Combining mechanofluorochromism and microfluidics to detect forces on single microalgae cells – CHROMIC

The aim of the CHROMIC project is to develop new microfluidic circuits functionalized by mechanofluorochromic materials, i.e. materials whose fluorescence emission is sensitive to mechanical forces, then to use these new devices to measure the force exerted on a single microalgae passing through the circuit and finally to link the force applied in the microfluidic circuit to the increase in the extraction yield of the compounds produced by the microalgae. Our strategy for carrying out this multidisciplinary project is based on 4 stages. Firstly, mechanofluorochromic coatings will be prepared from polydiacetylene-fluorophore dyads, designed to combine versatile synthesis, high sensitivity to mechanical forces, high brightness and biocompatibility. Next, the response of these mechanofluorochromic coatings to friction forces will be calibrated using an AFM coupled to a fluorescence microscope: the tip of the AFM used in contact mode will apply a variable and controlled force, and the variation in the associated fluorescence emission will be recorded simultaneously. In the 3rd step, the microfluidic circuit will be optimised with a parallel architecture enabling a large number of microalgae to be analysed simultaneously, the size of the channels and restrictions will be adapted to study three species of microalgae of interest, and the associated image analysis protocol will be automated. Finally, three species of microalgae varying in size, rigidity and cell wall composition will be studied, and the mechanical force exerted by passage through the microfluidic restrictions, measured by mechanofluorochromism, will be correlated with the extraction yield of the compounds of interest. This project thus proposes a completely new approach to the measurement of forces at the scale of the single cell.