Effects of high and low level 1265 nm laser irradiation on HCT116 cancer cells

The mechanism responsible for the oxidative stress due to photobiomodulation induced by 1265 nm laser is still unclear. Mitochondria are assumed to be the most probable acceptors of the 1265 nm laser irradiation. We study oxidative stress, mitochondrial potential, GSH, cell viability, DNA damage. We demonstrated that narrowband (highcoherent) and wideband lasers employed at the doses of 9.45 and 66.6-400 J/cm2, respectively, induce a dose-dependent cell death, increase ROS level, disturb mitochondrial functioning and can damage DNA. Thus, the 1265 nm lasers can affect the HCT116 cells through mitochondrial damage. Energy density increase contributes to cell damaging without heating effects

The light-oxygen effect in biological cells enhanced by highly localized surface plasmon-polaritons

Here at the first time we suggested that the surface plasmon-polariton phenomenon which it is well described in metallic nanostructures could also be used for explanation of the unexpectedly strong oxidative effects of the low-intensity laser irradiation in living matters (cells, tissues, organism). We demonstrated that the narrow-band laser emitting at 1265 nm could generate significant amount of the reactive oxygen species (ROS) in both HCT116 and CHO-K1 cell cultures. Such cellular ROS effects could be explained through the generation of highly localized plasmon-polaritons on the surface of mitochondrial crista. Our experimental conditions, the low-intensity irradiation, the narrow spectrum band (<4 nm) of the laser and comparably small size bio-structures (~10 μm) were shown to be sufficient for the plasmon-polariton generation and strong laser field confinement enabling the oxidative stress observed

Non-resonant operation of microcavity Brillouin lasers

We present theoretical framework to describe Brillouin lasing in microcavities in the case of a significant mismatch between the Brillouin shift and the cavity intermode spacing. We show that despite an increase of the lasing threshold a significant increase of the Brillouin power in comparison with the resonance case is achievable. A necessary condition for this effect is the optimal value of the pump frequency detuning from the cavity mode frequency. An increase of the Brillouin threshold is accompanied by narrowing of the spectrum range where the Brillouin signal could be generated in non-resonant case. Besides, with the optimal pump frequency detuning the Brillouin signal noise level is reduced. Analytical results are in quantitative agreement with the results of numerical simulations

The photobiomodulation of vital parameters of the cancer cell culture by low dose of near-IR laser irradiation

The mechanisms underlining the cell adaptive and/or activating oxidative stress, called low level light or photobiomodulation therapies (PBMT), still remain unclear for the near-infrared spectrum range (750-3000 nm), especially for the 1265-1270 nm range (highest absorption by molecular oxygen). It is most probable that the mitochondria may also appear to be the main target for these wavelengths. It is known that mitochondria can generate ROS under visible and 800-1060 nm spectrum range irradiation, which in turn control voltage-dependent anion channels (VDAC). Here we investigated cellular damage regarding VDAC activity, level of oxidative stress, malondialdehyde content, cell viability, mitochondrial potential and mass, GSH level, mitochondrial and nuclear DNA damage in the cancer cell culture exposed to low-level laser irradiation at 1265 nm. We used a continuous wave laser with output power 4 mW; the energy densities employed were 0.3-9.45 J/cm 2. We observed that the laser radiation at 1265 nm can induce the oxidative stress, enhance apoptosis, and disturb mitochondrial functioning at the energy density of 9.54 J/cm 2. In addition, inhibition of VDAC enhances the observed effects. It has been shown that the laser irradiation at 1265 nm damages mitochondrial DNA but does not affect the nuclear DNA. The performed experiments bring us to the conclusion that the laser irradiation at 1265 nm can affect cells through mitochondrial damage and the inhibition of VDAC enhances effects of PBMT

Frequency Comb Fiber Generator Based on Photonic Bandgap Amplifier

We report on a model of a fiber frequency comb generator that develops an approach to harmonically mode-locked fiber laser design based on dissipative four-wave mixing. In our version of this approach, we assume an amplifying one-dimensional photonic crystal as a key cavity element combining the properties of an intra-cavity filter and a power amplifier. Using standard equations describing the signal transformation in the ring cavity and the output fiber cascade, we have demonstrated the possibility of the application of the proposed model as a generator of broadband frequency comb with controllable line spacing

Amplification of surface plasmon polariton wave in single-walled carbon nanotube using electric current pump

We propose a surface plasmon polariton amplification technique based on direct energy transfer from a dc electric current flowing in a carbon nanotube. It is shown that when the synchronization conditions are satisfied, when the surface plasmon polariton wave velocity is close to the drift velocity of the charge carriers in the nanotube, the surface wave is significantly enhanced

Amplification of surface plasmon polariton wave in single-walled carbon nanotube using electric current pump

We propose a surface plasmon polariton amplification technique based on direct energy transfer from a dc electric current flowing in a carbon nanotube. It is shown that when the synchronization conditions are satisfied, when the surface plasmon polariton wave velocity is close to the drift velocity of the charge carriers in the nanotube, the surface wave is significantly enhanced

Surface plasmon polariton generation in a carbon nanotube on dielectric substrate

International audienc

Resonant amplification of surface plasmon polaritons with an electric current in a single-walled carbon nanotube lying on a spatially modulated substrate

International audienc