Raman spectroscopy is a powerful non-invasive tool for detection and classification of chemical composition of materials including biological tissues. In this work, we report an in vitro Raman study on animal skin samples with a focus on high-frequency vibrations such as symmetric CH3 stretching mode at 2934 cm-1, and the symmetric CH2 vibration mode at 2854 cm-1, OH stretching modes near 3412 cm-1, and bounded OH mode near 3284 cm-1. Raman data was acquired with a customized InGaAs based Raman spectrometer that consolidates the NIR (866 nm) light and the InGaAs detector and is particularly suitable for probing high-frequency vibrations. The Raman spectra of fat, tendon, and muscle tissues are also analyzed to determine the spectroscopic identities of CH and OH groups in skin. Our results suggest that the protein is beneficial for the maintenance of skin hydration, as it has higher water capacity and greater capability to retain water than lipids. This conclusion is consistent with the additional discovery that water exists in fat mainly as unbound type, while part of water exists as bound type in muscle.

中文翻译：

---

脂质和蛋白质组成与动物组织水合作用的体外拉曼研究

拉曼光谱是一种强大的非侵入性工具，用于检测和分类包括生物组织在内的材料的化学成分。在这项工作中，我们报告了对动物皮肤样品的体外拉曼研究，重点是高频振动，例如 2934 cm-1 处的对称 CH3 拉伸模式和 2854 cm-1 处的对称 CH2 振动模式，OH 拉伸模式在 3412 cm-1 附近，在 3284 cm-1 附近有界 OH 模式。拉曼数据是使用定制的基于 InGaAs 的拉曼光谱仪采集的，该光谱仪整合了 NIR (866 nm) 光和 InGaAs 检测器，特别适用于探测高频振动。还分析了脂肪、肌腱和肌肉组织的拉曼光谱，以确定皮肤中 CH 和 OH 基团的光谱特性。我们的研究结果表明，蛋白质有利于维持皮肤水合作用，因为它比脂质具有更高的水容量和更强的保水能力。这一结论与脂肪中水分主要以未结合型存在，而部分水以结合型存在于肌肉中的额外发现相一致。