Photoresponsive ion extraction/release systems (PRIONERS)

The goal of this project is the development of a universal tool for a photo-triggered extraction or release of small ionic species from a polymeric matrix, with an eventual application in cells. Initially, we will establish methods required for both irreversible and reversible extraction/release systems. Later, a successful first stage will lead to novel optical sensor concepts. In conclusion, we aim to achieve a sound foundation on which the coming years of research in this field will be built. The first part of the project will focus on the design of irreversible PRIONERS based on decomposing photoactive compounds (PACs). We will show that a complex of a charged dye and an oppositely charged PAC (i.e. a photoacid generator) will be destroyed by UV light and allow the triggered release of the dye, thereby visualizing the triggered release of charged species from a polymeric matrix. The next step is to extend the system to visible light excitation using photosensitizers. Finally, specificity for the ion-exchange will be introduced using ionophores and the ion extraction will be demonstrated using Ca2+ as a model ion. As part of this task we will establish particle casting methods for different particle sizes and properties. Employing PACs that are neither decomposed nor irreversibly converted upon illumination while still being able to attract or release protons depending on their state will convert one-way PRIONERS into dynamic, regenerative systems. As a first step to realize this task, we will establish a method for measuring the illumination-dependent pKa value of compounds and evaluate several spiropyran and azo-derivatives using a custom-made flow-cell. After identifying compounds with large pKa shift upon illumination in a polymer matrix, further optimizations and enhancements will be realized by finding the best PAC/ion-exchanger ratio, by including ionophores for selective ion-exchange properties and by analytical characterization of the photoswitching process, i.e. reproducibility, photostability and reversibility. Finally, the best performing compounds will be incorporated into particles and used for reversible extraction/release studies employing 3D optical calcium imaging methods. The return phase will focus on the development of advanced, dynamic optical ion sensors based on the results from the first stage of the project. A dynamic change of the equilibrium curve in optical ion sensors allows previously unimaginable sensor designs. As an example we will develop an optical ion sensor that can be switched on and off dynamically using light.

No additional funding sources recorded.