Prediction of Water Relaxation Time Using Near Infrared Spectroscopy
Prediction of Water Relaxation Time Using Near Infrared Spectroscopy
复制标题
使用近红外光谱预测水弛豫时间
DOI：
10.1111/jfpe.14095
复制
发表时间：
2022
影响因子：
3
通讯作者：
Ryo Shirakashi
中科院分区：
文献类型：
--
作者：
Junkai Zhang;Hiroaki Matsuura;Ryo Shirakashi
水的分子转动弛豫时间被认为是评价生物材料劣化速率的重要参数。在这项工作中，我们提出并验证了一种利用傅里叶变换近红外光谱来预测水在生物材料中的驰豫时间的方法，该方法具有无创、低成本、高空间分辨率以及时间效率的优点。将具有双余弦势垒的水偶极子转动布朗运动的朗之万方程应用于水-糖体系，该方程的解给出了松弛时间与势垒高度的函数关系。我们假设这个势垒高度相当于糖溶液中水的氢键强度的增加。根据测得的水在4500~5500 cm−1处的近红外吸收带，计算了纯水和糖溶液的氢键强值。该方法得到的弛豫时间与介电谱的测量结果吻合较好。实际应用水在生物材料的长期保存研究中起着重要的作用，因为水是许多化学反应的媒介，这些化学反应最终导致生物材料的变质。原则上，超低温保存和干保存都涉及降低水分子的流动性，以降低化学反应速度。旋转弛豫时间作为水分子流动性的指标被证明与蛋白质的变质速率直接相关。与介电谱或磁共振等测量水松弛时间的传统方法相比，FT-IR系统具有成本低、非侵入性、时间效率高等优点，并且可以用红外显微镜提供高达μm级的空间分辨率。因此，我们的方法可以为监测作物生长和评价储藏食品的质量提供方便。
Molecular rotational relaxation time of water is believed to be an important parameter to evaluate the deterioration rate of biomaterial. In this work, we proposed and verified a method of using Fourier‐transform near infrared spectroscopy, which has advantages of non‐invasion, low‐cost, high spatial resolution as well as being time efficient, to predict the relaxation time of water in biomaterial. The Langevin equation of rotational Brownian motion of water dipole with double‐fold cosine potential barrier, solution of which gives the relaxation time as a function of potential barrier height, was applied to water–saccharide systems. We assumed that this potential barrier height is comparable to the increase of hydrogen bond strength of water in saccharide solution. The hydrogen bond strength values of pure water and saccharide solutions were calculated from the measured NIR absorbance band of water at 4500 –5500 cm−1. The relaxation times yielded by this method are in good agreement with those measured by dielectric spectroscopy.Practical ApplicationsWater plays important role in the investigation of long‐term preservation of biomaterials, since it is the medium of many chemical reactions which eventually lead to the deterioration. In principle, both cryopreservation and dry‐preservation involve the reduction of the mobility of water molecules to reduce chemical reaction rates. The rotational relaxation time as an indicator of molecular mobility of water was proved directly related to the protein deterioration rate. Compared with conventional methods of measuring water relaxation time such as dielectric spectroscopy or magnetic resonance, FT‐IR system has many advantages: low cost, non‐invasion, time efficient, and can provide spatial resolution up to μm level with infrared microscope. Therefore, our method may provide convenience to monitor crop growth and evaluate the quality of food in storage.