The Bioeffects Resulting from Prokaryotic Cells and Yeast Being Exposed to an 18 GHz Electromagnetic Field

Abstract

The mechanisms by which various biological effects are triggered by exposure to an electromagnetic field are not fully understood and have been the subject of debate. Here, the effects of exposing typical representatives of the major microbial taxa to an 18 GHz microwave electromagnetic field (EMF)were studied. It appeared that the EMF exposure induced cell permeabilisation in all of the bacteria and yeast studied, while the cells remained viable (94% throughout the exposure), independent of the differences in cell membrane fatty acid and phospholipid composition. The resulting cell permeabilisation was confirmed by detection of the uptake of propidium iodine and 23 nm fluorescent silica nanospheres using transmission electron microscopy (TEM) and confocal laser scanning microscopy (CLSM). Upon EMF exposure, the bacterial cell membranes are believed to become permeable through quasi-endocytosis processes. The dosimetry analysis revealed that the EMF threshold level required to induce the uptake of the large (46 nm) nanopsheres was between three and six EMF doses, with a specific absorption rate (SAR) of 3 kW/kg and 5 kW/kg per exposure, respectively, depending on the bacterial taxa being studied. It is suggested that the taxonomic affiliation and lipid composition (e.g. the presence of phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of uptake of the large nanospheres (46 nm). Multiple 18 GHz EMF exposures over a one-hour period induced periodic anomalous increases in the cell growth behavior of two Staphylococcus aureus strains, namely ATCC 25923 and CIP 65.8T.

Exposure to high-frequency electromagnetic field triggers rapid uptake of large nanosphere clusters by pheochromocytoma cells

“…The nanosphere uptake following EMF exposure was quantified according to the fluorescence intensity generated from the silica nanospheres internalized by the PC 12 cells using a FLUOstar Omega microplate reader (BMG LABTECH, Cary, NC, USA), a method that has been used previously. 12 The mass m of a silica nanosphere was determined from the density of silica ρ and the volume of a silica nanosphere V, related to the radius r as V = π 4 3 r 3 . The average radius of a green nanosphere was 11.75×10 -7 cm (Corpuscular), and hence the volume was estimated to be 6.8×10 -18 cm 3 , and mass 1.8×10 -17 g. The mass of a single nanosphere was used to calculate the number of internalized nanospheres.…”

“…10,11 Although permeabilization was observed in all cell types, thereby suggesting a similar mechanism of induction, the differences in cell membrane fatty acid and phospholipid composition, such as the presence of pentadecanoic fatty acid or phosphatidyl-glycerol, determined the specific dose of 18-GHz EMF exposure required to induce permeabilization and the size and number of nanoparticles that could be internalized by thus-treated cells. 12 This phenomenon presents a motivating opportunity as an alternative method for rapidly inducing a transient increase in membrane permeability as a means to attain more efficient uptake of biomolecules, dyes and tracers, and genetic material by cells in drug delivery and gene therapy applications. This approach may be particularly useful for applications where permanent membrane damage or cell death is not desired, since the aforementioned treatment did not negatively affect cell viability regardless of the microorganism species being treated.…”

“…This approach may be particularly useful for applications where permanent membrane damage or cell death is not desired, since the aforementioned treatment did not negatively affect cell viability regardless of the microorganism species being treated. [12][13][14] However, in order to facilitate the translation of this phenomenon into real-life applications, more effort is needed to understand the mechanisms by which EMFs modulate key cellular processes and affect cell viability, particularly in mammalian cells.…”

Bioelectromagnetics Research within an Australian Context: The Australian Centre for Electromagnetic Bioeffects Research (ACEBR)

“…This research determined, for the first time, that regardless of the differences in cell wall/membrane structures, exposure to 18 GHz EMF induced cell permeabilisation, as confirmed via the ability of the cells to uptake silica nanospheres (23 nm and 46 nm in diameter), in all of the cell types studied, in a manner that could not be duplicated using conventional heating methods under similar bulk temperature conditions [29,30,31]. Moreover, a large proportion of the cells remained viable (85%) throughout the exposures (excluding erythrocytes) as confirmed directly using the colony-forming units counting technique.…”

“…These results are important in that the membrane effects do not occur with Peltier plate-induced equivalent bulk temperature increases, and cannot be explained via traditional electroporation mechanisms, which require brief pulsed fields [32]. It is hypothesised that the taxonomic affiliation and cell wall/membrane structures (e.g., the presence of peptidoglycan layer, mannoprotein/β-glucan layer, phosphatidyl-glycerol and/or pentadecanoic fatty acid) may affect the extent of permeabilisation to allow the uptake of 46 nm nanospheres [29,30]. However, precisely how this relates to EMF itself is not clear.…”