by vapor pressure osmometry and dissipative particle dynamics

Peptide amphiphiles are one of the most promising materials in the biomedical field, so much effort has been devoted to characterizing the mechanism of their self-assembly and thermosensitive gelation. In this work, vapor pressure osmometry measurements were carried out to parameterize the thermosensitivity of interactions between peptide amphiphiles in an aqueous solution. The osmometry measurement verified that the peptides became more hydrophobic as temperature increased, which was quantitatively described with the Flory-Huggins χ parameter. Thereafter, a coarse-grained molecular model was used to simulate peptide amphiphiles dissolved in an aqueous solution. The temperature sensitive coarse-grained parameter a HW, which is the repulsive force between the hydrophilic head of the peptide amphiphile and water was estimated from the aforementioned experimentally obtained χ. Furthermore, the effects of concentration and temperature on the self-assembly behavior of peptide amphiphiles were quantitatively studied by dissipative particle dynamics. The simulation results revealed that a HW plays an important role in self-assembly characteristics and in the resulting microstructure of the peptide amphiphiles, which coincides with previous experimental and computational findings. The methodology in quantitatively linking the coarse-grained parameter from experiment and theory provides a sensible foundation for bridging future simulation studies with experimental work on macromolecules.