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Förslaget inkom 2006-09-04

Diploma work on determination of diffusion rates directly in the microscope using fluorescence recovery after photobleaching (FRAP)

The morphology at different length scales ranging from nanometres to micrometers of different materials is of great importance for their diffusion properties. Examples of such properties are diffusion of water soluble compounds, release of active compounds like drugs or antioxidants, water uptake, molecular exclusion in chromatography, barrier properties, texture, rheological properties and taste release. Important applications can be found within pharmaceuticals, foods, hygiene, biomaterials and biotechnology.

Recently, new techniques have made it possible to measure the diffusion rate directly in the microscope. Microscopes can be equipped with the feature to bleach arbitrary regions in the sample. When the bleaching region is defined in the software, the microscope scans the laser beam over the sample in a raster pattern while modulating the beam intensity according to the designed pattern. Up to date, the subsequent evaluation of the FRAP data is mostly based on the time-dependent variation of the mean intensity of the bleached spot or the variations of the intensity at the centre of the bleached spot. The proposed diploma work focus on the possible improvements that can be achieved if the time-dependent concentration profile in the bleached spot and the effect of polydispersity of the diffusing molecules are included in the FRAP evaluation model. Initial encouraging tests of a FRAP experiment where the averaged radial concentration profile is measured and fitted to the solution of the diffusion equation have been performed.

The diploma work involves application of the latest FRAP models but also development of new models. It is good if the applicant has an interest of mathematics, image processing or physics. The diploma work will be supervised by Mats Rudemo at Mathematical Statistics and Niklas Lorén at SIK, and it forms a part of a large SSF project called ¿structure and mobility in heterogeneous systems¿. If you are interested please contact Mats Rudemo, [email protected], 031 ¿ 772 35 75 or Niklas Lorén, [email protected], 031 ¿ 335 13 14 for further information.


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