Fluorescence imaging typically involves tagging components of a sample with matched fluorophores, then measuring the fluorescence intensity of the sample when it is stimulated with an excitation source. Fluorescence lifetime imaging microscopy (FLIM) is a technique whereby the decay time of a fluorescence signal is used, instead of its intensity. While this adds a layer of complexity and cost, it can be a much more reliable method of obtaining information about the the cell's microenvironment. For instance, when a fluorophore is in close proximity to another molecule, Förster resonant energy transfer (FRET) occurs. In the FRET process, a fluorophore transfers its energy (which would normally be fluoresced) to the nearby molecule. This acts to quench the fluorescence lifetime, causing it to be shorter than the fluorophore's usual lifetime decay. Measuring the lifetime of the fluorophore can then be an excellent indicator of protein-protein interaction.

I am prototyping a high-throughput high content microscope system that implements FLIM for use in drug discovery systems. The system is being optimized for speed to match high-throughput standards, as well as high spatial and temporal resolution.

Tsikouras, A., Ning, J., Ng. S., Sinclair, P., Berman, R., Andrews, D.W., Fang, Q. (2012) Streak camera crosstalk reduction using a multiple delay optical fiber bundle. Optics Letters. 37: 250-252.

Tsikouras, A. (2014), “Designing a scanning system for multiplexed confocal FLIM microscopy using refractive window tilting,” Society of Biomolecular Imaging and Informatics 1. Tsikouras, A., Yeh, S.C., Fang, Q. (2014), “Instrumentation design for high-speed FLIM for applications in high-content screening,” Electrochemical Society Meeting 225, 1487.
Tsikouras, A., Ning, J., Ng. S., Sinclair, P., Berman, R., Andrews, D.W., Fang, Q. (2012), High-throughput FLIM-FRET nanoimaging for quantification of protein-protein interactions in high-content screening [oral presentation]. SPIE Optics + Photonics (conference). 8460-04.

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