Liquid crystalline materials have been shown to be an excellent host matrix enabling the easy observation of bacteria movements. In some cases, even the high sensitivity of such matrix was used to control materials’ properties by bacteria. Motivated by the key role played by bacteria in the health and food industries, our group is working on the development of dynamic micro control techniques by using photosensitivity of azobenzene or DSCG molecules. We think that the capability to control their movement may be useful for many applications, and, in the present work, we explore the possibility of such active control of the movement of flagellated bacteria (a bacterium that can swim thanks to the rotation of its helix). We demonstrate that we can dynamically change the swimming direction of bacteria by incorporating them into a liquid crystal where the phase transition is locally controlled by UV illumination. We shall also mention briefly about other types of control (magnetic, isomeriz)
Azobenzene molecules have attracted important interest for photodynamic drug release and therapy applications. Often, their impact on the environment is directly associated to the photoinduced mechanical deformation of the molecule (when transferring from its Trans form to the Cis form). In the present talk, we demonstrate that the chemical impact of this transformation (pH, toxicity, etc.) also must be considered. We shall describe our work on the development of an optical control method of biological membranes based on the photoisomerization process. On the example of E-coli bacteria, we shall show that the isomerization process can indeed be used to control their behavior, but the changes in pH and toxicity are also playing important roles. Interestingly, while there are still many open questions, our preliminary results point out on the possibility of controlling protonic pump channels in a selective way.
We shall describe our work on the development of an optical control method based on the destabilization of biological membranes. As a destabilization agent, we explore the use of an azobenzene molecule that has both hydrophobic and hydrophilic ends. Our working hypothesis is based on the photo induced microscopic volume changes that can be obtained as a result of photo isomerization of azobenzene molecules inside the membrane. The current results, challenges and possible avenues will be presented and discussed.
Several experimental approaches are explored to introduce the E. coli bacteria in a liquid anisotropic host. Fonctionalization of the bacterial surface is experimented with 2 different molecules. The 5CB is first used as host and it is shown that, while the bacteria survive at short term in such an environment, they aggregate into colonies. Water solution of the cromolyn sodium salt is also explored with success and the time stability of corresponding sandwich-like structures is characterized.
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