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Permeability maximization in fluctuating polymer networks

  • Date: May 17, 2018
  • Time: 11:00 - 12:00
  • Speaker: Won Kyu Kim, PhD
  • Institute for Soft Matter and Functional Materials, Helmholtz-Zentrum Berlin, Berlin, Germany
  • Location: Max-Planck-Institut für Dynamik und Selbstorganisation (MPIDS)
  • Room: Seminar Room 0.79
  • Host: MPIDS
  • Contact: ramin.golestanian@ds.mpg.de
Permeability, a measure of the ability of macromolecules` transport through crowded surroundings such as hydrogels, determines important control of response, feed back reaction, and diffusion of reactants therein. Living systems are abundant in biological hydrogels such as extracellular polymeric substances (EPS), nuclear pores, mucus gels, and extracellular matrixes (ECM), which are complex molecular assemblies composed of hydrated polymer network gels [1]. Permeability in living systems is of great importance since it enables selective barrier crossings in molecular transport. We develop a model of semi-flexible cross-linked polymer gel networks by means of extensive coarse-grained simulations and theory. The gel system consists of randomly formed tetra-functional network regions and also bulk regions where the macromolecular tracers diffuse in both regions, enabling a quantitative study of partitioning, diffusivity, and permeability. We found that permeability is maximized at the optimal polymer network density and inter-particle interactions between the networks and the macromolecular tracers. This nontrivial phenomenon is triggered by a competition between partitioning [2,3,4] and diffusion [3], which eventually leads to a self-organization of crowded systems. The gel undergoes a sharp collapse transition with changing network-network and network-tracer interactions [2,3]. Throughout a wide range of parameter space of the solvent quality, network-tracer coupling, and gel volume fraction, a rich topology of the partitioning landscape is found [2]. In addition, the macromolecule diffusivity inside the gel is highly correlated to the gel structural transitions, and in conjugation with the partitioning we obtain the permeability, which turns out to be a drastic nonmonotonic function in the parameter space. We also present a theory for the first time to show the permeability maximization of diffusive macromolecules in crowded systems. Finally, we discuss possible resonance-activation phenomena [6] in biomolecular transport through fluctuating biological hydrogels.

[1] J. Witten and K. Ribbeck, Nanoscale 9, 8080 (2017).
[2] W. K. Kim, A. M.-Jordá, R. Roa, M. Kanduč, and J. Dzubiella, Macromolecules 50, 6227 (2017).
[3] R. Roa, W. K. Kim, M. Kanduč, J. Dzubiella, and S. Angioletti-Uberti, ACS Catalysis 7, 5604 (2017).
[4] M. Kanduč, R. Chudoba, K. Palczynski, W. K. Kim, R. Roa, and J. Dzubiella, Phys. Chem. Chem. Phys. 19, 5906 (2017).
[5] S. Wu, J. Dzubiella, J. Kaiser, M. Drechsler, X. Guo, M. Ballauff, and Y. Lu, Angewandte Chemie 51, 2229 (2012).
[6] W. K. Kim, C. Hyeon and W. Sung, Proceedings of the National Academy of Sciences USA 109, 14410 (2012).
 
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