Ultrasensitive detection and tracking of nanoparticles on model lipid membrane systems by interferometric scattering microscopy

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In recent years, scientists have focused on methods to uncover the fundamental principles of life, with single particle tracking (SPT) emerging as a prominent technique. SPT enables the tracking of organelles and single molecules, aiding in the understanding of their roles within cellular machinery. This thesis investigates lipid diffusion, a key component of cell membranes, by tracking single gold nanoparticles (GNPs) attached to lipids in model membrane systems through interferometric scattering microscopy (iSCAT). This work achieves imaging speeds up to 1 MHz and localization precision within a few nanometers, significantly exceeding current fluorescence-based methods. Additionally, it successfully detects GNPs as small as 5 nm in diameter, addressing concerns about the impact of labeling on molecular motion. iSCAT offers a precise measurement strategy for lipid diffusion studies. Model membranes, which provide a controlled environment, are utilized to explore membrane phenomena. This research includes detailed characterization of supported lipid bilayers (SLBs), pore-spanning membranes (PSMs), and giant unilamellar vesicles (GUVs), specifically examining the diffusion of DOPE lipids in a DOPC lipid membrane across all three systems. The experimental and analytical techniques developed here lay the groundwork for future investigations into various biomedical and biophysical questions.