Fast, label free super resolution live cell imaging using rotating coherent scattering (ROCS) microscopy
Living cells are highly dynamic systems with cellular structures being often below the optical resolution limit. Super resolution microscopes, usually based on fluorescence cell labelling, are usually too slow to resolve small, dynamic structures. We present a label free microscopy technique, which can generate thousands of super resolved, high contrast images at a frame rate of 100 Hertz and without any post processing. The technique is based on oblique sample illumination with coherent light, an approach believed to be not applicable in life sciences because of too many interference artefacts. However, by circulating an incident laser beam by 360deg during one image acquisition, relevant image information is amplified. By combining total internal reflection illumination with dark field detection, structures as small as 150 nm become separable through local destructive interferences. The technique images local changes in refractive index through scattered laser light and is applied to living mouse macrophages and helical bacteria revealing unexpected dynamic processes.
Scientific reports