Characterization of the cell-substrate interface using surface plasmon resonance microscopy

In this thesis an improved surface plasmon resonance microscopy(SPRM) setup has been developed which combines a projector basedSPRM widefield mode with several SPRM scanning modes for theinvestigation of the cell-substrate interface.Widefield SPRM can be used to image the cell-substrate adhesion areasqualitatively. Here, the resolution is strongly dependent on the lightsource. While coherent laser light gives rise to speckle noise, whichfrustrates the resolution of small cellular structures such as neuronaldendrites, using a projector as an incoherent light source allows for ahigh resolution imaging.Scanning SPRM can be used to determine the cell-substrate distancequantitatively. So far, the accuracy of these measurements was compromisedby the assumption of a homogeneous refractive index (RI). Inthis thesis, it is shown that the RI can be extracted from the SPRM signalat each scanning point at the cell-substrate interface which allowed foran improvement of the distance accuracy by a factor of 25 comparedto the standard analysis technique realizing a distance accuracy of upto 1.5nm. The measurements of RI and distance were validated byseveral reference measurements.The RI of the cell gives interesting insights into the cellular structureand cellular processes. Scanning the cell-substrate interface, it couldbe shown that the RI profile of a cell can reveal the position of cellorganelles and give quantitative values for their refractive indices whilethe scanning SPRM also allows for the reconstruction of the 3D structureof the basal cell membrane