Beneduci Amerigo, Cosentino Katia, Romeo Stefania, Massa Rita, Chidichimo Giuseppe
Department of Chemistry and Chemical Technologies, University of Calabria, Arcavacata di Rende (CS), Italy.
Soft Matter. 2014 Aug 14;10(30):5559-67. doi: 10.1039/c4sm00551a.
The nonthermal biological effects of millimeter waves have been mainly attributed to the interaction with biological membranes. Several data on biomimetic membrane systems seem to support this conclusion. In this paper a mechanistic hypothesis is evaluated to explain such an interaction taking into account experimental NMR data on deuterium-labeled phospholipid vesicles. These data showed that millimeter waves induce a time and a hydration-dependent reduction of the water ordering around the phosphocholine headgroups. This effect is here interpreted as a change in membrane water partitioning, due to the coupling of the radiation with the fast rotational dynamics of bound water molecules, that results in a measurable relocation of water molecules from the inner to the outer binding regions of the membrane interface. When millimeter wave exposure is performed in the vicinity of the transition point, this effect can lead to an upward shift of the membrane phase transition temperature from the fluid to the gel phase. At a macroscopic level, this unique sensitivity may be explained by the universal dynamic behaviour of the membranes in the vicinity of the transition point, where a pretransitional increase of membrane area fluctuations, i.e., of the mean area per phospholipid headgroup, is observed. Exposure to millimeter waves increases the above fluctuations and enhances the second order character of the transition.
毫米波的非热生物效应主要归因于与生物膜的相互作用。关于仿生膜系统的一些数据似乎支持这一结论。在本文中，考虑到氘标记磷脂囊泡的实验核磁共振数据，对一种解释这种相互作用的机制假说进行了评估。这些数据表明，毫米波会导致磷酰胆碱头部基团周围水的有序性随时间和水合作用而降低。这种效应在这里被解释为膜水分配的变化，这是由于辐射与结合水分子的快速旋转动力学耦合，导致水分子从膜界面的内结合区域到外结合区域的可测量重新定位。当在转变点附近进行毫米波照射时，这种效应可导致膜相变温度从流体相向上转变为凝胶相。在宏观层面上，这种独特的敏感性可以通过转变点附近膜的普遍动态行为来解释，在该点观察到膜面积波动（即每个磷脂头部基团的平均面积）的预转变增加。暴露于毫米波会增加上述波动并增强转变的二级特征。
