Ruigrok, H.J., Arnaud-Cormos D., Hurtier A., Poque-Haro E., Poulletier de Gannes F., Ruffié G., Bonnaudin F, Lagroye I., Sojic N., Arbault S., Lévêque P., Veyret B. and Percherancier Y.
The existence of effects of radiofrequency field exposure at environmental levels on living tissues and organisms remains controversial, in particular regarding potential ‘‘nonthermal’’ effects produced in the absence of temperature elevation. Therefore, we investigated whether TRPV1, one of the most studied thermosensitive channels, can be activated by the heat produced by radiofrequency fields and by some specific nonthermal interaction with the fields. We have recently shown that TRPV1 activation can be assessed in real-time on live cells using the bioluminescence resonance energy transfer technique. Taking advantage of this innovative assay, we monitored TRPV1 thermal and chemical modes of activation under radiofrequency exposure at 1800 MHz using different signals (CW, GSM, UMTS, LTE, Wi-Fi and WiMAX) at specific absorption rates between 8 and 32 W/kg. We showed that, as expected, TRPV1 channels were activated by the heat produced by radiofrequency field exposure of transiently-transfected HEK293T cells, but found no evidence of TRPV1 activation in the absence of temperature elevation under radiofrequency field exposure. There was no evidence either that, at fixed temperature, radiofrequency exposure altered the maximal efficacy of the agonist Capsaicin to activate TRPV1.
Girard F., Peret M., Dumont N., Badets V., Blanc S., Gazeli K., Noël C., Belmonte T., Marlin L., Cambus J.P., Simon G., Sojic N., Held B., Clément F. and Arbault S.
The understanding of plasma-liquid interactions is of major importance, not only in physical chemistry, chemical engineering and polymer science, but in biomedicine as well as to better control the biological processes induced on/in biological samples by Cold Atmospheric Plasmas (CAPs). Moreover, plasma-air interactions have to be particularly considered since these CAPs propagate in the ambient air. Herein, we developed a helium-based CAP setup equipped with a shielding-gas device, which allows the control of plasma-air interactions. Thanks to this device, we obtained specific diffuse CAPs, with the ability to propagate along several centimetres in the ambient air at atmospheric pressure. Optical Emission Spectroscopy (OES) measurements were performed on these CAPs during their interaction with a liquid medium (Phosphate-Buffered Saline PBS 10 mM, pH 7.4) giving valuable information about the induced chemistry as a function of the shielding gas composition (variable O2/(O2+N2) ratio). Several excited species were detected including N2+(First Negative System, FNS), N2(Second Positive System, SPS) and HO· radical. The ratios between nitrogen/oxygen excited species strongly depend on the O2/(O2+N2) ratio. The liquid chemistry developed after CAP treatment was investigated by combining electrochemical and UV-visible absorption spectroscopy methods. We detected and quantified stable oxygen and nitrogen species (H2O2, NO2-, NO3-) along with Reactive Nitrogen Species (RNS) such as the peroxynitrite anion ONOO-. It appears that the RNS/ROS (Reactive Oxygen Species) ratio in the treated liquid depends also on the shielding gas composition. Eventually, the composition of the surrounding environment of CAPs seems to be crucial for the induced plasma chemistry and consequently, for the liquid chemistry. All these results demonstrate clearly that for physical, chemical and biomedical applications, which are usually achieved in ambient air environments, it is necessary to realize an effective control of plasma-air interactions.
I. Hernández Delgado, S. Pascal, C. Besnard, S. Voci, L. Bouffier, N. Sojic, J. Lacour.
A series of nine C‐functionalized cationic diazaoxa triangulene dyes (DAOTA) has been successfully synthesized and fully characterized, including X‐ray structural analysis of four derivatives. The introduction of electron‐withdrawing or donating functions enables a tuning of both electrochemical and photochemical properties with, for instance, two consecutive (reversible) reductions or oxidations observed for nitro or amino derivatives, respectively. The substituents impacted also the optical properties, with absorption maxima varying from 529 to 640 nm and fluorescence being shifted from the yellow to the red range, up to 656 nm.
Lefrançois P., Goudeau B., Arbault S.
Phospholipid Giant Unilamellar Vesicles (GUVs) are usually prepared by electroformation in water, that is in a low-conductivity solution. We developed a protocol allowing their electroformation in the most common physiological buffer, the phosphate-buffered saline (PBS). This was achieved based on a specific sequence of increasing electrical fields and for the two usual electrode types for electroformation, namely Indium Tin Oxide-coated glass slides and Pt electrodes. These GUVs are stable over time (hour time-scale) and they can be isolated or micro-injected. The membrane composition was modified by adding cholesterol in order to adjust its mechanical properties. The optimal proportion of cholesterol vs. total phospholipid concentration was 20 mol % ratio which increases membrane rigidity and facilitates vesicle microinjection.
L. Bouffier, N. Sojic, A. Kuhn.
This section of Current Opinion in Electrochemistry includes 17 articles contributed by groups from all over the world and we hope they will give the reader a representative vision of the latest achievements in the different areas of research. All selected authors are very active in frontier studies on physical and nanoelectrochemistry.
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