Effects of 1.5 GHz electromagnetic exposure on large unilamellar vesicle (LUV) model membranes

The increasing use of high-frequency electromagnetic systems raises important questions regarding their potential biological effects and the relative contribution of thermal and non-thermal interaction mechanisms. We investigated the effects of exposure to 1.5 GHz electromagnetic fields (EMFs) on model lipid membranes using Large Unilamellar Vesicles (LUV). Vesicle suspensions were exposed to pulsed EMFs under fractionated protocols (3, 6, or 13 shots) or uninterrupted pulsed exposures of matched duration. Membrane responses were assessed by 31 P nuclear magnetic resonance (NMR), dynamic light scattering (DLS), temperature and pH measurements. DLS showed no significant changes in vesicle size distribution, while pH remained stable across conditions. NMR changes were detected only after the 13-shots protocol, including a reduced chemical shift difference (Δδ) and broadening of the external phosphate resonance. Peak integrals remained unchanged, with no detectable loss of phosphate signal. Temperature monitoring revealed protocol-dependent heating, with the largest increase during uninterrupted 1 h exposure. However, no significant NMR changes occurred under this condition, whereas NMR changes occurred after the 13-shots protocol without measurable heating. Thus, the spectroscopic changes were not simply related to the measured temperature increase. Overall, 1.5 GHz EMF exposure was associated with limited, protocol-dependent spectroscopic changes without major alterations in vesicle stability.