| Affiliation: | 1. School of Chemistry, Australian Centre for Astrobiology, and ARC CoE for Synthetic Biology, UNSW Sydney, Sydney, NSW, 2052 Australia
These authors contributed equally to this work.;2. School of Chemistry, Australian Centre for Astrobiology, and ARC CoE for Synthetic Biology, UNSW Sydney, Sydney, NSW, 2052 Australia;3. School of Physics, The University of Sydney, Sydney, NSW, 2006 Australia;4. School of Chemistry, The University of Sydney, Sydney, NSW, 2006 Australia |
| Abstract: | The hydrodynamic effects of macromolecular crowding inside cells are often studied in vitro by using polymers as crowding agents. Confinement of polymers inside cell-sized droplets has been shown to affect the diffusion of small molecules. Here we develop a method, based on digital holographic microscopy, to measure the diffusion of polystyrene microspheres that are confined within lipid vesicles containing a high concentration of solute. We apply the method to three solutes of varying complexity: sucrose, dextran, and PEG, prepared at ～7 % (w/w). We find that diffusion inside and outside the vesicles is the same when the solute is sucrose or dextran that is prepared below the critical overlap concentration. For poly(ethylene glycol), which is present at a concentration higher than the critical overlap concentration, the diffusion of microspheres inside vesicles is slower, hinting at the potential effects of confinement on crowding agents. |
