Permeability changes induced by 130 GHz pulsed radiation on cationic liposomes loaded with carbonic anhydrase

Abstract

The effects of pulsed 130 GHz radiations on lipid membrane permeability were investigated by using cationic liposomes containing dipalmitoyl phosphatidylcholine (DPPC), cholesterol, and stearylamine. Carbonic anhydrase (CA) was loaded inside the liposomes and the substrate p-nitrophenyl acetate (p-NPA) added in the bulk aqueous phase. Upon permeation across the lipid bilayer, the trapped CA catalyzes the conversion of the p-NPA molecules into products. Because the self-diffusion rate of p-NPA across intact liposomes is very low the CA reaction rate, expressed as Delta A/min, is used to track membrane permeability changes. The effect of 130 GHz radiation pulse-modulated at low frequencies of 5, 7, or 10 Hz, and at time-averaged incident intensity (I(AV)) up to 17 mW/cm(2) was studied at room temperature (22 degrees C), below the phase transition temperature of DPPC liposomes. At all the tested values of I(AV) a significant enhancement of the enzyme reaction rate in CA-loaded liposomes occurred when the pulse repetition rate was 7 Hz. Typically, an increase from Delta A/min = 0.0026 +/- 0.0010 (n = 11) to Delta A/min = 0.0045 +/- 0.0013 (n = 12) (P < 0.0005) resulted at I(AV) = 7.7 mW/cm(2). The effect of 130 GHz pulse-modulated at 7 Hz was also observed on cationic liposomes formed with palmitoyloleoyl phosphatidylcholine (POPC), at room temperature (22 degrees C), above the phase transition temperature of POPC liposomes.

Terahertz Radiation Effects and Biological Applications

“…In this context, we studied the effects of THz radiation on the permeability of a membrane model system (liposome), which, in contrast to living cells, is well defined and only has a limited number of parameters, allowing an accurate evaluation of membrane effects induced by electromagnetic radiation [41]. The effects induced by 0.13 THz radiation pulse-modulated at low frequencies of 5, 7 or 10 Hz, and at timeaveraged incident intensity (I AV ) up to 17 mW/cm 2 was studied in real-time during the irradiation.…”

Effects of Millimeter Waves Radiation on Cell Membrane - A Brief Review

“…Changes on the permeability of lipid bilayer membranes were reported by RamundoOrlando et al [47]. The effects induced by 130 GHz radiations, pulse-modulated at low frequencies of 5, 7 or 10 Hz, and at time-averaged incident intensity (I AV ) up to 17 mW/cm 2 were studied in real-time during the irradiation of cationic liposomes loaded with carbonic anhydrase.…”

Regulatory effects of terahertz waves

“…Set of experiments with the use of a coloring material which does not penetrate through intact membranes (Trypan Blue), and reveals living cell, and electrophysiological analyze showed that THz irradiation creates conditions for penetrating of those substances into living cells, which do not usually penetrate [25]. Besides, it had been established that penetrance of phospholipid liposomes increases significantly after 130 GHz irradiation with density 10-17 mW/cm² [26].…”