Direct label-free measurement of the distribution of small molecular weight compound inside thick biological tissue using coherent Raman microspectroscopy.
Distributions of small molecular weight (less than 300 Da) compounds inside biological tissue have been obscure because of the lack of appropriate methods to measure them. Although fluorescence techniques are widely used to characterise the localisation of large biomolecules, they cannot be easily applied to the cases with small molecule compounds. We used CARS spectroscopy to detect and identify a label-free small molecule compound. To facilitate detection in aqueous environment, we utilised time-resolved and phase-sensitive techniques to reduce non-resonant background generated from water. We applied this technique to detect small molecular weight compound, taurine, inside mouse cornea tissue immersed in taurine solution as an initial model experiment. We detected a Raman peak of taurine near wavenumber 1033 cm(-1) inside cornea and successfully characterised its depth profile in the tissue. Our CARS spectra measurement can be a promising method to measure and visualise the distribution of small bio-related compounds in biological background without using any labeling, paving the way for new cell biological analysis in various disciplines.
Department of Neuroanatomy and Cellular Neurobiology, &Center for Brain Integration Research, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.
Masahiko
M
Kawagishi
Department of Applied Physics, Tokyo University of Agriculture and Technology (TUAT), Koganei, Japan.
Yuki
Y
Obara
Department of Applied Physics, Tokyo University of Agriculture and Technology (TUAT), Koganei, Japan.
Takayuki
T
Suzuki
Wired Co., Ltd., Komae, Japan.|Development of Advanced Measurement and Analysis Systems (SENTAN), Japan Science and Technology Agency (JST), Tokyo, Japan.
Masumi
M
Hayashi
Department of Applied Physics, Tokyo University of Agriculture and Technology (TUAT), Koganei, Japan.|Interdisciplinary Research Unit in Photon-nano Science, Tokyo University of Agriculture and Technology (TUAT), Koganei, Japan.|Development of Advanced Measurement and Analysis Systems (SENTAN), Japan Science and Technology Agency (JST), Tokyo, Japan.
Kazuhiko
K
Misawa
Department of Neuroanatomy and Cellular Neurobiology, &Center for Brain Integration Research, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University (TMDU), Tokyo, Japan.|Development of Advanced Measurement and Analysis Systems (SENTAN), Japan Science and Technology Agency (JST), Tokyo, Japan.
Sumio
S
Terada
D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D003315:Cornea / Q000378:metabolism; D051379:Mice; D008970:Molecular Weight; D017550:Spectroscopy, Fourier Transform Infrared; D013059:Spectrum Analysis, Raman / Q000379:methods; D013654:Taurine / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution
D013654:Taurine