Cell permeability induced by 18GHz electromagnetic field Elena Ivanova Nano-Biotech Lab

Transcription

1 Science & Wireless, Australian Centre for Electromagnetic Bioeffects Research, 8 th December 2015 Cell permeability induced by 18GHz electromagnetic field Elena Ivanova Nano-Biotech Lab

2 Outline Electromagnetic field (EMF) effects at microwaves (MWs) frequencies EMF experimental set up Responses of cells to 18 GHz EMF Hypothetical mechanism: quasi-endocytosis

3 18 GHz electromagnetic field The electromagnetic spectrum (Banik et al., 2003) In the region between radio and infrared frequency Calculated wavelength in water is 2.3 mm (Shamis et al. 2011).

4 MW bioeffects Alternating the electromagnetic field strength, frequency, wave forms, modulation and time of interaction (Banik et al. 2003) The sterilisation/inactivation effect due to the rise in bulk temperature Specific electromagnetic effects? (Shamis et al. 2012, Appl. Microbiol. Biotech) Cell death (Adey 1993) An increase in the enzyme activities of Staphylococcus aureus after exposure to 2.45 GHz MW radiation (Dreyfuss and Chipley 1980) An increase in the rate of ATP hydrolysis, which was ten times greater than that observed using conventional heating methods (Sun et al. 1988) 18 GHz EMF exposures at sub-lethal temperature (40 C) induced cell permeability in Escherichia coli cells (Shamis et al. 2011, Appl. Environ. Biotech)

5 EMF experimental setup Diminishing the non-uniform power absorption by placing the sample on a ceramic pedestal that made the field distribution relatively even The temperature was measured 90 times from 15 positions (five different locations and three depth-levels) Wavelength (2.3 mm) and depth of penetration (1.04 mm) disregard the possibility of non-even heating due to nonuniform field distribution (Shamis et al., 2011). Electromagnetic field modelling of the EMF chamber using CST Microwave Studio 3D Electromagnetic Simulation Software (CST, Framingham, MA, USA)

6 Where c is the specific heat capacity of the medium (kj kg -1 C -1 ), and is the time derivative of the temperature determined at t = 0 s ( C s -1 ). EMF experimental setup Maximum MW absorption of water at 20 C and 40 C occurs at about 18 GHz (Clark and Sutton 1996) and 25 GHz (Hasted 1972) Consecutive EMF exposures with temperature increased from 20 C to 40 C in 1 min, following by cooling from 40 C to 20 C in 2 min between exposures Controls: Cells without any exposure Heated cells with mimicked heating rates of EMF exposures (Peltier plate) specific absorption rate (SAR):

7 Cell permeability after 18 GHz EMF exposures Nanospheres (23 nm, green and 46 nm, red) uptake Cell viability: up to 85% Number of exposures (four, five or six) Scanning electron microscopy (SEM) Confocal laser scanning microscopy (CLSM) SEM scale bars are 1 μm and CLSM scale bars are 5 μm. (Nguyen et al., 2015, Sci Rep)

8 Cell permeability after 18 GHz EMF exposures Internalization of 23.5 nm silica nanospheres into the EMF exposed cells (TEM, Scale bars are 200 nm).

9 Rabbit red blood cells permeability Nanospheres (23 nm) internalization by the rabbit red blood cells after EMF exposures SEM, scale bars 10 μm.

10 EMF induced quasi-endocytosis High frequency EMFs affect smaller molecules such as water and through their resultant high frequency vibrations could be able to generate an external mechanical stimulation of cell membrane Changes in structural conformation of membrane lipids and proteins can lead to changes of membrane fluidity Sub-cellular compartmentalization in the studied cells, allowed the internalization of silica nanospheres The variation in the ability to internalize large molecules may be due to the differences in cell wall structure and/or the membrane phospholipids compositions of the cells

11 Acknowledgements Prof. Andrew Wood Prof. Russell Crawford Dr. Robert L. McIntosh Dr. A. Taube Dr. I. Sbarski Dr. Y. Shamis Peter The Hong Phong Nguyen Illawarra Health and Medical Research Institute, University of Wollongong Prof. Rodney Croft This project is supported by the Australian Centre for Electromagnetic Bioeffects Research, NH&MRC Centre of Research Excellence, Australia