Spectroscopic studies of autofluorescence substances existing in human tissue: influences of lactic acid and porphyrins.
The influence of lactic acid or porphyrins on the optical properties of tissue fluorophores is investigated by autofluorescence (AF) spectroscopy measurement with a GaN-based ultraviolet laser diode along with Fourier-transform IR (FTIR) spectroscopy measurement. As the lactic-acid concentration becomes dense, the AF peak intensity from elastin and desmosine solutions become wholly weak. A similar reduction in the AF intensity is observed for nicotinamide adenine dinucleotide (NADH) solutions. FTIR analysis indicates that the lactic acid causes the conformational change in elastin and the oxidation of NADH, which can be related to changes in the AF properties. The peak intensity of the tissue fluorophores also becomes weak when porphyrins are added, although the conformational change in each tissue fluorophore is not confirmed from FTIR analysis. Judging from the change in the scattering-light intensity of the excitation source, the observed change mainly originates from the absorption of the excitation source by porphyrins.
Kagami Memorial Laboratory for Materials Science and Technology, Waseda University, 2-8-16 Nishiwaseda, Shinjuku Tokyo, 169-0051 Japan.
Yasuhiro
Y
Ueda
Masakazu
M
Kobayashi
D045424:Complex Mixtures / Q000032:analysis / Q000737:chemistry; D003238:Connective Tissue / Q000737:chemistry*; D006801:Humans; D019344:Lactic Acid / Q000032:analysis / Q000737:chemistry*; D049449:Luminescence; D011166:Porphyrins / Q000032:analysis / Q000737:chemistry*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013056:Spectrophotometry, Ultraviolet / Q000379:methods*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*
D045424:Complex Mixtures; D011166:Porphyrins; D019344:Lactic Acid