Green Light Irradiation Research Articles

Encapsulated Triplet–Triplet Annihilation-Based Upconversion in the Aqueous Phase for Sub-Band-Gap Semiconductor Photocatalysis

We herein report the first instance of aqueous-phase photosensitization of semiconductor photocatalysts (WO(3) loaded with Pt) through triplet-triplet annihilation (TTA)-based upconversion of sub-band-gap photons. The TTA-based upconversion (UC) was achieved in the aqueous phase by encapsulating the solvent phase containing a benchmark platinum(II) octaethylporphyrin/9,10-diphenylanthracene sensitizer/acceptor pair in a rigid polymer shell in the form of aqueous dispersible microcapsules. A mixture of hexadecane and polyisobutylene was used as the inner solvent phase. This eliminated the need for the deoxygenation step that is essential for existing TTA-based UC processes and enabled stable UC to occur even after a month of exposure to the ambient environment. The photoluminescence properties were examined, and UC-assisted photochemical production of hydroxyl radical from green (532 nm) light irradiation was demonstrated for the first time.

Visible Light Photocatalytic Synthesis of Benzothiophenes

The photocatalytic reaction of o-methylthio-arenediazonium salts with alkynes yields substituted benzothiophenes regioselectively through a radical annulation process. Green light irradiation of eosin Y initiates the photoredox catalysis. The scope of the reaction was investigated by using various substituted diazonium salts and different alkynes.

Ultraviolet Irradiation-Dependent Fluorescence Enhancement of Hemoglobin Catalyzed by Reactive Oxygen Species

Ultraviolet (UV) light has a potent effect on biological organisms. Hemoglobin, an oxygen-transport protein, plays an irreplaceable role in sustaining life of all vertebrates. In this study we scrutinize the effects of ultraviolet irradiation (UVI) as well as visible irradiation on the fluorescence characteristics of bovine hemoglobin (BHb) in vitro. Data show that UVI results in fluorescence enhancement of BHb in a dose-dependant manner. Furthermore, UVI-induced fluorescence enhancement is significantly increased when BHb is pretreated with hydrogen peroxide (H2O2), a type of reactive oxygen species (ROS). Meanwhile, The water-soluble antioxidant vitamin C suppresses this UVI-induced fluorescence enhancement. In contrast, green light irradiation does not lead to fluorescence enhancement of BHb no matter whether H2O2 is acting on the BHb solution or not. Taken together, these results indicate that catalysis of ROS and UVI-dependent irradiation play two key roles in the process of UVI-induced fluorescence enhancement of BHb.

ChemInform Abstract: Metal‐Free, Visible‐Light Mediated Direct C—H Arylation of Heteroarenes with Aryl Diazonium Salts.

AbstractUnder optimized conditions using eosin Y as a photoredox catalyst and green light LED irradiation, a variety of aryldiazonium salts can be applied to the arylation of furan, thiophenes, an N‐protected pyrrole, and nitrobenzene.

Abstract 5656: Preclinical evaluation of cytotoxic effect of photosensitive fluorescent protein in human cancer cells

Abstract Photodynamic therapy (PDT) is an anticancer therapy to induce tumor-specific cytotoxicity by accumulation of photosensitizers (PSs) and following non-toxic light irradiation to tumor tissues. Non-toxic light irradiation induces the PS-mediated generation of reactive oxygen species (ROS) and subsequent cytotoxicity in tumor cells. For clinical application, some kinds of PSs, such as photofrin and laserphyrin, are intravenously injected before light irradiation in anticancer PDT. However, the lack of sufficient and continuous accumulation of PSs in tumor tissues makes difficult to eradicate tumor cells by PDT. Therefore, the development of novel PSs that accumulate to tumor tissues more efficiently and persistently is required to improve the antitumor effect of PDT. Recently, a bioengineered fluorescent protein KillerRed has been reported to generate ROS upon green light irradiation, suggesting a potential of KillerRed fluorescent protein as a novel PS. In this study, we investigated the antitumor effect of KillerRed fluorescent protein in human cancer cells in combination with PDT. Transient transfection with KillerRed expression vector induced the photosensitive cytotoxicity upon green light irradiation within a few hours in human cancer HeLa and OST cells. To further evaluate the cytotoxic effect of KillerRed fluorescent protein in human cancer cells, we obtained the stable transfectants expressing cytotoxic KillerRed or non-cytotoxic Katushka fluorescent protein from human lung cancer H1299 cells. Green light irradiation induced the cytotoxic effect within one hour in H1299-KillerRed cells, but not in H1299-Katushka or H1299 cells. H1299-KillerRed cells irradiated with green light showed significantly higher levels of ROS, which was confirmed by intracellular fluorescence level of 2′,7′-Dichlorodihydrofluorescein Diacetate, than H1299-Katushka or H1299 cells. Immunocytochemistry further revealed that green light-irradiated H1299-KillerRed cells showed the apoptotic cell death with the cleavage of caspase-3 24 hours after irradiation. These results suggest that KillerRed fluorescent protein is a potent novel PS inducing ROS generation and apoptotic cell death in tumor cells in anticancer PDT. The development of virus-mediated delivery system for tumor-specific induction of KillerRed fluorescent protein is under way. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5656. doi:1538-7445.AM2012-5656

Editorial: The Nonsense of Biofuels

Fossil fuels, like mineral oil, coal, and natural gas, are derived from the biomass of ancient times. As such, they are indirect products of photosynthesis. It is therefore appropriate to ask whether we can use currently available biomass and convert it into biofuels like biodiesel and biogas. Biohydrogen might be another option. Often one can read that biofuels are CO2-neutral and therefore a weapon against global warming. Their production is also supposed to reduce the amount of petrol and natural gas to be imported into many countries, thus making them less dependent on energy import. In the following, I shall discuss the efficiencies of the processes required to produce biofuels, compare them with alternatives, draw the obvious conclusions, and present some visions.

Synthesis and magnetic characterization of magnetite obtained by monowavelength visible light irradiation

Magnetite (Fe3O4) nanoparticles were controllably synthesized by aerial oxidation FeIIEDTA solution under different monowavelength light-emitting diode (LED) lamps irradiation at room temperature. The results of the X-ray diffraction (XRD) spectra show the formation of magnetite nanoparticle further confirmed by Fourier transform infrared spectroscope (FTIR) and the difference in crystallinity of as-prepared samples. Fe3O4 particles are nearly spherical in shape based on transmission electron microscopy (TEM). Average crystallite sizes of magnetite can be controlled by different irradiation light wavelengths from XRD and TEM: 50.1, 41.2, and 20.3nm for red, green, and blue light irradiation, respectively. The magnetic properties of Fe3O4 samples were investigated. Saturation magnetization values of magnetic nanoparticles were 70.1 (sample M-625), 65.3 (sample M-525), and 58.2 (sample M-460)emu/g, respectively.

Photochromism of Europium and Gadolinium Co-Doped Barium Haloapatite

A white-amethyst photochromic material, Ba10(PO4)6ClF:Eu2+,Gd3+, was synthesized. This material is sensitive to electromagnetic waves from ultraviolet (UV) to X-ray. The material changes its color from white to amethyst under UV or X-ray irradiation. The photo-colored sample can be bleached by green light irradiation or heat-treatment. Another striking feature of these compounds is their resistance to fatigue. A model that involves the ionization of the 5d electron of Eu2+ to conduction band states and subsequent trapping by a positive lattice defect is proposed for the photochromism in this compound.

Photocatalytic Activity and Characterization of Carbon-Modified Titania for Visible-Light-Active Photodegradation of Nitrogen Oxides

A variety of carbon-modified titania powders were prepared by impregnation method using a commercial available titania powder, Hombikat UV100, as matrix material while a range of alcohols from propanol to hexanol were used as precursors of carbon sources. Rising the carbon number of alcoholic precursor molecule, the modified titania showed increasing visible activities ofNOxphotodegradation. The catalyst modified with cyclohexanol exhibited the best activities of 62%, 62%, 59%, and 54% for the totalNOxremoval under UV, blue, green, and red light irradiation, respectively. The high activity with long wavelength irradiation suggested a good capability of photocatalysis in full visible light spectrum. Analysis of UV-visible spectrum indicated that carbon modification promoted visible light absorption and red shift in band gap. XPS spectroscopic analysis identified the existence of carbonate species (C=O), which increased with the increasing carbon number of precursor molecule. Photoluminescence spectra demonstrated that the carbonate species suppressed the recombination rate of electron-hole pair. As a result, a mechanism of visible-light-active photocatalyst was proposed according to the formation of carbonate species on carbon-modified TiO2.

Photodynamic Therapy with Indocyanine Green Injection and Near-Infrared Light Irradiation Has Phototoxic Effects and Delays Paralysis in Spinal Metastasis

The purpose of this study was to investigate the phototoxic effects of photodynamic therapy (PDT) with indocyanine green (ICG) and near-infrared light irradiation on rat mammary adenocarcinoma cells, and its therapeutic efficacy in a rat model of spinal metastasis. Although PDT has been successfully used as a non-radiation treatment for many malignancies, it has not yet been clinically applied for treating spinal metastasis. For the phototoxicity study, CRL-1666 cells were treated with PDT and cell viability was measured by WST-1 assay. For the efficacy study, 26 female Fischer 344 rats with spinal metastasis in the L6 vertebra were divided into three treatment groups: PDT with local injection of ICG (9 rats), PDT with systemic injection of ICG (10 rats), and no treatment or control (7 rats). Both the PDT groups received near-infrared light irradiation with a total energy of 10 J (1 W for 10 sec). The light was delivered directly through a single silica probe which was set on the left side of the L6 vertebral body. Hindlimb motor function was monitored according to the Basso-Beattie-Bresnahan (BBB) scale. Further, the observation periods were calculated to determine the survival time. The PDT exerted immediate and persistent phototoxic effects. Furthermore, the PDT with local injection of ICG as well as systemic injection of ICG delayed the deterioration of paralysis and prolonged the observation period. PDT with ICG injection and near-infrared light irradiation could be an effective local adjuvant treatment for spinal metastasis.

Osteoblast Differentiation of Amniotic Fluid-Derived Stem Cells Irradiated with Visible Light

The effect of visible light irradiation on the expression of pluripotent genes (Oct-4, Sox2, and Nanog) in amniotic fluid-derived stem cells (AFSCs) and on the osteogenic differentiation ability of AFSCs was investigated using light-emitting diodes (LEDs) at 0-2 mW/cm(2) in various wavelengths: [blue (470 nm), green (525 nm), yellow (600 nm), and red (630 nm)]. Pluripotent gene expression in AFSCs was up-regulated by visible light irradiation from a LED for more than 6 h. Green light irradiation of AFSCs up-regulated the expression of pluripotent genes more significantly than irradiation with other light. The osteogenic differentiation of AFSCs was facilitated by green and blue light irradiation. Facilitated differentiation into osteogenic cells by visible light irradiation was not mediated by reactive oxygen species (ROS); alkaline phosphatase activity (a marker of early osteogenic differentiation) and gene expression of osteopontin (a marker of late osteogenic differentiation) did not change significantly between AFSCs in differentiation medium with or without a ROS scavenger (vitamin C). The mitogen-activated protein kinase/extracellular signal-regulated protein kinase pathway, as well as other unknown signaling pathways, may be responsible for the activation of signaling pathways that facilitate the differentiation of AFSCs into osteogenic cells on light irradiation.

The influence of photochromotherapy on the injured nerve under experimental conditions (a histological study)

The objective of the present neurohistological study using an experimental model of compressive-ischemic neuropathy (40 white rats) was to estimate the influence of photochromotherapy on the injured nerve filament. It was shown that light of different wavelengths had differential effect on the nerve tissue. The exposure to blue light reduced the severity of traumatic lesion as apparent from a decrease in the number of filaments undergoing degenerative changes and their enhanced argentophilia. Irradiation with red light caused a marked decrease in the degree of vacuolization with moderate argentophilia suggesting normalization of ion transport and recovery of nerve conductivity. Green light irradiation promoted remyelinization of nerve filaments (a marked increase of the number of Schwann cells).

Indole‐3‐acetic acid: A potential new photosensitizer for photodynamic therapy of acne vulgaris

ALA (5-aminolevulinic acid) photodynamic therapy (PDT) is a new treatment option for acne. However, it needs a relatively long incubation period and adverse effects are common. Indole-3-acetic acid (IAA) is not toxic by itself but produces free radicals with ultraviolet B. In this study we examined the potential of IAA as a photosensitizer for acne treatment. Free radical formation was measured after visible light irradiation of IAA. Antimicrobial effect was evaluated by assessing growth suppression of Propionibacterium acnes and Staphylococcus aureus after IAA PDT. To evaluate the histological changes, skin biopsies were performed on nude mice skin after IAA PDT. To evaluate the clinical efficacy of IAA PDT, 14 acne patients were treated with the following IAA PDT regimen: three times each with a 15 minutes incubation period and a 2-week interval. The number of inflammatory lesions and the amount of sebum secretion were then assessed. IAA produced free radicals with green light irradiation. Importantly, IAA lost its photosensitizing ability after exposure to certain amount of light. This implies IAA PDT would not require post-procedure photo-protection. The growth of P. acnes and S. aureus were significantly suppressed with IAA PDT. In addition, IAA PDT treated skin showed destruction of follicular ostia epithelium. Interestingly, there was no significant difference between a 4 hours and a 30 minutes incubation, which means that longer absorption time is not necessary for IAA PDT. In the clinical study, inflammatory lesions and sebum secretion were significantly reduced. The procedure was painless and no adverse effect was observed. Photo-protection was not performed and there were no further phototoxic responses. IAA PDT has therapeutic effects on acne via its antimicrobial activities, its sebum-reducing effect and through relieving follicular occlusion. It is a very simple and safe treatment option for acne.

Selective photocatalytic oxidation of aromatic alcohols to aldehydes in an aqueous suspension of gold nanoparticles supported on cerium(iv) oxide under irradiation of green light

Gold nanoparticles supported on cerium(IV) oxide powder showing strong absorption at around 550 nm due to surface plasmon resonance oxidized aromatic alcohols to corresponding aldehydes almost quantitatively in an aqueous suspension under irradiation of green light.

Photochromism enhancement in reduced tridymite BaMgSiO4 by Fe-doping

We have investigated the influence of 38 kinds of metal ions on photochromism in BaMgSiO4 (BMS). We have found that the doped Fe ions are the most effective to enhance the photochromism. The Fe-doped BMS shows great sensitivity to blue light (wavelength λ = 405 nm) and turns bright pink. The colored Fe-doped BMS is bleached by green light (λ = 532 nm) irradiation. The coloration-bleaching process is repeatable. The color density of the photochromism depends on the wavelength of irradiation lights. We think that the photochromism enhancement is due to the electron deeper traps formed by the doped Fe ions.

Cover Picture: Metal‐Free, Cooperative Asymmetric Organophotoredox Catalysis with Visible Light (Angew. Chem. Int. Ed. 4/2011)

Highly enantioselective α-alkylations of aldehydes are achieved through the cooperative combination of an organocatalytic cycle and a photocatalytic cycle—represented by the slices of citrus fruits in the “catalytic cocktail”. The beautifully orange-colored photocatalyst eosin Y and green-light irradiation are used to replace noble-metal catalysts, as explained by K. Zeitler et al. in their Communication on page 951 ff. (Cover graphics were designed in cooperation with Georg Neumann.)

Selective photosensitized oxidation and its catalytic regulation of monoterpene with molecular oxygen in different reaction media

The photo-catalytic oxidation of α-pinene, β-pinene and limonene with molecular oxygen sensitized by tetrachlorotetraiodo-fluorescein sodium salt (RB) has been studied in different reaction media under green light irradiation. Simple and efficient photosensitized oxidation equipment was employed successfully to improve the efficiency of the photosensitized reaction. The results indicate that the photosensitized oxidation products can be directly obtained without after-treatment by reductive reagent. Furthermore, it was found that the product distributions are remarkably affected by reaction media, and that N,N-dimethylformamide (DMF) can regulate the selectivity to products. In particular, the good selectivity (85%) to the main product (myrtenal) and the excellent conversion (99%) were obtained in the absence of any other catalysts when DMF was used as reaction solvent in the photosensitized oxidation of β-pinene. Moreover, the possible photosensitized oxidation reaction mechanism in different media was suggested in the present work.

Blue-green light photochromism in europium doped BaMgSiO4

BaMgSiO 4 (BMS) can be sensed to blue light (wavelength λ=405 nm) by doped europium (Eu). Eu doped BMS turns to bright pink, and is bleached by green light (λ=475–532 nm) irradiation in several seconds. The coloration-decoloration process is repeatable and first. The colored state hardly changes for over 480 h (20 days), and is stable even at 100 °C. The blue-green light photochromism can be explained by electron transfers between doped Eu and oxygen defects. The doped Eu broadens the absorption band of BMS, and supplies excited electrons. The oxygen defects form electron traps, which catch excited electrons, and become F-like color centers.

Metal‐Free, Cooperative Asymmetric Organophotoredox Catalysis with Visible Light

The dawn of old stars: Classic xanthene dyes like eosin Y (gr. εoς=goddess of dawn) and green-light irradiation can replace precious metal complexes for the organocatalytic asymmetric α-alkylation of aldehydes, thus rendering the process purely organic.

Green light radiation effects on free radicals inhibition in cellular and chemical systems

Free radicals generation is inhibited through green light (GL) irradiation in cellular systems and in chemical reactions. Standard melanocyte cultures were UV-irradiated and the induced cellular reactive oxygen species (ROS) were quantified by the fluorescence technique. The same cell cultures, previously protected by a 24 h GL exposure, displayed a significantly lower ROS production. A simple chemical reaction is subsequently chosen, in which the production of free radicals is well defined. Paraffin wax and mineral oil were GL irradiated during thermal degradation and the oxidation products checked by chemiluminescence [CL] and Fourier transform infrared spectra [FT-IR]. The same clear inhibition of the radical oxidation of alkanes is recorded. A quantum chemistry modeling of these results is performed and a mechanism involving a new type of Rydberg macromolecular systems with implications for biology and medicine is suggested.