Description
"Optical interference microscopy is a valuable tool for label-free visualization of biological cells. Recent advances in interferometric scattering (iSCAT) microscopy have enabled the observation of nanoscopic objects and cellular structures by detecting their linear scattering light through interference. While the importance of stable and strong illumination photon flux for reducing photon noise is well recognized, the impact of light coherence has been largely overlooked. Higher spatial and temporal coherence facilitates sustained interference, enhancing high-contrast detection of nanoscopic objects. However, excessive coherence can introduce noise, such as speckles and fringes, which may reduce spatial resolution in complex three-dimensional samples like biological cells. Optimizing illumination coherence is thus crucial for high-performance iSCAT microscopy.
In this work, we optimized the coherence properties of the light source for iSCAT imaging, targeting applications in interferometric nanoparticle tracking analysis (iNTA) and mass photometry. By carefully selecting parameters of spatiotemporal coherence, we improved signal sensitivity and minimized background noise. These adjustments enabled us to accurately track nanoparticles and detect individual biomolecules, leveraging the single-molecule sensitivity of iSCAT. This technique also benefits from minimal sample preparation, requiring only small sample volumes, which is advantageous for both iNTA and mass detection applications. Additionally, our system facilitating the observation of rapid cell dynamics at the nanoscale. This enhancement allows for the visualization of key cellular processes and interactions, contributing to a deeper understanding of biological functions.
In summary, optimizing light coherence in iSCAT microscopy significantly advances its application in nanoparticle tracking and mass detection, while also supporting high-resolution imaging of cellular dynamics with minimal sample preparation.
Keywords: interferometric scattering microscopy, spatial coherence, cell dynamics, nanoparticle, nanoparticle tracking analysis, label-free imaging"
