Hu Yong-xiang, Liu Rong, Zhang Wen, Xu Ke-xin
Guang Pu Xue Yu Guang Pu Fen Xi. 2017 Feb;37(2):491-6.
In this paper, two-dimensional (2D) correlation spectroscopy analysis was applied to investigate the influence of the main component in blood and the systematic drift during the measurement on the specificity of glucose in the near-infrared (NIR) spectroscopy. First, the NIR transmittance of glucose aqueous solutions was measured and the 2D correlation NIR spectra were calculated under the perturbation of glucose concentration. Based on the comparative analysis for synchronous and asynchronous 2D correlation spectra, the characteristic absorption peaks of glucose in the combination band and the overtone band were determined. Then a small amount of albumin was added into glucose aqueous solutions, and the transmittance was recorded to perform 2D correlation spectroscopy analysis under the perturbation of glucose concentration. However, the absorption of glucose in the first overtone band (1590nm) and second overtone band (1195nm) was no longer homologous in the 2D correlation spectra, which means that the albumin may reduce the specificity of glucose. Further, the oral glucose tolerance test of healthy volunteer was conducted and the NIR diffuse reflectance of left palm was collected in vivo. The 2D correlation analysis results showed that, the homology of glucose in the diffuse reflectance was also destroyed. Moreover, as the spectral variation from the glucose concentration change is too low to be covered by that induced by systematic drift easily, some background correction methods were usually required. For the transmittance experiment of glucose aqueous solutions and the diffuse reflectance experiment of human body, the pure water sample and 5% diffuse reflectance standard were used as the reference, respectively. Then 2D correlation spectroscopy was developed under the perturbation of measurement time. Results showed that, smaller band shift was observed in the slice spectra of 2D correlation synchronous spectra after the corresponding background correction, and the specificity of glucose was improved both in the in vitro and in vivo experiments. So for the non-invasive glucose sensing by NIR spectroscopy, the wavelengths should be chosen carefully to avoid the absorption band of some interfering components which may destroy the homology of glucose and make spectral interpretation more complicated. And the selection of reference samples for relative measurement is also important to improve the specificity of glucose.
本文应用二维（2D）相关光谱分析来研究血液中的主要成分以及测量过程中的系统漂移对近红外（NIR）光谱中葡萄糖特异性的影响。首先，测量了葡萄糖水溶液的近红外透射率，并在葡萄糖浓度扰动下计算了二维相关近红外光谱。通过对同步和异步二维相关光谱的对比分析，确定了葡萄糖在合频带和倍频带中的特征吸收峰。然后向葡萄糖水溶液中加入少量白蛋白，并记录透射率，以便在葡萄糖浓度扰动下进行二维相关光谱分析。然而，在二维相关光谱中，葡萄糖在第一倍频带（1590nm）和第二倍频带（1195nm）处的吸收不再具有同源性，这意味着白蛋白可能会降低葡萄糖的特异性。此外，对健康志愿者进行了口服葡萄糖耐量试验，并在体内采集了左手掌的近红外漫反射率。二维相关分析结果表明，漫反射率中葡萄糖的同源性也被破坏。而且，由于葡萄糖浓度变化引起的光谱变化过小，很容易被系统漂移引起的变化所掩盖，因此通常需要一些背景校正方法。对于葡萄糖水溶液的透射率实验和人体的漫反射率实验，分别使用纯水样品和5%漫反射率标准作为参考。然后在测量时间的扰动下开展二维相关光谱分析。结果表明，经过相应的背景校正后，二维相关同步光谱的切片光谱中观察到的谱带位移较小，并且在体外和体内实验中葡萄糖的特异性均得到了提高。所以对于近红外光谱无创葡萄糖传感而言，应谨慎选择波长，以避免某些干扰成分的吸收带，这些吸收带可能会破坏葡萄糖的同源性并使光谱解释更加复杂。并且选择参考样品进行相对测量对于提高葡萄糖的特异性也很重要。
