Dresden 2014 – scientific programme
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BP: Fachverband Biologische Physik
BP 12: Posters: Imaging
BP 12.11: Poster
Tuesday, April 1, 2014, 09:30–12:30, P1
Refractive index studies of biological cells and nuclei using digital holographic microscopy — •Mirjam Schürmann1, Jana Scholze1, Chii J. Chan2, Paul Müller1, Andrew E. Ekpenyong1, Kevin J. Chalut2, and Jochen Guck1,2 — 1Biotechnology Center, TU Dresden, Tatzberg 47/49, 03107 Dresden, Germany — 2Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
In recent years, digital holographic microscopy (DHM) has increasingly been used in biophysical and cell biological studies for the determination of the refractive index of cells. This quantitative phase microscopy technique is non-invasive, in comparison to other traditional imaging techniques, which often require external labelling of biological samples. Previous work in our group on cell differentiation revealed a lineage-specific modulation in the cells' refractive index, suggesting the use of DHM as a useful tool for marker-free studies of cell differentiation. Recently we have also used DHM to study the optical properties of the cell nucleus, which may reflect its epigenetic nature. In contrast to other studies suggesting a high refractive index of cell nuclei compared to the cytoplasm, the present study reveals that the refractive index of isolated cell nuclei of a variety of cell types can be lower than the refractive index of the cell. In addition, nuclear refractive index was found to be highly sensitive to external salt concentrations. This characterisation of the optical properties of nuclei is important for the proper interpretation of laser trapping experiments of cells or the use of light scattering techniques in tissues, such as optical coherence tomography, for diagnostic purposes.