Chemotaxis is defined as an oriented movement along a chemical gradient. Biological chemotaxis is crucial for any living organism, because it represents its ability to locate sources of nutrition and to move towards them. In our present case, we study a non-biological system, where decanol droplets move on a glass substrate, which is covered by a thin layer of sodium decanoate. The droplets exhibit the ability to move towards local additions of NaCl.
The parametric dependence of the chemotactic response with respect to background concentration of sodium decanoate and the strength of the NaCl concentration gradient has been mapped. Several scenarios that utilize chemotaxis - namely migration over a non-linear path, delivery of a chemically reactive cargo, selection of the direction of motion according to the strength of the chemoattractant source, and temperature-triggered release of the chemoattractant - have been demonstrated.
Present poster focuses on experiments and theoretical models that could help us to determine, which forces are primarily responsible for the phenomena of chemotaxis in our respective system. There are few hypotheses, one of them suggests the movement may primarily be caused by convective flows, induced by surface tension gradient and Marangoni effect (the mass transfer along an interface between two fluids towards regions of higher surface tension). Another is based on interaction of droplet with the substrate and the droplet shape changes in concentration gradient (meaning the difference between its advancing and receding angle on a solid surface). In present poster, these and other hypotheses will be discussed.
novakma@vscht.cz
