IMAGING WITH EXTRINSIC RAMAN LABELS

In two separate examples we demonstrate the use of extrinsic Raman sca ttering probes for imaging of biological samples. First, the distribut ion of cholesterol in a rat eye Lens is determined with the use of the Raman scattered light from filipin, a molecule which binds specifical ly to cholesterol. The protein distribution in the same eye lens was o btained by using the 1450-cm(-1) CH2 and CH3 bending modes as an intri nsic marker for protein. It appears that the cholesterol is concentrat ed in the membranes of the eye lens fibers, whereas the protein is dis tributed more evenly. Second, we demonstrate that phenotyping of lymph ocytes can be done by using the Raman scattering of (antibody-coated) polystyrene spheres. The lymphocyte population was also fluorescently labeled with anti-CD4-FITC to demonstrate that Raman and fluorescence labeling can be used simultaneously. Finally, we discuss the potential advantages and disadvantages of using Raman labels.