The mechanism of biomembrane curvature generation has been studied for decades because of its role in many cellular functions. In this article, N-varied dissipative particle dynamics was used to investigate the relationship between membrane curvature generation and self-assembly of anchored proteins, and a protein aggregation mechanism of curvature generation was proposed. According to the mechanism, the curvature production is enhanced by the self-assembly of proteins, and the enhancement depends on the protein hydrophobic length. Contrary to the theoretic predictions that shallow insertion depth of proteins is more effective in producing positive membrane curvature, our simulations show the opposite trend if the self-assembly of proteins is taken into account. Furthermore, for the membrane proteins with deep insertion, simulations indicate that the self-assembly of proteins may induce membrane vesiculation at negative membrane tensions. In addition, the protein aggregates can sense the membrane curvature, although the way they respond to the local curvature again depends on the protein hydrophobic length. Especially, the self-assembly of shallow inserting proteins is significantly affected by the local membrane curvature.

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In this work, the kinetic process of collision-driven solute exchange in an aqueous phase in which micelles are used as solute carriers is investigated by dissipative particle dynamics simulations. Here, we try to answer two questions about the exchange process of hydrophobic solute molecules: How the solute molecules are exchanged and what factors affect the process. For the first question, the simulation results indicate that, after a stage of intermittent collision between two neighboring aggregates, there are roughly three sequential events in a coalescence stage: (1) molecular contact, (2) neck formation, and (3) neck growth. The coalescence stage is followed by a stage of solute transfer and diffusion. It is found that there are two rate-limiting steps in the whole process of solute exchange, i.e., the break of the water film between two neighboring aggregates and the nucleation of a pore between two surfactant films. For the second question, the effects of the collision velocity, the surface tension, the repulsive interaction between the surfactant films of the colliding aggregates, as well as the steric repulsion are examined. For example, the simulation results show that the depletion force plays an important role during the coalescence stage, while the initial collision velocity basically does not change the fusion ratio. The results also demonstrate that the surface tension and interaction show different effects on the different stages of a solute exchange process.

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Computer simulations were used to study the cluster formation of anchored proteins in a membrane. The rate and extent of clustering was found to be dependent upon the hydrophobic length of the anchored proteins embedded in the membrane. The cluster formation mechanism of anchored proteins in our work was ascribed to the different local perturbations on the upper and lower monolayers of the membrane and the intermonolayer coupling. Simulation results demonstrated that only when the penetration depth of anchored proteins was larger than half the membrane thickness, could the structure of the lower monolayer be significantly deformed. Additionally, studies on the local structures of membranes indicated weak perturbation of bilayer thickness for a shallowly inserted protein, while there was significant perturbation for a more deeply inserted protein. The origin of membrane-mediated protein-protein interaction is therefore due to the local perturbation of the membrane thickness, and the entropy loss-both of which are caused by the conformation restriction on the lipid chains and the enhanced intermonolayer coupling for a deeply inserted protein. Finally, in this study we addressed the difference of cluster formation mechanisms between anchored proteins and transmembrane proteins.

Developing multifunctional wound dressings, possessing not only skin-like mechanical properties and adaptability, long-lasting moisture, and temperature tolerance that maximally mimics the human skin but also on-demand adhesion without unnecessary bleeding and secondary damage upon peeling, is necessary but remains a challenge. Herein, a novel dual cross-linked and multifunctional hydrogel, termed PSNC hydrogel for polymerized sulfobetaine methacrylate (SBMA), N-(2-amino-2oxyethyl)acrylamide (NAGA), and 1-carboxy-N-methyl-N-di(2methacryloyloxy-ethyl)methanaminium inner salt (CBMAX), was fabricated as a wound dressing for burn injuries via one-pot radical polymerization in glycerine (GLY)/H 2 O solvent. The dual crosslinked network of the PSNC hydrogel combined the double hydrogen bonding of N-(2-amino-2-oxyethyl)acrylamide (NAGA) with a covalently cross-linked zwitterionic network, endowing the hydrogel with skin−like mechanical properties with a high stretchability of 1613.8 ± 79.8%, a tensile strength of 77.5 ± 1.8 kPa, and a tensile modulus of 1.9 ± 0.1 kPa. Moreover, the hydrogel with well-developed adaptability can withstand skin deformation without breaking or debonding attributed to its good tissue adhesiveness and self-healing ability. Further, the utilization of the GLY/H 2 O binary solvent effectively prevented the crystallization and evaporation of free water, endowing the hydrogel with not only longlasting moisture but also excellent temperature tolerance in a wide range from −20 to 60 °C. More importantly, the PSNC hydrogel could effectively accelerate wound healing of burn injuries and could be easily removed on-demand with saline without causing secondary damage due to intense hydration. Such a novel PSNC zwitterionic hydrogel could be a promising candidate for the treatment of burn wounds and tissue regeneration.

Due to environmental disturbances such as local human activity and global warming, melting of massive ground ice has resulted in thermokarst ponds, which are extensively distributed in the Qinghai-Tibet Plateau (QTP). Besides the global warming, the thermokarst pond, as a major heat source, speeds up the moisture change and degradation of its surrounding permafrost. To analyze the long-term coupled moisture-heat process near a representative nonpenetrative thermokarst pond in a permafrost region, abundant temperature data over multiple years at different depths and horizontal distances from the center of the thermokarst pond have been collected at a field experimental station in QTP. A numerical model is built to analyze this thermokarst pond. The temperature and moisture processes of surrounding permafrost are simulated by this model and compared with measured temperature data. Our results show that if the rate of air temperature rise is 0.048°C/yr, which refers to a 2.4°C temperature rise over 50 years, the thawing fronts underneath the thermokarst pond move downward at a linear rate of 0.18 m/yr and the permafrost beneath the pond center would disappear after the year of 2281. Beyond that time, the impact range of the pond on the natural ground increases to about 50 m in horizontal direction. So a dish-shape thawing zone occurs around the thermokarst pond. Simultaneously, the moisture state is greatly changed in 2281 and becomes completely different from that in 2013. All of these would inevitably deteriorate the ecological and environmental system in QTP.