Curcumin Alters Membrane Phase-Separation, Particle Size Distribution, Permeability, and Anisotropy Differently in Unsaturated or Saturated Small Unilamellar Vesicles

1532-Pos Board B302 Quantitative Scheme for Full-Field Polarization Rotating Fluorescence Microscopy (PROM) using a Liquid Crystal Variable Retarder John F. Lesoine. National Institute of Standards and Technology, Gaithersburg, MD, USA. We present a quantitative scheme for full-field polarization rotating fluorescence microscopy (PROM). A quarter-wave plate, in combination with a liquid crystal variable retarder (LCVR), provides a tunable method to rotate polarization states of light prior to its being coupled into a fluorescence microscope. A calibration of the polarization properties of the incident light is performed in order to correct for elliptical polarization states. This calibration allows the response of the sample to linear polarization states of light to be recovered. Three known polarization states of light can be used to determine the average fluorescent dipole orientations in the presence of a spatially varying DC offset or background polarization-invariant fluorescence signal. To demonstrate the capabilities of this device we measured a series of full-field fluorescence polarization images from fluorescent analogs incorporated in the lipid membrane of Burkitts lymphoma CA46 cells. The fluorescent lipid-like analogs used in this study are molecules that are labeled by either a DiI (1,1’-Dioctadecyl 3,3,3’,3’Tetramethylindocarbocyanine) fluorophore in its head group or a BODIPY (4,4-difluoro-4-bora-3a,4a-diaza-s-indacene) molecule in its acyl chain. A spatially-varying contrast in the normalized amplitude was observed on the cell surface, where the orientation of the DiI molecules is tangential to the cell membrane. The internally labeled cellular structures showed zero response to changes in linear polarization, and the net linear polarization amplitude for these regions was zero. The method is then applied to study acyl chain structural phase transitions in model vesicles in addition to the probing of acyl chain structural order during cellular chemotaxis. This instrument provides a low cost calibrated method that may be coupled to existing fluorescence microscopes to perform investigations of cellular processes that involve a change in molecular orientations.