Using a variety of spectroscopic techniques, we have investigated the role of phospholipid, principally dipalmitoylphosphatidylcholine (DPPC), in respiration. Because of the high content of protein there is a significant fluorescence associated with pulmonary surfactants. Since dispersive Raman spectroscopic techniques using visible laser excitation cannot be applied to highly fluorescing samples, we have used the new Fourier transform (FT) Raman approach coupled with near-infrared laser excitation. This spectroscopic technique allows one not only to obtain a Raman spectrum, but to determine spectral peak frequencies with high precision. Progress has been made in clarifying the role of the various protein proteins of native lung surfactant, but no clear, unequivocal picture has yet been forthcoming, here or elsewhere. We are still pursuing that goal. We have, however, established FT Raman spectroscopy as a practical tool for sorting out suitable lung surfactant substitutes.
