RESUMO
Raman spectroscopy has proven to be an effective tool for molecular analysis in different applications. In clinical diagnostics, its application has enabled nondestructive investigation of biological tissues and liquids. The human perilymph, for example, is an inner ear liquid, essential for the hearing sensation. The composition of this liquid is correlated with pathophysiological parameters and was analyzed by extraction and mass spectrometry so far. In this work, we present a fiber optic probe setup for the Raman spectroscopic sampling of inner ear proteins in solution. Multivariate data analysis is applied for the discrimination of individual proteins (heat shock proteins) linked to a specific type of hearing impairment. This proof-of-principle is a first step toward a system for sensitive and continuous in vivo perilymph investigation in the future.
Assuntos
Tecnologia de Fibra Óptica/métodos , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP90/metabolismo , Perilinfa/metabolismo , Análise Espectral Raman/instrumentação , Análise Espectral Raman/métodos , Algoritmos , Aspirina/química , Calibragem , Desenho de Equipamento , Escherichia coli , Tecnologia de Fibra Óptica/instrumentação , Proteínas de Choque Térmico HSP70/química , Proteínas de Choque Térmico HSP90/química , Humanos , Análise dos Mínimos Quadrados , Análise Multivariada , Perilinfa/química , Análise de Componente Principal , Prolina/química , Estudo de Prova de Conceito , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Análise de Regressão , Processamento de Sinais Assistido por ComputadorRESUMO
Optical techniques are effective tools for diagnostic applications in medicine and are particularly attractive for the noninvasive analysis of biological tissues and fluids in vivo. Noninvasive examinations of substances via a fiber optic probe need to consider the optical properties of biological tissues obstructing the optical path. This applies to the analysis of the human perilymph, which is located behind the round window membrane. The composition of this inner ear liquid is directly correlated to inner ear hearing loss. In this work, experimental methods for studying the optical properties of the human round window membrane ex vivo are presented. For the first time, a comprehensive investigation of this tissue is performed, including optical transmission, forward scattering, and Raman scattering. The results obtained suggest the application of visible wavelengths (>400 nm) for investigating the perilymph behind the round window membrane in future.
Assuntos
Perda Auditiva Neurossensorial/diagnóstico por imagem , Janela da Cóclea/diagnóstico por imagem , Orelha Interna/diagnóstico por imagem , Humanos , Perilinfa/diagnóstico por imagem , Análise Espectral RamanRESUMO
Resonance Raman spectroscopy (RRS) is a promising technique for investigating samples with low concentrations of single constituents or many different constituents. The wavelength dependent resonance enhancement (resonance profile) of the respective molecule yields information about the targeted species and reveals the optimal wavelength for high resolution RRS. A significant increase of the Raman scattered intensity can already be achieved in the vicinity of the molecules' absorption band (preresonance). Measuring such preresonance and resonance profiles requires precise control of excitation conditions and careful assessment of the spectral accuracy of the setup. We present a comprehensive procedure for the acquisition of preresonance profiles in Raman spectroscopy. An experimental setup for recording the single spectra is combined with an efficient algorithm for data postprocessing. The procedure is demonstrated on amino acids measured in the UV and can be applied to any molecule and wavelength range.