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SUMMARY:A microfluidic diffusion chamber for the analysis of soft biologic
 al matter - Professor Jure Derganc\, Institute of Biophysics\, University 
 of Ljubljana\, Slovenia
DTSTART:20150522T130000Z
DTEND:20150522T140000Z
UID:TALK58943@talks.cam.ac.uk
CONTACT:Dr Eileen Nugent
DESCRIPTION:Controlled exchange of solution around soft biological samples
  (e.g.\, cells\, lipid vesicles\, protein particles...) is a challenging t
 ask: hydrodynamic flows associated with the solution exchange can irrevers
 ibly deform the sample or simply flush it away. We have therefore develope
 d a microfluidic diffusion chamber where the solution exchange is accompli
 shed solely on the basis of diffusion. The sample is transferred into the 
 chamber by optical tweezers and analysed under a standard optical microsco
 pe. In this talk I will describe the design of the chamber and show that t
 he flow velocity in the chamber decays exponentially with the distance fro
 m its entrance\, leaving its back part effectively flow-free. Also\, we fi
 nd that above a critical height/width ratio of the chamber\, a vortex emer
 ges at the chamber entrance. I will then show two applications of the diff
 usion chamber for soft biological samples. First\, I will present reversib
 le intercalation of LPS (lipopolysaccharide) into the membrane of flaccid 
 giant lipid vesicles and subsequent changes of vesicle shapes. Second\, I 
 will show the reversible response of large protein aggregates (protein par
 ticles) to changes in pH\, ionic strength\, urea or sugar concentration\, 
 which shed light on the nature of interactions within the aggregate.
LOCATION:Small Lecture Theatre\, Cavendish Laboratory
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