Interactions between 60-GHz millimeter waves and artificial biological membranes: dependence on radiation parameters

Due to the increasing interest in millimeter-wave (MMW) applications for wireless communication systems, the investigation of their potential biological effects is of utmost importance. In this paper, we report experimental results of the study of interactions between low-power radiation at 60 GHz and artificial models of biological membranes. In the first part of this study, we demonstrate an increase of superficial pressure of phospholipid monolayers during MMW exposure. Two of the most prominent in quantity lipid constituents of biological membranes, dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine, are considered. The role of different radiation parameters, namely, power density, polarization, amplitude modulation, permanent, and discontinuous exposure, is discussed. The results have proved to be reproducible in independent experiments. In the second part of this study, through atomic force microscopy analysis, we investigate the influence of MMW radiation on the microdomain distribution in mixed phospholipid monolayers with phase separation. No significant modifications are observed in microdomain distribution after 5 h of exposure. The main outcomes of this study lead to the conclusion that short-term low-power MMW exposures result in an increase of lateral pressure of the phospholipid monolayer, but their influence is not sufficiently strong to disturb phospholipid microdomain organization in biomembranes