Resonance Raman spectroscopy of amino acids and proteins

Resonant enhancement of Raman signals is well suited to increase sensitivity in samples with low concentration such as biological tissue. We propose an experimental technique for recording resonance profiles of amino acids and proteins. The shape indicates the optimal excitation wavelength and yields valuable information about the molecules themselves. For comparison of spectra obtained at different excitation wavelengths, the experimental setup needs to be carefully characterized and calibrated. Challenges occurring here and possible solutions are discussed. The study provides the basis for ex vivo measurements on more complex samples such as proteins located in the human perilymph. The composition of this inner ear liquid is essential for hearing and cannot be analyzed non-invasively so far. The long term aim is to implement this technique as a fiber based endoscope for non-invasive measurements during surgeries (e. g. cochlear implants) making it available as a diagnostic tool for physicians. This project is embedded in the interdisciplinary cluster of excellence “Hearing for all” (H4A) which aims at a major breakthrough in hearing research.