Final Report Summary - LIGHTTOUCH (Feeling with Light – Development of a multimodal optofluidic platform for high-content blood cell analysis) The overall objective of this project was to harness the advantages of high-throughput, FACS-like analysis and marry it with innovative photonic approaches for advanced functional and structural, high-content analysis. The goal was the development of a multimodal, microfluidic, laser trap-assisted cell screening platform technology – µFLAX. Cells in suspension are flowed through a microfluidic lab-on-a-chip system and serially trapped and immobilized by a dual-beam laser trap. Once held stationary in the optical trap, the cell can be analyzed for many different biochemical, mechanical and structural parameters until it is sufficiently characterized. Main innovation was the use of cell mechanical properties as a sensitive, inherent cell marker, combination of quantitative phase microscopy with microfluidic delivery for marker-free structural analysis, reliable fluorescence microscopy on suspended cells, and the use of an optical trap for contact-free cell rotation enabling single-cell tomography. We have essentially completed, and even exceeded, the deliverables set in all work packages, and have combined the individual parts into one synergistic platform technology. Specifically, we have improved the theoretical modeling of forces and deformations of cells in the optical stretcher, have upgraded the microfluidic chip to be made of glass and to provide the possibility for sorting, have implemented fluorescence detection and imaging, have incorporated quantitative phase imaging, have established contact-free cell rotation and single-cell refractive index tomography, and have implemented temperature control by using different laser sources. This constitutes the delivery on the original premise of µFLAX – a multimodal, microfluidic, laser trap-assisted cell screening platform technology. Apart from these technological advances, we have demonstrated the utility of µFLAX by elucidating the contribution of Ect2 to the mitosis of cells, showing that the refractive index of cell nuclei, contrary to wide-spread opinion, is lower than that of the cytoplasm, and identified the origin of remarkable temperature responses of cells and nuclei, to name but few. We have also firmly established the mechanical fingerprint of blood cells upon activation and infection, using both µFLAX but also a recently developed high-throughput method called real-time deformability cytometry. The latter provides throughput 4-6 orders of magnitude higher than µFLAX, and is thus much better suited for the clinical applications originally envisioned. In summary, the project has achieved all of its objectives, and in addition, has gone much beyond its foreseeable scope by the utilization of newly developed technology.
