New extraordinary methods for simulation of Brownian motion in biological gels

Diffusion is one important transport mechanism in many materials used by man. The rate by which a molecule diffuses through a certain material is determined to a large extent by the structure of the material. The relevant lengths-scales, depending on the type of material and application, may be in the nano- or micrometer range. Knowledge about the intrinsic coupling between diffusion rate and morphology is important in many applications; release of drugs or antioxidants in medicine or functional foods, water uptake in biological systems, molecular separation in liquid chromatography, barrier properties in various packing materials, rheological properties and taste to mention just a few.

Diffusion may be described by a random motion process called Brownian motion. In a simple liquid the probability for a molecule to move in a certain direction is spatially uniform. However, if the motion is hindered by a physical constraint like a cell wall, membrane or polymer gel strand, the diffusion process is not so simple to describe analytically. This is why computer simulations are becoming more important every year as the computer power increase. This is a prerequisite to perform computer simulations at the length-scale required in order to understand how the surrounding structure influences the global diffusion rate of molecules in inhomogeneous materials.

In previous diploma works, Brownian dynamic simulations of diffusion of small molecules in a 3D biopolymer gel structure (see the figure above) have been performed. The results have been compared with experimental results obtained by NMR Diffusometry to verify that the simulations are performed correctly. This diploma work involves Monte Carlo simulations of larger molecules in a 3D biopolymer gel structure and introduction of interactions between the diffusing molecules and the surrounding gel matrix using a novel method for Brownian motion simulations.

The applicant should have an interest in mathematics, computer programming or statistical physics. The diploma work will be supervised by Mats Kvarnström at the Fraunhofer-Chalmers Centre and by Niklas Lorén at the Swedish Institute for Food and Biotechnology (SIK). Examiner will be Magnus Nydén at the department of Applied Surface Chemistry at Chalmers. If you are interested please contact Mats Kvarnström, 031-7724264, [email protected], Magnus Nydén, 031 – 772 29 73, [email protected], or Niklas Lorén, [email protected], 031 – 335 13 14 for further information.