Photoirradiation System Research Articles

Simultaneous Determination of Kynurenine and Kynurenic Acid by High-Performance Liquid Chromatography Photoirradiation System Using a Mobile Phase Containing 18-crown-6.

A high-performance liquid chromatography (HPLC) system has been developed for the fluorometric determination of kynurenine (KYN) and kynurenic acid (KYNA) in human serum using a mobile phase containing 18-crown-6. A retention time of KYNA was adjusted with pH of phosphate buffer in 18-crown-6. KYN and KYNA were separated on a CAPCELLPAK C18 (250 × 4.6 mm i.d.). The mobile phase consisted of 35 mmol/L phosphate buffer (pH 8.0)/methanol (85/15, v/v) containing 35 mmol/L hydrogen peroxide and 10 mmol/L 18-crown-6. The retention times of KYN and KYNA were 18and 24 minutes, respectively. The calibration graphs of KYN and KYNA were linear over the range 180 to 2900 and 1 to 84 nmol/L by injecting a 50-μL volume of KYN and KYNA, respectively. Pretreatment of serum was achieved by deproteinization only. The mean recoveries of KYN and KYNA from serum were more than 97%.

Design and validation of an open-source modular Microplate Photoirradiation System for high-throughput photobiology experiments.

Research in photobiology is currently limited by a lack of devices capable of delivering precise and tunable irradiation to cells in a high-throughput format. This limits researchers to using expensive commercially available or custom-built light sources which make it difficult to replicate, standardize, optimize, and scale experiments. Here we present an open-source Microplate Photoirradiation System (MPS) developed to enable high-throughput light experiments in standard 96 and 24-well microplates for a variety of applications in photobiology research. This open-source system features 96 independently controlled LEDs (4 LEDs per well in 24-well), Wi-Fi connected control and programmable graphical user interface (GUI) for control and programming, automated calibration GUI, and modular control and LED boards for maximum flexibility. A web-based GUI generates light program files containing irradiation parameters for groups of LEDs. These parameters are then uploaded wirelessly, stored and used on the MPS to run photoirradiation experiments inside any incubator. A rapid and semi-quantitative porphyrin metabolism assay was also developed to validate the system in wild-type fibroblasts. Protoporphyrin IX (PpIX) fluorescence accumulation was induced by incubation with 5-aminolevulinic acid (ALA), a photosensitization method leveraged clinically to destroy malignant cell types in a process termed photodynamic therapy (PDT), and cells were irradiated with 405nm light with varying irradiance, duration and pulsation parameters. Immediately after light treatment with the MPS, subsequent photobleaching was measured in live, adherent cells in both 96-well and a 24-well microplates using a microplate reader. Results demonstrate the utility and reliability of the Microplate Photoirradiation System to irradiate cells with precise irradiance and timing parameters in order to measure PpIx photobleaching kinetics in live adherent cells and perform comparable experiments with both 24 and 96 well microplate formats. The high-throughput capability of the MPS enabled measurement of enough irradiance conditions in a single microplate to fit PpIX fluorescence to a bioexponential decay model of photobleaching, as well as reveal a dependency of photobleaching on duty-cycle—but not frequency—in a pulsed irradiance regimen.

In Vitro Photoirradiation System for Simultaneous Irradiation with Different Light Doses at a Fixed Temperature.

In this work an irradiance and temperature controlled in-vitro system for conducting investigations in PDT and phototherapy is presented. The development of new light sources has caused a considerable increase in research and application of several photodynamic (PDT) therapeutic methods, as well as other light-based therapeutic techniques. However, further work is needed to fully understand and elucidate the mechanisms as well as to increase the effectiveness of PDT. Nowadays, there are no commercial systems to perform automated light exposure experiments with cultured cells. Also, there are very few reports of similar photoirradiation systems. The system is composed of 24 independent light-emitting diodes that can be used to irradiate separate wells in a microwell plate. The system includes a module to measure changes in temperature within each irradiated well without contact. The light sources are placed on a plate that can easily be changed in order to irradiate at different wavelengths. The performance of the system is fully controlled with a computer, and all the experimental data are properly recorded. The design, construction, operation, and a full characterization of the system are presented. A novel fully automated photoirradiation system has been developed. The system allows the design of the experiments in this area with precise dosimetry, temperature, and irradiation regime controls reducing manipulation of the samples and saving time.

Development of a photoirradiation system for photodynamic therapy with dosimetric control

Photodynamic Therapy is a well know treatment based on light interaction with a photosensitizing drug, used in the treatment of certain diseases like cancer. In this issue, the development of asystem for superficial irradiation, which allows the application of Photodynamic Therapy at 630nm using a light emitting diode as a radiation source. It is proposed a control for the energy dose delivery in depth, which incorporates the calculations from a radiation distribution model. Also it is reported the construction and characterization of optical phantoms in aqueous suspensions, used for models’ verification and system performance testing.

여드름 치료를 위한 PWM 기반 광 조사 시스템 설계

As one of photo dynamic therapies, the existing LED photo irradiation method with 635 nm continuous wave has most frequently been used for acne treatment, it suffered from a low energy efficiency and generation of a large amount of heat in tissues requiring improvement measures. In this thesis, a LED photo irradiation system for acne treatment has been designed using PWM(Pulse Width Modulation) mode to enhance the energy efficiency and prevent thermal destruction in tissues. System configuration consisting largely of timer module, PWM module, and photo transfer device has been designed with the use of 1 W LED at a wavelength of 660 nm for the photo transfer device to increase skin penetration depth for treatment of acne. Frequency and wave form generated by using PWM control was verified along with confirmation of output energy of 660 nm LED and surface temperatures of tissues, followed by evaluation of stable energy outputs and stability of tissues. The results indicated that whereas power loss was high and thermal destruction in tissues was exhibited when C.W mode was used to obtain the optical energy of 1 W LED at a wavelength of 660 nm for acne treatment, realization of PWM mode allowed lowering of power consumption for LED through pulse width modulation, and no occurrence of thermal destruction in tissues, suggesting that PWM mode is safer and more effective for treatment of acne than C.W mode.

An Active Photoreceptor Intermediate Revealed by In Situ Photoirradiated Solid-State NMR Spectroscopy

A novel, to our knowledge, in situ photoirradiation system for solid-state NMR measurements is improved and demonstrated to successfully identify the M-photointermediate of pharaonis phoborhodopsin (ppR or sensory rhodopsin II), that of the complex with transducer (ppR/pHtrII), and T204A mutant embedded in a model membrane. The 13C NMR signals from [20-13C]retinal-ppR and ppR/pHtrII revealed that multiple M-intermediates with 13-cis, 15-anti retinal configuration coexisted under the continuously photoirradiated condition. NMR signals observed from the photoactivated retinal provide insights into the process of photocycle in the ppR/pHtrII complex.

Determination of free radicals generated from light exposed ketoprofen

Ketoprofen [(RS)-2-(3-benzoylphenyl)propanoic acid] has been widely used for the treatment of inflammatory diseases and musculoskeletal injury. However, there is concern over its phototoxicity and photosensitization potential as side effects. In the present study, we examined photodynamic action of ketoprofen, determined free radicals and active oxygen species generated from ketoprofen by photo-irradiation, which have been implicated as the phototoxicity and photosensitization. The generation of superoxide anion, hydroxyl radical and singlet oxygen were determined by electron spin resonance (ESR), chemiluminescence analyzer (CLA) and the on-line photo irradiated superoxide anion detection system, when ketoprofen was exposed by the ultraviolet lamp or the chemical lamp. The on-line light exposed superoxide anion detection system was developed to catch superoxide anions generated at an instant and estimate quantitatively risk of the light-sensitive disease of drugs. These radicals were maintained for 20 min at the ESR spectrum measurement using the spin trapping reagent, 5,5-dimethyl-1-pyrroline- N-oxide (DMPO), though these signals were declining gradually. The degradation products were analyzed to identify the chemical structures. The pathway of the photo degradation and generation of the active oxygen species was estimated by the experimental results obtained in this study.

Enhanced Formation of Ozone by the Addition of Chloropicrin (Trichloronitromethane) to Propene/NO/Air/Photoirradiation Systems

Abstract The photolysis of chloropicrin in air at 1 atm was performed in a 6-m3 photochemical reaction chamber with a combination of Xe arc lamps and Pyrex filters as a light source. Phosgene was obtained as one of the main products with a yield of unity. No nitrosyl chloride was observed, which supports the C–N scission mechanism for the photolysis. Photochemical ozone formation was enhanced when chloropicrin was added to the propene/NO/air/photoirradiation system after the ozone concentration maximum had been reached. The ozone-formation factor for chloropicrin under the conditions employed was, however, estimated to be 0.25 mole of ozone formed per mole of the decomposed chloropicrin. This implies that the Cl atom, itself, contributes to the destruction of ozone rather than to the formation of ozone under the experimental conditions. NO2 released from chloropicrin is the source of enhanced ozone. If the amount of chloropicrin as a soil fumigant increases, it can cause an increase of the ozone concentration in suburban and/or rural areas.

The Complexation of Zinc Tetraphenylporphyrintrisulfonate by Viologen and Its Role in Photoredox Processes

Abstract The formation of the cation radicals of viologen dyes was established when an aqueous solution containing zinc tetraphenylporphyrintrisulfonate (Zn–TPPS3), viologen dye, and 2-mercaptoethanol was irradiated by visible light. The reduction of viologen has been studied kinetically; its reduction rate may be expressed as follows: v=\fracd[V+]dt=\left(\frack3[Zn−TPPS3]01+K1[V2+]+K2[V+]\ight)\left(\frack4[V2+]k−3+k4[V2+]\ight)\left(\frack6[RSH]k5[V+]+k6[RSH]\ight), where [V2+], [V+], and [RSH] are the concentrations of the oxidized form and the reduced form of viologen, and 2-mercaptoethanol respectively. On the basis of the rate expression, a reaction mechanism containing the complexation of Zn–TPPS3 by viologen was proposed. On the addition of hydrogenase to the above photoirradiation system, hydrogen evolution was observed by the irradiation of visible light.

PHOTO-INDUCED HYDROGEN EVOLUTION IN THE PRESENCE OF NADPH AS AN ELECTRON DONATING AGENT

Abstract The cation radical of methylviologen was formed when an aqueous solution containing photosensitizer, methylviologen (MV2+), and NADPH was irradiated by visible light. On the addition of hydrogenase to the photo-irradiation system hydrogen evolution was observed.

Kinetics and mechanism of photo-induced methyl viologen reduction with an organic dye and hydrogen evolution from water by hydrogenase

The formation of the cation radical of methyl viologen was established when an aqueous solution containing an organic dye, methyl viologen, and mercaptoethanol was irradiated by visible light. The reduction of methyl viologen has been studied kinetically and the reduction rate was expressed as follows. ▪ where [S], [MV 2+], [MV +], and [RSH] are the respective concentrations of the dye photosensitizer, oxidized and reduced forms of methyl viologen, and mercaptoethanol. On the basis of the rate expression, the reaction mechanism is discussed. On the addition of hydrogenase to the above photoirradiation system, hydrogen evolution was observed by the irradiation of visible light.

Photo-induced cleavage of water with tris(2,2′-bipyridine) ruthenium dication or hematoporphyrin in alkaline solution

The formation of the cation radical or methyl viologen was established when an alkaline solution containing hematoporphyrin (Hm) or tris(2,2′-bipyridine) ruthenium dication (Ru(bpy) 2+ 3) was irradiated by visible light. Hydroxyl ion served as reducing agent in these systems. The reduction of methyl viologen has been studied kinetically and the reaction mechanism is discussed On addition of colloidal platinum to the above photo-irradiation system, hydrogen evolution was observed by water reduction. [A part of the paper has been published in Inorg. Chim. Acta, 53 L149 (1981)].

Hydrogen evolution from water by use of viologen polymers as electron transfer catalyst

AbstractThe behavior of viologen polymer (P‐V2+) as an electron transfer catalyst in the reaction of hydrogen generation was studied. In the photoirradiation system, which contains triethanolamine (TEA), Ru(bpy)3+3, and P‐V2+, the amount of hydrogen evolution was less than methyl viologen (MV2+); P‐V2+, however, was more effective in sodium dithionite as the electron donor and showed higher initial rates than MV2+.

KINETICS AND MECHANISM OF PHOTO‐INDUCED METHYL VIOLOGEN REDUCTION WITH ZINC‐MESO‐TETRAPHENYLPORPHYRINTRISULFONIC ACID AND HYDROGEN EVOLUTION FROM WATER HYDROGENASE

Abstract— The formation of the cation radical of methyl viologen was established when an aqueous solution containing zinc‐meso‐tetraphenylporphyrintrisulfonic acid, methyl viologen and mercaptoethanol was irradiated by visible light. The reduction of methyl viologen has been studied kinetically and the reduction rate expressed as followswhere [Zn]0 is the total amount of zinc compounds in the system.On the basis of the rate expression, the reaction mechanism is discussed.On the addition of hydrogenase to the above photoirradiation system, hydrogen evolution was observed by both the irradiation of sunlight and a tungsten lamp.

Photoreduction of methyl viologen by triphenylamine and hydrogen generation with hydrogenase

The formation of the cation radical of methyl viologen was established when an acetonitrile-water solution containing methyl viologen and triphenylamine was irradiated by near ultraviolet light. The reduction of methyl viologen has been studied kinetically, and the reduction rate was expressed as follows. ▪ On the addition of hydrogenase to the above photoirradiated system hydrogen evolution after water reduction was observed. The mechanisms of methyl viologen reduction and hydrogen evolution are discussed.

Kinetics and mechanism of methyl viologen reduction and hydrogen generation by visible light with tris (2,2′-bipyridine) ruthenium dication

Abstract The formation of the cation radical of methyl viologen was established when an aqueous solution containing Ru(bpy)2+3, methyl viologen and triethanolamine was irradiated by visible light. The reduction of methyl viologen has been studied kinetically, and the reduction rate expressed as follows . Each rate constant was determined and the reaction mechanism is discussed. On the addition of hydrogenase to the above photoirradiation system, hydrogen evolution was observed by water reduction. The mechanism of hydrogen evolution is also discussed.

Hydrogen generation by visible light with tris-(2,2′-bipyridine) ruthenium dication

Abstract The formation of methyl viologen anion radical in the reaction with photoexcited Ru(bpy) 2+ 3 in the presence of the weak reducing agent triethanolamine, has been established. An attempt was made to reduce water to hydrogen by using the electron transfer system which combines the Ru(bpy) 2+ 3 an methyl viologen photoirradiation system and hydrogenase, or colloidal platinum, for hydrogen production. The following reaction mechanism is proposed. Further, it was found that colloidal platinum could replace the K 2 PtCl 6 used by Lehn to give similar results.

Photopolymerization of methyl methacrylate in the presence of saccharide

AbstractPhotopolymerization of methyl methacrylate (MMA) in aqueous solution of saccharide was investigated. Glucose, cellobiose, maltose, and fructose accelerated the photopolymerization in the hard glass system, but α‐methyl‐d‐glucoside was inactive. On the other hand, on remarkable effect of saccharide except fructose was observed in the quartz glass system. A conversion in the hard glass system increased with irradiation time and with concentration of saccharide, which showed the effect in the order of ketose > aldose > nonreducing saccharide. Scission of glucosidic bonds and decomposition of reducing groups of saccharide molecule took place in the quartz glass system, but there was no reduction in the reducing power of saccharide in the hard glass system. By studying the ESR of the photoirradiated system containing saccharide, MMA, and water, no radical of saccharide was found in hard glass systems, but an increase in growing radical of MMA was clearly observed in systems with the coexistence of ketose and aldose, while α‐methyl‐d‐glucoside was inactive. It is believed, therefore, that both ketose and aldose contribute effectively to initiate the photopolymerization without any change in their own structures. On the other hand, reducing groups of saccharide play a very important role in the sensitizing action of the initiation.