Effect of low power laser irradiation on disconnecting the membrane-attached hemoglobin from erythrocyte membrane

In our previous study we found that low power laser irradiation improved the erythrocyte deformability, but the mechanism is unclear. The membrane-attached hemoglobin (Hbm) may be one of the determining factors for the erythrocyte deformability. We report here for the first time, that laser irradiation can reduce the Hbm contents in pig's erythrocytes, providing the explanation for the improvement of erythrocyte deformability. The decrease of the Hbm was proportional to the irradiation dose, but the relative change of Hbm was saturated around 35%. The 532 nm laser was more efficient at lowering Hbm than the 632.8 nm laser, consistent with the absorption spectrum of Hbm.     

NO-hemoglobin may be a light-sensitive source of nitric oxide both in solution and in red blood cells

Hemoglobin in solution and inside red blood cells forms a complex with nitric oxide exhibiting a specific EPR signal both at room and liquid nitrogen temperatures. In the present paper it was shown that the nitrosyl complex of hemoglobin (NO-Hb) is photochemically sensitive and hence may serve as a source of free NO under He-Cd laser irradiation (441 nm). It was found that at laser light radiant power of 3.9 mW, room temperature and in the presence of oxygen, 50% decrease of NO-Hb EPR signal occurred at doses of 54, 30, and 18 kJ/m2 for NO-hemoglobin solution, hemolysed and intact erythrocytes, respectively. The detection of free NO produced as a result of NO-Hb photolysis was performed by means of a spin trap, nitronyl nitroxyl radical NNR, which in the presence of NO is transformed into imino nitroxyl radical (INR) showing different EPR signal. In isolated hemoglobin solution, 20 mM INR was accumulated under irradiation with the maximal dose of 700 kJ/m2. In intact cells the HbFe(2+)-NO photolysis and NO release occur with essentially higher efficacy. To produce 100 mM INR, a dose of 290 kJ/m2 was needed in erythrocyte lysates and 100 kJ/m2 in intact red blood cell suspension. Measurements of absorption spectra showed that in all systems studied (NO-Hb in solution, intact erythrocytes and hemolysed erythrocytes) NO-Hb concentration decreased after irradiation by 14-22% with simultaneous formation of methemoglobin. These observations show that NO-Hb may serve as a store of nitric oxide from which free NO can be released by intensive illumination.     

Lasers used in analytical micropyrolysis

Laser micropyrolysis gas chromatography mass spectrometry (GC-MS) allows analytical pyrolysis to be conducted with micro-spatial resolution. Despite the large range of contemporary laser sources, most previous laser pyrolysis studies have been conducted with continuous wave (CW) infrared irradiation. Here, the laser micropyrolysis analysis of a Sydney torbanite was conducted with three different laser sources - 1. CW 532 nm; 2. Q-Switched (QSw) pulsed 1064 nm; and 3. QSw pulsed 266 nm - to compare the molecular analyses attributes of different laser types (λ: 266-1064 nm; CW or QSw). The CW 532 nm laser irradiation consistently produced high concentrations of n-hydrocarbons, with lesser amounts of cyclic and aromatic hydrocarbons, similar to previous analyses with both CW 1064 nm laser pyrolysis and conventional analytical pyrolysis [1]. In contrast, both the IR and UV QSw pulsed irradiation sources provided poor and varied data. Relatively low concentrations of n-hydrocarbons were occasionally produced, but most often no structurally significant products were detected. The poor maintenance of hydrocarbon structural units by the short pulse lasers can be attributed to the very high power density delivered, leading to excessive degradation of the irradiated macromolecule.     

Penetration of laser light through red blood cell ghosts

Hemoglobin is the main absorber of visible light in blood and blood-perfused tissues. However, hemoglobin is released from a red blood cell (RBC) during hemolysis. Hemolysis may be caused by a large number of medical conditions, including photodynamic therapy (PDT) and this subsequently can affect passage of light through the treated biological structures. The purpose of the present study was to determine the penetration of a laser beam through a suspension of hemoglobin-free human red blood cells (RBCs) - ghosts. Although hemoglobin has been efficiently removed from the samples used in our experiments, our measurements show that the samples still effectively attenuate the radiant power of penetrating laser light. We established penetration depths of 12.6mm and 15.4mm for two different laser light wavelengths, 532nm and 630nm, respectively. The penetration depth of laser light was about one order of magnitude higher for hemoglobin-free RBC ghosts as compared to intact RBCs [8,10,12]. These results can be important in case of phototherapy or biostimulation, since all photons that penetrate in a biological object may interact with it and evoke biological response.     

The biological effects of 632.8-nm low energy He-Ne laser on peripheral blood mononuclear cells in vitro

The aim of this study was to examine the proliferation of peripheral blood mononuclear cells due to the low energy 632.8-nm He-Ne laser application. The results of previous studies supported the hypothesis that low level laser therapy (LLLT) might have an increasing effect on the proliferation of lymphocytes and production of cytokines. The effect of laser irradiation was investigated by comparing the proliferation of peripheral blood mononuclear cells (PBMC) with a mitogenic stimulator, PHA (phytohemaglutinin) and laser irradiation. PBMCs of control samples, only laser irradiated samples, PHA included samples and both PHA included and laser irradiated samples were quantified and compared. Results of [3H] Thymidine test, 20 s laser irradiated and 40 s laser irradiated samples' proliferation were found statistically higher than control samples. There was no significant difference between control and 60 s laser irradiated samples. PHA also showed its ability to proliferate cells. PHA included samples and both PHA included and laser irradiated samples' proliferation was higher than both control and only laser irradiated samples. Our results showed that He-Ne laser application enhanced the proliferation significantly. Moreover, laser dose was noted as a significant parameter. On the other hand, LLLT by itself was found less effective than PHA.     

Cytokine production after helium-neon laser irradiation in cultures of human peripheral blood mononuclear cells.

The effects of laser light on the immune system have not been extensively characterized. Low-power laser sources, such as the helium-neon (He-Ne) laser with a wavelength of 632.8 nm, have been found to produce photobiological effects with evidence of interference with immunological functions. We have investigated the effects of He-Ne laser irradiation on Ficoll-Hypaque-isolated human peripheral blood mononuclear cells (PBMC). Cultured cells were irradiated for various times at two selected intensities and then stimulated with different mitogens. The rate of incorporation of 3H-thymidine into the DNA of stimulated cells decreased with increasing energy density. The levels of interleukin-1 alpha (IL-1 alpha), interleukin-2 (IL-2), tumour necrosis factor-alpha (TNF-alpha) and interferon-gamma (IFN-gamma) in supernatants of the cultures were determined (irradiated either before or after stimulation). When stimulating cells after irradiation, significantly increased levels of all cytokines were detected after 30 min of irradiation (18.9 J cm-2), whereas after 60 min of irradiation (37.8 J cm-2) cytokine levels were found to be significantly decreased.     

Two- and three-wavelength laser multiphoton ionization for highly sensitive detection in solution

Novel two- and three-wavelength laser multiphoton ionization techniques for highly sensitive detection in solution have been established. The photocurrent signal obtained for benzo[a]pyrene by irradiation at 355 nm in n-heptane was effectively enhanced by additional simultaneous irradiation at 532 and/or 1064 nm. The additional irradiation at 532 nm (5 mJ) doubled the signal-to-noise ratio, while that at 1064 nm (30 mJ) increased it 5.5-fold relative to that obtained when only the 355 nm radiation was used. The simultaneous action of 355, 532 (5 mJ) and 1064 (25 mJ) nm radiation further improved the S/N ratio; the detection limit was as low as 1.9 x 10(-10)M. The 532 nm radiation enhanced the photocurrent signal more effectively than did the 1064 nm radiation.     

Beneficial Effect of Quercetin on Erythrocyte Properties in Type 2 Diabetic Rats

Diabetes mellitus is characterized by tissue oxidative damage and impaired microcirculation, as well as worsened erythrocyte properties. Measurements of erythrocyte deformability together with determination of nitric oxide (NO) production and osmotic resistance were used for the characterization of erythrocyte functionality in lean (control) and obese Zucker diabetic fatty (ZDF) rats of two age categories. Obese ZDF rats correspond to prediabetic (younger) and diabetic (older) animals. As antioxidants were suggested to protect erythrocytes, we also investigated the potential effect of quercetin (20 mg/kg/day for 6 weeks). Erythrocyte deformability was determined by the filtration method and NO production using DAF-2DA fluorescence. For erythrocyte osmotic resistance, we used hemolytic assay. Erythrocyte deformability and NO production deteriorated during aging—both were lower in older ZDF rats than in younger ones. Three-way ANOVA indicates improved erythrocyte deformability after quercetin treatment in older obese ZDF rats only, as it was not modified or deteriorated in both (lean and obese) younger and older lean animals. NO production by erythrocytes increased post treatment in all experimental groups. Our study indicates the potential benefit of quercetin treatment on erythrocyte properties in condition of diabetes mellitus. In addition, our results suggest potential age-dependency of quercetin effects in diabetes that deserve additional research.     

Time-dependent responses of wounded human skin fibroblasts following phototherapy

BACKGROUND AND OBJECTIVE: The penetration and distribution of laser light in target tissue is dependent on the wavelength of the light. One problem with most of the published data on laser irradiation is that most studies do not record the duration between the exposure and the evaluation. This study aimed to establish if the dose, wavelength or duration of effect (1h or 24h) influences the biological responses of irradiated fibroblasts. MATERIALS AND METHODS: The study established cellular responses of normal and wounded human skin fibroblasts to helium-neon (632.8 nm), diode (830 nm) and Nd:YAG (1064 nm) laser irradiation using one exposure of 5 J/cm(2) or 16 J/cm(2) on day 1 and again on day 4. Cellular responses to laser irradiation were evaluated by measuring changes in cell viability (ATP viability and caspase 3/7 activity) and cell proliferation (ALP enzyme activity and bFGF expression), 1h and 24h post irradiation. RESULTS: Wounded cells exposed to 5 J/cm(2) using 632.8 nm showed an increase in ATP viability after 1h, a decrease in caspase 3/7 activity after 24h and an increase in cell proliferation after 24h. The results suggest that changes in parameters such as ATP viability should be observed directly after laser irradiation (1h) whereas other parameters such as caspase 3/7 activity, bFGF expression and ALP enzyme activity should be measured at least 24h after the final exposure. CONCLUSION: This study confirms that the duration of effect should be included as one of the main laser parameters when reporting on the effects of laser irradiation. It is important to establish time-dependent responses as the results may provide an understanding of the cellular responses following laser irradiation.     

纳米管钛酸的ESR特性及其可见光照的影响

本文报道了纳米管钛酸在真空-0.1MPa、温度100℃的条件下,经过不同时间处理后的ESR特性及其可见光照的影响.发现纳米管钛酸经一定处理后,不经光照即出现g=2.003ESR信号,该信号是由捕获一个电子的氧空位(V_o)产生的,此信号随着处理时间的延长而增强;在532nm的可见光照射下,随着光照时间的延长信号强度随之增加,达到一定强度值后,不再随光照时间的延长而增加;光源关闭后,信号强度又逐渐减小,但不能恢复到原来信号强度的水平.     

Wavelength dependence on the elemental analysis of glass by Laser Induced Breakdown Spectroscopy

Laser Induced Breakdown Spectroscopy (LIBS) is presented as a tool for the elemental analysis of glass in forensic applications. Two harmonics of the Nd:YAG laser at 266 nm and 532 nm were used as the irradiation source for the analysis of several glass standards and soda–lime glass samples of interest to forensic scientists. Both lasers were kept at a constant energy of 20 mJ and focused using a 150 mm focal length lens. A series of experiments were also conducted to determine the importance of wavelength on lens-to-sample distance (LTSD) at each wavelength. It was determined that the optimal LTSD was found at ~ 1–2 mm focused into the surface for both wavelengths yet the crater depth resulting from the irradiation at 266 nm was significantly deeper (112 µm) than that from the 532 nm laser (41 µm). In addition, the analytical performance of LIBS on 5 NIST glasses and 6 automobile glasses at both wavelengths is reported. Good correlation for the quantitative analysis results for the trace and minor elements Sr, Ba and Al are reported along with the calibration curves, in most cases R² > 0.95, using absolute intensities at various emission lines. Although 266 nm resulted in more mass removal, the 532 nm produced greater emission intensities. A slightly higher plasma density was determined for irradiation by 532 nm using the Stark broadening technique in comparison to the 266 nm irradiation.     

Studies of Silver Nanoparticles by Laser Ablation Method

The laser ablation technique has been employed to study silver colloidal formation. Laser intensities, irradiation wavelengths (1064 nm and 532 nm), and solvents (water, methanol, and isopropanol) were all considered. Changes of the maximum UV-Visible absorbance of the solutions with laser intensities exhibited nonlinear behavior for 1064 nm and 532 nm and displayed better ablation efficiency at 532 nm. Larger mean sizes were observed at 532 nm or at higher pulse energy. For solvent effect, the bigger particle sizes were generated in H₂O. As to colloidal stability, isopropanol, which has a lower dielectric constant than water, was found to stabilize Ag nanoparticles without protecting reagents over six months. Preliminary results in 2-butanol suggested that the viscosity of solvent may need to be considered in addition to the dielectric constant.     

Enhanced wavelength-sensitivity of volume holographic grating with dual-photoinitiation system in polymer-dispersed liquid crystal

We propose a method to improve the wavelength-sensitivity of a volume holographic grating by mixing dual-photoinitiation dopants, namely, rose bengal (RB)/N-phenylglycine (NPG) system and methylene blue (MB)/p-toluenesulfonic acid (PTSA) system, which enable the fabrication of gratings upon both green and red light illumination. The RB/NPG green light photoinitiation system is chosen in combination with the red-active MB/PTSA system because RB and MB absorb light near 567 and 665 nm independently. In this case, the holographic gratings, recorded in polymer-dispersed liquid crystal, can be fabricated simultaneously by two different visible laser lights with an output wavelength of 532 and 632.8 nm. The electro-optical performances of the gratings exposed upon 532 and 632.8 nm have been implemented: the diffraction efficiencies (DE) are 75% and 57% respectively when the exposure time is optimised to 2 min and 17 min; the threshold voltage is approximately 2.9 V/μm. The enhanced wavelength-sensitivity of holographic gratings allows for the storage of three-dimensional (3D) images on the same hologram plate, and these 3D images are easily reconstructed by both red and green light.     

The effect of green laser light irradiation on whole blood platelets

BACKGROUND: Laser light irradiation is assumed to have biostimulating effect in various cell types. However, there is still a lack of information concerning response of blood platelets to laser light irradiation. METHODS: In our study we used flow cytometry to monitor the effect of a green Nd-YAG laser (532 nm, 30 mW) irradiation on platelet activation and the expression of activated GPIIbIIIa glycoprotein complex (fibrinogen receptor) of whole blood platelets stained with fluorolabelled monoclonal antibody PAC-1. Also the formation of platelet microparticles and aggregates in a population of whole blood platelets following such irradiation was evaluated. RESULTS: Effects of laser light on platelet activation and reactivity were significant over a wide range of applied energies (p<0.01). While low and medium laser light energies (18 and 54 J) increased platelet activation, the irradiation with a high-energy laser light (108 J) resulted in depressed platelet reactivity and attenuated platelet response to activators. In addition, laser light irradiation had significant influence on the formation of platelet microparticles in either resting (p<0.05) or ADP-activated (p<0.05) platelets, while no significant effect was observed in collagen-activated platelets. On the other hand, laser light irradiation significantly increased the formation of platelet aggregates both in resting (p<0.01) and agonists-activated (p<0.05) platelets. CONCLUSIONS: Our results clearly point that the laser light irradiation of blood platelets can trigger signal transduction, leading to platelet activation, as well as the gradual loss of natural platelet reactivity and platelets' ability to respond to activating agents.     

Erythrocyte response to near-infrared radiation

The effects of NIR (near-infrared radiation 700-2,000 nm) on bovine erythrocytes in plasma was studied as a continuation of earlier studies. Cell shape was observed and the changes of ratio of hemolysis and electrokinetic potential measured as a function of irradiation time. After 10 min of irradiation, the shape of erythrocyte cells was mainly echinocytic. When these cells were incubated at 311 K for 24 h they regained their initial shape, but fresh erythrocytes that were irradiated for 30 min and aged in vitro did not. These phenomena are due to: (1) the absorption of NIR excitation by hemoglobin; the primary photochemical process being the photo-dissociation of oxyhemoglobin to deoxyhemoglobin. Resulting shape and ratio of hemolysis, structural changes and oxidative stress follow higher deoxyhemoglobin concentration. (2) The absorption of the NIR excitation by proteins, water and lipids. After NIR absorption the membrane surface dehydrates, leading to enhanced protonation and dissociation of hydrogen-bonded complexes. This in turn leads to a change in electrokinetic potential.     

Epoxy-based Polymer Containing Imidazole-type Azo Chromophores for Integrated Waveguide Applications

In this work, an epoxy-based polymer containing 2-phenylazo-4, 5-dicyanoimidazole chromophores (BP-IZ-DC) was synthesized and characterized by spectroscopic methods. The polymer showed unusual photo-bleachable property and the refractive index of the polymer could be readily modified by irradiation with a laser beam at visible wavelength. The irradiation with a laser beam at 488 nm caused a much more significant change of the refractive index than irradiation with 532 nm laser light. Upon the irradiation with the laser beam (488 nm, 100 mW/cm²) for 1 h, the refractive index decreased from 1.6512 to 1.5802. By using the photo-bleachable azo polymer, channel waveguide was fabricated by light irradiation through a mask and the light-transmission ability of the waveguide was evaluated.     

Laser-assisted synthesis of Au-Ag alloy nanoparticles in solution

By using laser-induced heating, we prepared Au-Ag nanoalloys via three different procedures: (i) mixture of Au nanoparticles and Ag(+) ions irradiated by a 532 nm laser, (ii) mixture of Au and Ag nanoparticles irradiated by a 532 nm laser, and (iii) mixture of Au and Ag nanoparticles irradiated by a 355 nm laser. Procedure i is advantageous for the production of spherical alloy nanoparticles; in procedures ii and iii, nanoalloys with a sintered structure have been obtained. The morphology of the obtained nanoalloys depends not only on the laser wavelength but also on the concentration of nanoparticles in the initial mixture. When the total concentration of Ag and Au nanoparticles in the mixture is increased, large-scale interlinked networks have been observed upon laser irradiation. It is expected that this selective heating strategy can be extended to prepare other bi- or multi-metallic nanoalloys.     

Effects of different light irradiations on structure and optical properties of methoxy-substituted tetraphenylporphyrins

UV lamp, filtered halogen lamp (at 425 nm) and Green laser (532 nm) experiments on a series of meso-substituted tetra phenyl porphyrin, TPP, bearing methoxy peripheral groups together with a metal derivate of 3,4 dimethoxy TPP were lead to different protonation and aggregation structures. Properties of irradiated porphyrins were investigated using their absorption and emission spectra in dichloromethane solution. The results show that the optical properties of the TPP derivates depend on light irradiation source, which shows the tuning of the absorption and emission spectra of the TPP derivates. From the dynamic light scattering measurements, the size distribution of samples was estimated about 5–15 nm in solvent after irradiation. Atomic force microscopy images of deposited porphyrins on the glass surface were shown average particle size between 10 and 30 nm. Particularly, self-assembly of the porphyrin derivates was also observed when green laser was used. We suggest that the irradiation source plays an important role in the controlling of size and morphology of products, and we propose a self-organization model to explain the formation of the porphyrin nanostructures.     

Laser-photophoretic migration and fractionation of human blood cells

Laser photophoretic migration behavior of human blood cells in saline solution was investigated under the irradiation of Nd:YAG laser beam (532 nm) in the absence and the presence of the flow in a fused silica capillary. Red blood cells (RBC) were migrated faster than white blood cells (WBC) and blood pellets to the direction of propagation of laser light. The observed photophoretic velocity of RBC was about 11 times faster than those of others. This was understood from the larger photophoretic efficiency of RBC than that of WBC, which was simulated based on the Mie scattering theory. Furthermore, it was found that, during the photophoretic migration, RBCs spontaneously orientated parallel to the migration direction so as to reduce the drag force. Finally, it was demonstrated that RBC and WBC were separated in a micro-channel flow system by the laser photophoresis.     

Cooperative phenomena in two-pulse, two-color laser photocoagulation of cutaneous blood vessels.

A novel laser system has been developed to study the effects of multiple laser pulses of differing wavelengths on cutaneous blood vessels in vivo, using the hamster dorsal skin flap preparation and in vitro, using cuvettes of whole or diluted blood. The system permits sequenced irradiation with well-defined intrapulse spacing at 532 nm, using a long-pulse frequency-doubled Nd:YAG laser, and at 1064 nm, using a long-pulse Nd:YAG laser. Using this system, we have identified a parameter space where two pulses of different wavelengths act in a synergistic manner to effect permanent vessel damage at radiant exposures where the two pulses individually have little or no effect. Using a two-color pump-probe technique in vitro, we have identified a phenomenon we call greenlight-induced infrared absorption, where a pulse of green light causes photochemical and photothermal modifications to the chemical constituents of blood and results in enhanced infrared absorption. We identify a new chemical species, met-hemoglobin, not normally present in healthy human blood but formed during laser photocoagulation which we believe is implicated in the enhanced near-infrared absorption.