Lucassen G W, van Veen G N, Jansen J A
J Biomed Opt. 1998 Jul;3(3):267-80. doi: 10.1117/1.429890.
Water content is an important factor for skin condition. The determination of the hydration state of the skin is necessary to obtain basic knowledge about the penetration and loss of water in the skin stratum corneum. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy is used to measure hydration of the stratum corneum. In this study we apply direct band fitting of the water bending, combination, and OH stretch bands over the 4000-650 cm-1 wave number range. Measurements are performed on the volar aspect of the forearm using a Nicolet 800 FTIR spectrometer equipped with an ATR unit with a ZnSe crystal. Hydration of the skin is obtained by occlusion keeping the forearm pressed onto the crystal. Spectra are recorded before and after occlusion up to 30 min. The spectra are fitted with a nonlinear least-squares algorithm with Gaussian bands. Separate band fits of water, normal stratum corneum, and occluded hydrated stratum corneum spectra are obtained yielding band parameters of the individual water contributions in the bending mode at 1640 cm-1, the combination band at 2125 cm-1, and the OH stretches in the hydrated skin stratum corneum spectra. A scaling factor representing the contribution of the water spectrum into the skin stratum corneum spectrum is determined during the occlusion process. In comparison to the dependence of the infrared absorbance ratio in time used by Potts, our scaling factor shows a more distinct transition from enhanced signal due to increased contact area to extra signal due to water content at maximum contact area. Band fit analysis of hydrated skin stratum corneum ATR-FTIR spectra offers the possibility for quantitative determination of individual water band parameters. © 1998 Society of Photo-Optical Instrumentation Engineers.
水分含量是影响皮肤状况的一个重要因素。测定皮肤的水合状态对于了解角质层中水分的渗透和流失的基本知识是必要的。衰减全反射傅里叶变换红外（ATR - FTIR）光谱法用于测量角质层的水合作用。在本研究中，我们在4000 - 650 cm-1波数范围内对水的弯曲、组合和OH伸缩振动带进行直接谱带拟合。使用配备ZnSe晶体ATR单元的Nicolet 800傅里叶变换红外光谱仪在前臂掌侧进行测量。通过将前臂压在晶体上进行封闭来获得皮肤的水合作用。在封闭前后直至30分钟记录光谱。光谱用具有高斯带的非线性最小二乘法算法进行拟合。分别获得水、正常角质层和封闭水合角质层光谱的谱带拟合，得到在1640 cm-1弯曲模式下、2125 cm-1组合带以及水合皮肤角质层光谱中OH伸缩振动的各个水贡献的谱带参数。在封闭过程中确定一个表示水光谱对角质层光谱贡献的比例因子。与Potts使用的红外吸光度比随时间的依赖性相比，我们的比例因子显示出从因接触面积增加导致的信号增强到最大接触面积时因水分含量导致的额外信号的更明显转变。水合皮肤角质层ATR - FTIR光谱的谱带拟合分析为定量测定各个水带参数提供了可能性。© 1998 光电仪器工程师协会。
