Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, SO17 1BJ, UK.
Faculty of Medicine, University of Southampton, Highfield, Southampton, SO17 1BJ, UK.
Sci Rep. 2017 Aug 4;7(1):7356. doi: 10.1038/s41598-017-07842-0.
Mid-infrared (MIR) spectroscopy is a powerful tool for characterising the vibrations of molecular bonds and is therefore ideal for label-free detection of chemical species. Recent research into thin-film deposition and etching techniques for mid-infrared materials shows potential for realising miniaturised bedside biosensors for clinical diagnostics exploiting MIR spectroscopy, to replace laboratory based-techniques. However, lack of refractive index information for commonly encountered biological media and analytes hampers optimisation of biosensor performance for maximum sensitivity, especially for devices exploiting evanescent spectroscopy. Here we present refractive index data for human whole blood and several aqueous solutions of general interest to the clinical community: anticoagulants, analgesics and buffers. The refractive indices are generally dominated by the water content of each sample and the whole blood spectra exhibit additional strong features due to protein content. Furthermore, we present a generalised method for extracting complex refractive indices of aqueous solutions in the mid-infrared region using conventional attenuated total reflection Fourier transform spectroscopy (ATR-FTIR) without the need for collimated or polarised incident light, as is required for existing methods.
中红外（MIR）光谱是一种用于描述分子键振动的强大工具，因此非常适合用于对化学物质进行无标记检测。最近对中红外材料的薄膜沉积和刻蚀技术的研究表明，有可能实现利用 MIR 光谱的小型化床边生物传感器，以替代基于实验室的技术进行临床诊断。然而，缺乏常见生物介质和分析物的折射率信息，限制了生物传感器性能的优化，以实现最大灵敏度，特别是对于利用消逝光谱的设备。在这里，我们为人体全血和临床界常用的几种水溶液提供了折射率数据：抗凝剂、镇痛药和缓冲液。折射率通常主要由每个样品的含水量决定，而全血光谱由于蛋白质含量而表现出额外的强特征。此外，我们提出了一种使用常规衰减全反射傅里叶变换光谱（ATR-FTIR）在中红外区域提取水溶液复折射率的通用方法，无需准直或偏振入射光，而这是现有方法所必需的。
