Attenuated Total Reflection–Fourier Transform Infrared Spectroscopy as a Possible Method to Investigate Biophysical Parameters of Stratum Corneum In Vivo

Abstract

We investigated the use of attenuated total reflection-Fourier transform infrared spectroscopy as a method to study differences in the molecular components of human stratum corneum in vivo. These variations as a function of the anatomic site and of the depth into its layered structure are important to understand the biology and physiology of the tissue. In this preliminary study we have investigated spectroscopic changes in 18 healthy individuals. Total reflection-Fourier transform infrared spectroscopy represents a potentially powerful tool to study biophysical properties of surfaces. We observed that, in vivo, biophysical parameters of the stratum corneum (such as hydration, lipid composition, and conformation of the aliphatic chains) are indeed dependent on the anatomic site. As in total reflection-Fourier transform infrared spectroscopy experiments the penetration depth of the evanescent field into the stratum corneum is comparable with the thickness of a layer of corneocytes, this technique can be used to follow the distribution of lipids, water, and proteins as a function of depth into the tissue. We found that, in vivo, these molecular components are non-uniformly distributed, in agreement with the presence of water and lipid reservoirs as observed with ex vivo ultrastructural investigations. Composition and conformational order of lipids are also a function of depth into the stratum corneum. Finally we compared the in vivo superficial hydration measured using the infrared absorption of the OH stretch of water, with the hydration measured using the Skicon hygrometer. Our results indicate that total reflection-Fourier transform infrared spectroscopy might be useful to measure important chemical and biophysical parameters of stratum corneum in vivo.

FT-IR Spectroscopy Study in Early Diagnosis of Skin Cancer

“…The absorption bands of the stretching vibrations of vOH and vNH groups of glycosaminoglycans, proteins, and collagen of the skin, as well as the stretching vibration bands of the water molecules in the cells appear in the spectral region between 4000 and 3000 cm -1 as previously reported (12)(13)(14)(15)(16)(17)(18). In Figure 1, the broad band at approximately 3484 cm -1 in the spectra of N and NEV is assigned to the stretching vibration of vOH groups of water molecules, and to the vOH of polysaccharides of the hyaluronic acid (HA).…”

“…As it is known, the hydrogen bond is important in stabilizing the protein helix and any change implies that the physiological environment has changed. We have found that these changes are very important and constitute a basic criterion in order to characterize the disease and its progression (10)(11)(12)(13)(14)(15)(16)(17)(18).…”

“…This is a major advantage of Attenuated Total Reflection (ATR)-FT-IR spectroscopy for the histopathological assessment of skin cancers. However, the depths achieved by IR spectroscopy cannot exceed 20 μm (13). In the present work we used ATR-FT-IR spectroscopy to evaluate the spectral differences between healthy cells and BCC, melanoma, and nevus in vitro, in order to identify characteristic "marker bands" that can be used for diagnostic purposes.…”

Influence of physico-chemical, mechanical and morphological fingerpad properties on the frictional distinction of sticky/slippery surfaces

“…The spectra obtained in this study (figure 3) were very similar to those presented in the literature for human fingers or other parts of the human body in vivo [43] and for SC biopsies in vitro [25].…”

“…Between each analysis, the 0.8 cm 2 surface of the IRE was gently cleaned with high purity ethanol. In ATR, the IR radiation penetration depth depends on the contact pressure between the sample and the IRE [41,43]. To minimize penetration depth variations from one subject to another, the experimenter applied with his own forefinger a nearly constant loading of 5 N on the subject's fingernail.…”