Detection of protein-protein interactions within biological nano-domains by single molecule programmable array microscopy

Fluorescence lifetime imaging (FLIM) is a sensitive tool to investigate protein-protein interactions in biology and may have some niche applications for early detection of cancer in liquid biospies. The gold-standard for such a technique is time-correlated single photon counting (TCSPC). For imaging, this has largely been exploited in laser scanning microscopy techniques. However, these imaging modalities are limited primarily by their particularly slow acquisition speeds compared to conventional imaging methodologies especially when the sample is sparse. We have developed a simple optical platform to exploit the sparseness of single molecule imaging and apply this to preliminary study of the heterodimer status of EGFR and HER3, in cell secreted vesicles (exosomes). In parallel we perform single EV trapping experiments with an ABEL trap to extend our spectroscopic analysis. We perform both fluorescence lifetime spectroscopy and SMLM on single exosomes in vitro to assess changes in the proclivity of heterodimer formation following Osimertinib treatment in lung cancer cells (H1975), which may elude to a possible functional role in cancer treatment resistance.