Pulsed Light Irradiation Research Articles

Impact of intense pulse light irradiation on BALB/c mouse skin—in vivo study on collagens, matrix metalloproteinases and vascular endothelial growth factor

Our aim was to investigate the effects of intense pulsed light (IPL) on collagen expression in BALB/c mouse skin and confirm its relative molecular mechanisms. The dorsal skin of BALB/c mice was irradiated by IPL. Before treatment and from 1 day to 8 weeks (1 day, 3 days, 5 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 6 weeks and 8 weeks) after treatment, the irradiated skin specimens were examined. The histology showed dermis thickening, accompanied with increased collagen and better organization. After IPL irradiation from 2 W up to 8 W, the staining of collagen types I and III in the IPL-treated groups was stronger than in the sham groups (P < 0.05), and the mRNA expression levels of the procollagen types I and III had also increased (P < 0.05). The up-regulation effects of IPL irradiation were time-dependent. The mRNA expression levels of matrix metalloproteinase (MMP)-1 and MMP-2 decreased progressively after IPL irradiation at 2 W up to 8 W (P < 0.05), and this down-regulation effect of IPL was also time-dependent. However, the mRNA expression of vascular endothelial growth factor (VEGF) had shown no obvious change by the end of the experiment (P > 0.05). Taking these factors together, we can conclude that IPL irradiation can not only enhance new collagen production, but also decrease collagen degradation in photo-rejuvenation mechanisms in mouse skin.

A Parallel Approach for Subwavelength Molecular Surgery Using Gene-Specific Positioned Metal Nanoparticles as Laser Light Antennas

An optical technique for the parallel manipulation of nanoscale structures with molecular resolution is presented. Bioconjugated metal nanoparticles are thereby positioned at the location of interest, such as, e.g., certain DNA sequences along metaphase chromosomes, prior to pulsed laser light irradiation of the whole sample. The nanoparticles are designed to absorb the introduced energy highly efficiently, in that way acting as nanoantenna. As result of the interaction, structural changes of the sample with subwavelength dimensions and nanoscale precision are observed at the location of the particles. The process leading to the nanolocalized destruction is caused by particle ablation as well as thermal damage of the surrounding material.

Differences between cytotoxicity in photodynamic therapy using a pulsed laser and a continuous wave laser: study of oxygen consumption and photobleaching

Oxygen consumption at the targeted site has a significant effect on dosimetry in photodynamic therapy (PDT). However, oxygen consumption in PDT using a pulsed laser as a light source has not been clarified. We therefore investigated the dependence of cytotoxicity on the oxygen consumption and the photosensitizer photobleaching of PDT using a pulsed laser by comparing with that using a continuous wave (CW) laser. Mouse renal carcinoma cells (Renca) were incubated with a second-generation photosensitizer, PAD-S31. The cells were then irradiated with either a 670-nm nanosecond pulsed light from the 3rd harmonics of a Nd:YAG laser-pumped optical parametric oscillator with a peak fluence rate of approximately 1 MW/cm(2) at 30 Hz or a 670-nm CW diode laser with a total light dose of 40 J/cm(2). Regardless of laser source, cytotoxic effects exhibited cumulative dose responses to the photosensitizer ranging from 12 to 96 microg/ml. However, cytotoxic effect of PDT using the pulsed light was significantly less than that using the CW light with the photosensitizer concentrations of 24 and 48 microg/ml under identical fluence rates. During PDT, the cells exposed to the pulsed light consumed oxygen more slowly, resulting in a lower amount of oxygen consumption when compared with PDT using CW light. In accordance with oxygen consumption, the pulsed light induced significantly less photobleaching of the photosensitizer than the CW light did. These results indicate that the efficiency of PDT using pulsed light is less when compared with CW light, probably being related to suppressed oxygen consumption during the pulsed light irradiation.

Pulsed white light in combination with UV-C and heat to reduce storage rot of strawberry

Abstract Three physical methods—pulsed white light, heat, and ultraviolet-C (UV-C, λ=254 nm) irradiation—were used in different combinations for surface decontamination of strawberry fruit. Strawberries were inoculated with conidia of Botrytis cinerea. Over 10 days, fungal development and structural damage (e.g. holes, changes in fruit firmness) were daily recorded. Pulsed light treatments consisted of 30 μs pulses at a frequency of 15 Hz for a total duration of 40 to 250 s. For the combination experiments, the UV-C doses were 0.5 or 1.0 kJ m−2 and the heat treatments were at 40 and 45 °C for 3 or 15 min. Pulsed light treatments alone had no positive or negative effect. Combining a thermal and an UV-C treatment allowed for a decrease of the thermal treatment to 40 °C for the same level of fungal inactivation. No external fruit damage was reported at this temperature of 40 °C. A combination of a thermal treatment with light pulses did not result in a significant difference in fungal growth. Combining two illumination treatments did not cause a significant decrease in fungal development. In both cases, however, the period before the first observation of fungal growth was increased by 1 or 2 days. Induced resistance against fungal infections in treated fruit was not observed after pulsed light treatment. These induced reactions of treated berries were observed after UV-C treatment of strawberries, but not observed when a thermal treatment was used.

Photoresponse of self-organizing chemical systems

Research works on the self-organization phenomena in chemical systems are reviewed with particular emphasis on their response to the photo-irradiation, for which most of the works have been performed in the author's laboratory. In the present review, a brief survey is given for the recent developments of research on the self-organization phenomena observed in dark. Then, the determination of action spectra for the photo-irradiated self-organizing chemical systems is described with a few examples, together with a discussion on the advantages of employing the irradiated light intensity as a control parameter. Experimental results for the chemical systems under the stationary and pulse light irradiation are summarized and discussed for the redox oscillators including the Belousov-Zhabotinsky and the Briggs-Rauscher systems and their variations. Discussions are also given for various types of pH oscillators under photo-irradiation. Finally, experimental observations on chaos and multistability, the most characteristic features in the field of self-organizing chemical systems, are surveyed and discussed. Possibility of the photo-control of chaos and multistability is discussed with examples of the Briggs-Rauscher system and of the pH oscillator system, H 2 O 2 - SO 2 - 3 - Fe(CN) 4 - 6 - HCO - 3 .

Damage of yeast cells induced by pulsed light irradiation

DNA damage, such as formation of single strand breaks and pyrimidine dimers was induced in yeast cells after irradiation by pulsed light, which were essentially the same as observed with continuous ultraviolet (UV) light. The UV-induced DNA damage is slightly higher than seen with pulsed light. However, increased concentration of eluted protein and structural change in the irradiated yeast cells were observed only in the case of pulsed light. A difference in the inactivation effect between pulsed light and UV light was found and this suggested cell membrane damage induced by pulsed light irradiation. It is proposed that pulsed light can be used as an effective sterilizing method for the yeast Saccharomyces cerevisiae.

Magneto-optical effects in quantum wells irradiated with light pulses

A method to detect and investigate the magnetopolaron effect in semiconductor quantum wells in a strong magnetic field, based on pulse light irradiation, and measuring the reflected and transmitted pulses, is proposed. It is shown that a beating amplitude on the frequencies, corresponding to the magnetopolaron energy level splitting, depends strongly on the exciting pulse width. The existence of time points of the total reflection and total transparency is predicted. High orders of the perturbation theory on electron-electromagnetic field interaction are taken into account.

Formation of a two-dimensional periodic structure of local melting regions on a silicon surface upon pulsed light irradiation

The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures is discussed.

P-1039 - In vivo vasorelaxation induced by continuous or pulsed ultraviolet light irradiation

P-1039 - In vivo vasorelaxation induced by continuous or pulsed ultraviolet light irradiation

New high-resolution phonon spectroscopy using impulsive stimulated Brillouin scattering

Impulsive stimulated Brillouin scattering is applied to a new high-resolution phonon spectroscopy, where phonons created by two crossing pump pulses are observed using diffraction of a cw probe light in both time and frequency domains. In time domain, real-time behavior can be detected sensitively using a digital oscilloscope, while in frequency domain, measurements with high resolution are attainable by means of a spherical Fabry–Perot interferometer. Several examples of the measurements on liquid samples are demonstrated for clarifying various aspects of the phonon generation by the present method: the mechanism of the generation under pulsed light irradiation, the propagation of the generated phonon, the resonance excitation, and the interference with the other nonlinear optical processes. The relation with the ordinary light scattering is also discussed.

Coating ablation and surface modification by pulsed light radiation

Abstract The harnessing of light energy for industrial and commercial applications has expanded enormously in the last 30 years, i.e. since the invention of the laser. In the surface preparation field, significant laser applications include surface divestment (coatings, corrosion and contamination), annealing and glazing. In many instances, widespread commercial implementation of laser surface processing is impeded by cost-effectiveness issues. A more efficient alternative is described, which employs xenon flashlamp (rather than laser) radiation for surface preparation. The results of xenon flashlamp processing are presented. In certain instances, post-irradiation surfaces exhibit improved coating adhesion and resistance to corrosion. Finally, an advanced pinchlamp source with potential applications in the field of nuclear decontamination is discussed.

Time-resolved study of thin nickel silicide layer growth at the nickel film-Si(100) interface

A time-resolved study of the initial stages of the formation of nickel silicide by pulsed incoherent light irradiation is described. Unreacted intermixed Ni-Si layer formation is shown to be an essential first step for silicide growth. The silicide layer emerges from the Ni-Si mixed layer by a disordered-to-crystalline transformation at a threshold nickel concentration corresponding to the crystalline silicide composition.