Linear and ring polypeptides complexed with oppositely charged surfactants: the cohesion of the complexes as revealed in atomistic simulations.

The use of linear supercharged unfolded polypeptides (SUPs) and oppositely charged surfactants in aqueous solution has demonstrated impressive adhesive properties. These substances possess biocompatibility, biodegradability and other necessary properties for practical application as a biomedical glue in wound repair. The success of these substances, coupled with limited knowledge about such systems, provides hope for enhancing the performance of the final product. One potential approach involves altering the topology of the polypeptide chain. In this article, we conduct a comparative analysis to examine the behavior of the ring and linear chains of a polypeptide in aqueous solution. This analysis utilizes full-atomic computer modeling to monitor the properties of the chains. We investigate the temperature dependence of the shape and size of individual polypeptides in the solution, as well as the formation of complexes via mixing the polypeptide chains with oppositely charged sodium dodecylbenzene sulfonate (SDBS) surfactant molecules in a stoichiometric ratio. Additionally, we explore the cohesive properties of the resulting complex through power experiments involving the extraction of single polypeptide chains out of the SUP-SDBS complexes.

Swelling, collapse and ordering of rod-like microgels in solution: Computer simulation studies.

Polymer microgels have proven to be highly promising macromolecular objects for a wide variety of applications. In particular, the soft particles of an anisotropic (rod-like) shape are of special interest because of their potential use in tissue engineering or materials design. However, a little is known about the physical behavior of such microgels in solution, which inspired us to study them using mesoscopic computer simulations. For single networks, depending on the solvent quality, the dimensional characteristics were obtained for microgels of different molecular weight, crosslinking density and aspect ratio. In particular, the conditions for the rod-to-rod (preserving the nonspherical shape) and rod-to-sphere collapse were found. In addition, the effect of the liquid-crystalline (LC) ordering was demonstrated for the ensemble of rod-like microgels at different swelling ratios, and the influence of microgel aspect ratio on the volume fraction of the LC transition was shown.