Mini review on photosensitization by plants in grazing herbivores.

PubMed

Hussain, Syeda M; Herling, Valdo Rodrigues; Rodrigues, Paulo Henrique Mazza; Naz, Ishrat; Khan, Hamayun; Khan, Muhammad Tahir

2018-06-01

Photosensitization is severe dermatitis or oxidative/chemical changes in the epidermal tissues activated by the light-induced excitation of molecules within the tissue. It is a series of reactions mediated through light receptors and is more common when the plant-produced metabolites are heterocyclic/polyphenols in nature. The areas affected are exposed body parts and mostly non-pigmented areas with least ultraviolet protection. Similarly, cellular alteration also occurs in the affected animal's dermal tissues and body parts and grazing animals by the accumulation and activation of photodynamic molecules. Photo-oxidation can also occur within the plant due to the generation of reactive oxygen species causing damage and degradation in the form of free radicals and DNA. During the last few decades, many new tropical grass species have been introduced in the grazing lands which are genetically modified, and the animals grazing on them are facing various forms of toxicity including photosensitization. The plant's secondary metabolites/drugs may cause toxicity when bacteria, viral agents, fungi (Pithomyces chartarum), or neoplasia injures the liver and prevents the phylloerythrin excretion. All these may disturb the liver enzymes and blood profile causing a decrease in weight and production (wool and milk etc.) with severe dermal, digestive, and nervous problems. Recent advancements in OMICS (cellomics, ethomics, metabolomics, metabonomics, and glycomics) have enabled us to detect and identify the plants' secondary metabolites and changes in the animal's physiology and histopathology as a causative of photosensitivity. The review focuses on types of photosensitization, reasons, secondary metabolic compounds, chemistry, and environmental effect on plants.

Kindler syndrome: report of three cases in a family and a brief review.

PubMed

Yazdanfar, Ameneh; Hashemi, Banafsheh

2009-02-01

Kindler syndrome is an autosomal recessive disorder with neonatal blister formation, photosensitivity, atrophy, abnormal pigmentation, and fragility of the skin. Skin atrophy is more prominent on the extremities and the skin manifestations improve with age. We report three cases in a family which present the clinical and pathologic manifestations of Kindler syndrome. All of the three cases reported here present skin changes on the extremities, face, and neck, including hyper- and hypopigmentation, atrophy, and telangiectasia. The condition in these cases started soon after birth. Two of these cases also had mucosal involvement. Increased photosensitivity and sunburn after minimal sun exposure should lead physicians to examine the skin for poikiloderma and the mouth for fragility of the gums, periodontitis and other associated findings. Also, patients should be questioned about any history of blister formation as well as family history.

Effect of cadmium chloride on the distal retinal pigment cells of the fiddler crab, Uca pugilator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reddy, P.S.; Fingerman, M.; Nguyen, L.K.

1997-03-01

Crustaceans have two sets of pigmentary effectors, chromatophores and retinal pigment cells. Retinal pigments control the amount of light striking the rhabdom, the photosensitive portion of each ommatidium, screening the rhabdom in bright light and uncovering it in darkness or dim light. Migration of the distal pigment in the fiddler crab, Uca pugilalor, is regulated by a light-adapting hormone and a dark-adapting hormone. The black chromatophores of this crab are also controlled by a pair of hormones. Both pigmentary effectors exhibit circadian rhythms. The effects of some organic and inorganic pollutants on the ability of Uca pugilator to change colormore » have been described. Exposure of this crab to naphthalene or cadmium results in decreased ability to disperse the pigment in their black chromatophores, the exposed crabs becoming paler than the unexposed crabs. Norepinephrine triggers release of both the black pigment-dispersing hormone and the light-adapting hormone. In view of the facts that (a) these hormones which regulate the black chromatophores and distal pigment are synthesized in and released from the eyestalk neuroendocrine complex, (b) the black pigment-dispersing hormone and the light-adapting hormone may actually be the same hormone. having two different activities and (c) release of both the black pigment-dispersing hormone and the light-adapting hormone is triggered by norepinephrine, the present investigation was carried out to determine the effect of cadmium on distal pigment migration in Uca pugilator. More specifically, for comparison with the previously reported effect of cadmium on pigment migration in the black chromatophores, we wished to determine whether the distal pigment of fiddler crabs exposed to cadmium chloride is capable of as wide a range of movement as in unexposed crabs, and if not what might be the explanation. This is the first report of the effect of a pollutant on a retinal pigment of any crustacean. 12 refs., 3 tabs.« less

Laser targeted photo-occlusion of rat choroidal neovascularization without collateral damage.

PubMed

Nishiwaki, Hirokazu; Zeimer, Ran; Goldberg, Morton F; D'Anna, Salvatore A; Vinores, Stanley A; Grebe, Rhonda

2002-02-01

Laser targeted photo-occlusion (LTO) is a novel method being developed to treat choroidal neovascular membranes (CNV) in age-related and other macular degenerations. A photosensitive agent, encapsulated in heat-sensitive liposomes, is administered intravenously. A low power laser warms the targeted tissue and releases a bolus of photosensitizer. The photosensitizer is activated after it clears from the normal choriocapillaris but not from the CNV. Forty-five experimental CNV were induced in seven rats. Five weeks after LTO, complete occlusion was observed by laser targeted angiography (LTA) in 76% of treated CNV, and partial occlusion was found in the remaining 24%. The tissues outside the CNV but within the area treated by LTO showed no flow alteration and no dye leakage. All untreated CNV were patent on LTA at 5 weeks. Light microscopy and electron microscopy confirmed the results in treated and control lesions. Moreover, treated areas next to lesions showed normal photoreceptors, retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaris. These results indicate that LTO may improve current photodynamic therapy by alleviating the need for repeated treatments and by avoiding the long-term risks associated with damage to the RPE and occlusion of normal choriocapillaries.

Melanopsin photoreception in the eye regulates light-induced skin colour changes through the production of α-MSH in the pituitary gland.

PubMed

Bertolesi, Gabriel E; Hehr, Carrie L; McFarlane, Sarah

2015-09-01

How skin colour adjusts to circadian light/dark cycles is poorly understood. Melanopsin (Opn4) is expressed in melanophores, where in vitro studies suggest it regulates skin pigmentation through a 'primary colour response' in which light photosensitivity is translated directly into pigment movement. However, the entrainment of the circadian rhythm is regulated by a population of melanopsin-expressing retinal ganglion cells (mRGCs) in the eye. Therefore, in vivo, melanopsin may trigger a 'secondary colour response' initiated in the eye and controlled by the neuro-endocrine system. We analysed the expression of opn4m and opn4x and melanin aggregation induced by light (background adaptation) in Xenopus laevis embryos. While opn4m and opn4x are expressed at early developmental times, light-induced pigment aggregation requires the eye to become functional. Pharmacological inhibition of melanopsin suggests a model whereby mRGC activation lightens skin pigmentation via a secondary response involving negative regulation of alpha-melanocyte-stimulating hormone (α-MSH) secretion by the pituitary. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

The Photosensitivity of Rhodopsin Bleaching and Light-Induced Increases of Fundus Reflectance in Mice Measured In Vivo With Scanning Laser Ophthalmoscopy

PubMed Central

Zhang, Pengfei; Goswami, Mayank; Zawadzki, Robert J.; Pugh, Edward N.

2016-01-01

Purpose To quantify bleaching-induced changes in fundus reflectance in the mouse retina. Methods Light reflected from the fundus of albino (Balb/c) and pigmented (C57Bl/6J) mice was measured with a multichannel scanning laser ophthalmoscopy optical coherence tomography (SLO-OCT) optical system. Serial scanning of small retinal regions was used for bleaching rhodopsin and measuring reflectance changes. Results Serial scanning generated a saturating reflectance increase centered at 501 nm with a photosensitivity of 1.4 × 10−8 per molecule μm2 in both strains, 2-fold higher than expected were irradiance at the rod outer segment base equal to that at the retinal surface. The action spectrum of the reflectance increase corresponds to the absorption spectrum of mouse rhodopsin in situ. Spectra obtained before and after bleaching were fitted with a model of fundus reflectance, quantifying contributions from loss of rhodopsin absorption with bleaching, absorption by oxygenated hemoglobin (HbO2) in the choroid (Balb/c), and absorption by melanin (C57Bl/6J). Both mouse strains exhibited light-induced broadband reflectance changes explained as bleaching-induced reflectivity increases at photoreceptor inner segment/outer segment (IS/OS) junctions and OS tips. Conclusions The elevated photosensitivity of rhodopsin bleaching in vivo is explained by waveguide condensing of light in propagation from rod inner segment (RIS) to rod outer segment (ROS). The similar photosensitivity of rhodopsin in the two strains reveals that little light backscattered from the sclera can enter the ROS. The bleaching-induced increases in reflectance at the IS/OS junctions and OS tips resemble results previously reported in human cones, but are ascribed to rods due to their 30/1 predominance over cones in mice and to the relatively minor amount of cone M-opsin in the regions scanned. PMID:27403994

Wavelength-dependent photoresponse of biological and aqueous model systems using the photodynamic plant pigment hypericin.

PubMed

Kubin, A; Alth, G; Jindra, R; Jessner, G; Ebermann, R

1996-11-01

Photodynamic eradication of tumour cells in vivo depends on the presence of a photosensitizer, light delivery to the cells, and an oxygen supply. Hypericin, a polycyclic quinone with absorption maxima in the ultraviolet and visible ranges, was prepared for clinical use as a photosensitizer. Due to antitumoral and antineoplastic activities as well as the generation of singlet oxygen after photoexcitation, hypericin was applied in clinical oncology and photodynamic therapy. Hypericin was administered subcutaneously (20 micrograms hypericin in 200 microliters Nacl/pyridine solution) into the ante brachium (forearm) of two volunteers. After the diffusion and equilibration of 120 min phototesting was carried out using outdoor light exposure, halogen lamp, laser 514 nm (argon), laser 632 nm (argon dye) and laser 670 nm (diode laser), from 60 to 120 J cm-2. Positive phototests to outdoor light exposure, halogen lamp and laser 514 nm were characterized by rubescence, oozing, vesiculation and darting pain. Phototests with laser 632 nm and 670 nm showed no effects after irradiation. When hypericin was administered topically on skin, erythema and flaring could not be induced by any irradiation. These results suggest that hypericin is a potent photosensitizer only within the UV and green light ranges. This characteristic photoresponse could also be obtained in guinea pig papillary muscle (GPPM) bioassay, which may be established as a model for photosensitizer testing. Irradiation of hypericin-incubated GPPM with 514 nm (20 J cm-2) led to a decrease of the contractile force of about 31%. However, excitation with 632 nm and 670 nm did not cause inotropic effects on GPPM. In addition, hypericin and Photosan 3 were shown to be capable of sensitizing the photo-oxidation of sodium linoleate. This assay should be established for testing interactions between photosensitizers and light sources in vitro.

The photophysics of monomeric bacteriochlorophylls c and d and their derivatives: properties of the triplet state and singlet oxygen photogeneration and quenching

NASA Technical Reports Server (NTRS)

Krasnovsky, A. A. Jr; Cheng, P.; Blankenship, R. E.; Moore, T. A.; Gust, D.

1993-01-01

Measurements of pigment triplet-triplet absorption, pigment phosphorescence and photosensitized singlet oxygen luminescence were carried out on solutions containing monomeric bacteriochlorophylls (Bchl) c and d, isolated from green photosynthetic bacteria, and their magnesium-free and farnesyl-free analogs. The energies of the pigment triplet states fell in the range 1.29-1.34 eV. The triplet lifetimes in aerobic solutions were 200-250 ns; they increased to 280 +/- 70 microseconds after nitrogen purging in liquid solutions and to 0.7-2.1 ms in a solid matrix at ambient or liquid nitrogen temperatures. Rate constants for quenching of the pigment triplet state by oxygen were (2.0-2.5) x 10(9) M-1 s-1, which is close to 1/9 of the rate constant for diffusion-controlled reactions. This quenching was accompanied by singlet oxygen formation. The quantum yields for the triplet state formation and singlet oxygen production were 55-75% in air-saturated solutions. Singlet oxygen quenching by ground-state pigment molecules was observed. Quenching was the most efficient for magnesium-containing pigments, kq = (0.31-1.2) x 10(9) M-1 s-1. It is caused mainly by a physical process of singlet oxygen (1O2) deactivation. Thus, Bchl c and d and their derivatives, as well as chlorophyll and Bchl a, combine a high efficiency of singlet oxygen production with the ability to protect photochemical and photobiological systems against damage by singlet oxygen.

Curative effect of photodynamic therapy for 42 cases of moderate or late stage in esophagus cancer

NASA Astrophysics Data System (ADS)

Bai, Xiao-Min; Shen, Guang-Rong; Chen, Weng-Ge; Guo, Tao

1998-11-01

34 patients with advanced esophagus cancer and 8 cases of cancer of gastric cardia were treated by photodynamic therapy. The therapeutic effectiveness of the treatment was evaluated according the criteria used in China. CR 63.2 percent SR 11.3 percent, MR 2 percent. The total effective rate was 76.5 percent. There was no significant side effect in this group except mild skin photosensitization and pigmentation and exacerbation of pain in a few cases.

Investigating the role of melanin in UVA/UVB- and hydrogen peroxide-induced cellular and mitochondrial ROS production and mitochondrial DNA damage in human melanoma cells.

PubMed

Swalwell, Helen; Latimer, Jennifer; Haywood, Rachel M; Birch-Machin, Mark A

2012-02-01

Skin cancer incidence is dramatically increasing worldwide, with exposure to ultraviolet radiation (UVR) a predominant factor. The UVA component initiates oxidative stress in human skin, although its exact role in the initiation of skin cancer, particularly malignant melanoma, remains unclear and is controversial because there is evidence for a melanin-dependent mechanism in UVA-linked melanoma studies. Nonpigmented (CHL-1, A375), moderately pigmented (FM55, SKmel23), and highly pigmented (FM94, hyperpigmented FM55) human melanoma cell lines have been used to investigate UVA-induced production of reactive oxygen species using FACS analysis, at both the cellular (dihydrorhodamine-123) and the mitochondrial (MitoSOX) level, where most cellular stress is generated. For the first time, downstream mtDNA damage (utilizing a quantitative long-PCR assay) has been investigated. Using UVA, UVB, and H(2)O(2) as cellular stressors, we have explored the dual roles of melanin as a photoprotector and photosensitizer. The presence of melanin has no influence over cellular oxidative stress generation, whereas, in contrast, melanin protects against mitochondrial superoxide generation and mtDNA damage (one-way ANOVA with post hoc Tukey's analysis, P<0.001). We show that if melanin binds directly to DNA, it acts as a direct photosensitizer of mtDNA damage during UVA irradiation (P<0.001), providing evidence for the dual roles of melanin. Copyright © 2011 Elsevier Inc. All rights reserved.

Association of Systemic Lupus Erythematosus Clinical Features with European Population Genetic Substructure

PubMed Central

Calaza, Manuel; Witte, Torsten; Papasteriades, Chryssa; Marchini, Maurizio; Migliaresi, Sergio; Kovacs, Attila; Ordi-Ros, Josep; Bijl, Marc; Santos, Maria Jose; Ruzickova, Sarka; Pullmann, Rudolf; Carreira, Patricia; Skopouli, Fotini N.; D'Alfonso, Sandra; Sebastiani, Gian Domenico; Suarez, Ana; Blanco, Francisco J.; Gomez-Reino, Juan J.; Gonzalez, Antonio

2011-01-01

Systemic Lupus Erythematosus (SLE) is an autoimmune disease with a very varied spectrum of clinical manifestations that could be partly determined by genetic factors. We aimed to determine the relationship between prevalence of 11 clinical features and age of disease onset with European population genetic substructure. Data from 1413 patients of European ancestry recruited in nine countries was tested for association with genotypes of top ancestry informative markers. This analysis was done with logistic regression between phenotypes and genotypes or principal components extracted from them. We used a genetic additive model and adjusted for gender and disease duration. Three clinical features showed association with ancestry informative markers: autoantibody production defined as immunologic disorder (P = 6.8×10−4), oral ulcers (P = 6.9×10−4) and photosensitivity (P = 0.002). Immunologic disorder was associated with genotypes more common in Southern European ancestries, whereas the opposite trend was observed for photosensitivity. Oral ulcers were specifically more common in patients of Spanish and Portuguese self-reported ancestry. These results should be taken into account in future research and suggest new hypotheses and possible underlying mechanisms to be investigated. A first hypothesis linking photosensitivity with variation in skin pigmentation is suggested. PMID:22194982

Comparison of Riboflavin and Toluidine Blue O as Photosensitizers for Photoactivated Disinfection on Endodontic and Periodontal Pathogens In Vitro.

PubMed

Nielsen, Henrik Krarup; Garcia, Javier; Væth, Michael; Schlafer, Sebastian

2015-01-01

Photoactivated disinfection has a strong local antimicrobial effect. In the field of dentistry it is an emerging adjunct to mechanical debridement during endodontic and periodontal treatment. In the present study, we investigate the effect of photoactivated disinfection using riboflavin as a photosensitizer and blue LED light for activation, and compare it to photoactivated disinfection with the widely used combination of toluidine blue O and red light. Riboflavin is highly biocompatible and can be activated with LED lamps at hand in the dental office. To date, no reports are available on the antimicrobial effect of photoactivated disinfection using riboflavin/blue light on oral microorganisms. Planktonic cultures of eight organisms frequently isolated from periodontal and/or endodontic lesions (Aggregatibacter actinomycetemcomitans, Candida albicans, Enterococcus faecalis, Escherischia coli, Lactobacillus paracasei, Porphyromonas gingivalis, Prevotella intermedia and Propionibacterium acnes) were subjected to photoactivated disinfection with riboflavin/blue light and toluidine blue O/red light, and survival rates were determined by CFU counts. Within the limited irradiation time of one minute, photoactivated disinfection with riboflavin/blue light only resulted in minor reductions in CFU counts, whereas full kills were achieved for all organisms when using toluidine blue O/red light. The black pigmented anaerobes P. gingivalis and P. intermedia were eradicated completely by riboflavin/blue light, but also by blue light treatment alone, suggesting that endogenous chromophores acted as photosensitizers in these bacteria. On the basis of our results, riboflavin cannot be recommended as a photosensitizer used for photoactivated disinfection of periodontal or endodontic infections.

Naphthalocyanine-complexes as potential photosensitizers for PDT of tumors

NASA Astrophysics Data System (ADS)

Shopova, Maria; Woehrle, Dieter; Mantareva, Vanya; Mueller, Silke

1999-07-01

In the present paper information about the synthesis and results on the pharmacokinetic and experimental photodynamic therapy (PDT) of naphthalocyanines are given. The photodynamic activity of differently substituted zinc(II)- and silicon(IV)-naphthalocyanines using liposomes or Cremophor EL as drug-delivery systems is shown on different tumor models. For the evaluation of the phototherapeutic effect different assessment criteria were used, including light and electron microscope observations. The main conclusions which can be arrived at on the basis of our findings are the following: silicon(IV)-naphthalocyanine seems to be not a very effective tumor sensitizer, especially in the treatment o pigmented melanoma, while zinc(II)-naphthalocyanines appear to be very promising for PDT of tumors. Their selective targeting and slow clearance from tumor tissue, fast clearance from skin and pronounced phototherapeutic effect on different tumor models and especially at melanotic tumors, even after application of low drug doses, make this group of photosensitizers very attractive for successful PDT of cancer.

Lipid based nanocarriers system for topical delivery of photosensitizers.

PubMed

Md, Shadab; Haque, Shadabul; Madheswaran, Thiagarajan; Zeeshan, Farrukh; Meka, Venkata Srikanth; Radhakrishnan, Ammu K; Kesharwani, Prashant

2017-08-01

Topical photodynamic therapy (PDT) is a non-invasive technique used in the treatment of malignant and non-malignant skin diseases. It offers great promise because of its simplicity, enhanced patient compliance, localisation of the photosensitizer, as well as the use of light and oxygen to achieve photocytotoxicity. Despite progress in photosensitizer-mediated topical PDT, its clinical application is limited by poor penetration of photosensitizers through the skin. Therefore, much effort has been made to develop nanocarriers that can tackle the challenges of conventional photosensitizer-mediated PDT for topical delivery. This review discusses recent data on the use of different types of lipid-based nanocarriers in delivering photosensitizer for topical PDT. Copyright © 2017 Elsevier Ltd. All rights reserved.

Competitive quenching: a possible novel approach in protecting RPE cells from damage during PDT.

PubMed

Weinberger, Dov; Ron, Yonina; Lusky, Moshe; Gaaton, Dan; Orenstein, Arie; Blank, Michael; Mandel, Mathilda; Livnat, Tamar; Barliya, Tilda; Lavie, Gad

2005-04-01

The purpose of this study is to demonstrate feasibility of using our novel concept, termed competitive quenching, for protecting the choroidal extravascular compartment and retinal pigment epithelium (RPE) from verteporfin (VP)-induced phototoxicity using hypericin. Furthermore, we aim to achieve partitioning of the quencher, hypericin, in the extravascular space and VP within the microvascular compartment of the chorio-retinal complex in vivo. We protect RPE cells from damage inflicted by photoactivated VP by introducing hypericin into these cells prior to photosensitization to quench the photosensitizing activity of VP. Cell protection levels were measured by MTT and Hemacolor viability assays. Wavelength range used for VP photoexcitation (700 +/- 40 nm) excludes the absorption range of hypericin, preventing the latter from photoactivation. Pharmacokinetic conditions, in which hypericin spreads throughout the choroidal and retinal extravascular space while VP is confined to the vasculature, are delineated using double-fluorescence imaging. Cell viability increased 3- to 5-fold when 10-20 microM hypericin were present in RPE cells during photosensitization with 0.1-0.5 microM VP. VP fluorescence intensity was unchanged by the presence of hypericin in the cells. Hypericin administered intravenously to rats was confined to the choroidal vasculature after 15 min to 2 hr. Subsequently, hypericin partitioned to the choroidal and retinal extravascular space. VP administered at this time was confined to the microvasculature. RPE and choroid may potentially be protected by compartmentalizing hypericin to the extravascular compartment while VP administered shortly before photosensitization is confined to the microvasculature. Adverse photodynamic therapy (PDT) damage to choroidal tissues adjacent to neovasculature targeted for photoablation have the potential of being prevented by competitive quenching with hypericin.

Incidental retinal phototoxicity associated with ingestion of photosensitizing drugs.

PubMed

Mauget-Faÿsse, M; Quaranta, M; Francoz, N; BenEzra, D; Mauget-Fa, M

2001-07-01

to report on the possible correlation between incident retinal phototoxicity and the use of photosensitizing drugs. four patients were examined because of scotomas and visual loss after an incidental exposure to a strong light source. One patient (two eyes) was exposed to standard camera flash; one patient (one eye) had a brief exposure to welding light; one patient (two eyes) underwent uncomplicated phacoemulsifications with intraocular lens implantation. The fourth patient had a severe retinal phototoxicity following a secondary intraocular lens implantation. All four patients underwent a thorough assessment including history of systemic drug use. These patients had ophthalmologic evaluation including: best corrected visual acuity (ETDRS charts), fundus examination, fluorescein and indocyanine green angiographies and were followed for 1 year. on presentation, the mean visual acuity was 7.5/20 (range: 20/400-20/20). Fundus examination disclosed yellow-gray sub-retinal lesions in all affected eyes. Early phase fluorescein angiography showed one or multiple hypofluorescent spots surrounded by a halo of hyperfluorescent window defect. In the late phase, some of these spots leaked the fluorescein dye. Indocyanine green angiography demonstrated hypofluorescent spots throughout with ill-defined borders of hyperfluorescence observed during the late stages. The common finding in these four patients was the fact that they were all taking one or more photosensitizing drugs (hydrochlorothiazide, furosemide, allopurinol, and benzodiazepines). Three of the patients had a full visual recovery a few months after the phototoxicity. The fourth patient remained with a visual acuity of 20/60 12 months after the light exposure. Despite the visual recovery, non-homogeneous retinal pigment epithelial disturbances persisted in all affected eyes. phototoxicity following incidental light exposure may occur in patients taking drugs of photosensitizing potential. Therefore, the thorough history of systemic drug ingestion should be obtained if patients have exposure to strong light sources.

Visible Light-Induced Carbonylation Reactions with Organic Dyes as the Photosensitizers.

PubMed

Peng, Jin-Bao; Qi, Xinxin; Wu, Xiao-Feng

2016-09-08

Dyes can CO do it: Organic dyes and pigments are usually applied in textile dyeing, which can be dated back to the Neolithic period. Interestingly, the possibility to use organic dyes as photoredox catalysts has also been noticed by organic chemists and applied in organic synthesis. Carbonylation reactions as a powerful procedure in carbonyl-containing compound preparation have also been studied. In this manuscript, the recent achievements in using organic dyes as visible-light sensitizers in carbonylation chemistry are summarized and discussed. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hypericin-mediated selective photomodification of connective tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hovhannisyan, V., E-mail: hovv@phys.ntu.edu.tw; Guo, H. W.; Chen, Y. F., E-mail: yfchen@phys.ntu.edu.tw

2014-12-29

Controllable modification of biological molecules and supramolecular components of connective tissue are important for biophysical and biomedical applications. Through the use of second harmonic generation imaging, two-photon fluorescence microscopy, and spectrofluorimetry, we found that hypericin, a natural pigment, induces photosensitized destruction of collagen fibers but does not affect elastic fibers and lipids in chicken tendon, skin, and blood vessels. We demonstrated the dynamics and efficiency of collagen photomodification and investigated mechanisms of this processes. Our results suggest that hypericin–mediated photoprocesses in biological tissues may be useful in biomedical applications that require selective modification of connective tissues.

A palladium label to monitor nanoparticle-assisted drug delivery of a photosensitizer into tumor spheroids by elemental bioimaging.

PubMed

Niehoff, Ann-Christin; Moosmann, Aline; Söbbing, Judith; Wiehe, Arno; Mulac, Dennis; Wehe, Christoph A; Reifschneider, Olga; Blaske, Franziska; Wagner, Sylvia; Sperling, Michael; von Briesen, Hagen; Langer, Klaus; Karst, Uwe

2014-01-01

In this study, the cellular uptake of the second generation photosensitizer 5,10,15,20-tetrakis(3-hydroxyphenyl)porphyrin (mTHPP) was investigated using laser ablation coupled to inductively coupled plasma mass spectrometry (LA-ICP-MS) at a spatial resolution of 10 μm. To achieve high sensitivity, the photosensitizer was tagged with palladium. As a tumor model system, a 3D cell culture of the TKF-1 cell line was used. These tumor spheroids were incubated with the Pd-tagged photosensitizer embedded in poly(lactic-co-glycolic acid) (PLGA) nanoparticles to investigate the efficiency of nanoparticle based drug delivery. An accumulation of the drug in the first cell layers of the tumor spheroid was observed. In the case of nanoparticle based drug delivery, a significantly more homogeneous distribution of the photosensitizer was achieved, compared to tumor spheroids incubated with the dissolved photosensitizer without the nanoparticular drug delivery system. The infiltration depth of the Pd-tagged photosensitizer could not be increased with rising incubation time, which can be attributed to the adsorption of the photosensitizer onto cellular components.

Influence of thermal light correlations on photosynthetic structures

NASA Astrophysics Data System (ADS)

de Mendoza, Adriana; Manrique, Pedro; Caycedo-Soler, Felipe; Johnson, Neil F.; Rodríguez, Ferney J.; Quiroga, Luis

2014-03-01

The thermal light from the sun is characterized by both classical and quantum mechanical correlations. These correlations have left a fingerprint on the natural harvesting structures developed through five billion years of evolutionary pressure, specially in photosynthetic organisms. In this work, based upon previous extensive studies of spatio-temporal correlations of light fields, we hypothesize that structures involving photosensitive pigments like those present in purple bacteria vesicles emerge as an evolutionary response to the different properties of incident light. By using burstiness and memory as measures that quantify higher moments of the photon arrival statistics, we generate photon-time traces. They are used to simulate absorption on detectors spatially extended over regions comparable to these light fields coherence length. Finally, we provide some insights into the connection between these photo-statistical features with the photosynthetic membrane architecture and the lights' spatial correlation. Facultad de Ciencias Uniandes.

Intrinsically photosensitive retinal ganglion cells.

PubMed

Do, Michael Tri Hoang; Yau, King-Wai

2010-10-01

Life on earth is subject to alternating cycles of day and night imposed by the rotation of the earth. Consequently, living things have evolved photodetective systems to synchronize their physiology and behavior with the external light-dark cycle. This form of photodetection is unlike the familiar "image vision," in that the basic information is light or darkness over time, independent of spatial patterns. "Nonimage" vision is probably far more ancient than image vision and is widespread in living species. For mammals, it has long been assumed that the photoreceptors for nonimage vision are also the textbook rods and cones. However, recent years have witnessed the discovery of a small population of retinal ganglion cells in the mammalian eye that express a unique visual pigment called melanopsin. These ganglion cells are intrinsically photosensitive and drive a variety of nonimage visual functions. In addition to being photoreceptors themselves, they also constitute the major conduit for rod and cone signals to the brain for nonimage visual functions such as circadian photoentrainment and the pupillary light reflex. Here we review what is known about these novel mammalian photoreceptors.

The phototoxicity of phenothiazinium-based photosensitizers to bacterial membranes.

PubMed

Hussain, Saimah; Harris, Frederick; Phoenix, David A

2006-02-01

The ability of phenothiazinium-based photosensitizers to induce photodamage to Escherichia coli membranes is investigated. Phenothiazinium-based photosensitizers were found to be somewhat lipophilic (log P>0.7) and to induce surface-pressure changes (3-12 mN m(-1)) in lipid monolayers mimetic of bacterial membranes, implying that these molecules are able to penetrate biological membranes. Under dark and light conditions (3.15 J cm(-1) for 30 min), phenothiazinium-based photosensitizers were incubated with E. coli cells. These cells showed levels of dark bacteriolysis that ranged between 6% and 13%, with light conditions leading to no significant increase in these levels. Gas chromatography-based analyses showed such incubations to produce no significant changes in the levels of C(16) and C(18) fatty acid chain saturation found in E. coli whole lipid-extracts. It is concluded that the phenothiazinium-based photosensitizers studied may not use E. coli membranes as their primary photodynamic target, but may inflict photodamage on cytoplasmic targets, possibly DNA.

Encapsulation of Carotenoids

NASA Astrophysics Data System (ADS)

Ribeiro, Henelyta S.; Schuchmann, Heike P.; Engel, Robert; Walz, Elke; Briviba, Karlis

Carotenoids are natural pigments, which are synthesized by microorganisms and plants. More than 600 naturally occurring carotenoids have been found in the nature. The main sources of carotenoids are fruits, vegetables, leaves, peppers, and certain types of fishes, sea foods, and birds. Carotenoids may protect cells against photosensitization and work as light-absorbing pigments during photosynthesis. Some carotenoids may inhibit the destructive effect of reactive oxygen species. Due to the antioxidative properties of carotenoids, many investigations regarding their protective effects against cardiovascular diseases and certain types of cancers, as well as other degenerative illnesses, have been carried out in the last years (Briviba et al. 2004; Krinsky et al. 2004; Kirsh et al. 2006). A diet rich in carotenoids may also contribute to photoprotection against UV radiation (Stahl et al. 2006). In vitro studies have shown that carotenoids such as β-cryptoxanthin and lycopene stimulate bone formation and mineralization. The results may be related to prevention of osteoporosis (Kim et al. 2003; Yamaguchi and Uchiyama 2003; 2004; Yamaguchi et al. 2005).

Melanopsin tristability for sustained and broadband phototransduction.

PubMed

Emanuel, Alan Joseph; Do, Michael Tri Hoang

2015-03-04

Mammals rely upon three ocular photoreceptors to sense light: rods, cones, and intrinsically photosensitive retinal ganglion cells (ipRGCs). Rods and cones resolve details in the visual scene. Conversely, ipRGCs integrate over time and space, primarily to support "non-image" vision. The integrative mechanisms of ipRGCs are enigmatic, particularly since these cells use a phototransduction motif that allows invertebrates like Drosophila to parse light with exceptional temporal resolution. Here, we provide evidence for a single mechanism that allows ipRGCs to integrate over both time and wavelength. Light distributes the visual pigment, melanopsin, across three states, two silent and one signaling. Photoequilibration among states maintains pigment availability for sustained signaling, stability of the signaling state permits minutes-long temporal summation, and modest spectral separation of the silent states promotes uniform activation across wavelengths. By broadening the tuning of ipRGCs in both temporal and chromatic domains, melanopsin tristability produces signal integration for physiology and behavior. Copyright © 2015 Elsevier Inc. All rights reserved.

A safety study of a novel photosensitizer, sinoporphyrin sodium, for photodynamic therapy in Beagle dogs.

PubMed

Lin, Ni; Li, Chao; Wang, Zhonghua; Zhang, Jingxuan; Ye, Xiangfeng; Gao, Wenjing; Wang, Aiping; Jin, Hongtao; Wei, Jinfeng

2015-04-01

Sinoporphyrin sodium (DVDMS) is a novel hematoporphyrin-like photosensitizer developed for photodynamic therapy (PDT), an effective therapeutic modality for tumor treatment; however, the safety of photosensitizer-based PDT is always of great concern. The purpose of the current study was to investigate the potential repeated-dose toxicity and describe the toxicokinetic process of DVDMS-based PDT in Beagle dogs. The dogs were randomly allocated to six groups, and then were administrated a DVDMS preparation intravenously at dose levels of 0, 1, 3, 9, 1 and 9 mg per kg body weight, respectively; then, the latter two groups were illuminated 24 h later with a 630 nm laser for 10 min, once every seven days for 5 weeks. During the study period, clinical signs, mortality, body weight, food consumption, body temperature, ophthalmoscopy, hematology, serum biochemistry, urinalysis, electrocardiograms, toxicokinetics, organ weights, gross anatomy and histopathology were examined. After the administration, no deaths were observed; however, the dogs that received PDT showed skin swelling and ulceration, indicating that DVDMS-PDT induced a phototoxic effect. DVDMS led to an increase in blood coagulation in dogs in the 9 mg kg(-1) group and in the two PDT groups on Day 35, whereas it induced a decrease in dogs in the 3 mg kg(-1) group and in the two PDT groups on Day 49. The toxicokinetic study showed that the systematic exposure of DVDMS in dogs occurred in a dose-dependent manner, and DVDMS did not accumulate in blood plasma. The DVDMS-based PDT group showed no obvious treatment-related pathological changes; however, slight or mild brown-and-yellow pigmentation of DVDMS (or its metabolite) was observed to deposit in the liver, spleen, local lymph nodes and marrow of dogs in the mid- and high-dose groups, as well as the high-dose PDT group. In females, the absolute and relative spleen weights increased in dogs in the 9 mg kg(-1) DVDMS groups with and without PDT during the treatment and recovery period, respectively. The target organs are presumed to be the liver and immune organs (spleen, bone marrow and lymph nodes), while all of the responses were slight. Based on the results above, the no-observed-adverse-effect level (NOAEL) was considered to be 1 mg kg(-1), and DVDMS-PDT appeared to be a safe and promising anti-tumor therapy in the clinic.

Photo-excitation of carotenoids causes cytotoxicity via singlet oxygen production

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoshii, Hiroshi, E-mail: yoshii@nirs.go.jp; Faculty of Medical Sciences, University of Fukui, Eiheiji, Fukui 910-1193; Yoshii, Yukie, E-mail: yukiey@nirs.go.jp

Highlights: Black-Right-Pointing-Pointer Some photo-excited carotenoids have photosensitizing ability. Black-Right-Pointing-Pointer They are able to produce ROS. Black-Right-Pointing-Pointer Photo-excited fucoxanthin can produce singlet oxygen through energy transfer. -- Abstract: Carotenoids, natural pigments widely distributed in algae and plants, have a conjugated double bond system. Their excitation energies are correlated with conjugation length. We hypothesized that carotenoids whose energy states are above the singlet excited state of oxygen (singlet oxygen) would possess photosensitizing properties. Here, we demonstrated that human skin melanoma (A375) cells are damaged through the photo-excitation of several carotenoids (neoxanthin, fucoxanthin and siphonaxanthin). In contrast, photo-excitation of carotenoids that possess energymore » states below that of singlet oxygen, such as {beta}-carotene, lutein, loroxanthin and violaxanthin, did not enhance cell death. Production of reactive oxygen species (ROS) by photo-excited fucoxanthin or neoxanthin was confirmed using a reporter assay for ROS production with HeLa Hyper cells, which express a fluorescent indicator protein for intracellular ROS. Fucoxanthin and neoxanthin also showed high cellular penetration and retention. Electron spin resonance spectra using 2,2,6,6-tetramethil-4-piperidone as a singlet oxygen trapping agent demonstrated that singlet oxygen was produced via energy transfer from photo-excited fucoxanthin to oxygen molecules. These results suggest that carotenoids such as fucoxanthin, which are capable of singlet oxygen production through photo-excitation and show good penetration and retention in target cells, are useful as photosensitizers in photodynamic therapy for skin disease.« less

Cone pigments in human deutan colour vision defects.

PubMed Central

Alpern, M; Wake, T

1977-01-01

1. The Nagel anomaloscope, neutral points and dichromatic matches to a spectral green light identified a population of seventy red-green dichromats. 2. The anomaloscope settings allow the calculation of the relative action spectrum of the match at the wave-length of the red (645 nm) and green (535 nm) primaries. The distribution of this ratio is bimodal; there are two clusters with a gap of about 0-75 long units between. Among the thirty-eight deuteranopes there are wide differences in anomaloscope matches; similar differences appear among the thirty-two protanopes. 3. Retinal densitometry of the foveas of fifteen of the deuteranopes is compared and contrasted with measurements on trichromats. In the former, only one photolabile pigment is found in the red-green region of the spectrum; normals always have two. The view of Rushton (1965a) that deuteranopes have erythrolabe but no measurable chlorolabe is confirmed for each member of this group. 4. Simple deuteranomalous show two red-green cone pigments. The difference spectra of extreme deuteranomalous are very similar to those found in deuteranopia. 5. Individual differnce in kinetics (photosensitivity, time constant of regeneration) and in the density and lambdamax of the difference spectrum of erythrolabe in deuteranopia are appreciable; the reasons for these differences are not clear. PMID:301185

High prevalence of minor symptoms in tattoos among a young population tattooed with carbon black and organic pigments.

PubMed

Høgsberg, T; Hutton Carlsen, K; Serup, J

2013-07-01

The prevalence of mild adverse reactions, i.e. complaints, in tattoos is sparsely described. The demography of tattoos in a young population representing an index population of the recent trend was studied. The prevalence of complaints related to tattoos, and tattoos by number, size, localization and colour were registered. The data were collected through personal interviews and examinations of consecutive individuals who spontaneously attended a clinic of venereology. Of 154 participants with 342 tattoos, 27% reported complaints in a tattoo beyond 3 months after tattooing. The complaints were predominantly related to black and red pigments. The participants reported complaints in 16% of their tattoos. Fifty-eight per cent of those complaints were sun induced. The complaints varied in intensity but were mainly minor. Skin elevation and itching were most frequent. The responders stated overall satisfaction with 80% of all tattoos. Eight per cent of tattoos were situated on anatomical sites prohibited by Danish law. We found a remarkably high prevalence of tattoo complaints, including photosensitivity, among young individuals tattooed with carbon black and organic pigments especially red. © 2012 The Authors. Journal of the European Academy of Dermatology and Venereology © 2012 European Academy of Dermatology and Venereology.

Ultrasonic activation and chemical modification of photosensitizers enhances the effects of photodynamic therapy against Enterococcus faecalis root-canal isolates.

PubMed

Tennert, C; Drews, A M; Walther, V; Altenburger, M J; Karygianni, L; Wrbas, K T; Hellwig, E; Al-Ahmad, A

2015-06-01

The aim of this study was to evaluate the effect of photodynamic therapy (PDT) on Enterococcus faecalis biofilms in artificially infected root canals using modified photosensitizers and passive ultrasonic activation. Two hundred and seventy extracted human teeth with one root canal were instrumented utilizing ProTaper files, autoclaved, infected with E. faecalis T9 for 72 h and divided into different groups: irrigation with 3% sodium hypochlorite (NaOCl), 20% ethylenediaminetetraacetic acid (EDTA), or 20% citric acid, PDT without irrigation, PDT accompanied by irrigation with NaOCl, EDTA, or citric acid, PDT using an EDTA-based photosensitizer or a citric-acid-based photosensitizer and PDT with ultrasonic activation of the photosensitizer. A 15 mg/ml toluidine blue served as the photosensitizer, activated by a 100 mW LED light source. Sterile paper points were used for sampling the root canals and dentin chips were collected to assess the remaining contamination after treatment. Samples were cultured on blood agar plates and colony forming units were quantified. PDT alone achieved a reduction in E. faecalis counts by 92.7%, NaOCl irrigation alone and combined with PDT by 99.9%. The antibacterial effects increased by the combination of irrigation using EDTA or citric acid and PDT compared to irrigation alone. More than 99% of E. faecalis were killed using PDT with the modified photosensitizers and ultrasonic activation. NaOCl based disinfection achieved the highest antimicrobial effect. Using PDT with an EDTA-based or citric-acid-based phozosensitizer or activating the photosensitizer with ultrasound resulted in a significantly higher reduction in E. faecalis counts compared to conventional PDT. Copyright © 2015 Elsevier B.V. All rights reserved.

Reactive oxygen species in plant pathogenesis: the role of perylenequinone photosensitizers.

PubMed

Daub, Margaret E; Herrero, Sonia; Chung, Kuang-Ren

2013-09-20

Reactive oxygen species (ROS) play multiple roles in interactions between plants and microbes, both as host defense mechanisms and as mediators of pathogenic and symbiotic associations. One source of ROS in these interactions are photoactivated, ROS-generating perylenequinone pigments produced via polyketide metabolic pathways in plant-associated fungi. These natural products, including cercosporin, elsinochromes, hypocrellins, and calphostin C, are being utilized as medicinal agents, enzyme inhibitors, and in tumor therapy, but in nature, they play a role in the establishment of pathogenic associations between fungi and their plant hosts. Photoactivated perylenequinones are photosensitizers that use light energy to form singlet oxygen (¹O₂) and free radical oxygen species which damage cellular components based on localization of the perylenequinone molecule. Production of perylenequinones during infection commonly results in lipid peroxidation and membrane damage, leading to leakage of nutrients from cells into the intercellular spaces colonized by the pathogen. Perylenequinones show almost universal toxicity against organisms, including plants, mice, bacteria, and most fungi. The producing fungi are resistant, however, and serve as models for understanding resistance mechanisms. Studies of resistance mechanisms by perylenequinone-producing fungi such as Cercospora species are leading to an understanding of cellular resistance to ¹O₂ and oxidative stress. Recent studies show commonalities between resistance mechanisms in these fungi with extensive studies of ¹O₂ and oxidative stress responses in photosynthetic organisms. Such studies hold promise both for improved medical use and for engineering crop plants for disease resistance.

Structure and ultrastructure of eyes and brains of Thalia democratica (Thaliacea, Tunicata, Chordata).

PubMed

Braun, Katrin; Stach, Thomas

2017-10-01

Salps are marine planktonic chordates that possess an obligatory alternation of reproductive modes in subsequent generations. Within tunicates, salps represent a derived life cycle and are of interest in considerations of the evolutionary origin of complex anatomical structures and life history strategies. In the present study, the eyes and brains of both the sexual, aggregate blastozooid and the asexual, solitary oozooid stage of Thalia democratica (Forskål, ) were digitally reconstructed in detail based on serial sectioning for light and transmission electron microscopy. The blastozooid stage of T. democratica possesses three pigment cup eyes, situated in the anterior ventral part of the brain. The eyes are arranged in a way that the optical axes of each eye point toward different directions. Each eye is an inverse eye that consists of two different cell types: pigment cells (pigc) and rhabdomeric photoreceptor cells (prcs). The oozooid stage of T. democratica is equipped with a single horseshoe-shaped eye, positioned in the anterior dorsal part of the brain. The opening of the horseshoe-shaped eye points anteriorly. Similar to the eyes of the blastozooid, the eye of the oozooid consists of pigment cells and rhabdomeric photoreceptor cells. The rhabdomeric photoreceptor cells possess apical microvilli that form a densely packed presumably photosensitive receptor part adjacent to the concave side of the pigc. We suggest correspondences of the individual eyes in the blastozooid stage to respective parts of the single horseshoe-shaped eye in the oozooid stage and hypothesize that the differences in visual structures and brain anatomies evolved as a result of the aggregate life style of the blastozooid as opposed to the solitary life style of the oozooid. © 2017 Wiley Periodicals, Inc.

Development of dye-sensitized solar cells based on naturally extracted dye from the maqui berry (Aristotelia chilensis)

NASA Astrophysics Data System (ADS)

Leyrer, Julio; Hunter, Renato; Rubilar, Monica; Pavez, Boris; Morales, Eduardo; Torres, Simonet

2016-10-01

The mini modules of dye-sensitized solar cells (DSSCs) were investigated for their conversion efficiency using anthocyanin-enriched extracts from maqui berry, which to date has never been tested in a DSSC. Anthocyanins are a group of red, purple, violet and blue water-soluble polyphenolic pigments widely found in berry fruits. Maqui berries are a particularly rich source. The aqueous extract concentrations of maqui fruit were tested at 750 and 1500 mg of anthocyanin/L. The immersion time to produce sensitized TiO2 film was 8 h. According to the experimental results, the conversion efficiency of the DSSC prepared with 750 mg of anthocyanin/L was 0.14%, with an open-circuit voltage (VOC) of 0.43 V, a short-circuit current density (JSC) of 0.38 mA/cm2, and a fill factor (FF) of 0.450. The conversion efficiency attained with 1500 mg of anthocyanin/L was 0.19%, with (VOC) of 0.45 V, (JSC) of 0.44 mA/cm2 and FF of 0.55. Therefore, a higher concentration brought about a higher photosensitized performance. The maqui extracts were successfully dye sensitized over a layer of TiO2 nanoparticles, providing useful information for further studies related to the use of natural pigments as sensitizers for solar cells.

Photodynamic therapy of hamster Greene melanoma in vitro and in vivo using bacteriochlorin-a as photosensitizer

NASA Astrophysics Data System (ADS)

Schuitmaker, J. J.; Van Best, Jaap A.; van Delft, J. L.; Jannink, J. E.; Oosterhuis, J. A.; Vrensen, Gijs F.; Ms Wolff-Rouendaal, Didi; Dubbelman, T. M.

1996-01-01

Efficient photodynamic therapy (PDT) of malignant melanoma may be possible with photosensitizers having absorption maxima in the far-red region e.g., above 700 nm. Bacteriochlorin a (BCA), a non toxic derivative of bacteriochlorphyllin a, has a high molecular absorption coefficient (32.000 M-1.cm-1) at 760 nm. At this wavelength tissue penetration of light is almost optimal and melanin absorption is relatively low. In several series of experiments BCA was proven to be a very effective photosensitizer, in vitro and in vivo. It is preferentially retained in experimental hamster Greene melanoma, rhabdomyosarcoma, RIF- and mamma tumors. Its fluorescence can be detected in vivo, thus enabling early tumor detection and it is rapidly cleared from the tissues which promises no, or minor skin photosensitivity. The effects of BCA-PDT were studied in vitro and in vivo using the heavily pigmented Hamster Greene Melanoma (HGM) cell line as a model. In vitro it was found that the uptake of BCA was time, concentration and temperature dependant. Upon illumination (10 Mw/cm2, 756 nm) after incubation with 2.5 (mu) g/ml BCA for 1 h, almost complete cell kill was obtained within seconds. Hamster Greene Melanoma implanted in the anterior eye chamber of rabbits is an accepted in vivo model for ocular melanoma. The effects of BCA-PDT using this model were studied by light- and electron microscopy. Immediately after PDT intracellular spaces were enlarged and blood vessels were clotted with swollen erythrocytes. Electron microscopy showed fused inner and outer membranes and affected cristae mitchondriales of some mitochondria. With time, the severity of tissue and cell damage increased. One day after irradiation tumor growth had stopped; fluorescein angiography showed non perfusion of the tumor. Histopathology showed almost complete tumor necrosis with occasionally viable cells at the tumor periphery. It is concluded that the direct mitochondrial damage and the vascular damage both contribute to BCA-PDT induced tumor necrosis.

Inactivation of Bacillus cereus by Na-chlorophyllin-based photosensitization on the surface of packaging.

PubMed

Luksiene, Z; Buchovec, I; Paskeviciute, E

2010-11-01

This study was focused on the possibility to inactivate food-borne pathogen Bacillus cereus by Na-chlorophyllin (Na-Chl)-based photosensitization in vitro and after attachment to the surface of packaging material. Bacillus cereus in vitro or attached to the packaging was incubated with Na-Chl (7·5×10(-8) to 7·5×10(-5) mol l(-1) ) for 2-60min in phosphate buffer saline. Photosensitization was performed by illuminating cells under a light with a λ of 400nm and an energy density of 20mW cm(-2) . The illumination time varied 0-5min and subsequently the total energy dose was 0-6J cm(-2) . The results show that B. cereus vegetative cells in vitro or attached to the surface of packaging after incubation with 7·5×10(-7) mol l(-1) Na-Chl and following illumination were inactivated by 7log. The photoinactivation of B. cereus spores in vitro by 4log required higher (7·5×10(-6) mol l(-1) ) Na-Chl concentration. Decontamination of packaging material from attached spores by photosensitization reached 5log at 7·5×10(-5) mol l(-1) Na-Chl concentration. Comparative analysis of different packaging decontamination treatments indicates that washing with water can diminish pathogen population on the surface by <1log, 100ppm Na-hypochlorite reduces the pathogens about 1·7log and 200ppm Na-hypochlorite by 2·2log. Meanwhile, Na-Chl-based photosensitization reduces bacteria on the surface by 4·2 orders of magnitude. Food-borne pathogen B. cereus could be effectively inactivated (7log) by Na-Chl-based photosensitization in vitro and on the surface of packaging material. Spores are more resistant than vegetative cells to photosensitization-based inactivation. Comparison of different surface decontamination treatments indicates that Na-Chl-based photosensitization is much more effective antibacterial tool than washing with water or 200ppm Na-hypochlorite. Our data support the idea that Na-Chl-based photosensitization has great potential for future application as an environment-friendly, nonthermal surface decontamination technique. © 2010 The Authors. Journal of Applied Microbiology © 2010 The Society for Applied Microbiology.

Photosensory transduction in unicellular eukaryotes: a comparison between related ciliates Blepharisma japonicum and Stentor coeruleus and photoreceptor cells of higher organisms.

PubMed

Sobierajska, Katarzyna; Fabczak, Hanna; Fabczak, Stanisław

2006-06-01

Blepharisma japonicum and Stentor coeruleus are related ciliates, conspicuous by their photosensitivity. They are capable of avoiding illuminated areas in the surrounding medium, gathering exclusively in most shaded places (photodispersal). Such behaviour results mainly from motile photophobic response occurring in ciliates. This light-avoiding response is observed during a relatively rapid increase in illumination intensity (light stimulus) and consists of cessation of cell movement, a period of backward movement (ciliary reversal), followed by a forward swimming, usually in a new direction. The photosensitivity of ciliates is ascribed to their photoreceptor system, composed of pigment granules, containing the endogenous photoreceptor -- blepharismin in Blepharisma japonicum, and stentorin in Stentor coeruleus. A light stimulus, applied to both ciliates activates specific stimulus transduction processes leading to the electrical changes at the plasma membrane, correlated with a ciliary reversal during photophobic response. These data indicate that both ciliates Blepharisma japonicum and Stentor coeruleus, the lower eukaryotes, are capable of transducing the perceived light stimuli in a manner taking place in some photoreceptor cells of higher eukaryotes. Similarities and differences concerning particular stages of light transduction in eukaryotes at different evolutional levels are discussed in this article.

Dermatologic findings in 16 patients with Cockayne syndrome and cerebro-oculo-facial-skeletal syndrome.

PubMed

Frouin, Eric; Laugel, Vincent; Durand, Myriam; Dollfus, Hélène; Lipsker, Dan

2013-12-01

Cockayne syndrome (CS) and cerebro-oculo-facial-skeletal (COFS) syndrome are autosomal recessive diseases that belong to the family of nucleotide excision repair disorders. Our aim was to describe the cutaneous phenotype of patients with these rare diseases. A systematic dermatologic examination of 16 patients included in a European study of CS was performed. The patients were aged 1 to 28 years. Six patients (38%) had mutations in the Cockayne syndrome A (CSA) gene, and the remaining had Cockayne syndrome B (CSB) gene mutations. Fourteen patients were classified clinically as having CS and 2 as having COFS syndrome. Photosensitivity was present in 75% of the patients and was characterized by sunburn after brief sun exposure. Six patients developed symptoms after short sun exposure through a windshield. Six patients had pigmented macules on sun-exposed skin, but none developed a skin neoplasm. Twelve patients (75%) displayed cyanotic acral edema of the extremities. Eight patients had nail dystrophies and 7 had hair anomalies. The dermatologic findings of 16 cases of CS and COFS syndrome highlight the high prevalence of photosensitivity and hair and nail disorders. Cyanotic acral edema was present in 75% of our patients, a finding not previously reported in CS.

Multiepitope HER2 targeting enhances photoimmunotherapy of HER2-overexpressing cancer cells with pyropheophorbide-a immunoconjugates.

PubMed

Savellano, Mark D; Pogue, Brian W; Hoopes, P Jack; Vitetta, Ellen S; Paulsen, Keith D

2005-07-15

Multi-targeting strategies improve the efficacy of antibody and immunotoxin therapies but have not yet been thoroughly explored for HER2-based cancer treatments. We investigated multi-epitope HER2 targeting to boost photosensitizer immunoconjugate uptake as a way of enhancing photoimmunotherapy. Photoimmunotherapy may allow targeted photodynamic destruction of malignancies and may also potentiate anticancer antibodies. However, one obstacle preventing its clinical use is the delivery of enough photosensitizer immunoconjugates to target cells. Anti-HER2 photosensitizer immunoconjugates were constructed from two monoclonal antibodies (mAb), HER50 and HER66, using a novel method originally developed to label photosensitizer immunoconjugates with the photosensitizer, benzoporphyrin derivative verteporfin. Photosensitizer immunoconjugates were labeled instead with a promising alternative photosensitizer, pyropheophorbide-a (PPa), which required only minor changes to the conjugation procedure. Uptake and phototoxicity experiments using human cancer cells were conducted with the photosensitizer immunoconjugates and, for comparison, with free PPa. SK-BR-3 and SK-OV-3 cells served as HER2-overexpressing target cells. MDA-MB-468 cells served as HER2-nonexpressing control cells. Photosensitizer immunoconjugates with PPa/mAb molar ratios up to approximately 10 specifically targeted and photodynamically killed HER2-overexpressing cells. On a per mole basis, photosensitizer immunoconjugates were less phototoxic than free PPa, but photosensitizer immunoconjugates were selective for target cells whereas free PPa was not. Multiepitope targeted photoimmunotherapy with a HER50 and HER66 photosensitizer immunoconjugate mixture was significantly more effective than single-epitope targeted photoimmunotherapy with a single anti-HER2 photosensitizer immunoconjugate, provided photosensitizer immunoconjugate binding was saturated. This study shows that multiepitope targeting enhances HER2-targeted photoimmunotherapy and maintains a high degree of specificity. Consequently, it seems that multitargeted photoimmunotherapy should also be useful against cancers that overexpress other receptors.

Necrotic dermatitis in waterfowl associated with consumption of perennial rye grass (Lolium perenne).

PubMed

Rostami, Amir; Madani, Seyed Ahmad; Vajhi, Alireza

2011-03-01

Mute swans (Cygnus olor), whooper swans (Cygnus cygnus), and mixed-breed domestic geese (Anser anser domesticus) were presented for necrotic lesions on the feet, eyelids, and beak. Individuals from the same collection of birds had developed identical lesions during March-September of each of the previous 3 years. Vesicular and necrotic dermatitis involved only nonfeathered and nonpigmented areas of the integument. No abnormal clinical signs were seen on either carnivorous species or birds with pigmented skin from the same collection. The enclosure that housed the birds had been planted with perennial rye grass (Lolium perenne) 3 years previously. Based on the pathologic features and anatomic location of the lesions, the seasonal occurrence, the vegetation history of the enclosure, and the feeding behavior of the affected species, vesicular dermatitis resulting from photosensitization was the presumptive diagnosis. All affected birds recovered completely after the birds were removed from the enclosure, and no further clinical signs have been reported.

[Kindler syndrome. A new bullous dermatosis].

PubMed

Has, C

2009-08-01

The Kindler syndrome is a new form of inherited epidermolysis bullosa and the first genodermatosis caused by a defect of the focal adhesions. Kindlin-1, the deficient protein, plays an essential role in integrin activation and in the adhesion of keratinocytes to the extracellular matrix. The adhesion defect leads to skin blistering which begins at birth and ameliorates with age, and to mucosal fragility which leads to scarring and stricture formation. Skin atrophy and poikiloderma develop progressively. Photosensitivity is rather mild, but squamous cell carcinomas develop on sun-exposed areas mainly after the age of 40 years. The most important differential diagnoses are epidermolysis bullosa with mottled pigmentation and dystrophic epidermolysis bullosa. Management aims to treat the symptoms and prevent complications.

Novel approach to the microbial decontamination of strawberries: chlorophyllin-based photosensitization.

PubMed

Luksiene, Z; Paskeviciute, E

2011-05-01

This study is focused on the possibility to control microbial contamination of strawberries by chlorophyllin (Na-Chl)-based photosensitization. Moreover, photosensitization-induced effects on key quality attributes of treated strawberries was evaluated.   Strawberries were inoculated with Listeria monocytogenes ATC(L3) C 7644, soaked in 1mmol l(-1) Na-Chl for 5 min and illuminated for 30 min with visible light (λ = 400 nm, energy density 12 mW cm(-2) ). Results indicated that the decontamination of strawberries using photosensitization was 98% compared to control sample. Naturally occurring yeasts/microfungi and mesophiles were inhibited by 86 and 97%, respectively. The shelf life of treated strawberries was extended by 2 days. The total antioxidant activity of treated strawberries increased by 19%. No impact on the amount of phenols, anthocyanins or surface colour was detected.   Photosensitization may be an effective, nonthermal and environmentally friendly microbial decontamination technique which expands the shelf life of strawberries without any negative impact on antioxidant activity, and phenols, anthocyanins or colour formation. Experimental data support the idea that Na-Chl-based photosensitization can be a useful tool for the future development of nonthermal food preservation technology. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Antioxidant Properties of Astaxanthin in Oil-in-Water Emulsions with Differently-Charged Emulsifiers Under Chlorophyll Photosensitization.

PubMed

Yi, BoRa; Kim, Mi-Ja; Lee, JaeHwan

2018-03-01

The antioxidative or prooxidative properties of astaxanthin at the concentrations of 0, 10, and 100 μM were determined in oil-in-water (O/W) emulsions containing neutral, anionic, and cationic emulsifiers, which was Tween 20, sodium dodecyl sulfate, cetyltrimethylammonium bromide (CTAB), respectively, under chlorophyll photosensitization. The oxidative parameters and headspace volatiles were analyzed in O/W emulsions. In the 24 h period of visible light irradiation, 100 μM of astaxanthin acted as an antioxidant in O/W emulsions containing neutral and anionic emulsifiers. However, astaxanthin in O/W emulsions with a cationic emulsifier was neither an antioxidant nor a prooxidant. The profiles of volatile compounds showed that astaxanthin served as a singlet oxygen quencher in O/W emulsions containing neutral and anionic emulsifiers. However, in O/W emulsion with a cationic emulsifier, astaxanthin was neither a singlet oxygen quencher nor a free radical scavenger because prooxidant properties of CTAB overwhelmed the antioxidant effects of astaxanthin. Therefore, the antioxidant properties of astaxanthin were influenced by the emulsifier charges in O/W emulsions. Astaxanthin is a lipid-soluble pigment and has antioxidant, anticancer, and anti-inflammatory properties and beneficial effects on cardiovascular diseases. Many lipid-based foods are displayed on the shelves in the markets under fluorescent light. The addition of astaxanthin can extend the shelf life of O/W emulsion type foods such as beverage and dressing products under visible light irradiation. Also, oxidative stability in emulsion type foods containing astaxanthin rich natural ingredients can be predicted. © 2018 Institute of Food Technologists®.

Evolution of Vision

NASA Astrophysics Data System (ADS)

Ostrovsky, Mikhail

The evolution of photoreception, giving rise to eye, offers a kaleidoscopic view on selection acting at both the organ and molecular levels. The molecular level is mainly considered in the lecture. The greatest progress to date has been made in relation to the opsin visual pigments. Opsins appeared before eyes did. Two- and three-dimensional organization for rhodopsin in the rod outer segment disk membrane, as well as molecular mechanisms of visual pigments spectral tuning, photoisomerization and also opsin as a G-protein coupled receptor are considered. Molecular mechanisms of visual pigments spectral tuning, namely switching of chromophore (physiological time scale) and amino acid changes in the chromophore site of opsin (evolutionary time scale) is considered in the lecture. Photoisomerization of rhodopsin chromophore, 11-cis retinal is the only photochemical reaction in vision. The reaction is extemely fast (less that 200 fs) and high efficient (. is 0.65). The rhodopsin photolysis and kinetics of the earlier products appearance, photo- and bathorhodopsin, is considered. It is known that light is not only a carrier of information, but also a risk factor of damage to the eye. This photobiological paradox of vision is mainly due to the nature of rhodopsin chromophore. Photooxidation is the base of the paradox. All factors present in the phototrceptor cells to initiate free-radical photooxidation: photosensitizers, oxygen and substrates of oxidation: lipids and proteins (opsin). That is why photoprotective system of the eye structures appeared in the course of evolution. Three lines of protective system to prevent light damage to the retina and retina pigment epithelium is known: permanent renewal of rod and cone outer segment, powerful antioxidant system and optical media as cut-off filters where the lens is a key component. The molecular mechanisms of light damage to the eye and photoprotective system of the eye is considered in the lecture. The molecular mechanisms of phototransduction in vertebrates eye is also briefly considered in the lecture. Evolution of vision is an enormous subject for thought and investigation. In the postgenomic era evolutionary molecular physiology as a whole and evolutionary molecular physiology of vision can be considered as a key approach for understanding how genome is working.

Fullerene C60 and graphene photosensibiles for photodynamic virus inactivation

NASA Astrophysics Data System (ADS)

Belousova, I.; Hvorostovsky, A.; Kiselev, V.; Zarubaev, V.; Kiselev, O.; Piotrovsky, L.; Anfimov, P.; Krisko, T.; Muraviova, T.; Rylkov, V.; Starodubzev, A.; Sirotkin, A.; Grishkanich, A.; Kudashev, I.; Kancer, A.; Kustikova, M.; Bykovskaya, E.; Mayurova, A.; Stupnikov, A.; Ruzankina, J.; Afanasyev, M.; Lukyanov, N.; Redka, D.; Paklinov, N.

2018-02-01

A solid-phase photosensitizer based on aggregated C60 fullerene and graphene oxide for photodynamic inactivation of pathogens in biological fluids was studied. The most promising technologies of inactivation include the photodynamic effect, which consists in the inactivation of infectious agents by active oxygen forms (including singlet oxygen), formed when light is activated by the photosensitizer introduced into the plasma. Research shows features of solid-phase systems based on graphene and fullerene C60 oxide, which is a combination of an effective inactivating pathogens (for example, influenza viruses) reactive oxygen species formed upon irradiation of the photosensitizer in aqueous and biological fluids, a high photostability fullerene coatings and the possibility of full recovery photosensitizer from the biological environment after the photodynamic action.

The properties of single cones isolated from the tiger salamander retina

PubMed Central

Attwell, David; Werblin, Frank S.; Wilson, Martin

1982-01-01

1. The properties of isolated single cones were studied using the voltage-clamp technique, with two micro-electrodes inserted under visual control. 2. Single cones had input resistances, when impaled with two electrodes, of up to 270 MΩ. This is probably lower than the true membrane resistance, because of damage by the impaling electrodes. The cone capacitance was about 85 pF. 3. The cone membrane contains a time-dependent current, IB, controlled by voltage, and a separate photosensitive current. 4. The gated current, IB, is an inward current with a reversal potential around -25 mV. It is activated by hyperpolarization over the range -30 to -80 mV, and at constant voltage obeys first order (exponential) kinetics. The gating time constant is typically 50 ms at the resting potential of -45 mV, rises to 170 ms at -70 mV, and decreases for further hyperpolarization. 5. The spectral sensitivity curve of the cone light response peaks at 620 nm wave-length, and is narrower than the nomogram for vitamin A2-based pigments. The light responses of isolated cones are spectrally univariant. 6. Voltage-clamped photocurrents were recorded at various membrane potentials, for light steps of various intensities. The photocurrent reversed at around -8 mV. The time course of the photocurrent, for a given intensity, was approximately independent of voltage (although its magnitude was voltage-dependent). The shape of the peak current—voltage relation of the light-sensitive current was independent of light intensity (although its magnitude was intensity-dependent). 7. These results can be explained if: (a) light simply changes the number of photosensitive channels open, without altering the properties of an open channel; (b) the reactions controlling the production of internal transmitter, the binding of internal transmitter to the photosensitive channels, and the closing and opening of the channels are unaffected by the electric field in the cone membrane, even though at least some of these reactions take place in the membrane. 8. IB plays only a small role in shaping the cone voltage response to light. ImagesPlate 1 PMID:7131315

On the in vivo photochemical rate parameters for PDT reactive oxygen species modeling

NASA Astrophysics Data System (ADS)

Kim, Michele M.; Ghogare, Ashwini A.; Greer, Alexander; Zhu, Timothy C.

2017-03-01

Photosensitizer photochemical parameters are crucial data in accurate dosimetry for photodynamic therapy (PDT) based on photochemical modeling. Progress has been made in the last few decades in determining the photochemical properties of commonly used photosensitizers (PS), but mostly in solution or in vitro. Recent developments allow for the estimation of some of these photochemical parameters in vivo. This review will cover the currently available in vivo photochemical properties of photosensitizers as well as the techniques for measuring those parameters. Furthermore, photochemical parameters that are independent of environmental factors or are universal for different photosensitizers will be examined. Most photosensitizers discussed in this review are of the type II (singlet oxygen) photooxidation category, although type I photosensitizers that involve other reactive oxygen species (ROS) will be discussed as well. The compilation of these parameters will be essential for ROS modeling of PDT.

On the in-vivo photochemical rate parameters for PDT reactive oxygen species modeling

PubMed Central

Kim, Michele M.; Ghogare, Ashwini A.; Greer, Alexander; Zhu, Timothy C.

2017-01-01

Photosensitizer photochemical parameters are crucial data in accurate dosimetry for photodynamic therapy (PDT) based on photochemical modeling. Progress has been made in the last few decades in determining the photochemical properties of commonly used photosensitizers (PS), but mostly in solution or in-vitro. Recent developments allow for the estimation of some of these photochemical parameters in-vivo. This review will cover the currently available in-vivo photochemical properties of photosensitizers as well as the techniques for measuring those parameters. Furthermore, photochemical parameters that are independent of environmental factors or are universal for different photosensitizers will be examined. Most photosensitizers discussed in this review are of the type II (singlet oxygen) photooxidation category, although type I photosensitizers that involve other reactive oxygen species (ROS) will be discussed as well. The compilation of these parameters will be essential for ROS modeling of PDT. PMID:28166056

Effects of glycolic acid on light-induced skin pigmentation in Asian and caucasian subjects.

PubMed

Tsai, T F; Bowman, P H; Jee, S H; Maibach, H I; Paul, B H

2000-08-01

Topical use of alpha-hydroxy acid (AHA) may increase skin photosensitivity, as demonstrated by increased numbers of sunburst cells. However, effects of AHA on tanning have not been studied. Our purpose was to study whether short-term use of glycolic acid hastens resolution of pre-existing light-induced pigmentation and whether the skin becomes tan more easily in Asian and Caucasian subjects after such treatment. Six Asian and six Caucasian volunteers received separate irradiations of UVB and UVA to both sides of the lower back. In a double-blind fashion, patients then applied a 10% glycolic acid gel, pH 3.52, to one side of the back, including the irradiated area, and the contralateral extensor forearms once daily for 7 days and then twice daily for 2 weeks. A placebo gel, pH 5.75, was applied to the opposite sides. The subjects returned for measurement of residual tanning with a colorimeter and received additional irradiation to forearms and a second site on the back. Resulting pigmentation was measured immediately after irradiation, at 2 hours, and at 1 week. Increased UVB-induced skin tanning occurred on the forearm and the lower back in both races in areas pretreated with glycolic acid. UVA also caused increased tanning, but only on the extensor forearms in Asian subjects. Treatment with glycolic acid for 3 weeks had no effect on pre-existing light-induced pigmentation. Short-term topical treatment of glycolic acid caused an increase in UVB tanning as well as in UVA tanning in some subjects, even in the absence of overt irritation. The inclusion of UVB, and even UVA, sunscreen in AHA products may be warranted.

A second visual rhodopsin gene, rh1-2, is expressed in zebrafish photoreceptors and found in other ray-finned fishes.

PubMed

Morrow, James M; Lazic, Savo; Dixon Fox, Monica; Kuo, Claire; Schott, Ryan K; de A Gutierrez, Eduardo; Santini, Francesco; Tropepe, Vincent; Chang, Belinda S W

2017-01-15

Rhodopsin (rh1) is the visual pigment expressed in rod photoreceptors of vertebrates that is responsible for initiating the critical first step of dim-light vision. Rhodopsin is usually a single copy gene; however, we previously discovered a novel rhodopsin-like gene expressed in the zebrafish retina, rh1-2, which we identified as a functional photosensitive pigment that binds 11-cis retinal and activates in response to light. Here, we localized expression of rh1-2 in the zebrafish retina to a subset of peripheral photoreceptor cells, which indicates a partially overlapping expression pattern with rh1 We also expressed, purified and characterized Rh1-2, including investigation of the stability of the biologically active intermediate. Using fluorescence spectroscopy, we found the half-life of the rate of retinal release of Rh1-2 following photoactivation to be more similar to that of the visual pigment rhodopsin than to the non-visual pigment exo-rhodopsin (exorh), which releases retinal around 5 times faster. Phylogenetic and molecular evolutionary analyses show that rh1-2 has ancient origins within teleost fishes, is under similar selective pressure to rh1, and likely experienced a burst of positive selection following its duplication and divergence from rh1 These findings indicate that rh1-2 is another functional visual rhodopsin gene, which contradicts the prevailing notion that visual rhodopsin is primarily found as a single copy gene within ray-finned fishes. The reasons for retention of this duplicate gene, as well as possible functional consequences for the visual system, are discussed. © 2017. Published by The Company of Biologists Ltd.

Photosensitizer-Embedded Polyacrylonitrile Nanofibers as Antimicrobial Non-Woven Textile

PubMed Central

Stanley, Sarah L.; Scholle, Frank; Zhu, Jiadeng; Lu, Yao; Zhang, Xiangwu; Situ, Xingci; Ghiladi, Reza A.

2016-01-01

Toward the objective of developing platform technologies for anti-infective materials based upon photodynamic inactivation, we employed electrospinning to prepare a non-woven textile comprised of polyacrylonitrile nanofibers embedded with a porphyrin-based cationic photosensitizer; termed PAN-Por(+). Photosensitizer loading was determined to be 34.8 nmol/mg material; with thermostability to 300 °C. Antibacterial efficacy was evaluated against four bacteria belonging to the ESKAPE family of pathogens (Staphylococcus aureus; vancomycin-resistant Enterococcus faecium; Acinetobacter baumannii; and Klebsiella pneumonia), as well as Escherichia coli. Our results demonstrated broad photodynamic inactivation of all bacterial strains studied upon illumination (30 min; 65 ± 5 mW/cm2; 400–700 nm) by a minimum of 99.9996+% (5.8 log units) regardless of taxonomic classification. PAN-Por(+) also inactivated human adenovirus-5 (~99.8% reduction in PFU/mL) and vesicular stomatitis virus (>7 log units reduction in PFU/mL). When compared to cellulose-based materials employing this same photosensitizer; the higher levels of photodynamic inactivation achieved here with PAN-Por(+) are likely due to the combined effects of higher photosensitizer loading and a greater surface area imparted by the use of nanofibers. These results demonstrate the potential of photosensitizer-embedded polyacrylonitrile nanofibers to serve as scalable scaffolds for anti-infective or self-sterilizing materials against both bacteria and viruses when employing a photodynamic inactivation mode of action. PMID:28335205

A supramolecular photosensitizer system based on the host-guest complexation between water-soluble pillar[6]arene and methylene blue for durable photodynamic therapy.

PubMed

Yang, Kui; Wen, Jia; Chao, Shuang; Liu, Jing; Yang, Ke; Pei, Yuxin; Pei, Zhichao

2018-06-05

A supramolecular photosensitizer system WP6-MB was synthesized based on water-soluble pillar[6]arene and the photosensitizer methylene blue (MB) via host-guest interaction. MB can complex with WP6 directly with a high complex constant without further modification. In particular, WP6-MB can reduce the dark toxicity of MB remarkably. Furthermore, it can efficiently overcome photobleaching and extend the time for singlet oxygen production of MB upon light irradiation, which is significant for durable photodynamic therapy.

Transient spectra study on photo-dynamics of curcumin

NASA Astrophysics Data System (ADS)

Qian, Tingting; Wang, Mei; Wang, Jiao; Zhu, Rongrong; He, Xiaolie; Sun, Xiaoyu; Sun, Dongmei; Wang, Qingxiu; Wang, ShiLong

2016-09-01

A novel mechanism of DNA damage induced by photosensitized curcumin (Cur) was explored using laser flash photolysis, pulse radiolysis and gel electrophoresis. Cur neutral radical (Currad) was confirmed as an identical product in photo-sensitization of Cur by laser flash photolysis and pulse radiolysis. A series of reaction rate constants between Currad and nucleic acid bases/nucleotides were determined by pulse radiolysis. Gel electrophoresis was carried out to investigate damage induced by photosensitized Cur to biologically active DNA. The results indicate that the damage to DNA may be caused by Currad produced from the photosensitization of Cur.

Adverse effects associated with photodynamic therapy (PDT) of port-wine stain (PWS) birthmarks.

PubMed

Yuan, Kai-Hua; Gao, Jian-Hua; Huang, Zheng

2012-12-01

Several Chinese studies suggest that Hemoporfin-mediated photodynamic therapy (PDT) is an alternative treatment for port-wine stain (PWS) birthmarks. To evaluate treatment responses and adverse effects associated with Hemoporfin PDT for the treatment of PWS and their management. The medical records of 700 patients who underwent PDT treatment in our center were retrospectively examined. Treatment-related reactions and adverse effects were reviewed. Different types of PWS lesions and different individuals showed different immediate responses (e.g. swelling, color change, pain). To certain extents these reactions were a useful indicator of the treatment endpoint. Edema and scabbing were the most common post-treatment responses. Short-term (e.g. blister, eczematous dermatitis, cutaneous photosensitivity) and long-term (e.g. pigmentation change, scar formation) adverse effects were generally caused by the phototoxicity associated with the combination of photosensitizer and light exposure. Although PDT is a safe treatment alternative for PWS birthmarks, treatment parameters must be selected for each individual patient and cutaneous changes must be monitored during light irradiation to minimize the risk of adverse effects. Over estimation of required light dosage or failure to recognize cutaneous changes associated with adverse effects can increase the risk of a poor outcome. Copyright © 2012 Elsevier B.V. All rights reserved.

[Photosensitization and photoprotection by some drugs, metabolites and other compounds].

PubMed

Lozovskaia, E L; Makareeva, E N; Makedonov, I U

1997-01-01

Photosensitizing and photoprotecting efficiency of about a hundred of compounds, mainly drugs, was studied. The method based on chemiluminescence occurred along with photooxidation of glycyltryptophan under irradiation in UVB range in solution was used for testing. As a measure of photosensitizing efficiency the concentration of photosensitizer which induced two-fold increase of chemiluminescence intensity was chosen. The most effective photosensitizers are riboflavin, FAD, furagin, psoralene, vicasol, benzobarbital, mydocalm, angelicyn, furadonin, ethacridin, diazolin, folic acid. With regard to pharmacological doses of drugs in organism more dangerous sensitizers (in descending order) are p-aminosalicylic acid, furagin, riboflavin, benzobarbital, thiopental, chloramphenicol, nicodin, mydocalm, furadonin, oxolonic acid, furazolidone, psoralene, nicotinamide and diazolin. Photoprotecting effect was described by the concentration at which chemiluminescence intensity decreased twice. The most effective photoprotectors are etamsilat, quercetin, ftivazid, chlorpromazine, diprazine, thioridazine, aminophenazone, oxaphenamide. Concentration dependence for some of these drugs (etamsilat, chlorpromazine, diprazine, thioridazine) is non-monotonous: they inhibit photooxidation in low concentration (about 10(-7)-10(-6) M), but at higher concentrations (10(-5)-10(-4) M) photosensitization dominates over photoprotection.

Self-assembled chromophores within mesoporous nanocrystalline TiO2: towards biomimetic solar cells.

PubMed

Marek, Peter L; Sieger, Hermann; Scherer, Torsten; Hahn, Horst; Balaban, Teodor Silviu

2009-06-01

Artificial light-harvesting antennas consisting of self-assembled chromophores that mimic the natural pigments of photosynthetic bacteria have been inserted into voids induced in porous titania (TiO2, anatase) in order to investigate their suitability for hybrid solar cells. Mesoporous nanocrystalline TiO2 with additional uniform macropores was treated with precursor solutions of the pigment which was then induced to self-assemble within the voids. The chromophores were tailored to combine the self-assembly characteristics of the natural bacteriochlorophylls with the robustness of artificial Zn-porphyrins being stable for prolonged periods even upon heating to over 200 degrees C. They assemble on the TiO2 surface to form nano- to micro-crystalline structures with lengths from tens of nm up to several microm and show a photosensitization effect which is supposed to be dependent on the assembly size. The natural examples of these antennas are found in green sulfur bacteria which are able to use photosynthesis in deep water regions with minute light intensities. The implementation of biomimetic antennas for light harvesting and a better photon management may lead to a rise in efficiency of dye-sensitized solar cells also under low light illumination conditions.

Photosensitizer fluorescence emission during photodynamic therapy applied to dermatological diseases

NASA Astrophysics Data System (ADS)

Salas-García, I.; Fanjul-Vélez, F.; Ortega-Quijano, N.; Arce-Diego, J. L.

2011-09-01

Photodynamic Therapy (PDT) is an optical treatment modality that allows malignant tissue destruction. It is based on the administration of a photosensitizer and the posterior irradiation by an optical source. Photosensitizer molecules absorb the excitation light photons triggering a series of photochemical reactions in the presence of oxygen in the target tissue. During such interactions it is produced the de-excitation of the photosensitizer molecules in the singlet excited state which return to their minimum energy state by emitting fluorescence photons. These days, there are fixed clinical PDT protocols that make use of a particular optical dose and photosensitizer amount. However treatment response varies among patients and the type of pathology. In order to adjust an optimal dosimetry, the development of accurate predictive models plays an important role. The photosensitizer fluorescence can be used to estimate the degradation of the photoactive agent and as an implicit dosimetric measurement during treatment. However it is complex to know the fluorescence dependence with the depth in the tumor from observed fluorescence in the pathology surface. We present a first approach to predict the photosensitizer fluorescence dependence with depth during the PDT treatment applied to a skin disease commonly treated in the dermatological clinical practice. The obtained results permit us to know the photosensitizer temporal fluorescence evolution in different points of the tumor sample during the photochemical reactions involved in PDT with a predictive purpose related to the treatment evolution. The model presented also takes into account the distribution of a topical photosensitizer, the propagation of light in a biological media and the subsequent photochemical interactions between light and tissue. This implies that different parameters related with the photosensitizer distribution or the optical source characteristics could be adjusted to provide a specific treatment to a particular pathology.

UV and ionizing radiations induced DNA damage, differences and similarities

NASA Astrophysics Data System (ADS)

Ravanat, Jean-Luc; Douki, Thierry

2016-11-01

Both UV and ionizing radiations damage DNA. Two main mechanisms, so-called direct and indirect pathways, are involved in the degradation of DNA induced by ionizing radiations. The direct effect of radiation corresponds to direct ionization of DNA (one electron ejection) whereas indirect effects are produced by reactive oxygen species generated through water radiolysis, including the highly reactive hydroxyl radicals, which damage DNA. UV (and visible) light damages DNA by again two distinct mechanisms. UVC and to a lesser extend UVB photons are directly absorbed by DNA bases, generating their excited states that are at the origin of the formation of pyrimidine dimers. UVA (and visible) light by interaction with endogenous or exogenous photosensitizers induce the formation of DNA damage through photosensitization reactions. The excited photosensitizer is able to induce either a one-electron oxidation of DNA (type I) or to produce singlet oxygen (type II) that reacts with DNA. In addition, through an energy transfer from the excited photosensitizer to DNA bases (sometime called type III mechanism) formation of pyrimidine dimers could be produced. Interestingly it has been shown recently that pyrimidine dimers are also produced by direct absorption of UVA light by DNA, even if absorption of DNA bases at these wavelengths is very low. It should be stressed that some excited photosensitizers (such as psoralens) could add directly to DNA bases to generate adducts. The review will described the differences and similarities in terms of damage formation (structure and mechanisms) between these two physical genotoxic agents.

Crystal structure of phototoxic orange fluorescent proteins with α tryptophan-based chromophore

DOE PAGES

Pletneva, Nadya V.; Pletnev, Vladimir Z.; Sarkisyan, Karen S.; ...

2015-12-23

Phototoxic fluorescent proteins represent a sparse group of genetically encoded photosensitizers that could be used for precise light-induced inactivation of target proteins, DNA damage, and cell killing. Only two such GFP-based fluorescent proteins (FPs), KillerRed and its monomeric variant SuperNova, were described up to date. We present a crystallographic study of their two orange successors, dimeric KillerOrange and monomeric mKiller-Orange, at 1.81 and 1.57 Å resolution, respectively. They are the first orange-emitting protein photosensitizers with a tryptophan-based chromophore (Gln65-Trp66-Gly67). Same as their red progenitors, both orange photosensitizers have a water-filled channel connecting the chromophore to the β-barrel exterior and enablingmore » transport of ROS. In both proteins, Trp66 of the chromophore adopts an unusual trans-cis conformation stabilized by H-bond with the nearby Gln159. This trans-cis conformation along with the water channel was shown to be a key structural feature providing bright orange emission and phototoxicity of both examined orange photosensitizers.« less

Crystal Structure of Phototoxic Orange Fluorescent Proteins with a Tryptophan-Based Chromophore

PubMed Central

Pletneva, Nadya V.; Pletnev, Vladimir Z.; Sarkisyan, Karen S.; Gorbachev, Dmitry A.; Egorov, Evgeny S.; Mishin, Alexander S.; Lukyanov, Konstantin A.; Dauter, Zbigniew; Pletnev, Sergei

2015-01-01

Phototoxic fluorescent proteins represent a sparse group of genetically encoded photosensitizers that could be used for precise light-induced inactivation of target proteins, DNA damage, and cell killing. Only two such GFP-based fluorescent proteins (FPs), KillerRed and its monomeric variant SuperNova, were described up to date. Here, we present a crystallographic study of their two orange successors, dimeric KillerOrange and monomeric mKillerOrange, at 1.81 and 1.57 Å resolution, respectively. They are the first orange-emitting protein photosensitizers with a tryptophan-based chromophore (Gln65-Trp66-Gly67). Same as their red progenitors, both orange photosensitizers have a water-filled channel connecting the chromophore to the β-barrel exterior and enabling transport of ROS. In both proteins, Trp66 of the chromophore adopts an unusual trans-cis conformation stabilized by H-bond with the nearby Gln159. This trans-cis conformation along with the water channel was shown to be a key structural feature providing bright orange emission and phototoxicity of both examined orange photosensitizers. PMID:26699366

Temperature and Plant Adaptation. I. Interaction of Temperature and Light in the Synthesis of Chlorophyll in Corn 1

PubMed Central

McWilliam, J. R.; Naylor, A. W.

1967-01-01

The effect of temperature and light intensity have been studied in relation to the greening of etiolated corn (Zea mays cv. Pioneer 309-B) seedlings. Chlorophyll accumulation is rapid at high temperature (28°) under all conditions of light intensity. At low temperature (16°), and particularly in combination with high light intensity (3000-4500 ft-c), the accumulation of both chlorophyll and carotene is inhibited. Low pigment content at 16° is not directly due to a block in the pigment synthesizing mechanism, but rather to the photodestruction of chlorophyll prior to its stabilization in the membrane structure of the chloroplast lamellae. The parallel reduction in carotene content at high light intensity is probably a contributing factor, because of its role in protecting chlorophyll from photodestruction. The greater severity of photo-oxidation of chlorophyll at low temperature in corn when compared with wheat, appears to be due to a slower rate of protochlorophyllide synthesis and subsequent esterification. Thus in corn at 16° there is a prolongation of the photosensitive stage during chlorophyll synthesis. Photo-oxidation at 16° has also been shown to be a function of the incident light energy, with the photosynthetic pigments acting as receptors for their own destruction. In comparison with the behavior of corn, wheat seedlings green rapidly at high light intensity at both 16° and 28°. This contrasting temperature response with respect to chlorophyll synthesis may underlie a fundamental difference in adaptation of these 2 species to growth in the temperate zones of the world. PMID:16656709

Time-resolved luminescence measurements of the magnetic field effect on paramagnetic photosensitizers in photodynamic reactions

NASA Astrophysics Data System (ADS)

Mermut, O.; Bouchard, J.-P.; Cormier, J.-F.; Desroches, P.; Diamond, K. R.; Fortin, M.; Gallant, P.; Leclair, S.; Marois, J.-S.; Noiseux, I.; Morin, J.-F.; Patterson, M. S.; Vernon, M.

2008-02-01

The development of multimodal molecular probes and photosensitizing agents for use in photodynamic therapy (PDT) is vital for optimizing and monitoring cytotoxic responses. We propose a combinatorial approach utilizing photosensitizing molecules that are both paramagnetic and luminescent with multimodal functionality to perturb, control, and monitor molecular-scale reaction pathways in PDT. To this end, a time-domain single photon counting lifetime apparatus with a 400 nm excitation source has been developed and integrated with a variable low field magnet (0- 350mT). The luminescence lifetime decay function was measured in the presence of a sweeping magnetic field for a custom designed photosensitizing molecule in which photoinduced electron transfer was studied The photosensitizer studied was a donor-acceptor complex synthesized using a porphyrin linked to a fullerene molecule. The magneto-optic properties were investigated for the free-base photosensitizer complex as well as those containing either diamagnetic (paired electron) or paramagnetic (unpaired electron) metal centers, Zn(II) and Cu(II). The magnetic field was employed to affect and modify the spin states of radical pairs of the photosensitizing agents via magnetically induced hyperfine and Zeeman effects. Since the Type 1 reaction pathway of an excited triplet state photosensitizer involves the production of radical species, lifetime measurements were conducted at low dissolved oxygen concentration (0.01ppm) to elucidate the dependence of the magnetic perturbation on the photosensitization mechanistic pathway. To optimize the magnetic response, a solvent study was performed examining the dependence of the emission properties on the magnetic field in solutions of varying dielectric constants. Lastly, the cytotoxicity in murine tumor cell suspensions was investigated for the novel porphyrin-fullerene complex by inducing photodynamic treatments and determining the associated cell survival.

Sunlight-Dependent Hydrogen Production by Photosensitizer/Hydrogenase Systems.

PubMed

Adam, David; Bösche, Lisa; Castañeda-Losada, Leonardo; Winkler, Martin; Apfel, Ulf-Peter; Happe, Thomas

2017-03-09

We report a sustainable in vitro system for enzyme-based photohydrogen production. The [FeFe]-hydrogenase HydA1 from Chlamydomonas reinhardtii was tested for photohydrogen production as a proton-reducing catalyst in combination with eight different photosensitizers. Using the organic dye 5-carboxyeosin as a photosensitizer and plant-type ferredoxin PetF as an electron mediator, HydA1 achieves the highest light-driven turnover number (TON HydA1 ) yet reported for an enzyme-based in vitro system (2.9×10 6  mol(H 2 ) mol(cat) -1 ) and a maximum turnover frequency (TOF HydA1 ) of 550 mol(H 2 ) mol(HydA1) -1  s -1 . The system is fueled very effectively by ambient daylight and can be further simplified by using 5-carboxyeosin and HydA1 as a two-component photosensitizer/biocatalyst system without an additional redox mediator. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Development of Smart Phthalocyanine-based Photosensitizers for Photodynamic Therapy

NASA Astrophysics Data System (ADS)

Chow, Yun Sang

Phthalocyanines are versatile functional dyes that have shown great potential in cancer theranostics, especially in photodynamic therapy (PDT). This research work aims to develop "smart" phthalocyanine-based photosensitizers for targeted PDT. This thesis describes the synthesis, spectroscopic characterization, photophysical properties, and in vitro photodynamic activities of several series of carefully designed phthalocyanine-based photosensitizers. Chapter 1 presents an overview of PDT, including its historical development, photophysical mechanisms, and biological mechanisms. Various classes of photosensitizers are introduced with emphasis putting on phthalocyanines, which exhibit ideal characteristics of photosensitizers for PDT. In recent years, several approaches have been used to develop photosensitizers with higher tumor selectivity and minimal skin photosensitivity after PDT. Activatable photosensitizers can provide a "turn on" mechanism to offer an additional control of the specificity of treatment. Photosensitizers can also work cooperatively with the tumor-targeting groups or anticancer drugs so as to achieve targeted or dual therapy, which can enhance the efficacy of PDT. The novel approaches mentioned above have been widely used and combined to form multi-functional photosensitizing agents. These novel concepts and development of PDT are discussed and illustrated with relevant examples at the end of this chapter. To minimize the prolonged skin photosensitivity, photosensitizers that can only be activated by tumor-associated stimuli have been developed. Due to the abnormal metabolism in tumor tissues, their surface usually exhibits a lower pH compared to that of the normal tissues. Also, the pH difference between the intracellular and the physiological environment provides a pH-activation mechanism. Chapter 2 presents the synthesis and spectroscopic characterization of a pH-responsive zinc(II) phthalocyanine tetramer, in which the phthalocyanine units are self-quenched, but separated and activated after cleavage of the acetal linkages. The basic photophysical properties, activation behavior in fluorescence emission, singlet oxygen generation, and in vitro photodynamic activities of this compound have been investigated and compared with those of the non-cleavable analogue. The activation of this tetramer has been demonstrated in the aqueous medium and at the cellular level, in which the fluorescence emission and photosensitizing ability can be greatly enhanced. This tetramer exhibits low dark toxicity and enhanced cytotoxicity upon illumination toward the HT29 human colon adenocarcinoma cells. Glutathione (GSH) is another well-documented stimulus for the design of activatable photosensitizers. It is the most abundant biological thiol which acts as the reducing agent in many biochemical processes. The much higher intracellular GSH concentration compared with the extracellular GSH level provides an activation mechanism. By using this feature, we have developed a series of GSH-responsive phthalocyanine dendrons in order to optimize the molecular design of self-quenched activatable photosensitizers. The aggregation tendency and the activation behavior in fluorescence emission and singlet oxygen generation in aqueous media have been investigated. The in vitro properties of the phthalocyanine dendrons including relative intracellular fluorescence and photocytotoxicity are also examined and presented in Chapter 3.. Chapter 4 reports the molecular design and synthesis of a biotin-decorated GSH-responsive zinc(II) phthalocyanine trimer, in which the phthalocyanine units are severely self-quenched, but are separated and then activated upon cleavage of the disulfide bondings by GSH. The basic photophysical properties, cleavage kinetics, and activation behavior in fluorescence and photosensitizing ability of this compound have been investigated. Its in vitro photodynamic activity, cellular uptake by different cell lines, and intracellular fluorescence emission have also been examined. Apart from targeted PDT, dual therapy is another novel approach to improve the efficacy of PDT treatment. Chapter 5 describes the molecular design and synthesis of a novel doxorubicin-conjugated phthalocyanine trimer. Doxorubicin is a well-known drug for the treatment of a range of cancers. By conjugating this unit to a GSH-responsive zinc(II) phthalocyanine trimer, it is expected that the resulting hybrid can exhibit controlled toxicity. The basic photophysical properties and effects of GSH on the fluorescence emission and photosensitizing ability of this compound have been investigated. Its cytotoxicity in the presence and absence of light, cellular uptake, and intracellular fluorescence emission have been examined and are reported in this chapter. Chapter 6 describes a novel strategy to prepare low-symmetry phthalocyanines, which can serve as versatile platforms for the development of multi-functional phthalocyanine-based photosensitizers. By using an intracellular cyclization reaction of the pre-linked tetrakisphthalonitrile, the first ABCD-type zinc(II) phthalocyanine has been synthesized and characterized. By optimizing the reaction conditions, this compound can be prepared in 7.2 % yield. Chapter 7 concludes the present study while Chapter 8 reports the experimental details. All references mentioned in this thesis are provided in Chapter 9. 1H and 13C{1H} NMR spectra of all the new compounds are given in the Appendix. (Abstract shortened by ProQuest.).

The effect of blue light on periodontal biofilm growth in vitro.

PubMed

Fontana, Carla R; Song, Xiaoqing; Polymeri, Angeliki; Goodson, J Max; Wang, Xiaoshan; Soukos, Nikolaos S

2015-11-01

We have previously shown that blue light eliminates the black-pigmented oral bacteria Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, and Prevotella melaninogenica. In the present study, the in vitro photosensitivity of the above black-pigmented microorganisms and four Fusobacteria species (Fusobacterium nucleatum ss. nucleatum, F. nucleatum ss. vincentii, F. nucleatum ss. polymorphum, Fusobacterium periodonticum) was investigated in pure cultures and human dental plaque suspensions. We also tested the hypothesis that phototargeting the above eight key periodontopathogens in plaque-derived biofilms in vitro would control growth within the dental biofilm environment. Cultures of the eight bacteria were exposed to blue light at 455 nm with power density of 80 mW/cm2 and energy fluence of 4.8 J/cm2. High-performance liquid chromatography (HPLC) analysis of bacteria was performed to demonstrate the presence and amounts of porphyrin molecules within microorganisms. Suspensions of human dental plaque bacteria were also exposed once to blue light at 455 nm with power density of 50 mW/cm2 and energy fluence of 12 J/cm2. Microbial biofilms developed from the same plaque were exposed to 455 nm blue light at 50 mW/cm2 once daily for 4 min (12 J/cm2) over a period of 3 days (4 exposures) in order to investigate the cumulative action of phototherapy on the eight photosensitive pathogens as well as on biofilm growth. Bacterial growth was evaluated using the colony-forming unit (CFU) assay. The selective phototargeting of pathogens was studied using whole genomic probes in the checkerboard DNA-DNA format. In cultures, all eight species showed significant growth reduction (p < 0.05). HPLC demonstrated various porphyrin patterns and amounts of porphyrins in bacteria. Following phototherapy, the mean survival fractions were reduced by 28.5 and 48.2% in plaque suspensions and biofilms, respectively, (p < 0.05). DNA probe analysis showed significant reduction in relative abundances of the eight bacteria as a group in plaque suspensions and biofilms. The cumulative blue light treatment suppressed biofilm growth in vitro. This may introduce a new avenue of prophylactic treatment for periodontal diseases.

Eye Development in Sepia officinalis Embryo: What the Uncommon Gene Expression Profiles Tell Us about Eye Evolution.

PubMed

Imarazene, Boudjema; Andouche, Aude; Bassaglia, Yann; Lopez, Pascal-Jean; Bonnaud-Ponticelli, Laure

2017-01-01

In metazoans, there is a remarkable diversity of photosensitive structures; their shapes, physiology, optical properties, and development are different. To approach the evolution of photosensitive structures and visual function, cephalopods are particularly interesting organisms due to their most highly centralized nervous system and their camerular eyes which constitute a convergence with those of vertebrates. The eye morphogenesis in numerous metazoans is controlled mainly by a conserved Retinal Determination Gene Network (RDGN) including pax, six, eya , and dac playing also key developmental roles in non-retinal structures and tissues of vertebrates and Drosophila . Here we have identified and explored the role of Sof-dac, Sof-six1/2, Sof-eya in eye morphogenesis, and nervous structures controlling the visual function in Sepia officinalis . We compare that with the already shown expressions in eye development of Sof-otx and Sof-pax genes. Rhodopsin is the pigment responsible for light sensitivity in metazoan, which correlate to correlate visual function and eye development. We studied Sof-rhodopsin expression during retina differentiation. By in situ hybridization, we show that (1) all of the RDGN genes, including Sof-pax6 , are expressed in the eye area during the early developmental stages but they are not expressed in the retina, unlike Sof-otx , which could have a role in retina differentiation; (2) Sof-rhodopsin is expressed in the retina just before vision gets functional, from stage 23 to hatching. Our results evidence a role of Sof-six1/2, Sof-eya , and Sof-dac in eye development. However, the gene network involved in the retinal photoreceptor differentiation remains to be determined. Moreover, for the first time, Sof-rhodopsin expression is shown in the embryonic retina of cuttlefish suggesting the evolutionary conservation of the role of rhodopsin in visual phototransduction within metazoans. These findings are correlated with the physiological and behavioral observations suggesting that S. officinalis is able to react to light stimuli from stage 25 of organogenesis on, as soon as the first retinal pigments appear.

Eye Development in Sepia officinalis Embryo: What the Uncommon Gene Expression Profiles Tell Us about Eye Evolution

PubMed Central

Imarazene, Boudjema; Andouche, Aude; Bassaglia, Yann; Lopez, Pascal-Jean; Bonnaud-Ponticelli, Laure

2017-01-01

In metazoans, there is a remarkable diversity of photosensitive structures; their shapes, physiology, optical properties, and development are different. To approach the evolution of photosensitive structures and visual function, cephalopods are particularly interesting organisms due to their most highly centralized nervous system and their camerular eyes which constitute a convergence with those of vertebrates. The eye morphogenesis in numerous metazoans is controlled mainly by a conserved Retinal Determination Gene Network (RDGN) including pax, six, eya, and dac playing also key developmental roles in non-retinal structures and tissues of vertebrates and Drosophila. Here we have identified and explored the role of Sof-dac, Sof-six1/2, Sof-eya in eye morphogenesis, and nervous structures controlling the visual function in Sepia officinalis. We compare that with the already shown expressions in eye development of Sof-otx and Sof-pax genes. Rhodopsin is the pigment responsible for light sensitivity in metazoan, which correlate to correlate visual function and eye development. We studied Sof-rhodopsin expression during retina differentiation. By in situ hybridization, we show that (1) all of the RDGN genes, including Sof-pax6, are expressed in the eye area during the early developmental stages but they are not expressed in the retina, unlike Sof-otx, which could have a role in retina differentiation; (2) Sof-rhodopsin is expressed in the retina just before vision gets functional, from stage 23 to hatching. Our results evidence a role of Sof-six1/2, Sof-eya, and Sof-dac in eye development. However, the gene network involved in the retinal photoreceptor differentiation remains to be determined. Moreover, for the first time, Sof-rhodopsin expression is shown in the embryonic retina of cuttlefish suggesting the evolutionary conservation of the role of rhodopsin in visual phototransduction within metazoans. These findings are correlated with the physiological and behavioral observations suggesting that S. officinalis is able to react to light stimuli from stage 25 of organogenesis on, as soon as the first retinal pigments appear. PMID:28883798

Photodynamic detection in visualisation of cutaneous and oral mucosa premalignant and malignant lesions: two clinical cases

NASA Astrophysics Data System (ADS)

Jurczyszyn, Kamil; Ziólkowski, Piotr; Osiecka, Beata; Gerber, Hanna; Dziedzic, Magdalena

2008-11-01

Photodynamic diagnosis (PDD) is promising method of visualisation of premalignant and malignant lesions. PDD is consisted of two main agents: special chemical compound which is called photosensitizer and light. Photosensitizer has affinity to fast proliferating cells such as pre- or malignant. During light irradiation (with proper wavelength - corresponding to absorption peak of photosensitizer) photosensitizer gains energy and passes into excited singlet state S1. Returning to basic singlet state Sn, leads to fluorescence. Due to difference between concentration of photosensitizer in lesion and normal tissue it is possible to obtain high contrast image of lesion. Case #1: 53 years old woman with basal cell carcinoma (BCC) in nasal region; 20% delta-aminolevulinic acid as a precursor of photosensitizer on eucerin base was used. Case #2: 57 years old woman with multifocal oral leukoplakia on cheek mucosa and tongue; 2% chlorophyll gel as photosesitizer was used. All photographs were taken in white light without any filter and in blue and UV light with orange filter: in both cases the total area of the lesions appeared to be larger than it has been clinically observed. Thus, the PDD might be helpful in evaluation of margins of surgical excision of such lesions.

Study of photosensitization reaction progress in a 96 well plate with photosensitizer rich condition using Talaporfin sodium

NASA Astrophysics Data System (ADS)

Ogawa, Emiyu; Takahashi, Mei; Arai, Tsunenori

2013-02-01

To quantitatively investigate photosensitization reaction in vitro against myocardial cells with photosensitizer rich condition in solution using Talaporfin sodium in the well of a 96 well plate, we studied photosensitization reaction progress in this well. We have proposed non-thermal conduction block of myocardium tissue using the photosensitization reaction with laser irradiation shortly after Talaporfin sodium injection. In above situation, the photosensitizer is located outside the myocardial cells in high concentration. To understand interaction of the photosensitization reaction in which the photosensitizer distributes outside cells, the photosensitization reaction progress in the well was studied. Talaporfin sodium (799.69 MW) solution and a 663 nm diode laser were used. The photosensitizer solution concentrations of 12.5-37.5 μM were employed. The photosensitizer fluorescence with 0.29 W/cm2 in irradiance, which was optimized in previous cell death study, was measured during the laser irradiation until 40 J/cm2. The photosensitizer solution absorbance and dissolved oxygen pressure after the laser irradiation were also measured. We found that the photosensitization reaction progress had 2 distinctive phases of different reaction rate: rapid photosensitization reaction consuming dissolved oxygen and gentle photosensitization reaction with oxygen diffusion from the solution-air boundary. The dissolved oxygen pressure and photosensitizer solution absorbance were 30% and 80% of the initial values after the laser irradiation, respectively. Therefore, oxygen was rate-controlling factor of the photosensitization reaction in the well with the photosensitizer rich condition. In the oxygen diffusion phase, the oxygen pressure was maintained around 40 mmHg until the laser irradiation of 40 J/cm2 and it is similar to that of myocardium tissue in vivo. We think that our 96 well plate in vitro system may simulate PDT in myocardial tissue with photosensitization reaction parameters mentioned above.

Root phototropism: how light and gravity interact in shaping plant form

NASA Technical Reports Server (NTRS)

Kiss, John Z.; Correll, Melanie J.; Mullen, Jack L.; Hangarter, Roger P.; Edelmann, Richard E.

2003-01-01

The interactions among tropisms can be critical in determining the final growth form of plants and plant organs. We have studied tropistic responses in roots as an example of these type of interactions. While gravitropism is the predominant tropistic response in roots, phototropism also plays a role in the oriented growth in this organ in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism. In the flowering plant Arabidopsis, the photosensitive pigments phytochrome A (phyA) and phytochrome B (phyB) mediate this positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. While blue-light-based negative phototropism is primarily mediated by the phototropin family of photoreceptors, the phyA and phyAB mutants (but not phyB) were inhibited in this response relative to the WT. The differences observed in phototropic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in plants and that phytochrome plays a key role in integrating multiple environmental stimuli.

Epistatic interactions influence terrestrial–marine functional shifts in cetacean rhodopsin

PubMed Central

2017-01-01

Like many aquatic vertebrates, whales have blue-shifting spectral tuning substitutions in the dim-light visual pigment, rhodopsin, that are thought to increase photosensitivity in underwater environments. We have discovered that known spectral tuning substitutions also have surprising epistatic effects on another function of rhodopsin, the kinetic rates associated with light-activated intermediates. By using absorbance spectroscopy and fluorescence-based retinal release assays on heterologously expressed rhodopsin, we assessed both spectral and kinetic differences between cetaceans (killer whale) and terrestrial outgroups (hippo, bovine). Mutation experiments revealed that killer whale rhodopsin is unusually resilient to pleiotropic effects on retinal release from key blue-shifting substitutions (D83N and A292S), largely due to a surprisingly specific epistatic interaction between D83N and the background residue, S299. Ancestral sequence reconstruction indicated that S299 is an ancestral residue that predates the evolution of blue-shifting substitutions at the origins of Cetacea. Based on these results, we hypothesize that intramolecular epistasis helped to conserve rhodopsin's kinetic properties while enabling blue-shifting spectral tuning substitutions as cetaceans adapted to aquatic environments. Trade-offs between different aspects of molecular function are rarely considered in protein evolution, but in cetacean and other vertebrate rhodopsins, may underlie multiple evolutionary scenarios for the selection of specific amino acid substitutions. PMID:28250185

Root phototropism: how light and gravity interact in shaping plant form.

PubMed

Kiss, John Z; Correll, Melanie J; Mullen, Jack L; Hangarter, Roger P; Edelmann, Richard E

2003-06-01

The interactions among tropisms can be critical in determining the final growth form of plants and plant organs. We have studied tropistic responses in roots as an example of these type of interactions. While gravitropism is the predominant tropistic response in roots, phototropism also plays a role in the oriented growth in this organ in flowering plants. In blue or white light, roots exhibit negative phototropism, but red light induces positive phototropism. In the flowering plant Arabidopsis, the photosensitive pigments phytochrome A (phyA) and phytochrome B (phyB) mediate this positive red-light-based photoresponse in roots since single mutants (and the double phyAB mutant) were severely impaired in this response. While blue-light-based negative phototropism is primarily mediated by the phototropin family of photoreceptors, the phyA and phyAB mutants (but not phyB) were inhibited in this response relative to the WT. The differences observed in phototropic responses were not due to growth limitations since the growth rates among all the mutants tested were not significantly different from that of the WT. Thus, our study shows that the blue-light and red-light systems interact in plants and that phytochrome plays a key role in integrating multiple environmental stimuli.

Melasma: a clinical and epidemiological review*

PubMed Central

Handel, Ana Carolina; Miot, Luciane Donida Bartoli; Miot, Hélio Amante

2014-01-01

Melasma is a chronic acquired hypermelanosis of the skin, characterized by irregular brown macules symmetrically distributed on sun-exposed areas of the body, particularly on the face. It is a common cause of demand for dermatological care that affects mainly women (especially during the menacme), and more pigmented phenotypes (Fitzpatrick skin types III-V). Due to its frequent facial involvement, the disease has an impact on the quality of life of patients. Its pathogeny is not yet completely understood, although there are some known triggering factors such as sun exposure, pregnancy, sexual hormones, inflammatory processes of the skin, use of cosmetics, steroids, and photosensitizing drugs. There is also a clear genetic predisposition, since over 40% of patients reported having relatives affected with the disease. In this manuscript, the authors discuss the main clinical and epidemiological aspects of melasma. PMID:25184917

Evaluation of different photosensitizers for use in photochemical gene transfection.

PubMed

Prasmickaite, L; Høgset, A; Berg, K

2001-04-01

Many potentially therapeutic macromolecules, e.g. transgenes used in gene therapy, are taken into the cells by endocytosis, and have to be liberated from endocytic vesicles in order to express a therapeutic function. To achieve this we have developed a new technology, named photochemical internalization (PCI), based on photochemical reactions inducing rupture of endocytic vesicles. The aim of this study was to clarify which properties of photosensitizers are important for obtaining the PCI effect improving gene transfection. The photochemical effect on transfection of human melanoma THX cells has been studied employing photosensitizers with different physicochemical properties and using two gene delivery vectors: the cationic polypeptide polylysine and the cationic lipid 1,2-dioleoyl-3-trimethylammonium-propane (DOTAP). Photochemical treatment by photosensitizers that do not localize in endocytic vesicles (tetra[3-hydroxyphenyl]porphyrin and 5-aminolevulinic acid-induced protoporphyrin IX) do not stimulate transfection, irrespective of the gene delivery vector. In contrast, photosensitizers localized in endocytic vesicles stimulate polylysine-mediated transfection, and amphiphilic photosensitizers (disulfonated aluminium phthalocyanine [AlPcS2a] and meso-tetraphenylporphynes) show the strongest positive effect, inducing approximately 10-fold increase in transfection efficiency. In contrast, DOTAP-mediated transfection is inhibited by all photochemical treatments irrespective of the photosensitizer used. Neither AlPcS2a nor Photofrin affects the uptake of the transfecting DNA over the plasma membrane, therefore photochemical permeabilization of endocytic vesicles seems to be the most likely mechanism responsible for the positive PCI effect on gene transfection.

Photosensitized Chemically Amplified Resist (PSCAR) 2.0 for high-throughput and high-resolution EUV lithography: dual photosensitization of acid generation and quencher decomposition by flood exposure

NASA Astrophysics Data System (ADS)

Nagahara, Seiji; Carcasi, Michael; Shiraishi, Gosuke; Nakagawa, Hisashi; Dei, Satoshi; Shiozawa, Takahiro; Nafus, Kathleen; De Simone, Danilo; Vandenberghe, Geert; Stock, Hans-Jürgen; Küchler, Bernd; Hori, Masafumi; Naruoka, Takehiko; Nagai, Tomoki; Minekawa, Yukie; Iseki, Tomohiro; Kondo, Yoshihiro; Yoshihara, Kosuke; Kamei, Yuya; Tomono, Masaru; Shimada, Ryo; Biesemans, Serge; Nakashima, Hideo; Foubert, Philippe; Buitrago, Elizabeth; Vockenhuber, Michaela; Ekinci, Yasin; Oshima, Akihiro; Tagawa, Seiichi

2017-03-01

A new type of Photosensitized Chemically Amplified Resist (PSCAR) **: "PSCAR 2.0," is introduced in this paper. PSCAR 2.0 is composed of a protected polymer, a "photo acid generator which can be photosensitized" (PS-PAG), a "photo decomposable base (quencher) which can be photosensitized" (PS-PDB) and a photosensitizer precursor (PP). With this PSCAR 2.0, a photosensitizer (PS) is generated by an extreme ultra-violet (EUV) pattern exposure. Then, during a subsequent flood exposure, PS selectively photosensitizes the EUV exposed areas by the decomposition of a PS-PDB in addition to the decomposition of PS-PAG. As these pattern-exposed areas have the additional acid and reduced quencher concentration, the initial quencher loading in PSCAR 2.0 can be increased in order to get the same target critical dimensions (CD). The quencher loading is to be optimized simultaneously with a UV flood exposure dose to achieve the best lithographic performance and resolution. In this work, the PSCAR performance when different quenchers are used is examined by simulation and exposure experiments with the 16 nm half-pitch (HP) line/space (L/S, 1:1) patterns. According to our simulation results among resists with the different quencher types, the best performance was achieved by PSCAR 2.0 using PS-PDB with the highest possible chemical gradient resulting in the lowest line width roughness (LWR). PSCAR 2.0 performance has furthermore been confirmed on ASML's NXE:3300 with TEL's standalone pre-alpha flood exposure tool at imec. The initial PSCAR 2.0 patterning results on NXE:3300 showed the accelerated photosensitization performance with PS-PDB. From these results, we concluded that the dual sensitization of PS-PAG and PS-PDB in PSCAR 2.0 have a potential to realize a significantly improved resist performance in EUV lithography.

Development of photosensitive silsesquioxane

NASA Astrophysics Data System (ADS)

Tashiro, Yuji; Sekito, Takeshi; Iwata, Takafumi; Yokoyama, Daishi; Nonaka, Toshiaki

2008-11-01

We succeeded in development of SOG materials comprised of cage-type phenyl silsesquioxanes (PSQ) and their alkali soluble derivatives. The alkali soluble silsesquioxane (APSQ) can provide both positive and negative tone photosensitive SOG combination with diazo naphtoquinone (DNQ) and photo-base (acid) agent, respectively. Here we present feature of photolithography process and film properties for our SOG materials.

Fluorescence Imaging Assisted Photodynamic Therapy Using Photosensitizer-Linked Gold Quantum Clusters.

PubMed

Nair, Lakshmi V; Nazeer, Shaiju S; Jayasree, Ramapurath S; Ajayaghosh, Ayyappanpillai

2015-06-23

Fluorescence imaging assisted photodynamic therapy (PDT) is a viable two-in-one clinical tool for cancer treatment and follow-up. While the surface plasmon effect of gold nanorods and nanoparticles has been effective for cancer therapy, their emission properties when compared to gold nanoclusters are weak for fluorescence imaging guided PDT. In order to address the above issues, we have synthesized a near-infrared-emitting gold quantum cluster capped with lipoic acid (L-AuC with (Au)18(L)14) based nanoplatform with excellent tumor reduction property by incorporating a tumor-targeting agent (folic acid) and a photosensitizer (protoporphyrin IX), for selective PDT. The synthesized quantum cluster based photosensitizer PFL-AuC showed 80% triplet quantum yield when compared to that of the photosensitizer alone (63%). PFL-AuC having 60 μg (0.136 mM) of protoporphyrin IX was sufficient to kill 50% of the tumor cell population. Effective destruction of tumor cells was evident from the histopathology and fluorescence imaging, which confirm the in vivo PDT efficacy of PFL-AuC.

Analysis of photodynamic therapy applied to skin disorders by a topical photosensitizer

NASA Astrophysics Data System (ADS)

Fanjul-Vélez, F.; Romanov, O. G.; López-Escobar, M.; Rodriguez-Colmenares, M. A.; Ortega-Quijano, N.; Arce-Diego, J. L.

2008-11-01

Optical treatment of pathological tissues comprises techniques like Low Intensity Laser Treatment (LILT) or Photodynamic Therapy (PDT). PDT consists on the inoculation of a photosensitizer in the tissue, which tends to be accumulated in cancerous cells, and on the posterior optical radiation of the area. The photosensitizer, that can be topical or systemic, is excited and cell necrosis is provoked. The collateral harmful effects of other destructive techniques, like radiotherapy or chemotherapy, are avoided with PDT. PDT can also be used as a complementary technique of conventional excisional surgical operations. The application of PDT to skin disorders is straightforward due to the fact that it is an external and accessible tissue. In this work, we analyze the application of PDT to several skin pathologies and the results obtained, by means of mainly the usage of MetvixR as a topical photosensitizer and with an optical source in the range of 635 nm. The analysis includes a predictive model of the PDT process, based on an optical propagation equation and a photosensitizer degradation approach that provides an estimation of tissue destruction.

Effect of pigment concentration on fastness and color values of thermal and UV curable pigment printing

NASA Astrophysics Data System (ADS)

Baysal, Gulcin; Kalav, Berdan; Karagüzel Kayaoğlu, Burçak

2017-10-01

In the current study, it is aimed to determine the effect of pigment concentration on fastness and colour values of thermal and ultraviolet (UV) curable pigment printing on synthetic leather. For this purpose, thermal curable solvent-based and UV curable water-based formulations were prepared with different pigment concentrations (3, 5 and 7%) separately and applied by screen printing technique using a screen printing machine. Samples printed with solvent-based formulations were thermally cured and samples printed with water-based formulations were cured using a UV curing machine equipped with gallium and mercury (Ga/Hg) lamps at room temperature. The crock fastness values of samples printed with solvent-based formulations showed that increase in pigment concentration was not effective on both dry and wet crock fastness values. On the other hand, in samples printed with UV curable water-based formulations, dry crock fastness was improved and evaluated as very good for all pigment concentrations. However, increasing the pigment concentration affected the wet crock fastness values adversely and lower values were observed. As the energy level increased for each irradiation source, the fastness values were improved. In comparison with samples printed with solvent-based formulations, samples printed with UV curable water-based formulations yielded higher K/S values at all pigment concentrations. The results suggested that, higher K/S values can be obtained in samples printed with UV curable water-based formulations at a lower pigment concentration compared to samples printed with solvent-based formulations.

Fundamental study on photodynamic therapy for atrial fibrillation: effect of photosensitization reaction parameters on myocardial necrosis in vitro

NASA Astrophysics Data System (ADS)

Ogawa, Emiyu; Ito, Arisa; Arai, Tsunenori

2012-03-01

We studied necrotic cell death effect on myocardial cells with photosensitizer existed outside the cells varying photosensitization reaction parameters widely in vitro. We have developed non-thermal ablator with the application of photosensitization reaction for atrial fibrillation. Since laser irradiation is applied shortly after photosensitizer injection, the photosensitization reaction is induced outside the cells. The interaction for the myocardial cells by the photosensitization reaction is not well understood yet on various photosensitization reaction parameters. Rat myocardial cells were cultured in 96 well plates for 7 days. The photosensitization reaction was applied with talaporfin sodium (NPe6) and the semiconductor laser of 663nm wavelength. The average drug light interval was set 8 mins. The photosensitizer concentration and radiant exposure were varied from 5 to 40 μg/ml and 1.2 to 60 J/cm2, respectively. The well bottom was irradiated by the red laser with irradiance of 293 mW/cm2. The photosensitizer fluorescence was monitored during the photosensitization reaction. Alive cell rate was measured by WST assay after 2 hours from the irradiation. In the case of the photosensitizer concentration of 10 μg/ml, the myocardial cells were almost alive even thought 60 J/cm2 in the radiant exposure was applied. In the 15 μg/ml case, the alive cell rate was almost linear relation to the photosensitizer concentration and radiant exposure. We obtained that the threshold for myocardial cell necrosis on the photosensitizer concentration was around 15 μg/ml with 20 J/cm2 in the radiant exposure. This threshold on the photosensitizer concentration was similar to the reported threshold for cancer therapy.

Photosensitizers derived from 132-oxo-methyl pyropheophorbide-a: enhanced effect of indium(III) as a central metal in in vitro and in vivo photosensitizing efficacy.

PubMed

Rosenfeld, Andrew; Morgan, Janet; Goswami, Lalit N; Ohulchanskyy, Tymish; Zheng, Xiang; Prasad, Paras N; Oseroff, Allan; Pandey, Ravindra K

2006-01-01

The effects of an additional keto group on absorption wavelength and the corresponding metal complexes Zn(II), Cu(II) In(III) on singlet oxygen production and photodynamic efficacy were examined among the alkyl ether analogs of pyropheophorbide-a. For the preparation of the desired photosensitizers, the methyl 13(2)-oxo-pyropheophorbide-a obtained by reacting methyl pyropheophorbide-a with aqueous LiOH-THF was converted into a series of alkyl ether analogs. These compounds were evaluated for photophysical properties and in vitro (by means of the MTT assay and intracellular localization in RIF cells) and in vivo (in C3H mice implanted with RIF tumors) photosensitizing efficacy. Among the alkyl ether derivatives, the methyl 3-decyloxyethyl-3-devinyl-13(2)-oxo-pyropheophorbide-a was found to be most effective and the insertion of In(III) into this analog further enhanced its in vitro and in vivo photosensitizing efficacy. Fluorescence microscopy showed that, in contrast to the hexyl and dodecyl ether derivatives of HPPH (which localize in mitochondria and lysosomes, respectively), the diketo-analogs and their In(III) complexes localized in Golgi bodies. The preliminary in vitro and in vivo results suggest that, in both free-base and metalated analogs, the introduction of an additional keto group at the five-member exocyclic ring in pyropheophorbide-a diminishes its photosensitizing efficacy. This may be due to a shift in subcellular localization from mitochondria to the Golgi bodies. The further introduction of In(III) enhances photoactivity, but not by shifting the localization of the photosensitizer.

Optimal methodologies for terahertz time-domain spectroscopic analysis of traditional pigments in powder form

NASA Astrophysics Data System (ADS)

Ha, Taewoo; Lee, Howon; Sim, Kyung Ik; Kim, Jonghyeon; Jo, Young Chan; Kim, Jae Hoon; Baek, Na Yeon; Kang, Dai-ill; Lee, Han Hyoung

2017-05-01

We have established optimal methods for terahertz time-domain spectroscopic analysis of highly absorbing pigments in powder form based on our investigation of representative traditional Chinese pigments, such as azurite [blue-based color pigment], Chinese vermilion [red-based color pigment], and arsenic yellow [yellow-based color pigment]. To accurately extract the optical constants in the terahertz region of 0.1 - 3 THz, we carried out transmission measurements in such a way that intense absorption peaks did not completely suppress the transmission level. This required preparation of pellet samples with optimized thicknesses and material densities. In some cases, mixing the pigments with polyethylene powder was required to minimize absorption due to certain peak features. The resulting distortion-free terahertz spectra of the investigated set of pigment species exhibited well-defined unique spectral fingerprints. Our study will be useful to future efforts to establish non-destructive analysis methods of traditional pigments, to construct their spectral databases, and to apply these tools to restoration of cultural heritage materials.

Optical properties of anthocyanin dyes on TiO2 as photosensitizers for application of dye-sensitized solar cell (DSSC)

NASA Astrophysics Data System (ADS)

Ahliha, A. H.; Nurosyid, F.; Supriyanto, A.; Kusumaningsih, T.

2018-03-01

Dye-sensitized solar cell (DSSC) is one of the alternative energy that can convert light energy into electrical energy. The component of DSSC consists of FTO substrates, TiO2, electrolyte, dye sensitizer, and counter electrode. This study aim was to determine the effect of optical properties of anthocyanin dyes on efficiency of DSSC. The dye sensitizer used can be extracted from anthocyanin pigments such as dragon fruit, black rice, and red cabbage. The red cabbage sensitizer shows lower absorbance value in the visible range (450-580 nm), than dragon fruit and black rice. The chemical structure of each dye molecules has an R group (carbonyl and hydroxyl) that forms a bond with the oxide layer. Red cabbage dye cell has the highest efficiency, 0.06% then dragon fruit and black rice, 0.02% and 0.03%.

Multiple cutaneous malignancies in a patient of xeroderma pigmentosum.

PubMed

Grampurohit, Vandana U; Dinesh, U S; Rao, Ravikala

2011-01-01

Xeroderma pigmentosum is a genodermatosis characterized by photosensitivity and the development of cutaneous and internal malignancies at an early age. The basic defect underlying the clinical manifestations is a nucleotide excision repair defect, leading to defective repair of DNA damaged by ultraviolet radiation. These patients exhibit enhanced sensitivity to ionizing radiation. Patients with xeroderma pigmentosum who are younger than 20 years of age have a greater than 1000-fold increased risk of developing skin cancer. Early detection of these malignancies is necessary because they are fast growing, metastasize early and lead to death. Although, early detection and treatment of cutaneous malignancies will reduce the morbidity and mortality, genetic counseling remains the most important measure for preventing xeroderma pigmentosum. We report a case of xeroderma pigmentosum in an 18-year-old male presenting with multiple cutaneous malignancies: squamous cell carcinoma, malignant melanoma and pigmented basal cell carcinoma.

A Comparison of Singlet Oxygen Explicit Dosimetry (SOED) and Singlet Oxygen Luminescence Dosimetry (SOLD) for Photofrin-Mediated Photodynamic Therapy

PubMed Central

Kim, Michele M.; Penjweini, Rozhin; Gemmell, Nathan R.; Veilleux, Israel; McCarthy, Aongus; Buller, Gerald S.; Hadfield, Robert H.; Wilson, Brian C.; Zhu, Timothy C.

2016-01-01

Accurate photodynamic therapy (PDT) dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED) model has been developed for in vivo purposes. It involves the measurement of the key components in PDT—light fluence (rate), photosensitizer concentration, and ground-state oxygen concentration ([3O2])—to calculate the amount of reacted singlet oxygen ([1O2]rx), the main cytotoxic component in type II PDT. Experiments were performed in phantoms with the photosensitizer Photofrin and in solution using phosphorescence-based singlet oxygen luminescence dosimetry (SOLD) to validate the SOED model. Oxygen concentration and photosensitizer photobleaching versus time were measured during PDT, along with direct SOLD measurements of singlet oxygen and triplet state lifetime (τΔ and τt), for various photosensitizer concentrations to determine necessary photophysical parameters. SOLD-determined cumulative [1O2]rx was compared to SOED-calculated [1O2]rx for various photosensitizer concentrations to show a clear correlation between the two methods. This illustrates that explicit dosimetry can be used when phosphorescence-based dosimetry is not feasible. Using SOED modeling, we have also shown evidence that SOLD-measured [1O2]rx using a 523 nm pulsed laser can be used to correlate to singlet oxygen generated by a 630 nm laser during a clinical malignant pleural mesothelioma (MPM) PDT protocol by using a conversion formula. PMID:27929427

A Comparison of Singlet Oxygen Explicit Dosimetry (SOED) and Singlet Oxygen Luminescence Dosimetry (SOLD) for Photofrin-Mediated Photodynamic Therapy.

PubMed

Kim, Michele M; Penjweini, Rozhin; Gemmell, Nathan R; Veilleux, Israel; McCarthy, Aongus; Buller, Gerald S; Hadfield, Robert H; Wilson, Brian C; Zhu, Timothy C

2016-12-06

Accurate photodynamic therapy (PDT) dosimetry is critical for the use of PDT in the treatment of malignant and nonmalignant localized diseases. A singlet oxygen explicit dosimetry (SOED) model has been developed for in vivo purposes. It involves the measurement of the key components in PDT-light fluence (rate), photosensitizer concentration, and ground-state oxygen concentration ([³ O ₂])-to calculate the amount of reacted singlet oxygen ([¹ O ₂] rx ), the main cytotoxic component in type II PDT. Experiments were performed in phantoms with the photosensitizer Photofrin and in solution using phosphorescence-based singlet oxygen luminescence dosimetry (SOLD) to validate the SOED model. Oxygen concentration and photosensitizer photobleaching versus time were measured during PDT, along with direct SOLD measurements of singlet oxygen and triplet state lifetime ( τ Δ and τ t ), for various photosensitizer concentrations to determine necessary photophysical parameters. SOLD-determined cumulative [¹ O ₂] rx was compared to SOED-calculated [¹ O ₂] rx for various photosensitizer concentrations to show a clear correlation between the two methods. This illustrates that explicit dosimetry can be used when phosphorescence-based dosimetry is not feasible. Using SOED modeling, we have also shown evidence that SOLD-measured [¹ O ₂] rx using a 523 nm pulsed laser can be used to correlate to singlet oxygen generated by a 630 nm laser during a clinical malignant pleural mesothelioma (MPM) PDT protocol by using a conversion formula.

Electrophoretic deposited TiO 2 pigment-based back reflectors for thin film solar cells

DOE PAGES

Bills, Braden; Morris, Nathan; Dubey, Mukul; ...

2015-01-16

Highly reflective coatings with strong light scattering effect have many applications in optical components and optoelectronic devices. This paper reports titanium dioxide (TiO 2) pigment-based reflectors that have 2.5 times higher broadband diffuse reflection than commercially produced aluminum or silver based reflectors and result in efficiency enhancements of a single-junction amorphous Si solar cell. Electrophoretic deposition is used to produce pigment-based back reflectors with high pigment density, controllable film thickness and site-specific deposition. Electrical conductivity of the pigment-based back reflectors is improved by creating electrical vias throughout the pigment-based back reflector by making holes using an electrical discharge / dielectricmore » breakdown approach followed by a second electrophoretic deposition of conductive nanoparticles into the holes. While previous studies have demonstrated the use of pigment-based back reflectors, for example white paint, on glass superstrate configured thin film Si solar cells, this work presents a scheme for producing pigment-based reflectors on complex shape and flexible substrates. Finally, mechanical durability and scalability are demonstrated on a continuous electrophoretic deposition roll-to-roll system which has flexible metal substrate capability of 4 inch wide and 300 feet long.« less

Gene expression of a two-component regulatory system associated with sunscreen biosynthesis in the cyanobacterium Nostoc punctiforme ATCC 29133.

PubMed

Janssen, Jacob; Soule, Tanya

2016-01-01

Long-wavelength ultraviolet radiation (UVA) can damage cells through photooxidative stress, leading to harmful photosensitized proteins and pigments in cyanobacteria. To mitigate damage, some cyanobacteria secrete the UVA-absorbing pigment scytonemin into their extracellular sheath. Comparative genomic analyses suggest that scytonemin biosynthesis is regulated by the two-component regulatory system (TCRS) proteins encoded by Npun_F1277 and Npun_F1278 in the cyanobacterium Nostoc punctiforme ATCC 29133. To understand the dynamics of these genes, their expression was measured following exposure to UVA, UVB, high visible (VIS) irradiance and oxidative stress for 20, 40 and 60 min. Overall, both genes had statistically similar patterns of expression for all four conditions and were generally upregulated, except for those exposed to UVB by 60 min and for the cells under oxidative stress. The greatest UVA response was an upregulation by 20 min, while the response to UVB was the most dramatic and persisted through 40 min. High VIS irradiance resulted in a modest upregulation, while oxidative stress caused a slight downregulation. Both genes were also found to occur on the same transcript. These results demonstrate that these genes are positively responding to several light-associated conditions, which suggests that this TCRS may regulate more than just scytonemin biosynthesis under UVA stress. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Concentration-Dependence of Vitamin C in Combinations with Vitamin E and Zeaxanthin on Light-Induced Toxicity to Retinal Pigment Epithelial Cells†

PubMed Central

Różanowska, Małgorzata; Bakker, Linda; Boulton, Michael E.; Różanowski, Bartosz

2012-01-01

The purpose of this study was to determine the effects of increasing concentration of ascorbate alone and in combinations with α-tocopherol and zeaxanthin on phototoxicity to the retinal pigment epithelium. ARPE-19 cells were exposed to rose bengal and visible light in the presence and absence of antioxidants. Toxicity was quantified by an assay of cell reductive activity. 20 min exposure to visible light and photosensitizer decreased cell viability to ~42%. Lipophilic antioxidants increased viabilities to ~70%, ~61% and ~75% for α-tocopherol, zeaxanthin and their combination, respectively. Cell viabilities were ~70%, 56% and 5% after exposures in the presence of 0.35, 0.7 and 1.4 mM ascorbate, respectively. 45 min exposure increased cell death to ~74% and to >95% in the absence and presence of ascorbate, respectively. In the presence of ascorbate, zeaxanthin did not significantly affect phototoxicity. α-Tocopherol and its combination with zeaxanthin enhanced protective effects of ascorbate but did not prevent from ascorbate-mediated deleterious effects. In conclusion, there is a narrow range of concentrations and exposure times where ascorbate exerts photoprotective effects, exceeding which leads to ascorbate-mediated increase in photocytotoxicity. Vitamin E and its combination with zeaxanthin can enhance protective effects of ascorbate but do not ameliorate its deleterious effects. PMID:22924673

The Fowler-Nordheim behavior and mechanism of photo-sensitive field from SnS{sub 2} nanosheets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Suryawanshi, Sachin R.; Chaudhari, Nilima S.; Warule, Sambhaji S.

2015-06-24

Here in, we report photo-sensitive field emission measurements of SnS{sub 2} nanosheets at base pressure of ∼1×10{sup −8} mbar are reported. The nonlinear Fowler-Nordheim (F-N) plot is elucidate according to a (F-N) model of calculation based on shift in a saturation of conduction band current density after light illumination and prevalence of valence band current density at high electric field values. The model of calculation suggests that the slope variation before and after visible light illumination of the F-N plot, in the high-field and low-field regions, does not depend on the magnitude of saturation but also depend on charge carriermore » (electron) concentration get increased in conduction band. The F-N model of calculation is important for the fundamental understanding of the photo-sensitive field emission mechanism of semiconducting SnS{sub 2}. The replicate F-N plots exhibit similar features to those observed experimentally. The model calculation suggests that the nonlinearity of the F-N plot is a characteristic of the photo-enhanced energy band structure of the photo-sensitive semiconductor material.« less

Investigating the impact of oxygen concentration and blood flow variation on photodynamic therapy

NASA Astrophysics Data System (ADS)

Penjweini, Rozhin; Kim, Michele M.; Finlay, Jarod C.; Zhu, Timothy C.

2016-03-01

Type II photodynamic therapy (PDT) is used for cancer treatment based on the combined action of a photosensitizer, a special wavelength of light, oxygen (3O2) and generation of singlet oxygen (1O2). Intra-patient and inter-patient variability of oxygen concentration ([3O2]) before and after the treatment as well as photosensitizer concentration and hemodynamic parameters such as blood flow during PDT has been reported. Simulation of these variations is valuable, as it would be a means for the rapid assessment of treatment effect. A mathematical model has been previously developed to incorporate the diffusion equation for light transport in tissue and the macroscopic kinetic equations for simulation of [3O2], photosensitizers in ground and triplet states and concentration of the reacted singlet oxygen ([1O₂]rx) during PDT. In this study, the finite-element based calculation of the macroscopic kinetic equations is done for 2-(1- Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated PDT by incorporating the information of the photosensitizer photochemical parameters as well as the tissue optical properties, photosensitizer concentration, initial oxygen concentration ([3O2]0), blood flow changes and Φ that have been measured in mice bearing radiation-induced fibrosarcoma (RIF) tumors. Then, [1O2]rx calculated by using the measured [3O2] during the PDT is compared with [1O2]rx calculated based on the simulated [3O₂]; both calculations showed a reasonably good agreement. Moreover, the impacts of the blood flow changes and [3O2]0 on [1O2]rx have been investigated, which showed no pronounced effect of the blood flow changes on the long-term 1O2 generation. When [3O2]0 becomes limiting, small changes in [3O₂] have large effects on [1O2]rx.

Photoacoustic imaging of intravenously injected photosensitizer in rat burn models for efficient antibacterial photodynamic therapy

NASA Astrophysics Data System (ADS)

Tsunoi, Yasuyuki; Sato, Shunichi; Ashida, Hiroshi; Terakawa, Mitsuhiro

2012-02-01

For efficient photodynamic treatment of wound infection, a photosensitizer must be distributed in the whole infected tissue region. To ensure this, depth profiling of a photosensitizer is necessary in vivo. In this study, we applied photoacoustic (PA) imaging to visualize the depth profile of an intravenously injected photosensitizer in rat burn models. In burned tissue, pharmacokinetics is complicated; vascular occlusion takes place in the injured tissue, while vascular permeability increases due to thermal invasion. In this study, we first used Evans Blue (EB) as a test drug to examine the feasibility of photosensitizer dosimetry based on PA imaging. On the basis of the results, an actual photosensitizer, talaporfin sodium was used. An EB solution was intravenously injected into a rat deep dermal burn model. PA imaging was performed on the wound with 532 nm and 610 nm nanosecond light pulses for visualizing vasculatures (blood) and EB, respectively. Two hours after injection, the distribution of EB-originated signal spatially coincided well with that of blood-originated signal measured after injury, indicating that EB molecules leaked out from the blood vessels due to increased permeability. Afterwards, the distribution of EB signal was broadened in the depth direction due to diffusion. At 12 hours after injection, clear EB signals were observed even in the zone of stasis, demonstrating that the leaked EB molecules were delivered to the injured tissue layer. The level and time course of talaporfin sodium-originated signals were different compared with those of EB-originated signals, showing animal-dependent and/or drug-dependent permeabilization and diffusion in the tissue. Thus, photosensitizer dosimetry should be needed before every treatment to achieve desirable outcome of photodynamic treatment, for which PA imaging can be concluded to be valid and useful.

Melanogenesis inhibits respiration in B16-F10 melanoma cells whereas enhances mitochondrial cell content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meira, Willian Vanderlei; Heinrich, Tassiele Andréa; Cadena, Silvia Maria Suter Correia

Melanoma is a rare and aggressive skin tumor; the survival of patients diagnosed late is fairly low. This high mortality rate is due to the characteristics of the cells that allow them to be resistant to radiotherapy and conventional chemotherapy, besides of being able to evade the immune system. Melanin, the pigment responsible for skin, hair and eye color, seems to be involved in this resistance. The main function of melanin is to protect the cells against ultraviolet (UV) light by absorbing this radiation and reactive oxygen species (ROS) scavenging. But this pigment may have also a role as photosensitizer,more » because when it is irradiated with UVA light (320-400 nm), the generation of ROS was detected. Besides, the melanogenesis stimulation on B16-F10 cells resulted in cell cycle arrest, induction of a quiescent state, change in the expression of several proteins and alterations on ADP/ATP ratio. The present study aimed to investigate the influence of melanogenesis stimulation in mitochondrial function of B16-F10 melanoma cells. Therefore, we analyzed cells respiration, mitochondrial membrane potential (Δψ{sub m}) and mitochondria mass in B16-F10 melanoma cells stimulated with 0.4 mM L-tyrosine and 10 mM NH{sub 4}Cl. Our results showed that the induction of melanin synthesis was able to reduce significantly the oxygen consumption after 48 h of stimulation, without changes of mitochondrial membrane potential when compared to non-stimulated cells. Despite of respiration inhibition, the mitochondria mass was higher in cells with melanogenesis stimulation. We suggest that the stimulation in the melanin synthesis might be promoting the inhibition of electrons transport chain by some intermediate compound from the synthesis of the pigment and this effect could contribute to explain the entry in the quiescent state. - Highlights: • Melanoma pigmentation alters mitochondrial respiration. • Induction of melanin synthesis by 48 h do not change mitochondrial membrane potential. • Mitochondria mass was higher in cells with melanogenesis stimulation.« less

Coexistence of wave propagation and oscillation in the photosensitive Belousov-Zhabotinsky reaction on a circular route.

PubMed

Nakata, Satoshi; Morishima, Sayaka; Ichino, Takatoshi; Kitahata, Hiroyuki

2006-12-21

The photosensitive Belousov-Zhabotinsky (BZ) reaction was investigated on a circular ring, which was drawn using computer software and then projected on a film soaked with BZ solution using a liquid-crystal projector. Under the initial conditions, a chemical wave propagated with a constant velocity on the black ring under a bright background. When the background was rapidly changed to dark, coexistence of the oscillation on part of the ring and propagation of the chemical wave on the other part was observed. These experimental results are discussed in relation to the nature of the photosensitive BZ reaction and theoretically reproduced based on a reaction-diffusion system using the modified Oregonator model.

A compact fiber-optic probe-based singlet oxygen luminescence detection system.

PubMed

Gemmell, Nathan R; McCarthy, Aongus; Kim, Michele M; Veilleux, Israel; Zhu, Timothy C; Buller, Gerald S; Wilson, Brian C; Hadfield, Robert H

2017-02-01

This paper presents a novel compact fiberoptic based singlet oxygen near-infrared luminescence probe coupled to an InGaAs/InP single photon avalanche diode (SPAD) detector. Patterned time gating of the single-photon detector is used to limit unwanted dark counts and eliminate the strong photosensitizer luminescence background. Singlet oxygen luminescence detection at 1270 nm is confirmed through spectral filtering and lifetime fitting for Rose Bengal in water, and Photofrin in methanol as model photosensitizers. The overall performance, measured by the signal-to-noise ratio, improves by a factor of 50 over a previous system that used a fiberoptic-coupled superconducting nanowire single-photon detector. The effect of adding light scattering to the photosensitizer is also examined as a first step towards applications in tissue in vivo. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Investigation of human serum albumin (HSA) binding specificity of certain photosensitizers related to pyropheophorbide-a and bacteriopurpurinimide by circular dichroism spectroscopy and its correlation with in vivo photosensitizing efficacy.

PubMed

Chen, Yihui; Miclea, Razvan; Srikrishnan, Thamarapu; Balasubramanian, Sathyamangalam; Dougherty, Thomas J; Pandey, Ravindra K

2005-07-01

A series of pyropheophorbide-a and bacteriopurpurinimides were investigated to understand the correlation between HSA (site II) binding affinity and in vivo photosensitizing activity. In our study, photosensitizers that bound to site II of HSA produced a significant difference in the circular dichroism spectra of the corresponding complexes, especially at Soret band region of the photosensitizers. Our results suggest that CD spectroscopy of the photosensitizer-HSA complexes could be a valuable tool in screening new photosensitizers before evaluating them for in vivo efficacy.

Photoinduced water oxidation sensitized by a tetranuclear Ru(II) dendrimer.

PubMed

La Ganga, Giuseppina; Nastasi, Francesco; Campagna, Sebastiano; Puntoriero, Fausto

2009-12-07

A multimetallic ruthenium(II) dendrimer is used for the first time to photosensitize dioxygen production from water by IrO2 nanoparticles; the system is more efficient than an analogous system based on the more commonly used [Ru(bpy)3]2+-type photosensitizers, in particular for the ability of the dendrimer to take advantage of the red portion of the solar spectrum.

The beet Y locus encodes an anthocyanin-MYB-like protein that activates the betalain red pigment pathway

USDA-ARS?s Scientific Manuscript database

Almost all flowering plants produce red/violet, phenylalanine-based, anthocyanin pigments. A single order, the Caryophyllales, contains families that replace anthocyanins with tyrosine-based red and yellow betalain pigments. Close biological correlation of pigmentation patterns suggested that betala...

Photo-oxidation of ergosterol: indirect detection of antioxidants photosensitizers or quenchers of singlet oxygen.

PubMed

Lagunes, Irene; Trigos, Ángel

2015-04-01

Consumption of antioxidant supplements is associated to prevention of several diseases. However, recent studies suggest that antioxidants, besides scavenge free radicals could lead development of tumors. Due to conflicting reports on the antioxidant benefits, the capacity to photosensitize the generation of singlet oxygen of seven natural antioxidants was evaluated through photo-oxidation of ergosterol which proved to be an efficient method of indirect detection of singlet oxygen. Our results showed that curcumin, resveratrol and quercetin have pro-oxidant activity due they act as photosensitizers in generation of singlet oxygen. In addition, we observed that genistein, naringenin, β-carotene and gallic acid besides their antioxidant activity against ROS radicals, are capable of quenching ROS non-radicals as singlet oxygen. Finally, our results allow us to propose a new approach in classification of natural antioxidants scavengers of free radicals, based on their activity as quenchers of singlet oxygen or as photosensitizers in singlet oxygen generation. Copyright © 2015. Published by Elsevier B.V.

Synthesis, characterization, and subcellular localization studies of amino acid-substituted porphyrinic pigments

NASA Astrophysics Data System (ADS)

van Diggelen, Lisa; Khin, Hnin; Conner, Kip; Shao, Jenny; Sweezy, Margaretta; Jung, Anna H.; Isaac, Meden; Simonis, Ursula

2009-06-01

Stopping cancer in its path occurs when photosensitizers (PSs) induce apoptotic cell death after their exposure to light and the subsequent formation of reactive oxygen species. In pursuit of our hypothesis that mitochondrial localizing PSs will enhance the efficacy of the photosensitizing process in photodynamic therapy, since they provoke cell death by inducing apoptosis, we synthesized and characterized tetraphenylporphyrins (TPPs) that are substituted at the paraphenyl positions by two amino acids and two fluoro or hydroxyl groups, respectively. They were prepared according to the Lindsey-modified Adler-Longo methodology using trifluoromethanesulfonylchloride (CF3SO2Cl) as a catalyst instead of trifluoroacetic acid. The use of CF3SO2Cl yielded cleaner products in significantly higher yields. During the synthesis, not only the yields and work-up procedure of the TPPs were improved by using CF3SO2Cl as a catalyst, but also a better means of synthesizing the precursor dipyrromethanes was tested by using indium(III) chloride. Column chromatography, HPLC, and NMR spectroscopy were used to separate and characterize the di-amino acid-dihydroxy, or difluoro-substituted porphyrins and to ascertain their purity before subcellular localization studies were carried out. Studies using androgen-sensitive human prostate adenocarcinoma cells LNCaP revealed that certain amino acid substituted porphyrins that are positively charged in the slightly acidic medium of cancer cells are very useful in shedding light on the targets of TPPs in subcellular organelles of cancer cells. Although some of these compounds have properties of promising photosensitizers by revealing increased water solubility, acidic properties, and innate ability to provoke cell death by apoptosis, the cell killing efficacy of these TPPs is low. This correlates with their subcellular localization. The di-amino acid, di-hydroxy substituted TPPs localize mainly to the lysosomes, whereas the di-fluoro-substituted TPPs are trapped in the plasma membrane. Only a pheophorbide derivative recently synthesized in our laboratory localized to the mitochondria of LNCaP cells, which are at the center of cell death as is reflected in their key role during apoptosis, thus reassuring our attempts toward rational drug design.

DFT application for chlorin derivatives photosensitizer drugs modeling

NASA Astrophysics Data System (ADS)

Machado, Neila; Carvalho, B. G.; Téllez Soto, C. A.; Martin, A. A.; Favero, P. P.

2018-04-01

Photodynamic therapy is an alternative form of cancer treatment that meets the desire for a less aggressive approach to the body. It is based on the interaction between a photosensitizer, activating light, and molecular oxygen. This interaction results in a cascade of reactions that leads to localized cell death. Many studies have been conducted to discover an ideal photosensitizer, which aggregates all the desirable characteristics of a potent cell killer and generates minimal side effects. Using Density Functional Theory (DFT) implemented in the program Vienna Ab-initio Simulation Package, new chlorin derivatives with different functional groups were simulated to evaluate the different absorption wavelengths to permit resonant absorption with the incident laser. Gaussian 09 program was used to determine vibrational wave numbers and Natural Bond Orbitals. The chosen drug with the best characteristics for the photosensitizer was a modified model of the original chlorin, which was called as Thiol chlorin. According to our calculations it is stable and is 19.6% more efficient at optical absorption in 708 nm in comparison to the conventional chlorin e6. Vibrational modes, optical and electronic properties were predicted. In conclusion, this study is an attempt to improve the development of new photosensitizer drugs through computational methods that save time and contribute to decrease the numbers of animals for model application.

Professional photosensitive eczema of fishermen by contact with bryozoans: disabling occupational dermatosis.

PubMed

Clin, Benedicte; Stosse-Guevel, Catherine; Marquignon, Marie-France; Verneuil, Laurence; Letourneux, Marc

2008-01-01

Eczema associated with bryozoans is a form of occupational dermatosis caused by a living animal, involving contact eczema, occasionally associated with photosensitivity and concerning fishermen on a quasi-elective basis. This affection can prove to be extremely disabling, frequently generating disastrous social consequences, since the eviction of the responsible allergen is very often synonymous to occupational reclassification, a measure which fishermen, highly attached to their profession, have great difficulty in accepting. Based on the description of three cases of photosensitive eczema associated with contact with the bryozoan, Alcyonidium gelatinosum, identified in fishermen from the English Channel coastline, we describe the characteristics and the specificities of this occupational dermatosis, then approach the issue of its prevention, which, unfortunately, remains limited.

Visible-Light-Induced Nickel-Catalyzed Negishi Cross-Couplings by Exogenous-Photosensitizer-Free Photocatalysis.

PubMed

Abdiaj, Irini; Fontana, Alberto; Gomez, M Victoria; de la Hoz, Antonio; Alcázar, Jesús

2018-03-22

The merging of photoredox and transition-metal catalysis has become one of the most attractive approaches for carbon-carbon bond formation. Such reactions require the use of two organo-transition-metal species, one of which acts as a photosensitizer and the other one as a cross-coupling catalyst. We report herein an exogenous-photosensitizer-free photocatalytic process for the formation of carbon-carbon bonds by direct acceleration of the well-known nickel-catalyzed Negishi cross-coupling that is based on the use of two naturally abundant metals. This finding will open new avenues in cross-coupling chemistry that involve the direct visible-light absorption of organometallic catalytic complexes. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

21 CFR 73.350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2012 CFR

2012-04-01

... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.350 Mica-based pearlescent pigments. (a... the requirements of § 73.1496(a)(1). (2) Color additive mixtures for food use made with mica-based... color additive mixtures for coloring food. (b) Specifications. Mica-based pearlescent pigments shall...

21 CFR 73.350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.350 Mica-based pearlescent pigments. (a... the requirements of § 73.1496(a)(1). (2) Color additive mixtures for food use made with mica-based... color additive mixtures for coloring food. (b) Specifications. Mica-based pearlescent pigments shall...

21 CFR 73.350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2011 CFR

2011-04-01

... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.350 Mica-based pearlescent pigments. (a... the requirements of § 73.1496(a)(1). (2) Color additive mixtures for food use made with mica-based... color additive mixtures for coloring food. (b) Specifications. Mica-based pearlescent pigments shall...

21 CFR 73.350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2014 CFR

2014-04-01

... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.350 Mica-based pearlescent pigments. (a... the requirements of § 73.1496(a)(1). (2) Color additive mixtures for food use made with mica-based... color additive mixtures for coloring food. (b) Specifications. Mica-based pearlescent pigments shall...

21 CFR 73.350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2013 CFR

2013-04-01

... LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Foods § 73.350 Mica-based pearlescent pigments. (a... the requirements of § 73.1496(a)(1). (2) Color additive mixtures for food use made with mica-based... color additive mixtures for coloring food. (b) Specifications. Mica-based pearlescent pigments shall...

Comparison of singlet oxygen threshold dose for PDT.

PubMed

Zhu, Timothy C; Liu, Baochang; Kim, Michele M; McMillan, Dayton; Liang, Xing; Finlay, Jarod C; Busch, Theresa M

2014-02-01

Macroscopic modeling of singlet oxygen ( 1 O 2 ) is of particular interest because it is the major cytotoxic agent causing biological effects for type II photosensitizers during PDT. We have developed a macroscopic model to calculate reacted singlet oxygen concentration ([1O2] rx for PDT. An in-vivo RIF tumor mouse model is used to correlate the necrosis depth to the calculation based on explicit PDT dosimetry of light fluence distribution, tissue optical properties, and photosensitizer concentrations. Inputs to the model include 4 photosensitizer specific photochemical parameters along with the apparent singlet oxygen threshold concentration. Photosensitizer specific model parameters are determined for several type II photosensitizers (Photofrin, BPD, and HPPH). The singlet oxygen threshold concentration is approximately 0.41 - 0.56 mM for all three photosensitizers studied, assuming that the fraction of singlet oxygen generated that interacts with the cell is ( f = 1). In comparison, value derived from other in-vivo mice studies is 0.4 mM for mTHPC. However, the singlet oxygen threshold doses were reported to be 7.9 and 12.1 mM for a multicell in-vitro EMT6/Ro spheroid model for mTHPC and Photofrin PDT, respectively. The sensitivity of threshold singlet oxygen dose for our experiment is examined. The possible influence of vascular vs. apoptotic cell killing mechanism on the singlet oxygen threshold dose is discussed using the BPD with different drug-light intervals 3 hrs vs. 15 min. The observed discrepancies between different experiments warrant further investigation to explain the cause of the difference.

Comparison of singlet oxygen threshold dose for PDT

PubMed Central

Zhu, Timothy C; Liu, Baochang; Kim, Michele M.; McMillan, Dayton; Liang, Xing; Finlay, Jarod C.; Busch, Theresa M.

2015-01-01

Macroscopic modeling of singlet oxygen (1O2) is of particular interest because it is the major cytotoxic agent causing biological effects for type II photosensitizers during PDT. We have developed a macroscopic model to calculate reacted singlet oxygen concentration ([1O2]rx for PDT. An in-vivo RIF tumor mouse model is used to correlate the necrosis depth to the calculation based on explicit PDT dosimetry of light fluence distribution, tissue optical properties, and photosensitizer concentrations. Inputs to the model include 4 photosensitizer specific photochemical parameters along with the apparent singlet oxygen threshold concentration. Photosensitizer specific model parameters are determined for several type II photosensitizers (Photofrin, BPD, and HPPH). The singlet oxygen threshold concentration is approximately 0.41 – 0.56 mM for all three photosensitizers studied, assuming that the fraction of singlet oxygen generated that interacts with the cell is (f = 1). In comparison, value derived from other in-vivo mice studies is 0.4 mM for mTHPC. However, the singlet oxygen threshold doses were reported to be 7.9 and 12.1 mM for a multicell in-vitro EMT6/Ro spheroid model for mTHPC and Photofrin PDT, respectively. The sensitivity of threshold singlet oxygen dose for our experiment is examined. The possible influence of vascular vs. apoptotic cell killing mechanism on the singlet oxygen threshold dose is discussed using the BPD with different drug-light intervals 3 hrs vs. 15 min. The observed discrepancies between different experiments warrant further investigation to explain the cause of the difference. PMID:25999651

Preclinical studies of photodynamic therapy of intracranial tissues

NASA Astrophysics Data System (ADS)

Lilge, Lothar D.; Sepers, Marja; Park, Jane; O'Carroll, Cindy; Pournazari, Poupak; Prosper, Joe; Wilson, Brian C.

1997-05-01

The applicability and limitations of the photodynamic threshold model were investigated for an intracranial tumor (VX2) and normal brain tissues in a rabbit model. Photodynamic threshold values for four different photosensitizers, i.e., Photofrin, 5(delta) -aminolaevulinic acid (5(delta) -ALA) induced Protoporphyrin IX (PPIX), Tin Ethyl Etiopurpurin (SnET2), and chloroaluminum phthalocyanine (AlClPc), were determined based on measured light fluence distributions, macroscopic photosensitizer concentration in various brain structures, and histologically determined extent of tissue necrosis following PDT. For Photofrin, AlClPc, and SnET2, normal brain displayed a significantly lower threshold value than VX2 tumor. For 5(delta) -ALA induced PPIX and SnET2 no or very little white matter damage, equalling to very high or infinite threshold values, was observed. Additionally, the latter two photosensitizers showed significantly lower uptake in white matter compared to other brain structures and VX2 tumor. Normal brain structures lacking a blood- brain-barrier, such as the choroid plexus and the meninges, showed high photosensitizer uptake for all photosensitizers, and, hence, are at risk when exposed to light. Results to date suggest that the photodynamic threshold values iares valid for white matter, cortex and VX2 tumor. For clinical PDT of intracranial neoplasms 5(delta) -ALA induced PPIX and SnET2 appear to be the most promising for selective tumor necrosis.However, the photosensitizer concentration in each normal brain structure and the fluence distribution throughout the treatment volume and adjacent tissues at risk must be monitored to maximize the selectivity of PDT for intracranial tumors.

Characterization of Sorolla's gouache pigments by means of spectroscopic techniques

NASA Astrophysics Data System (ADS)

Roldán, Clodoaldo; Juanes, David; Ferrazza, Livio; Carballo, Jorgelina

2016-02-01

This paper presents the characterization of the Joaquín Sorolla's gouache sketches for the oil on canvas series "Vision of Spain" commissioned by A. M. Huntington to decorate the library of the Hispanic Society of America in New York. The analyses were focused on the identification of the elemental composition of the gouache pigments by means of portable EDXRF spectrometry in a non-destructive mode. Additionally, SEM-EDX and FTIR analyses of a selected set of micro-samples were carried out to identify completely the pigments, the paint technique and the binding media. The obtained results have confirmed the identification of lead and zinc white, vermillion, earth pigments, ochre, zinc yellow, chrome yellow, ultramarine, Prussian blue, chromium based and copper-arsenic based green pigments, bone black and carbon based black pigments, and the use of gum arabic as binding media in the gouache pigments.

Acidolysis small molecular phenolic ether used as accelerator in photosensitive diazonaphthaquinone systems

NASA Astrophysics Data System (ADS)

Zhou, Haihua; Zou, Yingquan

2006-03-01

The photosensitive compounds in the photosensitive coatings of positive PS plates are the diazonaphthaquinone derivatives. Some acidolysis small molecular phenolic ethers, which were synthesized by some special polyhydroxyl phenols with vinyl ethyl ether, are added in the positive diazonaphthaquinone photosensitive composition to improve its sensitivity, composed with photo-acid-generators. The effects to the photosensitivity, anti-alkali property, anti-isopropyl alcohol property, dot resolution and line resolution of the coatings are studied with different additive percent of the special phenolic ethers. In the conventional photosensitive diazonaphthaquinone systems for positive PS plates, the photosensitivity is improved without negative effects to resolution, anti-alkali and anti-isopropyl alcohol properties when added about 5% of the special acidolysis phenolic ethers, EAAE or DPHE, composed with photo-acid-generators.

Duration of skin photosensitivity and incidence of photosensitivity reactions after administration of verteporfin.

PubMed

Houle, Jean-Marie; Strong, H Andrew

2002-12-01

Verteporfin (Visudyne, Novartis AG) is a light-activated drug that reduces the risk of vision loss in patients with certain types of choroidal neovascularization (CNV). Because photosensitivity can occur with photosensitizers, it is important for ophthalmologists providing verteporfin therapy to understand its time course and duration, as well as the incidence of photosensitivity reactions. Data were obtained from three sources: 1) the time course of skin photosensitivity in 17 volunteers by measuring erythema/edema over time after verteporfin, using red light exposure; 2) the duration of skin photosensitivity in 30 patients with skin cancer by exposing skin to simulated solar light and calculating the daily minimal erythematous dose; and 3) the incidences of photosensitivity reactions as recorded in three phase III trials in patients with CNV secondary to age-related macular degeneration or pathologic myopia who received the regimen of verteporfin therapy currently approved by regulatory authorities (infusion of 6 mg/m(2) body surface area). 1) Skin photosensitivity was high at the first timepoint of 1.5 hours after dosing and decreased rapidly thereafter; 2) the duration of skin photosensitivity was dose dependent, ranging from 2.0 to 6.7 days at 6 to 20 mg/m(2), respectively (mean of 2 days at a dose of 6 mg/m(2)); and 3) photosensitivity reactions occurred in only 2.2% of patients in the phase III trials, including two severe events, one secondary to extravasation. All treatment-related reactions in the phase III trials occurred within the first 2 days after dosing, with the exception of two mild reactions and one moderate reaction that occurred 3 days after treatment. Verteporfin is associated with short-lived photosensitivity and a low incidence of photosensitivity reactions in clinical trials, most of which could probably have been avoided by adherence to protocol instructions for skin protection.

CHD2 variants are a risk factor for photosensitivity in epilepsy

PubMed Central

Myers, Candace T.; Leu, Costin; de Kovel, Carolien G. F.; Afrikanova, Tatiana; Cordero-Maldonado, Maria Lorena; Martins, Teresa G.; Jacmin, Maxime; Drury, Suzanne; Krishna Chinthapalli, V.; Muhle, Hiltrud; Pendziwiat, Manuela; Sander, Thomas; Ruppert, Ann-Kathrin; Møller, Rikke S.; Thiele, Holger; Krause, Roland; Schubert, Julian; Lehesjoki, Anna-Elina; Nürnberg, Peter; Lerche, Holger; Palotie, Aarno; Coppola, Antonietta; Striano, Salvatore; Gaudio, Luigi Del; Boustred, Christopher; Schneider, Amy L.; Lench, Nicholas; Jocic-Jakubi, Bosanka; Covanis, Athanasios; Capovilla, Giuseppe; Veggiotti, Pierangelo; Piccioli, Marta; Parisi, Pasquale; Cantonetti, Laura; Sadleir, Lynette G.; Mullen, Saul A.; Berkovic, Samuel F.; Stephani, Ulrich; Helbig, Ingo; Crawford, Alexander D.; Esguerra, Camila V.; Kasteleijn-Nolst Trenité, Dorothee G. A.

2015-01-01

Photosensitivity is a heritable abnormal cortical response to flickering light, manifesting as particular electroencephalographic changes, with or without seizures. Photosensitivity is prominent in a very rare epileptic encephalopathy due to de novo CHD2 mutations, but is also seen in epileptic encephalopathies due to other gene mutations. We determined whether CHD2 variation underlies photosensitivity in common epilepsies, specific photosensitive epilepsies and individuals with photosensitivity without seizures. We studied 580 individuals with epilepsy and either photosensitive seizures or abnormal photoparoxysmal response on electroencephalography, or both, and 55 individuals with photoparoxysmal response but no seizures. We compared CHD2 sequence data to publicly available data from 34 427 individuals, not enriched for epilepsy. We investigated the role of unique variants seen only once in the entire data set. We sought CHD2 variants in 238 exomes from familial genetic generalized epilepsies, and in other public exome data sets. We identified 11 unique variants in the 580 individuals with photosensitive epilepsies and 128 unique variants in the 34 427 controls: unique CHD2 variation is over-represented in cases overall (P = 2·17 × 10−5). Among epilepsy syndromes, there was over-representation of unique CHD2 variants (3/36 cases) in the archetypal photosensitive epilepsy syndrome, eyelid myoclonia with absences (P = 3·50 × 10−4). CHD2 variation was not over-represented in photoparoxysmal response without seizures. Zebrafish larvae with chd2 knockdown were tested for photosensitivity. Chd2 knockdown markedly enhanced mild innate zebrafish larval photosensitivity. CHD2 mutation is the first identified cause of the archetypal generalized photosensitive epilepsy syndrome, eyelid myoclonia with absences. Unique CHD2 variants are also associated with photosensitivity in common epilepsies. CHD2 does not encode an ion channel, opening new avenues for research into human cortical excitability. PMID:25783594

Comparative short-term inhalation toxicity of five organic diketopyrrolopyrrole pigments and two inorganic iron-oxide-based pigments

PubMed Central

Hofmann, Thomas; Ma-Hock, Lan; Strauss, Volker; Treumann, Silke; Rey Moreno, Maria; Neubauer, Nicole; Wohlleben, Wendel; Gröters, Sibylle; Wiench, Karin; Veith, Ulrich; Teubner, Wera; van Ravenzwaay, Bennard; Landsiedel, Robert

2016-01-01

Abstract Diketopyrrolopyrroles (DPP) are a relatively new class of organic high-performance pigments. The present inhalation and particle characterization studies were performed to compare the effects of five DPP-based pigments (coarse and fine Pigment Red 254, coarse and fine meta-chloro DPP isomer and one form of mixed chlorinated DPP isomers) and compare it to coarse and fine inorganic Pigment Red 101. Wistar rats were exposed head-nose to atmospheres of the respective materials for 6 h/day on 5 consecutive days. Target concentrations were 30 mg/m3 as high dose for all compounds and selected based occupational exposure limits for respirable nuisance dust. Toxicity was determined after end of exposure and after 3-week recovery using broncho-alveolar lavage fluid (BALF) and microscopic examinations of the entire respiratory tract. Mixed chlorinated DPP isomers and coarse meta-chloro DPP isomer caused marginal changes in BALF, consisting of slight increases of polymorphonuclear neutrophils, and in case of coarse meta-chloro DPP increased MCP-1 and osteopontin levels. Mixed chlorinated DPP isomers, Pigment Red 254, and meta-chloro DPP caused pigment deposits and phagocytosis by alveolar macrophages, slight hypertrophy/hyperplasia of the bronchioles and alveolar ducts, but without evidence of inflammation. In contrast, only pigment deposition and pigment phagocytosis were observed after exposure to Pigment Red 101. All pigments were tolerated well and caused only marginal effects in BALF or no effects at all. Only minor effects were seen on the lung by microscopic examination. There was no evidence of systemic inflammation based on acute-phase protein levels in blood. PMID:27387137

A general method for the quantitative assessment of mineral pigments.

PubMed

Ares, M C Zurita; Fernández, J M

2016-01-01

A general method for the estimation of mineral pigment contents in different bases has been proposed using a sole set of calibration curves, (one for each pigment), calculated for a white standard base, thus elaborating patterns for each utilized base is not necessary. The method can be used in different bases and its validity had ev en been proved in strongly tinted bases. The method consists of a novel procedure that combines diffuse reflectance spectroscopy, second derivatives and the Kubelka-Munk function. This technique has proved to be at least one order of magnitude more sensitive than X-Ray diffraction for colored compounds, since it allowed the determination of the pigment amount in colored samples containing 0.5 wt% of pigment that was not detected by X-Ray Diffraction. The method can be used to estimate the concentration of mineral pigments in a wide variety of either natural or artificial materials, since it does not requiere the calculation of each pigment pattern in every base. This fact could have important industrial consequences, as the proposed method would be more convenient, faster and cheaper. Copyright © 2015 Elsevier B.V. All rights reserved.

Synthetic organic pigments of the 20th and 21st century relevant to artist's paints: Raman spectra reference collection

NASA Astrophysics Data System (ADS)

Scherrer, Nadim C.; Stefan, Zumbuehl; Francoise, Delavy; Annette, Fritsch; Renate, Kuehnen

2009-08-01

Some 170 organic pigments relevant to artist's paints have been collected from historic collections and modern manufacturers. The number includes multiples of the same pigment from different sources and comprises 118 different color indices (C.I.). All of them have been analysed with FTIR spectroscopy and 125 pigments (93 different C.I. No.s) of particular relevance to artist's paints have been characterised with Raman spectroscopy so far. The pigment collection encompasses the following pigment classes and subgroups: monoazo pigments represented by acetoacetic arylide yellow (hansa yellow), β-naphthol, BON, naphthol AS and benzimidazolone; disazo pigments with disazo condensation, diarylide, bisacetoacetarylide, pyrazolone; azo-azomethin metal complex pigments; non-azo, polycyclic pigments such as phthalocyanines, diketopyrrolo-pyrroles (DPP), perylenes and perinones, quinacridones, isoindolinones, polycarbocyclic anthraquinones and dioxanines. The selection of references was based on availability (historic collections) and current use in 16 acrylic, alkyd and oil-based artist's paints, and it covers pigment colors PY yellow (27 C.I. No.s), PR red (38), PO orange (9), PB blue (8), PV violet (6), PG green (3) and PBr brown (2). Besides peak tables and spectra patterns, flow charts based on color, pigment class, group and individual color index are presented to help identification of unknowns and mixed paint samples. While Raman could isolate all different C.I. numbers, multiple references of the same C.I. from different sources could not be distinguished.

Retrospective analysis of drug photosensitivity in Norway

NASA Astrophysics Data System (ADS)

Selvaag, Edgar

1999-02-01

Reports on adverse drug reactions, as they were recorded at the Norwegian Medicines Control Authority beginning in the year 1970 up to 1994 were analyzed especially with regard to cutaneous reactions and photosensitivity reactions. During the time period, almost 13.000 side effects were reported. Out of these 799 reports involved the skin and appendages, and 64 out of these reports (8%) were classified as photosensitivity reactions. Tetracyclines, diuretics, antihypertensive agents, and urologicals were the drugs which most often caused photosensitivity reactions. In addition, a number of uncommon photosensitizing drugs were reported. The risk for photosensitization is discussed on the background of experimental data and the prescription rates of these substances.

Multilayer photosensitive structures based on porous silicon and rare-earth-element compounds: Study of spectral characteristics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kirsanov, N. Yu.; Latukhina, N. V., E-mail: natalat@yandex.ru; Lizunkova, D. A.

2017-03-15

The spectral characteristics of the specular reflectance, photosensitivity, and photoluminescence (PL) of multilayer structures based on porous silicon with rare-earth-element (REE) ions are investigated. It is shown that the photosensitivity of these structures in the wavelength range of 0.4–1.0 μm is higher than in structures free of REEs. The structures with Er{sup 3+} ions exhibit a luminescence response at room temperature in the spectral range from 1.1 to 1.7 μm. The PL spectrum of the erbium impurity is characterized by a fine line structure, which is determined by the splitting of the {sup 4}I{sub 15/2} multiplet of the Er{sup 3+}more » ion. It is shown that the structures with a porous layer on the working surface have a much lower reflectance in the entire spectral range under study (0.2–1.0 μm).« less

THE CHEMISTRY OF DAYLIGHT VISION

PubMed Central

Bliss, Alfred Frederick

1946-01-01

1. While several reports of photosensitive pigments from the retinas of animals possessing large numbers of cone cells have been published, the only study which could be confirmed was Wald's discovery of iodopsin, a red-sensitive pigment from chicken eyes. 2. In its chemical properties, such as the range of pH stability and the effect of polar organic solvents, iodopsin resembles rhodopsin but is considerably more labile. 3. A partial purification from inert yellow impurities has been effected by prehardening the retinas in pH 4.9 acetate buffer before extraction by 2 per cent digitonin. Rhodopsin was an inevitable contaminant in most methods of extraction, but could be reduced to about 10 per cent of the absorption due to iodopsin by extraction of unhardened retinas with 4 per cent Merck's saponin in ¾ saturated magnesium sulfate for about 1 hour. 4. The rate of bleaching of iodopsin was found to be first order and linear with respect to energy. 5. The bleaching effectiveness spectrum of iodopsin was determined with the aid of color filters of known energy transmission, and shows a maximum at 560 mµ in the yellow green with a lower plateau in the blue. The spectrum is in good agreement with the sensitivity of the human cones except for the wavelength of maximum bleaching effectiveness. The maximum sensitivity of the human cones is found at 540 mµ. 6. Previous reports of changes in pH and inorganic phosphate level of retinas due to bleaching could not be confirmed. PMID:19873462

The Arabidopsis aba4-1 mutant reveals a specific function for neoxanthin in protection against photooxidative stress.

PubMed

Dall'Osto, Luca; Cazzaniga, Stefano; North, Helen; Marion-Poll, Annie; Bassi, Roberto

2007-03-01

The aba4-1 mutant completely lacks neoxanthin but retains all other xanthophyll species. The missing neoxanthin in light-harvesting complex (Lhc) proteins is compensated for by higher levels of violaxanthin, albeit with lower capacity for photoprotection compared with proteins with wild-type levels of neoxanthin. Detached leaves of aba4-1 were more sensitive to oxidative stress than the wild type when exposed to high light and incubated in a solution of photosensitizer agents. Both treatments caused more rapid pigment bleaching and lipid oxidation in aba4-1 than wild-type plants, suggesting that neoxanthin acts as an antioxidant within the photosystem II (PSII) supercomplex in thylakoids. While neoxanthin-depleted Lhc proteins and leaves had similar sensitivity as the wild type to hydrogen peroxide and singlet oxygen, they were more sensitive to superoxide anions. aba4-1 intact plants were not more sensitive than the wild type to high-light stress, indicating the existence of compensatory mechanisms of photoprotection involving the accumulation of zeaxanthin. However, the aba4-1 npq1 double mutant, lacking zeaxanthin and neoxanthin, underwent stronger PSII photoinhibition and more extensive oxidation of pigments than the npq1 mutant, which still contains neoxanthin. We conclude that neoxanthin preserves PSII from photoinactivation and protects membrane lipids from photooxidation by reactive oxygen species. Neoxanthin appears particularly active against superoxide anions produced by the Mehler's reaction, whose rate is known to be enhanced in abiotic stress conditions.

The Arabidopsis aba4-1 Mutant Reveals a Specific Function for Neoxanthin in Protection against Photooxidative Stress[W

PubMed Central

Dall'Osto, Luca; Cazzaniga, Stefano; North, Helen; Marion-Poll, Annie; Bassi, Roberto

2007-01-01

The aba4-1 mutant completely lacks neoxanthin but retains all other xanthophyll species. The missing neoxanthin in light-harvesting complex (Lhc) proteins is compensated for by higher levels of violaxanthin, albeit with lower capacity for photoprotection compared with proteins with wild-type levels of neoxanthin. Detached leaves of aba4-1 were more sensitive to oxidative stress than the wild type when exposed to high light and incubated in a solution of photosensitizer agents. Both treatments caused more rapid pigment bleaching and lipid oxidation in aba4-1 than wild-type plants, suggesting that neoxanthin acts as an antioxidant within the photosystem II (PSII) supercomplex in thylakoids. While neoxanthin-depleted Lhc proteins and leaves had similar sensitivity as the wild type to hydrogen peroxide and singlet oxygen, they were more sensitive to superoxide anions. aba4-1 intact plants were not more sensitive than the wild type to high-light stress, indicating the existence of compensatory mechanisms of photoprotection involving the accumulation of zeaxanthin. However, the aba4-1 npq1 double mutant, lacking zeaxanthin and neoxanthin, underwent stronger PSII photoinhibition and more extensive oxidation of pigments than the npq1 mutant, which still contains neoxanthin. We conclude that neoxanthin preserves PSII from photoinactivation and protects membrane lipids from photooxidation by reactive oxygen species. Neoxanthin appears particularly active against superoxide anions produced by the Mehler's reaction, whose rate is known to be enhanced in abiotic stress conditions. PMID:17351115

Evolutionary dynamics of Rh2 opsins in birds demonstrate an episode of accelerated evolution in the New World warblers (Setophaga)

PubMed Central

Price, Trevor D.

2015-01-01

Low rates of sequence evolution associated with purifying selection can be interrupted by episodic changes in selective regimes. Visual pigments are a unique system in which we can investigate the functional consequences of genetic changes, therefore connecting genotype to phenotype in the context of natural and sexual selection pressures. We study the RH2 and RH1 visual pigments (opsins) across 22 bird species belonging to two ecologically convergent clades, the New World warblers (Parulidae) and Old World warblers (Phylloscopidae), and evaluate rates of evolution in these clades along with data from 21 additional species. We demonstrate generally slow evolution of these opsins: both Rh1 and Rh2 are highly conserved across Old World and New World warblers. However, Rh2 underwent a burst of evolution within the New World genus Setophaga, where it accumulated substitutions at 6 amino acid sites across the species we studied. Evolutionary analyses revealed a significant increase in dN/dS in Setophaga, implying relatively strong selective pressures to overcome long-standing purifying selection. We studied the effects of each substitution on spectral tuning and found they do not cause large spectral shifts. Thus substitutions may reflect other aspects of opsin function, such as those affecting photosensitivity and/or dark-light adaptation. Although it is unclear what these alterations mean for color perception, we suggest that rapid evolution is linked to sexual selection, given the exceptional plumage colour diversification in Setophaga. PMID:25827331

Highly reliable photosensitive organic-inorganic hybrid passivation layers for a-InGaZnO thin-film transistors

NASA Astrophysics Data System (ADS)

Bermundo, Juan Paolo; Ishikawa, Yasuaki; Yamazaki, Haruka; Nonaka, Toshiaki; Fujii, Mami N.; Uraoka, Yukiharu

2015-07-01

We report the fabrication of a photosensitive hybrid passivation material on amorphous InGaZnO (a-IGZO) thin-film transistors (TFTs) that greatly enhance its stability and improve its electrical characteristics. The hybrid passivation based on polysilsesquioxane is transparent and fabricated using a simple solution process. Because the passivation is photosensitive, dry etching was never performed during TFT fabrication. TFTs passivated with this material had a small threshold voltage shift of 0.5 V during positive bias stress, 0.5 V during negative bias stress, and -2.5 V during negative bias illumination stress. Furthermore, TFTs passivated by this layer were stable after being subjected to high relative humidity stress — confirming the superb barrier ability of the passivation. Analysis of secondary ion mass spectrometry showed that a large amount of hydrogen, carbon, and fluorine can be found in the channel region. We show that both hydrogen and fluorine reduced oxygen vacancies and that fluorine stabilized weak oxygen and hydroxide bonds. These results demonstrate the large potential of photosensitive hybrid passivation layers as effective passivation materials.

High aspect ratio patterning of photosensitive polyimide with low thermal expansion coefficient and low dielectric constant

NASA Astrophysics Data System (ADS)

Dick, Andrew R.; Bell, William K.; Luke, Brendan; Maines, Erin; Mueller, Brennen; Rawlings, Brandon; Kohl, Paul A.; Grant Willson, C.

2016-07-01

A photosensitive polyimide system based on amine catalyzed imidization of a precursor poly(amic ester) is described. The material is based on the meta ethyl ester of pyromellitic dianhydride and 2,2' bis(trifluoromethyl)benzidine. It acts as a negative tone resist when formulated with a photobase generator. The material exhibits a dielectric constant of 3.0 in the gigahertz range, a coefficient of thermal expansion of 6±2 ppm/K, and can be patterned to aspect ratios of >2 when formulated with a highly quantum efficient cinnamide type photobase generator.

21 CFR 73.1350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Mica-based pearlescent pigments. 73.1350 Section 73.1350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1350 Mica-based pearlescent pigments. (a...

21 CFR 73.1350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Mica-based pearlescent pigments. 73.1350 Section 73.1350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1350 Mica-based pearlescent pigments. (a...

21 CFR 73.1350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Mica-based pearlescent pigments. 73.1350 Section 73.1350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1350 Mica-based pearlescent pigments. (a...

21 CFR 73.1350 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Mica-based pearlescent pigments. 73.1350 Section 73.1350 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1350 Mica-based pearlescent pigments. (a...

Comparison of intracellular accumulation and cytotoxicity of free mTHPC and mTHPC-loaded PLGA nanoparticles in human colon carcinoma cells.

PubMed

Löw, Karin; Knobloch, Thomas; Wagner, Sylvia; Wiehe, Arno; Engel, Andrea; Langer, Klaus; von Briesen, Hagen

2011-06-17

The second generation photosensitizer mTHPC was approved by the European Medicines Agency (EMA) for the palliative treatment of advanced head and neck cancer in October 2001. It is known that mTHPC possesses a significant phototoxicity against a variety of human cancer cells in vitro but also exhibits dark toxicity and can cause adverse effects (especially skin photosensitization). Due to its poor water solubility, the administration of hydrophobic photosensitizer still presents several difficulties. To overcome the administration problems, the use of nanoparticles as drug carrier systems is much investigated. Nanoparticles based on poly(lactic-co-glycolic acid) (PLGA) have been extensively studied as delivery systems into tumours due to their biocompatibility and biodegradability. The goal of this study was the comparison of free mTHPC and mTHPC-loaded PLGA nanoparticles concerning cytotoxicity and intracellular accumulation in human colon carcinoma cells (HT29). The nanoparticles delivered the photosensitizer to the colon carcinoma cells and enabled drug release without losing its activity. The cytotoxicity assays showed a time- and concentration-dependent decrease in cell proliferation and viability after illumination. However, first and foremost mTHPC lost its dark toxic effects using the PLGA nanoparticles as a drug carrier system. Therefore, PLGA nanoparticles are a promising drug carrier system for the hydrophobic photosensitizer mTHPC.

Cell specific aptamer-photosensitizer conjugates as a molecular tool in photodynamic therapy

PubMed Central

Mallikaratchy, Prabodhika; Tang, Zhiwen

2010-01-01

This paper describes the application of a molecular construct of a photosensitizer and an aptamer for photo-therapeutically targeting tumor cells. The key step in increasing selectivity in chemotherapeutic drugs is to create effective molecular platforms that could target cancer cells but not normal cells. Recently, we have developed a strategy via cell-SELEX (Systematic Evolution of Ligands by Exponential Enrichment) to obtain cell specific aptamers using intact viable cells as targets to select aptamers that can recognize cell membrane proteins with high selectivity and excellent affinity. We have identified an aptamer TD05 that only recognizes Ramos cells, a Burkitt’s lymphoma cell line. Here, the high specificity of aptamers in target cell binding and an efficient phototherapy reagent, Ce6, are molecularly engineered to construct a highly selective Aptamer-photosensitizer conjugates (APS) to effectively destroy target cancer cells. Introduction of the APS conjugates followed by irradiation of light selectively destroyed target Ramos cells but not acute lymphoblastic leukemia and myeloid leukemia cell lines. This study demonstrates that the use of cancer specific aptamers conjugated to a photosensitizer will enhance the selectivity of photodynamic therapy. Coupled with the advantages of the cell-SELEX in generating multiple effective aptamers for diseased cell recognition, we will be able to develop highly efficient photosensitizer based therapeutical reagents for clinical applications. PMID:18058891

In vivo photoacoustic monitoring of photosensitizer in skin: application to dosimetry for antibacterial photodynamic treatment

NASA Astrophysics Data System (ADS)

Hirao, Akihiro; Sato, Shunichi; Saitoh, Daizoh; Shinomiya, Nariyoshi; Ashida, Hiroshi; Obara, Minoru

2009-02-01

To obtain efficient antibacterial photodynamic effect in traumatic injuries such as burns, depth-resolved dosimetry of photosensitizer is required. In this study, we performed dual-wavelength photoacoustic (PA) measurement for rat burned skins injected with a photosensitizer. As a photosensitizer, methylene blue (MB) or porfimer sodium was injected into the subcutaneous tissue in rats with deep dermal burn. The wound was irradiated with red (665 nm or 630 nm) pulsed light to excite photosensitizers and green (532 nm) pulsed light to excite blood in the tissue; the latter signal was used to eliminate blood-associated component involved in the former signal. Acoustic attenuation was also compensated from the photosensitizer-associated PA signals. These signal processing was effective to obtain high-contrast image of a photosensitizer in the tissue. Behaviors of MB and porfimer sodium in the tissue were compared.

Photodynamic Cell Killing Effects and Acute Skin Photosensitivity of Aluminum‐chloro‐tetrasulfonated Phthalocyanine and Hematoporphyrin Derivative

PubMed Central

Komatsu, Kazuto

1991-01-01

Aluminum‐chloro‐tetrasulfonated phthalocyanine (PC) showing an absorption peak at 678 nm was compared to hematoporphyrin derivative (MpD), a photosensitizer commonly used in the photodynamic therapy (PDT) of cancers. In vitro studies: KK‐47 cells were exposed to long‐wavelength ultraviolet (UVA) or red light (>600 nm, >640 nm and >660 nm) after drug sensitization. With UVA irradiation, a higher photodynamic cell killing effect was observed in the cells treated with HpD than with PC. However, with red light irradiation (both > 640 nm and >660 nm) PC resulted in greater cell damage. PC was less toxic to KK‐47 cells in the dark. In vivo studies: Using a gold vapor laser (GVL: 627.8 nm, 200 mW/cm2, 200 J/cm2), the photodynamic tumor response was determined in C3H/He mice bearing transplantable squamous cell carcinoma. No significant difference was observed in the tumor volume between the PC and HpD groups, except that the PC group (10.0 mg/kg body weight) showed a significantly higher remission rate (3/6) than the control group (0/10, P<0.05). Skin Photosensitivity test: Skin photosensitivity was estimated by measuring changes in back skin thickness due to photosensitization. With UVA irradiation, a stronger skin reaction was observed in the HpD group, while with visible light irradiation there was no significant difference between the HpD and PC groups. Based on the superior cell killing effect with red light, reduced toxicity to the cells in the dark and mild skin reaction with UVA, PC may be a more promising photosensitizer for PDT. PMID:1905706

Algal Accessory Pigment Detection Using AVIRIS Image-Derived Spectral Radiance Data

NASA Technical Reports Server (NTRS)

Richardson, Laurie L.; Ambrosia, Vincent G.

1996-01-01

Visual and derivative analyses of AVIRIS spectral data can be used to detect algal accessory pigments in aquatic communities. This capability extends the use of remote sensing for the study of aquatic ecosystems by allowing detection of taxonomically significant pigment signatures which yield information about the type of algae present. Such information allows remote sensing-based assessment of aquatic ecosystem health, as in the detection of nuisance blooms of cyanobacteria or toxic blooms of dinoflagellates. Remote sensing of aquatic systems has traditionally focused on quantification of chlorophyll a, a photoreactive (and light-harvesting) pigment which is common to all algae as well as cyanobacteria (bluegreen algae). Due to the ubiquitousness of this pigment within algae, chl a is routinely measured to estimate algal biomass both during ground-truthing and using various airborne or satellite based sensors, including AVIRIS. Within the remote sensing and aquatic sciences communities, ongoing research has been performed to detect algal accessory pigments for assessment of algal population composition. This research is based on the fact that many algal accessory pigments are taxonomically significant, and all are spectrally unique. Aquatic scientists have been refining pigment analysis techniques, primarily high performance liquid chromatography, or HPLC, to detect specific pigments as a time-saving alternative to individual algal cell identifications and counts. Remote sensing scientists are investigating the use of pigment signatures to construct pigment libraries analogous to mineral spectral libraries used in geological remote sensing applications. The accessory pigment approach has been used successfully in remote sensing using data from the Thematic Mapper, low-altitude, multiple channel scanners, field spectroradiometers and the AVIRIS hyperspectral scanner. Due to spectral and spatial resolution capabilities, AVIRIS is the sensor of choice for such studies. We present here our results on detection of algal accessory pigments using AVIRIS data.

In-vivo NMR studies of deuterium-labeled photosensitizers in mice tumor model

NASA Astrophysics Data System (ADS)

Ramaprasad, Subbaraya; Liu, Y. H.; Pandey, R. K.; Shiau, Fuu-Yau; Smith, Kevin M.

1993-06-01

Photodynamic therapy (PDT) has emerged as a promising modality for the treatment of cancer. We are using newly synthesized and chemically defined and characterized porphyrin photosensitizers that are specifically labeled with deuterium to perform in vivo NMR studies in a murine tumor model. In vivo magnetic resonance offers the potential for repetitive, safe, noninvasive evaluation of photosensitizers, tumor metabolism, and the effect of PDT on the tumor metabolism. In an effort to monitor noninvasively the photosensitizers in an in vivo tumor model, we are synthesizing several deuterium labeled photosensitizers which absorb red light at or above 630 nm. Development of methods to test these photosensitizers directly in humans is not feasible at this time, since these photosensitizers are new and we do not yet understand the side effects. In addition, we do not understand the potential benefits compared with Photofrin II, the widely used photosensitizer. To perform our in vivo deuterium NMR studies on mouse foot tumors, we have constructed a solenoid coil which operates at 30.7 MHz for the deuterium nucleus. We have been able to detect the deuterium labeled photosensitizer in the tumor after a direct intra-tumor injection. The use of 31P NMR to predict the possible outcome of PDT in these tumors is also discussed.

Fluorescent proteins as singlet oxygen photosensitizers: mechanistic studies in photodynamic inactivation of bacteria

NASA Astrophysics Data System (ADS)

Ruiz-González, Rubén.; White, John H.; Cortajarena, Aitziber L.; Agut, Montserrat; Nonell, Santi; Flors, Cristina

2013-02-01

Antimicrobial photodynamic therapy (aPDT) combines a photosensitizer, light and oxygen to produce reactive oxygen species (ROS), mainly singlet oxygen (1O2), to photo-oxidize important biomolecules and induce cell death. aPDT is a promising alternative to standard antimicrobial strategies, but its mechanisms of action are not well understood. One of the reasons for that is the lack of control of the photosensitizing drugs location. Here we report the use of geneticallyencoded fluorescent proteins that are also 1O2 photosensitizers to address the latter issue. First, we have chosen the red fluorescent protein TagRFP as a photosensitizer, which unlike other fluorescent proteins such as KillerRed, is able to produce 1O2 but not other ROS. TagRFP photosensitizes 1O2 with a small, but not negligible, quantum yield. In addition, we have used miniSOG, a more efficient 1O2 photosensitizing fluorescent flavoprotein that has been recently engineered from phototropin 2. We have genetically incorporated these two photosensitizers into the cytosol of E. coli and demonstrated that intracellular 1O2 is sufficient to kill bacteria. Additional assays have provided further insight into the mechanism of cell death. Photodamage seems to occur primarily in the inner membrane, and extends to the outer membrane if the photosensitizer's efficiency is high enough. These observations are markedly different to those reported for external photosensitizers, suggesting that the site where 1O2 is primarily generated proves crucial for inflicting different types of cell damage.

Comparative photodynamic therapy cytotoxicity of mannose-conjugated chlorin and talaporfin sodium in cultured human and rat cells.

PubMed

Shinoda, Yo; Takahashi, Tsutomu; Akimoto, Jiro; Ichikawa, Megumi; Yamazaki, Hiromi; Narumi, Atsushi; Yano, Shigenobu; Fujiwara, Yasuyuki

2017-01-01

Photodynamic therapy (PDT) is a Food and Drug Administration authorized method for cancer treatment, which uses photosensitizer and laser photo-irradiation to generate reactive oxygen species to induce cell death in tumors. Photosensitizers have been progressively developed, from first to third generation, with improvements in cell specificity, reduced side effects and toxicity, increased sensitivity for irradiation and reduced persistence of photosensitizer in healthy cells. These improvements have been achieved by basic comparative experiments between current and novel photosensitizers using cell lines; however, photosensitizers should be carefully evaluated because they may have cell type specificity. In the present study, we compared a third-generation photosensitizer, β-mannose-conjugated chlorin (β-M-chlorin), with the second generation, talaporfin sodium (NPe6), using seven different rat and human cell lines and a neuronal/glial primary culture prepared from rat embryos. NPe6 was more effective than β-M-chlorin in human-derived cell lines, and β-M-chlorin was more effective than NPe6 in rat primary cultures and rat-derived cell lines, except for the rat pheochromocytoma cell line, PC12. These differences of phototoxicity in different cell types are not because of differences in photosensitivity between the photosensitizers, but rather are associated with different distribution and accumulation rates in the different cell types. These data suggest that evaluation of photosensitizers for PDT should be carried out using as large a variety of cell types as possible because each photosensitizer may have cell type specificity.

Photosensitive epilepsy is associated with reduced inhibition of alpha rhythm generating networks

PubMed Central

Vaudano, Anna Elisabetta; Ruggieri, Andrea; Avanzini, Pietro; Gessaroli, Giuliana; Cantalupo, Gaetano; Coppola, Antonietta; Sisodiya, Sanjay M.

2017-01-01

Abstract See Hamandi (doi:10.1093/awx049) for a scientific commentary on this article. Photosensitivity is a condition in which lights induce epileptiform activities. This abnormal electroencephalographic response has been associated with hyperexcitability of the visuo-motor system. Here, we evaluate if intrinsic dysfunction of this network is present in brain activity at rest, independently of any stimulus and of any paroxysmal electroencephalographic activity. To address this issue, we investigated the haemodynamic correlates of the spontaneous alpha rhythm, which is considered the hallmark of the brain resting state, in photosensitive patients and in people without photosensitivity. Second, we evaluated the whole-brain functional connectivity of the visual thalamic nuclei in the various populations of subjects under investigation. Forty-four patients with epilepsy and 16 healthy control subjects underwent an electroencephalography-correlated functional magnetic resonance imaging study, during an eyes-closed condition. The following patient groups were included: (i) genetic generalized epilepsy with photosensitivity, 16 subjects (mean age 25 ± 10 years); (ii) genetic generalized epilepsy without photosensitivity, 13 patients (mean age 25 ± 11 years); (iii) focal epilepsy, 15 patients (mean age 25 ± 9 years). For each subject, the posterior alpha power variations were convolved with the standard haemodynamic response function and used as a regressor. Within- and between-groups second level analyses were performed. Whole brain functional connectivity was evaluated for two thalamic regions of interest, based on the haemodynamic findings, which included the posterior thalamus (pulvinar) and the medio-dorsal thalamic nuclei. Genetic generalized epilepsy with photosensitivity demonstrated significantly greater mean alpha-power with respect to controls and other epilepsy groups. In photosensitive epilepsy, alpha-related blood oxygen level-dependent signal changes demonstrated lower decreases relative to all other groups in the occipital, sensory-motor, anterior cingulate and supplementary motor cortices. Coherently, the same brain regions demonstrated abnormal connectivity with the visual thalamus only in epilepsy patients with photosensitivity. As predicted, our findings indicate that the cortical-subcortical network generating the alpha oscillation at rest is different in people with epilepsy and visual sensitivity. This difference consists of a decreased alpha-related inhibition of the visual cortex and sensory-motor networks at rest. These findings represent the substrate of the clinical manifestations (i.e. myoclonus) of the photoparoxysmal response. Moreover, our results provide the first evidence of the existence of a functional link between the circuits that trigger the visual sensitivity phenomenon and those that generate the posterior alpha rhythm. PMID:28334965

A novel light-dependent selection marker system in plants.

PubMed

Koh, Serry; Kim, Hongsup; Kim, Jinwoo; Goo, Eunhye; Kim, Yun-Jung; Choi, Okhee; Jwa, Nam-Soo; Ma, Jun; Nagamatsu, Tomohisa; Moon, Jae Sun; Hwang, Ingyu

2011-04-01

Photosensitizers are common in nature and play diverse roles as defense compounds and pathogenicity determinants and as important molecules in many biological processes. Toxoflavin, a photosensitizer produced by Burkholderia glumae, has been implicated as an essential virulence factor causing bacterial rice grain rot. Toxoflavin produces superoxide and H₂O₂ during redox cycles under oxygen and light, and these reactive oxygen species cause phytotoxic effects. To utilize toxoflavin as a selection agent in plant transformation, we identified a gene, tflA, which encodes a toxoflavin-degrading enzyme in the Paenibacillus polymyxa JH2 strain. TflA was estimated as 24.56 kDa in size based on the amino acid sequence and is similar to a ring-cleavage extradiol dioxygenase in the Exiguobacterium sp. 255-15; however, unlike other extradiol dioxygenases, Mn(2+) and dithiothreitol were required for toxoflavin degradation by TflA. Here, our results suggested toxoflavin is a photosensitizer and its degradation by TflA serves as a light-dependent selection marker system in diverse plant species. We examined the efficiencies of two different plant selection systems, toxoflavin/tflA and hygromycin/hygromycin phosphotransferase (hpt) in both rice and Arabidopsis. The toxoflavin/tflA selection was more remarkable than hygromycin/hpt selection in the high-density screening of transgenic Arabidopsis seeds. Based on these results, we propose the toxoflavin/tflA selection system, which is based on the degradation of the photosensitizer, provides a new robust nonantibiotic selection marker system for diverse plants. © 2010 The Authors. Plant Biotechnology Journal © 2010 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd.

Fly ash based zeolitic pigments for application in anticorrosive paints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaw, Ruchi, E-mail: shawruchi1@gmail.com; Tiwari, Sangeeta, E-mail: stiwari2@amity.edu

2016-04-13

The purpose of this work is to evaluate the utilization of waste fly ash in anticorrosive paints. Zeolite NaY was synthesized from waste fly ash and subsequently modified by exchanging its nominal cation Na{sup +} with Mg{sup 2+} and Ca{sup 2+} ions. The metal ion exchanged zeolite was then used as anticorrosive zeolitic pigments in paints. The prepared zeolite NaY was characterized using X-Ray diffraction technique and Scanning electron microscopy. The size, shape and density of the prepared fly ash based pigments were determined by various techniques. The paints were prepared by using fly ash based zeolitic pigments in epoxymore » resin and the percentages of pigments used in paints were 2% and 5%. These paints were applied to the mild steel panels and the anticorrosive properties of the pigments were assessed by the electrochemical spectroscopy technique (EIS).« less

New photosensitive systems for volume phase holography

NASA Astrophysics Data System (ADS)

Bianco, Andrea; Colella, Letizia; Galli, Paola; Zanutta, Alessio; Bertarelli, Chiara

2017-05-01

Volume phase holographic elements are becoming attractive thanks to the large efficiency and good optical quality. They are based on photosensitive materials where a modulation of the refractive index is induced. In this paper, we highlight the strategies to obtain a change in the refractive index in a dielectric material, namely a change in the material density and/or in the molecular polarizability. Moreover, we show the results achieved for materials that undergo the photo-Fries reaction as function of the molecular structure and the illumination conditions. We also report the results on a system based on the diazo Meldrum's acid where volatile molecules are produced upon light exposure.

Diffracted light from latent images in photoresist for exposure control

DOEpatents

Bishop, Kenneth P.; Brueck, Steven R. J.; Gaspar, Susan M.; Hickman, Kirt C.; McNeil, John R.; Naqvi, S. Sohail H.; Stallard, Brian R.; Tipton, Gary D.

1997-01-01

In microelectronics manufacturing, an arrangement for monitoring and control of exposure of an undeveloped photosensitive layer on a structure susceptible to variations in optical properties in order to attain the desired critical dimension for the pattern to be developed in the photosensitive layer. This is done by ascertaining the intensities for one or more respective orders of diffracted power for an incident beam of radiation corresponding to the desired critical dimension for the photosensitive layer as a function of exposure time and optical properties of the structure, illuminating the photosensitive layer with a beam of radiation of one or more frequencies to which the photosensitive layer is not exposure-sensitive, and monitoring the intensities of the orders of diffracted radiation due to said illumination including at least the first order of diffracted radiation thereof, such that when said predetermined intensities for the diffracted orders are reached during said illumination of photosensitive layer, it is known that a pattern having at least approximately the desired critical dimension can be developed on the photosensitive layer.

Mitochondria-targeting for improved photodynamic therapy

NASA Astrophysics Data System (ADS)

Ngen, Ethel J.

Photodynamic therapy (PDT) is an emerging cancer therapeutic modality, with great potential to selectively treat surface cancers, thus minimizing systemic side effects. In this dissertation, two approaches to deliver photosensitizers to mitochondria were investigated: 1) Reducing photosensitizer sizes to improve endocytosis and lysosomal localization. Upon irradiation the photosensitizers would then produce singlet oxygen which could rupture the lysosomal membrane releasing the lysosomally trapped photosensitizers to the cytosol, from where they could relocalize to mitochondria by passive diffusion (photochemical internalization). 2) Using delocalized lipophilic cationic dyes (DLCs) to exploit membrane potential differences between the cytoplasm and mitochondria in delivering photosensitizers to mitochondria. To investigate the effects of steric hindrance on mitochondrial localization and photodynamic response, a series of eight thiaporphyrins were studied. Two new thiaporphyrin analogues 6 and 8 with reduced steric hindrance at the 10- and 15- meso positions were studied in comparison to 5,20-diphenyl-10,15-bis[4 (carboxymethyleneoxy)-phenyl]-21,23-dithiaporphyrin 1, previously validated as a potential second generation photosensitizer. Although 6 showed an extraordinarily high uptake (7.6 times higher than 1), it was less potent than 1 (IC 50 = 0.18 muM versus 0.13 muM) even though they both showed similar sub-cellular localization patterns. This low potency was attributed to its high aggregation tendency in aqueous media (4 times higher than 1), which might have affected its ability to generate singlet oxygen in vitro . 8 on the other hand showed an even lower potency than 6 (2.28 vs 0.18 muM). However this was attributed to its low cellular uptake (20 times less than 6) and inefficient generation of singlet oxygen. Overall, although the structural modifications did improve the cellular uptake of 6, 6 was still less potent than the lead photosensitizers 1. Thus, other strategies to target mitochondria for improved photodynamic activity were investigated. In a continuing project, we evaluated the ability of delocalized lipophilic cationic dyes to deliver photosensitizers to mitochondria by exploiting the membrane potential difference between the cytoplasm and mitochondria. Two conjugates: a porphyrin--rhodamine B conjugate (TPP--Rh) and a porphyrin-acridine orange conjugate (TPP--AO), each possessing a single delocalized lipophilic cation, were designed and synthesized. The conjugates were synthesized by conjugating a monohydroxy porphyrin (TPP-OH) to rhodamine B (Rh B) and acridine orange base (AO), respectively, via saturated hydrocarbon linkers. To evaluate the efficiency of the conjugates as photosensitizers, their photophysical properties and in vitro photodynamic activities were studied in comparison to those of TPP-OH, the parent porphyrin photosensitizer. Although fluorescence energy transfer (FRET) was observed in the conjugates, they were capable of generating singlet oxygen at rates comparable to TPP-OH. In a final project, we evaluated the photophysical potential of TPP-Rh to act as a two-photon photosensitizer for PDT. Two-photon PDT is a rational approach used to improve light penetration through the skin. Rhodamine B is an effective two-photon chromophore and could significantly improve the two-photon absorption of the porphyrin photosensitizer in the TPP-Rh dyad system following energy transfer. Thus the porphyrin--rhodamine B dyad (TPP--Rh), previously demonstrated to preferentially accumulate in the mitochondria, was photophysically evaluated as a potential two-photon photosensitizer. To evaluate the efficiency of TPP-Rh as a two-photon photosensitizer, its two-photon photophysical properties were compared with those of its individual components (Rh B and TPP-OH). This included: the two-photon cross sections (sigma 2), RET kinetics and dynamics and rates of singlet oxygen generation. A FRET efficiency of ~99 % was observed from the Rh moiety (donor) to the TPP moiety (acceptor) of the system. This significantly enhanced the sigma 2 of TPP-Rh by ˜ 100 % (20 GM) compared to the parent TPP-OH. Furthermore, TPP-Rh produced singlet oxygen at a significantly faster rate than TPP-OH upon two-photon excitation. Thus, this indicates that conjugating photosensitizers to Rh B via short saturated hydrocarbon linkers could provide deeper tissue penetration, in addition to preferential mitochondrial accumulation for improved photodynamic response. (Abstract shortened by UMI.)

Carbon Dots as Versatile Photosensitizers for Solar-Driven Catalysis with Redox Enzymes.

PubMed

Hutton, Georgina A M; Reuillard, Bertrand; Martindale, Benjamin C M; Caputo, Christine A; Lockwood, Colin W J; Butt, Julea N; Reisner, Erwin

2016-12-28

Light-driven enzymatic catalysis is enabled by the productive coupling of a protein to a photosensitizer. Photosensitizers used in such hybrid systems are typically costly, toxic, and/or fragile, with limited chemical versatility. Carbon dots (CDs) are low-cost, nanosized light-harvesters that are attractive photosensitizers for biological systems as they are water-soluble, photostable, nontoxic, and their surface chemistry can be easily modified. We demonstrate here that CDs act as excellent light-absorbers in two semibiological photosynthetic systems utilizing either a fumarate reductase (FccA) for the solar-driven hydrogenation of fumarate to succinate or a hydrogenase (H 2 ase) for reduction of protons to H 2 . The tunable surface chemistry of the CDs was exploited to synthesize positively charged ammonium-terminated CDs (CD-NHMe 2 + ), which were capable of transferring photoexcited electrons directly to the negatively charged enzymes with high efficiency and stability. Enzyme-based turnover numbers of 6000 mol succinate (mol FccA) -1 and 43,000 mol H 2 (mol H 2 ase) -1 were reached after 24 h. Negatively charged carboxylate-terminated CDs (CD-CO 2 - ) displayed little or no activity, and the electrostatic interactions at the CD-enzyme interface were determined to be essential to the high photocatalytic activity observed with CD-NHMe 2 + . The modular surface chemistry of CDs together with their photostability and aqueous solubility make CDs versatile photosensitizers for redox enzymes with great scope for their utilization in photobiocatalysis.

Exploration of photosensitive polyimide as the modification layer in thin film microcircuit

NASA Astrophysics Data System (ADS)

Liu, Lily; Song, Changbin; Xue, Bin; Li, Jing; Wang, Junxi; Li, Jinmin

2018-02-01

Positive type photosensitive polyimide is used as the modification layer in the thin film transistors production process. The photosensitive polyimide is not only used as the second insulating layer, it can also be used instead of a mask because of the photosensitivity. A suitable curing condition can help photosensitive polyimide form the high performance polyimide with orderly texture inside, and the performance of imidization depends on the precise control of temperature, time, and heat control during the curing process. Therefore, experiments of different stepped up heating tests are made, and the ability of protecting silicon dioxide is analyzed.

Effect of soybean lecithin on iron-catalyzed or chlorophyll-photosensitized oxidation of canola oil emulsion.

PubMed

Choe, Jeesu; Oh, Boyoung; Choe, Eunok

2014-11-01

The effect of soybean lecithin addition on the iron-catalyzed or chlorophyll-photosensitized oxidation of emulsions consisting of purified canola oil and water (1:1, w/w) was studied based on headspace oxygen consumption using gas chromatography and hydroperoxide production using the ferric thiocyanate method. Addition levels of iron sulfate, chlorophyll, and soybean lecithin were 5, 4, and 350 mg/kg, respectively. Phospholipids (PLs) during oxidation of the emulsions were monitored by high performance liquid chromatography. Addition of soybean lecithin to the emulsions significantly reduced and decelerated iron-catalyzed oil oxidation by lowering headspace oxygen consumption and hydroperoxide production. However, soybean lecithin had no significant antioxidant effect on chlorophyll-photosensitized oxidation of the emulsions. PLs in soybean lecithin added to the emulsions were degraded during both oxidation processes, although there was little change in PL composition. Among PLs in soybean lecithin, phosphatidylethanolamine and phosphatidylinositol were degraded the fastest in the iron-catalyzed and the chlorophyll-photosensitized oxidation, respectively. The results suggest that addition of soybean lecithin as an emulsifier can also improve the oxidative stability of oil in an emulsion. © 2014 Institute of Food Technologists®

X ray photoelectron spectroscopy (XPS) analysis of Photosensitive ZrO2 array

NASA Astrophysics Data System (ADS)

Li, Y.; Zhao, G.; Zhu, R.; Kou, Z.

2018-03-01

Based on organic zirconium source as the starting material, by adding chemical modifiers which are made up with photosensitive ZrO2 sol. A uniformed ZrO2 array dot was fabricated with a mean diameter of around 800 nm. By using UV-vis spectra and X-ray photoelectron spectroscopy analysis method, studies the photosensitive ZrO2 gel film of photochemical reaction process and the photosensitive mechanism, to determine the zirconium atom centered chelate structure, reaction formed by metal chelate Zr atom for the center, and to establish the molecular model of the chelate. And studied the ultraviolet light in the process of the variation of the XPS spectra, Zr3d5/2 to 184.9 eV corresponding to the binding energy of the as the combination of state peak gradually reduce; By combining with the status of Zr-O peak gradually increase; The strength of the peak is gradually decline. This suggests that in the process of ultraviolet light photo chemical reaction happened. This study is of great significance to the micro fabrication of ZrO2 array not only to the memory devices but also to the optical devices.

The (6-4) Dimeric Lesion as a DNA Photosensitizer.

PubMed

Vendrell-Criado, Victoria; Rodríguez-Muñiz, Gemma M; Lhiaubet-Vallet, Virginie; Cuquerella, M Consuelo; Miranda, Miguel A

2016-07-04

Based on our previous investigations into the photophysical properties of the 5-methyl-2-pyrimidone (Pyo) chromophore, we now extend our studies to the photobehavior of the dimeric (6-4) thymine photoproducts (6-4 PP) to evaluate their capability to act as instrinsic DNA photosensitizers. The lesion presents significant absorption in the UVB/UVA region, weak fluorescence emission, a singlet-excited-state energy of approximately 351 kJ mol(-1) , and a triplet-excited-state energy of 297 kJ mol(-1) . Its triplet transient absorption has a maximum at 420-440 nm, a lifetime of around 7 μs, and a high formation quantum yield, ΦISC =0.86. This species is efficiently quenched by thymidine. Its DNA photosensitizing properties are demonstrated by a series of experiments run on a pBR322 plasmid. The lesion photoinduces both single-strand breaks and the formation of cyclobutane thymine dimers. Altogether, these results show that, the substitution of the pyrimidone ring at C4 by a 5-hydroxy-5,6-dihydrothymine does not cancel out the photosensitization properties of the chromophore. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Influence of aqueous media properties on aggregation and solubility of four structurally related meso-porphyrin photosensitizers evaluated by spectrophotometric measurements.

PubMed

Sobczyński, J; Tønnesen, H H; Kristensen, S

2013-02-01

Porphyrin photosensitizers tend to aggregate in aqueous solutions even in the micromolar concentration range. This is a challenge during formulation of e.g., parenteral preparations for photodynamic cancer therapy, or preparations for local or topical administration in antimicrobial photodynamic therapy. Monomerization is essential to achieve biocompatible drug formulations of high bioavailability and physiological response (i.e., photoreactivity) and low toxicity. The aggregation and solubilization of four structurally related meso-tetraphenyl porphyrin photosensitizers with nonionic (4-hydroxy), anionic (4-sulphonate; 4-carboxy) and cationic (4-trimethylanilinium) substituents were evaluated in various vehicles by use of UV-Vis spectroscopy. Substituents, overall charge and charge distribution influenced the pKa-values and interaction of the porphyrins with different solvents, excipients and impurities. Modification of medium polarity and solubilization by the nonionic surfactant Tween 80 adjusted the acid-base equilibria and increased the solubility by reduction of porphyrin aggregation. The selected porphyrins were sensitive towards ionic strength, temperature and inorganic impurities to various extents. The results will be further used during development of parenteral and topical formulations of porphyrin photosensitizers for use in photodynamic therapy of cancer and bacterial infections.

Computerized pigment design based on property hypersurfaces

NASA Astrophysics Data System (ADS)

Halova, Jaroslava; Sulcova, Petra; Kupka, Karel

2007-05-01

Competition is tough in the pigment market. Rational pigment design has therefore a competitive advantage, saving time and money. The aim of this work is to provide methods that can assist in designing pigments with defined properties. These methods include partial least squares regression (PLSR), neural network (NN) and generalized regression ANOVA model. Authors show how PLS bi-plot can be used to identify market gaps poorly covered by pigment manufacturers, thus giving an opportunity to develop pigments with potentially profitable properties.

A new photoelectrochemical biosensors based on DNA conformational changes and isothermal circular strand-displacement polymerization reaction.

PubMed

Zhang, Xiaoru; Xu, Yunpeng; Zhao, Yanqing; Song, Weiling

2013-01-15

We report a strategy for the transduction of DNA hybridization into a readily detectable photoelectrochemical signal by means of a conformational change analogous to electrochemical DNA (E-DNA) approach. To demonstrate the effect of distance change for photosensitizer to the surface of electrode on the change of photocurrent, photosensitizer Ru(bpy)(2)(dcbpy)(2+) tagged DNA stem-loop structures were self-assembled onto a nanogold modified ITO electrode. Hybridization induced a large conformational change in DNA structure, which in turn significantly altered the electron-transfer tunneling distance between the electrode and photosensitizer. The resulting change in photocurrent was proportional to the concentration of DNA in the range of 1.0×10(-10)-8.0×10(-9)M. In order to improve the sensitivity of the photoelectrochemical biosensor, an amplified detection method based on isothermal strand displacement polymerization reaction was employed. With multiple rounds of isothermal strand replication, which led to strand displacement and constituted consecutive signal amplification, a detection limit of 9.4×10(-14)M target DNA was achieved. Copyright © 2012 Elsevier B.V. All rights reserved.

A multi-analytical investigation of semi-conductor pigments with time-resolved spectroscopy and imaging

NASA Astrophysics Data System (ADS)

Nevin, A.; Cesaratto, A.; D'Andrea, C.; Valentini, Gianluca; Comelli, D.

2013-05-01

We present the non-invasive study of historical and modern Zn- and Cd-based pigments with time-resolved fluorescence spectroscopy, fluorescence multispectral imaging and fluorescence lifetime imaging (FLIM). Zinc oxide and Zinc sulphide are semiconductors which have been used as white pigments in paintings, and the luminescence of these pigments from trapped states is strongly dependent on the presence of impurities and crystal defects. Cadmium sulphoselenide pigments vary in hue from yellow to deep red based on their composition, and are another class of semiconductor pigments which emit both in the visible and the near infrared. The Fluorescence lifetime of historical and modern pigments has been measured using both an Optical Multichannel Analyser (OMA) coupled with a Nd:YAG nslaser, and a streak camera coupled with a ps-laser for spectrally-resolved fluorescence lifetime measurements. For Znbased pigments we have also employed Fluorescence Lifetime Imaging (FLIM) for the measurement of luminescence. A case study of FLIM applied to the analysis of the painting by Vincent Van Gogh on paper - "Les Bretonnes et le pardon de Pont-Aven" (1888) is presented. Through the integration of complementary, portable and non-invasive spectroscopic techniques, new insights into the optical properties of Zn- and Cd-based pigments have been gained which will inform future analysis of late 19th] and early 20th C. paintings.

Target-specific porphyrin-loaded hybrid nanoparticles to improve photodynamic therapy for cancer treatment

NASA Astrophysics Data System (ADS)

Vivero-Escoto, Juan L.; Vega, Daniel L.

2017-02-01

Photodynamic therapy (PDT) has emerged as an alternative approach to chemotherapy and radiotherapy for cancer treatment. The photosensitizer (PS) is perhaps the most critical component of PDT, and continues to be an area of intense scientific research. Traditionally, PS molecules like porphyrins have dominated the field. Nevertheless, these PS agents have several disadvantages, with low water solubility, poor light absorption, and reduced selectivity for targeted tissues being some of the main drawbacks. Polysilsesquioxane (PSilQ) nanoparticles provide an interesting platform for developing PS-loaded hybrid nanocarriers. Several advantages can be foreseen by using this platform such as carrying a large payload of PS molecules; their surface and composition can be tailored to develop multifunctional systems (e.g. target-specific); and due to their small size, nanoparticles can penetrate deep into tissues and be readily internalized by cells. In this work, porphyrin-loaded PSilQ nanoparticles with a high payload of photosensitizers were synthesized, characterized, and applied in vitro. The network of this nanomaterial is formed by porphyrin-based photosensitizers chemically connected via a redox-responsive linker. Under reducing environment such as the one found in cancer cells the nanoparticles can be degraded to efficiently release single photosensitizers in the cytoplasm. The platform was further functionalized with polyethylene glycol (PEG) and folic acid as targeting ligand to improve its biocompatibility and target specificity toward cancer cells overexpressing folate receptors. The effectiveness of this porphyrin-based hybrid nanomaterial was successfully demonstrated in vitro using MDA-MB-231 breast cancer cell line.

Using empirical orthogonal functions from remote sensing reflectance spectra to predict various phytoplankton pigment concentrations in the Eastern Tropical Atlantic

NASA Astrophysics Data System (ADS)

Bracher, Astrid; Taylor, Bettina; Taylor, Marc; Steinmetz, Francois; Dinter, Tilman; Röttgers, Rüdiger

2014-05-01

Phytoplankton pigments play a major role in photosynthesis and photoprotection. Their composition and abundance give information on characteristics of a phytoplankton community in respect to its acclimation to light, overall biomass and composition of major phytoplankton groups. Most phytoplankton pigments can be measured by applying HPLC techniques to filtered water samples. This method like other mathods analysing water samples in the laboratory is time consuming and therefore only a limited number of samples can be obtained. In order to obtain information on phytoplankton pigment composition with a better temporal and spatial composition, the rationale was to develop a method to get from continuous optical measurements pigment concentrations. We have used remote sensing reflectances (RRS) derived from ship-based hyper-spectral underwater radiometric and from satellite MERIS measurements (using the POLYMER algorithm developed by Steinmetz et al. 2011), sampled in the Eastern Tropical Atlantic, to predict the water surface concentration of various pigments or pigment groups in this area. A statistical model based on Empirical Orthogonal Function (EOF) analysis of these RRS spectra was developed. Then subsequently linear models with measured (collocated) pigment concentrations as the response variable and EOF loadings as predictor variables were constructed. The model results, which have been verified by cross validation, show that from the ship-based RRS measurements the surface concentrations of a suite of pigments and pigment groups can be well predicted, even when only a multi-spectral resolution of RRS data is chosen. Based on the MERIS reflectance data, only concentrations of total chlorophyll-a (chl-a), monovinyl-chl-a and the groups of photoprotective and photosynthetic carotenoids can be obtained with high quality. The model constructed on the satellite reflectances as input was also applied to one month of MERIS POLYMER data to predict for the whole Eastern Tropical Atlantic area the concentration of those pigments. Finally, the potential, limitations and future perspectives for the application of our generic method are discussed.

Probing Photosensitization by Functionalized Carbon Nanotubes

EPA Science Inventory

Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that can damage organisms by biomembrane oxidation or mediate CNTs' environmental transformations. The photosensitized nature of derivatized carbon nanotubes from various synthetic methods, and thus ...

Photosensitizer nanocarriers modeling for photodynamic therapy applied to dermatological diseases

NASA Astrophysics Data System (ADS)

Salas-García, I.; Fanjul-Vélez, F.; Ortega-Quijano, N.; López-Escobar, M.; Arce-Diego, J. L.

2011-02-01

Photodynamic Therapy involves the therapeutic use of photosensitizers in combination with visible light. The subsequent photochemical reactions generate reactive oxygen species which are considered the principal cytotoxic agents to induce cell death. This technique has become widely used in medicine to treat tumors and other nonmalignant diseases. However, there are several factors related to illumination or the photosensitizer that limit an optimal treatment outcome. The use of nanoparticles (NP) for PDT has been proposed as a solution to current shortcomings. In this way, there are NPs that act as carriers for photosensitizers, NPs that absorb the light and transfer the energy to the photosensitizer and NPs that are themselves photodynamically active. In dermatology, the use of topical photosensitizers produces a time dependent inhomogeneous distribution within the tumor, where the stratum corneum is the main barrier to the diffusion of the photosensitizer to the deeper layers of skin. This produces an insufficient photosensitizer accumulation in tumor tissues and therefore, a low therapeutic efficiency in the case of deep lesions. This work focuses in the use of NPs as photosensitizer carriers to improve the actual topical drug distribution in malignant skin tissues. We present a mathematical model of PS distribution in tumor tissue using NPs that takes into account parameters related to nanoparticles binding. Once the concentration profile of NPs into tissue is obtained, we use a photochemical model which allows us to calculate the temporal evolution of reactive oxygen species according to PS distribution calculated previously from NPs profile.

Inorganic photosensitizer coupled Gd-based upconversion luminescent nanocomposites for in vivo magnetic resonance imaging and near-infrared-responsive photodynamic therapy in cancers.

PubMed

Zhang, Ling'e; Zeng, Leyong; Pan, Yuanwei; Luo, Song; Ren, Wenzhi; Gong, An; Ma, Xuehua; Liang, Hongze; Lu, Guangming; Wu, Aiguo

2015-03-01

Inorganic photosensitizer coupled Gd-based upconversion luminescent (UCL) nanocomposites have potential application for both magnetic resonance imaging (MRI) and photodynamic therapy (PDT) of cancers using the light stability and biocompatibility of TiO2 inorganic photosensitizer. However, TiO2 inorganic photosensitizer could only be excited by ultraviolet (UV) light, which was harmful and weakly penetrable in tissues. In this work, folic acid (FA)-targeted NaGdF4:Yb/Tm@SiO2@TiO2 nanocomposites (FA-Gd-Si-Ti NPs) were constructed and synthesized for both in vivo MRI and near infrared (NIR)-responsive inorganic PDT, in which TiO2 component could be excited by NIR light due to the UCL performance of NaGdF4:Yb/Tm component converting NIR to UV light. The results showed the as-prepared FA-Gd-Si-Ti NPs had good biocompatibility in vitro and in vivo. Moreover, MR study indicated that FA-Gd-Si-Ti NPs were good T1-weighted MRI contrast agents with high longitudinal relaxivity (r1) of 4.53 mm(-1) s(-1), also in vivo MRI of nude mice showed "bright" signal in MCF-7 tumor. Under the irradiation of 980 nm laser at the power density of 0.6 W/cm(2) for 20 min, the viability of HeLa and MCF-7 cells incubated with FA-Gd-Si-Ti NPs could decrease from about 90 % to 35 % and 31%, respectively. Furthermore, in vivo PDT of MCF-7 tumor-bearing nude mice model showed that the inhibition ratio of tumors injected with FA-Gd-Si-Ti NPs reached up to 88.6% after 2-week treatment, compared with that of nude mice in control group. Based on the deep penetration of NIR light and the good biocompatibility of TiO2 inorganic photosensitizer, the as-prepared FA-Gd-Si-Ti NPs could have potential applications in both MRI and NIR-responsive PDT of cancers in deep tissues. Copyright © 2014 Elsevier Ltd. All rights reserved.

Photosensitive disorders in HIV

PubMed Central

2017-01-01

Photosensitive disorders are common, affecting up to 5% of HIV-positive patients. HIV itself induces photosensitivity but photoaggravated drug reactions, porphyria cutanea tarda and nutritional disorders such as pellagra are also more common in patients with HIV. In South Africa, actinic lichenoid leukomelanoderma of HIV is a unique photosensitive disorder which is associated with advanced HIV. It is important to be able to recognise these conditions and withdraw photosensitising medications wherever possible. PMID:29568622

Photosensitive disorders in HIV.

PubMed

Koch, Karen

2017-01-01

Photosensitive disorders are common, affecting up to 5% of HIV-positive patients. HIV itself induces photosensitivity but photoaggravated drug reactions, porphyria cutanea tarda and nutritional disorders such as pellagra are also more common in patients with HIV. In South Africa, actinic lichenoid leukomelanoderma of HIV is a unique photosensitive disorder which is associated with advanced HIV. It is important to be able to recognise these conditions and withdraw photosensitising medications wherever possible.

Pronounced photosensitivity of molecular [Ru(bpy)2(OSO)]+ solutions based on two photoinduced linkage isomers.

PubMed

Dieckmann, Volker; Eicke, Sebastian; Rack, Jeffrey J; Woike, Theo; Imlau, Mirco

2009-08-17

Photosensitive properties of [Ru(bpy)(2)(OSO)] PF(6) dissolved in propylene carbonate originating from photoinduced linkage isomerism have been studied by temperature and exposure dependent transmission and UV/Vis absorption spectroscopy. An exceeding photochromic photosensitivity of S = (63 +/- 10) x 10(3) cm l J(-1) mol(-1) is determined. It is attributed to a maximum population of 100% molecules in the photoinduced isomers, a unique absorption cross section per molecule and a very low light exposure of Q(0) = (0.25 +/- 0.03) Ws cm(-2) for isomerism. Relaxation studies of O-bonded to S-bonded isomers at different temperatures verify the existence of two distinct structures of linkage isomers determined by the activation energies of E(A,1) = (0.76 +/- 0.08) eV and E(A,2) = (1.00 +/- 0.14) eV.

Modeling a photoinduced planar-to-homeotropic anchoring transition triggered by surface azobenzene units in a nematic liquid crystal

NASA Astrophysics Data System (ADS)

Oswald, Patrick; Ignés-Mullol, Jordi

2017-09-01

The performance of light-controlled liquid crystal anchoring surfaces depends on the nature of the photosensitive moieties and on the concentration of spacer units. Here, we study the kinetics of photosensitive liquid crystal cells that incorporate an azobenzene-based self-assembled monolayer. We characterize the photoinduced homeotropic-to-planar transition and the subsequent reverse relaxation in terms of the underlying isomerization of the photosensitive layer. We show that the response time can be precisely adjusted by tuning the lateral packing of azobenzene units by means of inert spacer molecules. Using simple kinetic assumptions and a well-known model for the energetics of liquid crystal anchoring we are able to capture the details of the optical microscopy experimental observations. Our analysis provides fitted values for all the relevant material parameters, including the zenithal and the azimuthal anchoring strength.

Improved photosensitizers for photodynamic therapy

NASA Astrophysics Data System (ADS)

Pandey, Ravindra K.; Shiau, Fuu-Yau; Meunier, Isabelle; Ramaprasad, Subbaraya; Sumlin, Adam B.; Dougherty, Thomas J.; Smith, Kevin M.

1992-06-01

In order to evaluate the effect of substituents in photosensitizing activity, a series of long wavelength absorbing photosensitizers related to pyropheophorbides, bacteriopheophorbides, and benzoporphyrin derivatives were synthesized. Pheophorbide dimers, covalently joining two molecules of pyropheophorbide-a and bacteriopheophorbide-a with lysine as a cross-link were also prepared. The syntheses and spectroscopic properties of these compounds are discussed. Some of these compounds were tested for in vivo photosensitizing activity vis-a-vis Photofrin IITM, using the standard screening system of DBA/2 mice bearing transplanted SMT/F tumors. The preliminary in vivo results suggest that replacement of substituents at peripheral positions of the macrocycles causes a significant difference in photosensitizing efficacy.

Method for photo-altering a biological system to improve biological effect

DOEpatents

Hill, Richard A.; Doiron, Daniel R.; Crean, David H.

2000-08-01

Photodynamic therapy is a new adjunctive therapy for filtration surgery that does not use chemotherapy agents or radiation, but uses pharmacologically-active sensitizing compounds to produce a titratable, localized, transient, post operative avascular conjunctiva. A photosensitizing agent in a biological system is selectively activated by delivering the photosensitive agent to the biological system and laser activating only a spatially selected portion of the delivered photosensitive agent. The activated portion of the photosensitive agent reacts with the biological system to obtain a predetermined biological effect. As a result, an improved spatial disposition and effectuation of the biological effect by the photosensitive agent in the biological system is achieved.

Spatial photosensitizer fluorescence emission predictive analysis for photodynamic therapy monitoring applied to a skin disease

NASA Astrophysics Data System (ADS)

Salas-García, Irene; Fanjul-Vélez, Félix; Arce-Diego, José Luis

2012-03-01

The development of Photodynamic Therapy (PDT) predictive models has become a valuable tool for an optimal treatment planning, monitoring and dosimetry adjustment. A few attempts have achieved a quite complete characterization of the complex photochemical and photophysical processes involved, even taking into account superficial fluorescence in the target tissue. The present work is devoted to the application of a predictive PDT model to obtain fluorescence tomography information during PDT when applied to a skin disease. The model takes into account the optical radiation distribution, a non-homogeneous topical photosensitizer distribution, the time dependent photochemical interaction and the photosensitizer fluorescence emission. The results show the spatial evolution of the photosensitizer fluorescence emission and the amount of singlet oxygen produced during PDT. The depth dependent photosensitizer fluorescence emission obtained is essential to estimate the spatial photosensitizer concentration and its degradation due to photobleaching. As a consequence the proposed approach could be used to predict the photosensitizer fluorescence tomographic measurements during PDT. The singlet oxygen prediction could also be employed as a valuable tool to predict the short term treatment outcome.

Improved analysis of Monascus pigments based on their pH-sensitive UV-Vis absorption and reactivity properties.

PubMed

Shi, Kan; Chen, Gong; Pistolozzi, Marco; Xia, Fenggeng; Wu, Zhenqiang

2016-09-01

Monascus pigments, a mixture of azaphilones mainly composed of red, orange and yellow pigments, are usually prepared in aqueous ethanol and analysed by ultraviolet-visible (UV-Vis) spectroscopy. The pH of aqueous ethanol used during sample preparation and analysis has never been considered a key parameter to control; however, this study shows that the UV-Vis spectra and colour characteristics of the six major pigments are strongly influenced by the pH of the solvent employed. In addition, the increase of solvent pH results in a remarkable increase of the amination reaction of orange pigments with amino compounds, and at higher pH (≥ 6.0) a significant amount of orange pigment derivatives rapidly form. The consequent impact of these pH-sensitive properties on pigment analysis is further discussed. Based on the presented results, we propose that the sample preparation and analysis of Monascus pigments should be uniformly performed at low pH (≤ 2.5) to avoid variations of UV-Vis spectra and the creation of artefacts due to the occurrence of amination reactions, and ensure an accurate analysis that truly reflects pigment characteristics in the samples.

Inorganic yellow-red pigments without toxic metals

NASA Astrophysics Data System (ADS)

Jansen, M.; Letschert, H. P.

2000-04-01

Inorganic pigments have been utilized by mankind since ancient times, and are still widely used to colour materials exposed to elevated temperatures during processing or application. Indeed, in the case of glasses, glazes and ceramics, there is no alternative to inorganic pigments for colouring. However, most inorganic pigments contain heavy metals or transition metals that can adversely effect the environment and human health if critical levels are exceeded. Cadmium-based pigments in particular are a cause of concern: although the pigments are not toxic due to their very low solubility in water and dilute mineral acids, cadmium itself is toxic and can enter the environment in a bioavailable form through waste-disposal sites and incineration plants. This has led to regulations, based on the precautionary principle, that strongly restrict the use of cadmium pigments. And even though recent assessments have concluded that the risk to humans or the environment might be not as significant as originally feared, a strong demand for inherently safer substitutes remains. Here we demonstrate that solid solutions of the perovskites CaTaO 2N and LaTaON2 constitute promising candidates for such substitutes: their brilliance, tinting strength, opacity, dispersability, light-fastness and heat stability rival that of the cadmium pigments, while their colour can be tuned through the desired range, from yellow through orange to deep red, by simple composition adjustments. Because all the constituent elements are harmless, this perovskite-based inorganic pigment system seems a promising replacement that could eliminate one of the sources for cadmium emissions to the environment and some of the remaining concerns about pigment safety.

To Investigate the Absorption, Dynamic Contact Angle and Printability Effects of Synthetic Zeolite Pigments in an Inkjet Receptive Coating

NASA Astrophysics Data System (ADS)

Jalindre, Swaraj Sunil

Ink absorption performance in inkjet receptive coatings containing synthetic zeolite pigments was studied. Coating pigment pore and particle size distribution are the key parameters that influence in modifying media surface properties, thus affecting the rate of ink penetration and drying time (Scholkopf, et al. 2004). The primary objective of this study was: (1) to investigate the synthetic zeolite pigment effects on inkjet ink absorption, dynamic contact angle and printability, and (2) to evaluate these novel synthetic zeolite pigments in replacing the fumed silica pigments in conventional inkjet receptive coatings. In this research study, single pigment coating formulations (in equal P:B ratio) were prepared using microporous synthetic zeolite pigments (5A, Organophilic and 13X) and polyvinyl alcohol (PVOH) binder. The laboratory-coated samples were characterized for absorption, air permeance, roughness, drying time, wettability and print fidelity. Based on the rheological data, it was found that the synthetic zeolite formulated coatings depicted a Newtonian flow behavior at low shear; while the industry accepted fumed silica based coatings displayed a characteristically high pseudoplastic flow behavior. Our coated samples generated using microporous synthetic zeolite pigments produced low absorption, reduced wettability and accelerated ink drying characteristics. These characteristics were caused due to the synthetic zeolite pigments, which resulted in relatively closed surface structure coated samples. The research suggested that no single selected synthetic zeolite coating performed better than the conventional fumed silica based coatings. Experimental data also showed that there was no apparent relationship between synthetic zeolite pigment pore sizes and inkjet ink absorption. For future research, above coated samples should be evaluated for pore size distribution using Mercury Porosimeter, which quantifies surface porosity of coated samples. This presented approach can be easily used for investigating other such microporous coating pigments in formulating inkjet receptive coating. The research findings will benefit the coating formulators, engineers and material science students, in understanding the absorption characteristics of selected synthetic zeolite pigments thereby encouraging them in identifying other such alternative pigments in conventional inkjet receptive coatings.

Photodynamic therapy of vulvar intraepithelial neoplasia using 5-aminolevulinic acid.

PubMed

Hillemanns, P; Untch, M; Dannecker, C; Baumgartner, R; Stepp, H; Diebold, J; Weingandt, H; Pröve, F; Korell, M

2000-03-01

Photodynamic (PDT) therapy is a relatively new technique with unique properties that make it attractive for the local treatment of superficial epithelial disorders. The objective of this study was to investigate the clinical response of PDT with the photosensitizing agent 5-aminolevulinic acid (5-ALA) in patients with vulvar intraepithelial neoplasia (VIN) grades 1 to 3. Twenty-five patients with 111 lesions of VIN 1-3 were topically sensitized with 10 ml of a 20% solution of 5-ALA and treated with 57 cycles of laser light at 635 nm (100 J/cm(2)). Seventy (64%) of the 111 VIN lesions regressed after various PDT cycles. A complete response was achieved in 13 patients (52%) with 27 lesions. All patients with VIN 1 and mono- and bifocal VIN 2-3 showed complete clearance. However, a complete response could be achieved in only 4 (27%) of 15 women with multifocal VIN 2-3, whereas a partial response was noted in 9 of these patients with a total of 70 lesions, out of which 44 (63%) lesions disappeared. No response was seen in 2 patients with multifocal VIN 3. Histological assessment of the fluorescence-directed biopsies revealed that increased pigmentation and hyperkeratosis of the lesions were associated with low response rates. PDT using 5-ALA represents an alternative treatment modality for VIN which is easy to perform and has the advantage of minimal tissue destruction, low side effects and excellent cosmetic results. However, multifocal VIN disease with pigmented and hyperkeratinic lesions remains difficult to treat. Copyright 2000 Wiley-Liss, Inc.

Preliminary clinical data on a new photodynamic therapy photosensitizer: 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a (HPPH) for treatment of obstructive esophageal cancer

NASA Astrophysics Data System (ADS)

Dougherty, Thomas J.; Pandey, R. K.; Nava, Hector R.; Smith, Judy L.; Douglass, Harold O.; Edge, Stephen B.; Bellnier, David A.; O'Malley, Linda; Cooper, Michele

2000-03-01

The hexyl ether derivative or HPPH, has been identified as an optimal active in vivo photosensitizer in pre-clinical studies and has been evaluated clinically in obstructive esophageal cancer in five patients to date. The photosensitizer appears to have no systemic toxicity and be effective at low drug and light doses. Further, cutaneous photosensitivity appears to persist only 5-7 days.

Prostaglandin E2 is critical for the development of niacin-deficiency-induced photosensitivity via ROS production

NASA Astrophysics Data System (ADS)

Sugita, Kazunari; Ikenouchi-Sugita, Atsuko; Nakayama, Yasuko; Yoshioka, Haruna; Nomura, Takashi; Sakabe, Jun-Ichi; Nakahigashi, Kyoko; Kuroda, Etsushi; Uematsu, Satoshi; Nakamura, Jun; Akira, Shizuo; Nakamura, Motonobu; Narumiya, Shuh; Miyachi, Yoshiki; Tokura, Yoshiki; Kabashima, Kenji

2013-10-01

Pellagra is a photosensitivity syndrome characterized by three ``D's'': diarrhea, dermatitis, and dementia as a result of niacin deficiency. However, the molecular mechanisms of photosensitivity dermatitis, the hallmark abnormality of this syndrome, remain unclear. We prepared niacin deficient mice in order to develop a murine model of pellagra. Niacin deficiency induced photosensitivity and severe diarrhea with weight loss. In addition, niacin deficient mice exhibited elevated expressions of COX-2 and PGE syntheses (Ptges) mRNA. Consistently, photosensitivity was alleviated by a COX inhibitor, deficiency of Ptges, or blockade of EP4 receptor signaling. Moreover, enhanced PGE2 production in niacin deficiency was mediated via ROS production in keratinocytes. In line with the above murine findings, human skin lesions of pellagra patients confirmed the enhanced expression of Ptges. Niacin deficiency-induced photosensitivity was mediated through EP4 signaling in response to increased PGE2 production via induction of ROS formation.

Note: Measuring instrument of singlet oxygen quantum yield in photodynamic effects

NASA Astrophysics Data System (ADS)

Li, Zhongwei; Zhang, Pengwei; Zang, Lixin; Qin, Feng; Zhang, Zhiguo; Zhang, Hongli

2017-06-01

Using diphenylisobenzofuran (C20H14O) as a singlet oxygen (1O2) reporter, a comparison method, which can be used to measure the singlet oxygen quantum yield (ΦΔ) of the photosensitizer quantitatively, is presented in this paper. Based on this method, an automatic measuring instrument of singlet oxygen quantum yield is developed. The singlet oxygen quantum yield of the photosensitizer hermimether and aloe-emodin is measured. It is found that the measuring results are identical to the existing ones, which verifies the validity of the measuring instrument.

USING ACID-RESISTANT PHOTOSENSITIVE EMULSIONS TO OBTAIN LOCAL INHOMOGENEITIES WITH A HIGH RESOLVING POWER ON MONOCRYSTALS AND FILMS OF GERMANIUM AND SILICON (PRIMENENIE KISLOTOSTOYKHIKH SVETOCHUVSTVITELNYKH EMULSII DLYA POLUCHENIYA LOKALNYKH NEODNORODNOSTEI S VYSOKIM RAZRESHENIEM NA MONOKRISTALLAKH I PLENKAKH GERMANIYA I KREMNIYA),

DTIC Science & Technology

It was found that the esters of polystyrene and cinnamic acid , polyvinyl alcohol, and cinnamic acid have high dielectric characteristics that change...Photosensitive acid -resisting emulsions for use in photoengraving of semiconductor parts and semiconductor surfaces were synthesized and tested...organosilicon compounds, cinnamic aldehyde, emulsions based on azo and diazo compounds and polymeric polyesters--were tested. The photoengraving method

Coplanar asymmetrical reduced graphene oxide-titanium electrodes for polymer photodetectors.

PubMed

Pang, Shuping; Yang, Shubin; Feng, Xinliang; Müllen, Klaus

2012-03-22

Narrow gaps and a "built-in" potential originating from the different work functions of reduced graphene oxide (RGO) and titanium electrodes are used to explain the improved photosensitivity of the poly(3-hexylthiophene) photodetectors with asymmetrical RGO-Ti electrodes presented here compared to those based on symmetrical electrodes. Easy processing, high photosensitivity, high on/off ratio, and low energy consumption contribute to the promising potential of coplanar asymmetrical electrodes in the field of photoelectric devices. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Derivation of Human Differential Photoreceptor-like Cells from the Iris by Defined Combinations of CRX, RX and NEUROD

PubMed Central

Seko, Yuko; Azuma, Noriyuki; Kaneda, Makoto; Nakatani, Kei; Miyagawa, Yoshitaka; Noshiro, Yuuki; Kurokawa, Reiko; Okano, Hideyuki; Umezawa, Akihiro

2012-01-01

Examples of direct differentiation by defined transcription factors have been provided for beta-cells, cardiomyocytes and neurons. In the human visual system, there are four kinds of photoreceptors in the retina. Neural retina and iris-pigmented epithelium (IPE) share a common developmental origin, leading us to test whether human iris cells could differentiate to retinal neurons. We here define the transcription factor combinations that can determine human photoreceptor cell fate. Expression of rhodopsin, blue opsin and green/red opsin in induced photoreceptor cells were dependent on combinations of transcription factors: A combination of CRX and NEUROD induced rhodopsin and blue opsin, but did not induce green opsin; a combination of CRX and RX induced blue opsin and green/red opsin, but did not induce rhodopsin. Phototransduction-related genes as well as opsin genes were up-regulated in those cells. Functional analysis; i.e. patch clamp recordings, clearly revealed that generated photoreceptor cells, induced by CRX, RX and NEUROD, responded to light. The response was an inward current instead of the typical outward current. These data suggest that photosensitive photoreceptor cells can be generated by combinations of transcription factors. The combination of CRX and RX generate immature photoreceptors: and additional NEUROD promotes maturation. These findings contribute substantially to a major advance toward eventual cell-based therapy for retinal degenerative diseases. PMID:22558175

Melanopsin and the Non-visual Photochemistry in the Inner Retina of Vertebrates.

PubMed

Díaz, Nicolás M; Morera, Luis P; Guido, Mario E

2016-01-01

Melanopsin (Opn4), a member of the G-protein-coupled receptor family, is a vitamin A-based opsin in the vertebrate retina that has been shown to be involved in the synchronization of circadian rhythms, pupillary light reflexes, melatonin suppression and other light-regulated tasks. In nonmammalian vertebrates there are two Opn4 genes, Opn4m and Opn4x, the mammalian and Xenopus orthologs respectively. Opn4x is only expressed in nonmammalian vertebrates including reptiles, fish and birds, while Opn4m is found in a subset of retinal ganglion cells (RGCs), the intrinsically photosensitive (ip) RGCs of the inner retina of both mammals and nonmammalian vertebrates. All opsins described utilize retinaldehyde as chromophore, photoisomerized from 11-cis- to all-trans-retinal upon light exposure. Visual retinal photoreceptor cones and rods, responsible for day and night vision respectively, recycle retinoids through a process called the visual cycle that involves the retinal pigment epithelium or glial Müller cells. Although Opn4 has been characterized as a bistable photopigment, little is known about the mechanism/s involved in its chromophore regeneration. In this review, we will attempt to shed light on the visual cycle taking place in the inner retina and discuss the state of the art in the nonvisual photochemistry of vertebrates. © 2015 The American Society of Photobiology.

Explicit macroscopic singlet oxygen modeling for benzoporphyrin derivative monoacid ring A (BPD)-mediated photodynamic therapy.

PubMed

Kim, Michele M; Penjweini, Rozhin; Liang, Xing; Zhu, Timothy C

2016-11-01

Photodynamic therapy (PDT) is an effective non-ionizing treatment modality that is currently being used for various malignant and non-malignant diseases. In type II PDT with photosensitizers such as benzoporphyrin monoacid ring A (BPD), cell death is based on the creation of singlet oxygen ( 1 O 2 ). With a previously proposed empirical five-parameter macroscopic model, the threshold dose of singlet oxygen ([ 1 O 2 ] rx,sh ]) to cause tissue necrosis in tumors treated with PDT was determined along with a range of the magnitude of the relevant photochemical parameters: the photochemical oxygen consumption rate per light fluence rate and photosensitizer concentration (ξ), the probability ratio of 1 O 2 to react with ground state photosensitizer compared to a cellular target (σ), the ratio of the monomolecular decay rate of the triplet state photosensitizer (β), the low photosensitizer concentration correction factor (δ), and the macroscopic maximum oxygen supply rate (g). Mice bearing radiation-induced fibrosarcoma (RIF) tumors were treated interstitially with a linear light source at 690nm with total energy released per unit length of 22.5-135J/cm and source power per unit length of 12-150mW/cm to induce different radii of necrosis. A fitting algorithm was developed to determine the photochemical parameters by minimizing the error function involving the range between the calculated reacted singlet oxygen ([ 1 O 2 ] rx ) at necrosis radius and the [ 1 O 2 ] rx,sh . [ 1 O 2 ] rx was calculated based on explicit dosimetry of the light fluence distribution, the tissue optical properties, and the BPD concentration. The initial ground state oxygen concentration ([ 3 O 2 ] 0 ) was set to be 40μM in this study. The photochemical parameters were found to be ξ=(55±40)×10 -3 cm 2 mW -1 s -1 , σ=(1.8±3)×10 -5 μM -1 , and g=1.7±0.7μMs -1 . We have taken the literature values for δ=33μM, and β=11.9μM. [ 1 O 2 ] rx has shown promise to be a more effective dosimetry quantity for predicting necrosis than either light dose or PDT dose, where the latter is simplistically a temporal integral of the products of the photosensitizer concentration and light fluence rate. Copyright © 2016 Elsevier B.V. All rights reserved.

Tetrapyrrole-photosensitizers vectorization and plasma LDL: a physico-chemical approach.

PubMed

Bonneau, Stéphanie; Vever-Bizet, Christine; Mojzisova, Halina; Brault, Daniel

2007-11-01

A photosensitizer is defined as a chemical entity able to induce, under light-irradiation effect, a chemical or physical alteration of another chemical entity. Thanks to their preferential retention in proliferating tissues, some photosensitizers are therapeutically used such as in photodynamic therapy (PDT). Besides, this method has already been approved for several indications. The selectivity of photosenzitizers for cells in proliferation involves both their association with low density lipoproteins (LDLs) and their ability to cross membranes under various pH conditions. The photosensitizers used are in most cases based on the porphyrin structure, but other compounds, of which far-red-light absorption properties are most compatible with biological tissues irradiation, have been developed, such as phthalocyanines. This paper presents physico-chemical studies of the interaction of a disulfonated aluminium phthalocyanine (AlPcS2) with human LDLs. The data obtained are compared with the parameters of the interaction of these lipoproteins with deuteroporphyrin (DP) and chlorin e6 (Ce6). A close attention is paid to the dynamic aspects of these phenomena. The data obtained on these simple systems then allowed us to interpret the sub-cellular localization of the photosensitizers on a human line of fibroblasts, and to evaluate the influence of LDLs on the intracellular distribution of the compounds. This last point is of major importance because the localization of such photosensitizers (in particular AlPcS2) in endocytic vesicles and their subsequent ability to induce a release of the contents of these vesicles - including externally added macromolecules - into the cytosol is the basis for a recent method for macromolecule activation, named photochemical internalization (PCI). PCI has been shown to potentiate the biological activity of a large variety of macromolecules. The comprehension of the mechanisms governing this particular sub-cellular localization could allow the design of better candidates for PCI.

Contributions of Phenoxazone-Based Pigments to the Structure and Function of Nanostructured Granules in Squid Chromatophores.

PubMed

Williams, Thomas L; DiBona, Christopher W; Dinneen, Sean R; Labadie, Stephanie F Jones; Chu, Feixia; Deravi, Leila F

2016-04-19

Understanding the structure-function relationships of pigment-based nanostructures can provide insight into the molecular mechanisms behind biological signaling, camouflage, or communication experienced in many species. In squid Doryteuthis pealeii, combinations of phenoxazone-based pigments are identified as the source of visible color within the nanostructured granules that populate dermal chromatophore organs. In the absence of the pigments, granules experience a reduction in diameter with the loss of visible color, suggesting important structural and functional features. Energy gaps are estimated from electronic absorption spectra, revealing highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energies that are dependent upon the varying carboxylated states of the pigment. These results implicate a hierarchical mechanism for the bulk coloration in cephalopods originating from the molecular components confined within in the nanostructured granules of chromatophore organs.

Gamma-irradiation effect on a commercial composite anticorrosive pigment and acidity-to-alkalinity conversion

NASA Astrophysics Data System (ADS)

Song, Weiqiang; Niu, Kaihui; Wu, Longchao

2016-05-01

A commercial composite anticorrosive pigment based on aluminum dihydrogen tripolyphosphate was studied after exposure to gamma irradiation (Co60, 0, 20, 50, 100 and 150 kGy) using FTIR, XRD, TGA and acid-base titration technologies. Although the FTIR spectra showed that the effect of the irradiation on functional groups in the pigments was not obvious, the decrease in the crystal lattice parameters of the irradiated pigments was observed in the XRD spectra compared to the non-irradiated sample. But the extent of the lattice parameter decrease monotonically with the increase of absorbed dose from 20 to 150 kGy, which was attributed to the decomposition of water and the simultaneous occurrence of lattice damage when the pigments were exposed to gamma rays. Of particular significance was the displayed basicity of the aqueous solutions of the irradiated pigments compared to the acidity of the solution of the non-irradiated pigment, which was attributed to the decomposition of P-OH groups (combined water).

Possibility for a full optical determination of photodynamic therapy outcome

NASA Astrophysics Data System (ADS)

Vollet-Filho, J. D.; Menezes, P. F. C.; Moriyama, L. T.; Grecco, C.; Sibata, C.; Allison, R. R.; Castro e Silva, O.; Bagnato, V. S.

2009-05-01

The efficacy of photodynamic therapy (PDT) depends on a variety of parameters: concentration of the photosensitizer at the time of treatment, light wavelength, fluence, fluence rate, availability of oxygen within the illuminated volume, and light distribution in the tissue. Dosimetry in PDT requires the congregation of adequate amounts of light, drug, and tissue oxygen. The adequate dosimetry should be able to predict the extension of the tissue damage. Photosensitizer photobleaching rate depends on the availability of molecular oxygen in the tissue. Based on photosensitizers photobleaching models, high photobleaching has to be associated with high production of singlet oxygen and therefore with higher photodynamic action, resulting in a greater depth of necrosis. The purpose of this work is to show a possible correlation between depth of necrosis and the in vivo photosensitizer (in this case, Photogem®) photodegradation during PDT. Such correlation allows possibilities for the development of a real time evaluation of the photodynamic action during PDT application. Experiments were performed in a range of fluence (0-450 J/cm2) at a constant fluence rate of 250 mW/cm2 and applying different illumination times (0-1800 s) to achieve the desired fluence. A quantity was defined (ψ) as the product of fluorescence ratio (related to the photosensitizer degradation at the surface) and the observed depth of necrosis. The correlation between depth of necrosis and surface fluorescence signal is expressed in ψ and could allow, in principle, a noninvasive monitoring of PDT effects during treatment. High degree of correlation is observed and a simple mathematical model to justify the results is presented.

Magnetic resonance spectroscopy findings in photosensitive idiopathic generalized epilepsy.

PubMed

Aydin-Ozemir, Zeynep; Terzibasioglu, Ege; Altindag, Ebru; Sencer, Serra; Baykan, Betul

2010-01-01

Studies investigating the pathophysiology of epileptic photosensitivity indicate variable involvement of particular brain regions. Our aim was to identify metabolic differences between photosensitive idiopathic generalized epilepsy (IGE) patients and nonphotosensitive IGE patients and normal healthy subjects by using Magnetic Resonance Spectroscopy (MRS). Fourteen patients diagnosed with photosensitive IGE were investigated. The control groups consisted of 14 age- and sex-matched healthy volunteers and 14 IGE patients without photosensitivity. MRS measurements of N-acetylaspartate (NAA), choline-containing compounds (Cho), creatine (Cr) were performed in the frontal and occipital cortex and the thalamus bilaterally using a stimulated echo acquisition mode (STEAM) technique with a voxel size of 20 x 20 x 20 mm. The values of the patients with IGE were compared with those of the normal controls and within subgroups according to the clinical variables by appropriate statistical tests. Photosensitive IGE patients showed significantly decreased concentrations of NAA in the right frontal lobe and left thalamus, decreased NAA/Cr ratio in left thalamus and significantly increased concentrations of Cho/Cr ratio in the right frontal lobe and NAA/Cr in the left occipital lobe when compared to normal controls. Furthermore, left occipital NAA concentration increased and left thalamus NAA/Cr ratios were decreased from the IGE patients without photosensitivity but without reaching statistical significance. Our results support previous MR studies suggesting an asymmetrical neuronal dysfunction in favor of the dominant occipital cortex and thalamus in photosensitive IGE patients.

Using fluorescence to augment the efficacy of photodynamic therapy

NASA Astrophysics Data System (ADS)

Dickey, Dwayne J.; Liu, Weiyang; Naicker, Selvaraj; Woo, Thomas; Moore, Ronald B.; Tulip, John

2006-09-01

Photodynamic Therapy (PDT) is a relatively novel oncological treatment modality, in which a patient is administered a photosensitive drug, called a photosensitizer. After allowing sufficient time for biodistribution, the cancerous area is irradiated with light of the appropriate wavelength, activating the photosensitizer to produce highly reactive singlet oxygen, which produces a highly localized cell kill. The efficacy of PDT is determined by a) the intensity of the light b) the local concentration of the photosensitizer, and c) the availability of oxygen. However, with the clinical application of PDT, the patient is simply administered a body mass dependent quantity of photosensitizer, and then the target area is administered a prescribed amount of radiant energy (joules per cubic centimetre). For treatment of superficial malignancies, PDT has many successes; however, interstitial PDT (PDT of solid, internal malignancies) has inconsistent outcomes mostly due to the inability to predict, calculate or measure the variables that affect PDT: the radiation dose, oxygen concentration, and the photosensitizer concentration. We have developed sophisticated methods to determine the behaviour of light in homogeneous biological tissues. Tissue oxygen levels can be replenished by fractionating the light dose - allowing areas of your target tissue to go through a "dark" cycle during PDT. However, to date, there has not been an accurate method of determining tissue photosensitizer concentrations in-vivo. We are researching the efficacy of a novel hypocrellin derivative, SL-052. Like other photosensitizers available, SL-052 shows strong therapeutic photodynamic activity when irradiated by 635 nm light. Like most photosensitizers, SL-052 exhibits fluorescent activity, but SL-052 also shows strong fluorescent emission at 725nm when excited by 635 nm. The intensity of the fluorescent emission can been correlated with the local concentration of the photosenstizer. However, many clinically available photosensitizers require that fluorescence is excited using a wavelength of light much shorter than the therapeutic wavelength. This characteristic allows us to monitor the availability of the photosensitizer during PDT and to correlate the outcome of PDT to the observed fluorescence. In this paper, we monitor the temporal distribution of SL-052 in the Dunning R3327-AT cell line grown on the flank of a Fisher Copenhangen rats.

Estimation of Phytoplankton Accessory Pigments From Hyperspectral Reflectance Spectra: Toward a Global Algorithm

NASA Astrophysics Data System (ADS)

Chase, A. P.; Boss, E.; Cetinić, I.; Slade, W.

2017-12-01

Phytoplankton community composition in the ocean is complex and highly variable over a wide range of space and time scales. Able to cover these scales, remote-sensing reflectance spectra can be measured both by satellite and by in situ radiometers. The spectral shape of reflectance in the open ocean is influenced by the particles in the water, mainly phytoplankton and covarying nonalgal particles. We investigate the utility of in situ hyperspectral remote-sensing reflectance measurements to detect phytoplankton pigments by using an inversion algorithm that defines phytoplankton pigment absorption as a sum of Gaussian functions. The inverted amplitudes of the Gaussian functions representing pigment absorption are compared to coincident High Performance Liquid Chromatography measurements of pigment concentration. We determined strong predictive capability for chlorophylls a, b, c1+c2, and the photoprotective carotenoids. We also tested the estimation of pigment concentrations from reflectance-derived chlorophyll a using global relationships of covariation between chlorophyll a and the accessory pigments. We found similar errors in pigment estimation based on the relationships of covariation versus the inversion algorithm. An investigation of spectral residuals in reflectance data after removal of chlorophyll-based average absorption spectra showed no strong relationship between spectral residuals and pigments. Ultimately, we are able to estimate concentrations of three chlorophylls and the photoprotective carotenoid pigments, noting that further work is necessary to address the challenge of extracting information from hyperspectral reflectance beyond the information that can be determined from chlorophyll a and its covariation with other pigments.

Study on pigment dyeing opportunities of polyester and cotton-mix fiber

NASA Astrophysics Data System (ADS)

Nabieva, I. A.; Shamukimova, M. B.; Artikboeva, R. M.

2017-11-01

The process of coloring the dyeing pigments in polyether and cotton fibers for different fabrics, which are inclined to dye, have been studied in this article. Based on the experiences on pigments dyeing, it was suggested to study the materials with the dyeing pigment substances with the purpose of improving the technology of color forming.

Light-sensitive Lipid-based Nanoparticles for Drug Delivery: Design Principles and Future Considerations for Biological Applications

PubMed Central

Yavlovich, Amichai; Smith, Brandon; Gupta, Kshitij; Blumenthal, Robert; Puri, Anu

2011-01-01

Radiation-based therapies aided by nanoparticles have been developed since decades, and can be primarily categorized into two main platforms. First, delivery of payload of photo-reactive drugs (photosensitizers) using the conventional nanoparticles, and second, design and development of photo-triggerable nanoparticles (primarily liposomes) to attain light-assisted on-demand drug delivery. The main focus of this review is to provide an update of the history, current status and future applications of photo-triggerable lipid-based nanoparticles (light-sensitive liposomes). We will begin with a brief overview on the applications of liposomes for delivery of photosensitizers, including the choice of photosensitizers for photodynamic therapy, as well as the currently available light sources (lasers) used for these applications. The main segment of this review will encompass the details on the strategies to develop photo-triggerable designer liposomes for their drug delivery function. The principles underlying the assembly of photoreactive lipids into nanoparticles (liposomes) and photo-triggering mechanisms will be presented. We will also discuss factors that limit the applications of these liposomes for in vivo triggered drug delivery and emerging concepts that may lead to the biologically viable photo-activation strategies. We will conclude with our view point on the future perspectives of light-sensitive liposomes in the clinic. PMID:20939770

Quantification method for the appearance of melanin pigmentation using independent component analysis

NASA Astrophysics Data System (ADS)

Ojima, Nobutoshi; Okiyama, Natsuko; Okaguchi, Saya; Tsumura, Norimichi; Nakaguchi, Toshiya; Hori, Kimihiko; Miyake, Yoichi

2005-04-01

In the cosmetics industry, skin color is very important because skin color gives a direct impression of the face. In particular, many people suffer from melanin pigmentation such as liver spots and freckles. However, it is very difficult to evaluate melanin pigmentation using conventional colorimetric values because these values contain information on various skin chromophores simultaneously. Therefore, it is necessary to extract information of the chromophore of individual skins independently as density information. The isolation of the melanin component image based on independent component analysis (ICA) from a single skin image was reported in 2003. However, this technique has not developed a quantification method for melanin pigmentation. This paper introduces a quantification method based on the ICA of a skin color image to isolate melanin pigmentation. The image acquisition system we used consists of commercially available equipment such as digital cameras and lighting sources with polarized light. The images taken were analyzed using ICA to extract the melanin component images, and Laplacian of Gaussian (LOG) filter was applied to extract the pigmented area. As a result, for skin images including those showing melanin pigmentation and acne, the method worked well. Finally, the total amount of extracted area had a strong correspondence to the subjective rating values for the appearance of pigmentation. Further analysis is needed to recognize the appearance of pigmentation concerning the size of the pigmented area and its spatial gradation.

A novel automated instrument designed to determine photosensitivity thresholds (Conference Presentation)

NASA Astrophysics Data System (ADS)

Aguilar, Mariela C.; Gonzalez, Alex; Rowaan, Cornelis; De Freitas, Carolina; Rosa, Potyra R.; Alawa, Karam; Lam, Byron L.; Parel, Jean-Marie A.

2016-03-01

As there is no clinically available instrument to systematically and reliably determine the photosensitivity thresholds of patients with dry eyes, blepharospasms, migraines, traumatic brain injuries, and genetic disorders such as Achromatopsia, retinitis pigmentosa and other retinal dysfunctions, a computer-controlled optoelectronics system was designed. The BPEI Photosensitivity System provides a light stimuli emitted from a bi-cupola concave, 210 white LED array with varying intensity ranging from 1 to 32,000 lux. The system can either utilize a normal or an enhanced testing mode for subjects with low light tolerance. The automated instrument adjusts the intensity of each light stimulus. The subject is instructed to indicate discomfort by pressing a hand-held button. Reliability of the responses is tracked during the test. The photosensitivity threshold is then calculated after 10 response reversals. In a preliminary study, we demonstrated that subjects suffering from Achromatopsia experienced lower photosensitivity thresholds than normal subjects. Hence, the system can safely and reliably determine the photosensitivity thresholds of healthy and light sensitive subjects by detecting and quantifying the individual differences. Future studies will be performed with this system to determine the photosensitivity threshold differences between normal subjects and subjects suffering from other conditions that affect light sensitivity.

Skin photosensitivity as a model in photodynamic therapy

NASA Astrophysics Data System (ADS)

Richter, Anna M.; Jain, Ashok K.; Canaan, Alice J.; Meadows, Howard; Levy, Julia G.

1996-01-01

Skin photosensitivity is the most common side effect of photodynamic therapy (PDT) and in clinical situations needs to be avoided or at least minimized. However, because of the accessibility of skin tissue, skin photosensitivity represents a useful test system in vivo for evaluation of the pharmacokinetics of photosensitizers and light sources. Pig skin resembles in many aspects human skin and, therefore, is most suitable for these tests. Using pig skin photosensitivity as an end point, we evaluate the effect of cell loading with a photosensitizer, benzoporphyrin derivative (BPD verteporfin) following its intravenous administration either as a rapid bolus or slow infusion. Skin response to light activation indicated a very similar cell content of BPD. These results were in agrement with those obtained in an in vitro model. In addition, in the same pig skin photosensitivity model we compared the efficiency of activation of BPD with either laser (690 plus or minus 3 nm) or light-emitting diode (LED; 690 plus or minus 12 nm) light. Results indicated the equivalency of the two light sources in this test system, with LED light being slightly more efficient, due possibly to a fluence rate lower than laser light.

Nanoparticle-based photodynamic therapy on non-melanoma skin cancer

NASA Astrophysics Data System (ADS)

Fanjul-Vélez, F.; Arce-Diego, J. L.

2018-02-01

There are several advantages of Photodynamic Therapy (PDT) for nonmelanoma skin cancer treatment compared to conventional treatment techniques such as surgery, radiotherapy or chemotherapy. Among these advantages its noninvasive nature, the use of non ionizing radiation and its high selectivity can be mentioned. Despite all these advantages, the therapeutic efficiency of the current clinical protocol is not complete in all the patients and depends on the type of pathology. An adequate dosimetry is needed in order to personalize the protocol. There are strategies that try to overcome the current PDT shortcomings, such as the improvement of the photosensitizer accumulation in the target tissue, optical radiation distribution optimization or photochemical reactions maximization. These strategies can be further complemented by the use of nanostructures with conventional PDT. Customized dosimetry for nanoparticle-based PDT requires models in order to adjust parameters of different nature to get an optimal tumor removal. In this work, a predictive model of nanoparticle-based PDT is proposed and analyzed. Dosimetry in nanoparticle-based PDT is going to be influenced by photosensitizer-nanoparticle distribution in the malignant tissue, its influence in the optical radiation distribution and the subsequent photochemical reactions. Nanoparticles are considered as photosensitizer carriers on several types of non-melanoma skin cancer. Shielding effects are taken into account. The results allow to compare the estimated treatment outcome with and without nanoparticles.

Photochemical predictive analysis of photodynamic therapy with non-homogeneous topical photosensitizer distribution in dermatological applications

NASA Astrophysics Data System (ADS)

Salas-García, I.; Fanjul-Vélez, F.; Ortega-Quijano, N.; López-Escobar, M.; Arce-Diego, J. L.

2010-04-01

Photodynamic Therapy (PDT) is a therapeutic technique widely used in dermatology to treat several skin pathologies. It is based in topical or systemic delivery of photosensitizing drugs followed by irradiation with visible light. The subsequent photochemical reactions generate reactive oxygen species which are considered the principal cytotoxic agents to induce cell necrosis. In this work we present a PDT model that tries to predict the photodynamic effect on the skin with a topically administered photosensitizer. The time dependent inhomogeneous distribution of the photoactive compound protoporphyrin IX (PpIX) is calculated after obtaining its precursor distribution (Methyl aminolevulinate, MAL) which depends on the drug permeability, diffusion properties of the skin, incubation time and conversion efficiency of MAL to PpIX. Once the optical energy is obtained by means of the Beer Lambert law, a photochemical model is employed to estimate the concentration of the different molecular compounds taking into account the electronic transitions between molecular levels and particles concentrations. The results obtained allow us to know the evolution of the cytotoxic agent in order to estimate the necrotic area adjusting parameters such as the optical power, the photosensitizer concentration, the incubation and exposition time or the diffusivity and permeability of the tissue.

Effect of zircon-based tricolor pigments on the color, microstructure, flexural strength and translucency of a novel dental lithium disilicate glass-ceramic.

PubMed

Yuan, Kun; Wang, Fu; Gao, Jing; Sun, Xiang; Deng, Zai-Xi; Wang, Hui; Jin, Lei; Chen, Ji-Hua

2014-01-01

The purpose of this study was to investigate the effect of zircon-based tricolor pigments (praseodymium zircon yellow, ferrum zircon red, and vanadium zircon blue) on the color, thermal property, crystalline phase composition, microstructure, flexural strength, and translucency of a novel dental lithium disilicate glass-ceramic. The pigments were added to the glass frit, milled, pressed, and sintered. Ninety monochrome samples were prepared and the colors were analyzed. The effect of the pigments on thermal property, crystalline phase composition, and microstructure were determined by differential scanning calorimetry (DSC), X-ray diffraction (XRD), and scanning electron microscopy (SEM), respectively. Addition of the pigments resulted in the acquisition of subtractive primary colors as well as tooth-like colors, and did not demonstrate significant effects on the thermal property, crystalline phase composition, microstructure, and flexural strength of the experimental glass-ceramic. Although significant differences (p < 0.01) were observed between the translucencies of the uncolored and 1.0 wt % zircon-based pigment colored ceramics, the translucencies of the latter were sufficient to fabricate dental restorations. These results indicate that the zircon-based tricolor pigments can be used with dental lithium disilicate glass-ceramic to produce abundant and predictable tooth-like colors without significant adverse effects, if mixed in the right proportions. Copyright © 2013 Wiley Periodicals, Inc.

Color characterization of coatings with diffraction pigments.

PubMed

Ferrero, A; Bernad, B; Campos, J; Perales, E; Velázquez, J L; Martínez-Verdú, F M

2016-10-01

Coatings with diffraction pigments present high iridescence, which needs to be characterized in order to describe their appearance. The spectral bidirectional reflectance distribution functions (BRDFs) of six coatings with SpectraFlair diffraction pigments were measured using the robot-arm-based goniospectrophotometer GEFE, designed and developed at CSIC. Principal component analysis has been applied to study the coatings of BRDF data. From data evaluation and based on theoretical considerations, we propose a relevant geometric factor to study the spectral reflectance and color gamut variation of coatings with diffraction pigments. At fixed values of this geometric factor, the spectral BRDF component due to diffraction is almost constant. Commercially available portable goniospectrophotometers, extensively used in several industries (automotive and others), should be provided with more aspecular measurement angles to characterize the complex reflectance of goniochromatic coatings based on diffraction pigments, but they would not require either more than one irradiation angle or additional out-of-plane geometries.

3-D photo-patterning of refractive index structures in photosensitive thin film materials

DOEpatents

Potter, Jr., Barrett George; Potter, Kelly Simmons

2002-01-01

A method of making a three-dimensional refractive index structure in a photosensitive material using photo-patterning. The wavelengths at which a photosensitive material exhibits a change in refractive index upon exposure to optical radiation is first determined and then a portion of the surface of the photosensitive material is optically irradiated at a wavelength at which the photosensitive material exhibits a change in refractive index using a designed illumination system to produce a three-dimensional refractive index structure. The illumination system can be a micro-lenslet array, a macroscopic refractive lens array, or a binary optic phase mask. The method is a single-step, direct-write procedure to produce a designed refractive index structure.

IBT-based quantitative proteomics identifies potential regulatory proteins involved in pigmentation of purple sea cucumber, Apostichopus japonicus.

PubMed

Xing, Lili; Sun, Lina; Liu, Shilin; Li, Xiaoni; Zhang, Libin; Yang, Hongsheng

2017-09-01

Sea cucumbers are an important economic species and exhibit high yield value among aquaculture animals. Purple sea cucumbers are very rare and beautiful and have stable hereditary patterns. In this study, isobaric tags (IBT) were first used to reveal the molecular mechanism of pigmentation in the body wall of the purple sea cucumber. We analyzed the proteomes of purple sea cucumber in early pigmentation stage (Pa), mid pigmentation stage (Pb) and late pigmentation stage (Pc), resulting in the identification of 5580 proteins, including 1099 differentially expressed proteins in Pb: Pa and 339 differentially expressed proteins in Pc: Pb. GO and KEGG analyses revealed possible differentially expressed proteins, including"melanogenesis", "melanosome", "melanoma", "pigment-biosynthetic process", "Epidermis development", "Ras-signaling pathway", "Wnt-signaling pathway", "response to UV light", and "tyrosine metabolism", involved in pigment synthesis and regulation in purple sea cucumbers. The large number of differentially expressed proteins identified here should be highly useful in further elucidating the mechanisms underlying pigmentation in sea cucumbers. Furthermore, these results may also provide the base for further identification of proteins involved in resistance mechanisms against melanoma, albinism, UV damage, and other diseases in sea cucumbers. Copyright © 2017. Published by Elsevier Inc.

Inverted organic photosensitive devices

DOEpatents

Forrest, Stephen R.; Bailey-Salzman, Rhonda F.

2016-12-06

The present disclosure relates to organic photosensitive optoelectronic devices grown in an inverted manner. An inverted organic photosensitive optoelectronic device of the present disclosure comprises a reflective electrode, an organic donor-acceptor heterojunction over the reflective electrode, and a transparent electrode on top of the donor-acceptor heterojunction.

The influence of carotenoid acquisition and utilization on the maintenance of species-typical plumage pigmentation in male American goldfinches (Carduelis tristis) and northern cardinals (Cardinalis cardinalis).

PubMed

McGraw, K J; Hill, G E; Stradi, R; Parker, R S

2001-01-01

Birds display a tremendous variety of carotenoid-based colors in their plumage, but the mechanisms underlying interspecific variability in carotenoid pigmentation remain poorly understood. Because vertebrates cannot synthesize carotenoids de novo, access to pigments in the diet is one proximate factor that may shape species differences in carotenoid-based plumage coloration. However, some birds metabolize ingested carotenoids and deposit pigments that differ in color from their dietary precursors, indicating that metabolic capabilities may also contribute to the diversity of plumage colors we see in nature. In this study, we investigated how the acquisition and utilization of carotenoids influence the maintenance of species-typical plumage pigmentation in male American goldfinches (Carduelis tristis) and northern cardinals (Cardinalis cardinalis). We supplemented the diet of captive goldfinches with red carotenoids to determine whether males, which are typically yellow in color, were capable of growing red plumage. We also deprived cardinals of red dietary pigments to determine whether they could manufacture red carotenoids from yellow precursors to grow species-typical red plumage. We found that American goldfinches were able to deposit novel pigments in their plumage and develop a striking orange appearance. Thus, dietary access to pigments plays a role in determining the degree to which goldfinches express carotenoid-based plumage coloration. We also found that northern cardinals grew pale red feathers in the absence of red dietary pigments, indicating that their ability to metabolize yellow carotenoids in the diet contributes to the bright red plumage that they display.

Human photosensitivity: from pathophysiology to treatment.

PubMed

Verrotti, A; Tocco, A M; Salladini, C; Latini, G; Chiarelli, F

2005-11-01

Photosensitivity is a condition detected on the electroencephalography (EEG) as a paroxysmal reaction to Intermittent Photic Stimulation (IPS). This EEG response, elicited by IPS or by other visual stimuli of daily life, is called Photo Paroxysmal Response (PPR). PPRs are well documented in epileptic and non-epileptic subjects. Photosensitivity rarely in normal individuals evolves into epilepsy. Photosensitive epilepsy is a rare refex epilepsy characterized by seizures in photosensitive individuals. The development of modern technology has increased the exposition to potential seizure precipitants in people of all ages, but especially in children and adolescents. Actually, videogames, computers and televisions are the most common triggers in daily life of susceptible persons. The mechanisms of generation of PPR are poorly understood, but genetic factors play an important rule. The control of visually induced seizures has, generally a good prognosis. In patients known to be visually sensitive, avoidance of obvious source and stimulus modifications are very important and useful to seizure prevention, but in the large majority of patients with epilepsy and photosensitivity antiepileptic drugs are needed.

High-Throughput Fabrication of Flexible and Transparent All-Carbon Nanotube Electronics.

PubMed

Chen, Yong-Yang; Sun, Yun; Zhu, Qian-Bing; Wang, Bing-Wei; Yan, Xin; Qiu, Song; Li, Qing-Wen; Hou, Peng-Xiang; Liu, Chang; Sun, Dong-Ming; Cheng, Hui-Ming

2018-05-01

This study reports a simple and effective technique for the high-throughput fabrication of flexible all-carbon nanotube (CNT) electronics using a photosensitive dry film instead of traditional liquid photoresists. A 10 in. sized photosensitive dry film is laminated onto a flexible substrate by a roll-to-roll technology, and a 5 µm pattern resolution of the resulting CNT films is achieved for the construction of flexible and transparent all-CNT thin-film transistors (TFTs) and integrated circuits. The fabricated TFTs exhibit a desirable electrical performance including an on-off current ratio of more than 10 5 , a carrier mobility of 33 cm 2 V -1 s -1 , and a small hysteresis. The standard deviations of on-current and mobility are, respectively, 5% and 2% of the average value, demonstrating the excellent reproducibility and uniformity of the devices, which allows constructing a large noise margin inverter circuit with a voltage gain of 30. This study indicates that a photosensitive dry film is very promising for the low-cost, fast, reliable, and scalable fabrication of flexible and transparent CNT-based integrated circuits, and opens up opportunities for future high-throughput CNT-based printed electronics.

Design of high power LED-based UVA emission system and a photosensitive substance for clinical application in corneal radiation

NASA Astrophysics Data System (ADS)

Mota, Alessandro D.; Cestari, André M.; de Oliveira, André O.; Oliveira, Anselmo G.; Terruggi, Cristina H. B.; Rossi, Giuliano; Castro, Jarbas C.; Ligabô, João. P. B.; Ortega, Tiago A.; Rosa, Tiago

2015-09-01

This work presents an innovative cross-linking procedure to keratoconus treatment, a corneal disease. It includes the development of an ultraviolet controlled emission portable device based on LED source and a new formulation of a photosensitive drug called riboflavin. Thus new formulation improves drug administration by its transepithelial property. The UV reaction with riboflavin in corneal tissue leads to a modification of corneal collagen fibers, turning them more rigid and dense, and consequently restraining the advance of the disease. We present the control procedures to maintain UV output power stable up to 45mw/cm2, the optical architecture that leads to a homogeneous UV spot and the new formulation of Riboflavin.

The effect of dietary carotenoid access on sexual dichromatism and plumage pigment composition in the American goldfinch.

PubMed

McGraw, K J; Hill, G E; Stradi, R; Parker, R S

2002-02-01

We investigated potential dietary and biochemical bases for carotenoid-based sexual dichromatism in American goldfinches (Carduelis tristis). Captive male and female finches were given access to the same type and amount of carotenoid pigments in the diet during their nuptial molt to assess differences in the degree to which the two sexes incorporated ingested pigments into their plumage. When birds were fed a uniform, plain-seed diet, or one that was supplemented with the red carotenoid canthaxanthin, we found that males grew more colorful plumage than females. HPLC analyses of feather pigments revealed that male finches incorporated a higher concentration of carotenoids into their pigmented feathers than females. Compared to females, males also deposited significantly more canary xanthophyll B into feathers when fed a plain-seed diet and a greater concentration and proportion of canthaxanthin when fed a carotenoid-supplemented diet. These results indicate that sex-specific expression of carotenoid pigmentation in American goldfinches may be affected by the means by which males and females physiologically utilize (e.g. absorb, transport, metabolize, deposit) carotenoid pigments available to them in the diet.

Effect of UVC, UVB, UVA and a solar simulator on the survival of mouse melanoma cell lines differing in melanin content

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hill, H.Z.; Hill, G.J.; Cieszka, K.

These studies were designed to determine the survival of cells that vary in constitutive pigment levels after exposure to different UV wave lengths. The lamps employed emitted UVC (near monochromatic 254 nm), UVB (Philips TL01-88.7% of UV output is UVB), UVA (Philips HPW125-89% of output is at 365 nm) and Westinghouse FS20 (broad band UVB and UVA). Dish lids were used to cut off UVC in the UVB and FS20 experiments and 0.25 inch plate glass was used to cut off UVB in the UVA experiments. UVC photons interact with putative intracellular photosensitizers which in turn convert O{sub 2} tomore » active oxygen species which damage DNA to produce strand breaks, cross links and base damage. UVB acts by both mechanisms. The two cell lines studied were Cloudman S91/I3 (3.6 pg melanin/cell) and the closely related S91/amel (1.2 pg melanin/cell). Attached cells were covered with Ca{sup ++} and Mg{sup ++} free PBS and irradiated in the cold. Colonies were scored after 2 weeks. The two cell lines exhibit similar survival kinetics after UVC. S91/IE is more sensitive to killing by either UVB (TL01) or UVA. However, S91/amel cells are more sensitive to killing by UVB plus UVA (FS20). It is clear that UV of different qualities can interact to produce effects that would not be predicted based on responses to monochromatic wave lengths.« less

Nanodiamonds + bacteriochlorin as an infrared photosensitizer for deep-lying tumor diagnostics and therapy

NASA Astrophysics Data System (ADS)

Sharova, A. S.; Maklygina, YU S.; Lisichkin, G. V.; Mingalev, P. G.; Loschenov, V. B.

2016-08-01

The spectroscopic properties of potentially perspective nanostructure: diamond nanoparticles with a surface layer of IR-photosensitizer, bacteriochlorin, were experimentally investigated in this study. Such specific structure of the object encourages enhancement of the drug tropism to the tumor, as well as increasing of photodynamic penetration depth. The size distribution spectra of diamond nanoparticles; diamond nanoparticles, artificially covered with bacteriochlorin molecules layer, in aqueous solution, were obtained during the study. Based on the absorption and fluorescence spectra analysis, the benefits of functional nanostructure as a drug for deep-lying tumor diagnostics and therapy were reviewed.

Versatile digital micromirror device-based method for the recording of multilevel optical diffractive elements in photosensitive chalcogenide layers (AMTIR-1).

PubMed

Joerg, Alexandre; Vignaux, Mael; Lumeau, Julien

2016-08-01

A new alternative and versatile method for the production of diffractive optical elements (DOEs) with up to four phase levels in AMTIR-1 (Ge₃₃As₁₂Se₅₅) layers is demonstrated. The developed method proposes the use of the photosensitive properties of the layers and a specific in situ optical monitoring coupled with a reverse engineering algorithm to control the trigger points of the writing of the different diffractive patterns. Examples of various volume DOEs are presented.

In-vitro singlet oxygen threshold dose at PDT with Radachlorin photosensitizer

NASA Astrophysics Data System (ADS)

Klimenko, V. V.; Shmakov, S. V.; Kaydanov, N. E.; Knyazev, N. A.; Kazakov, N. V.; Rusanov, A. A.; Bogdanov, A. A.; Dubina, M. V.

2017-07-01

In this present study we investigate the Radachlorin photosensitizer accumulation in K562 cells and Hela cells and determined the cell viability after PDT. Using the macroscopic singlet oxygen modeling and cellular photosensitizer concentration the singlet oxygen threshold doses for K562 cells and Hela cells were calculated.

Methyl pyropheophorbide-a analogues: potential fluorescent probes for the peripheral-type benzodiazepine receptor. Effect of central metal in photosensitizing efficacy.

PubMed

Chen, Yihui; Zheng, Xiang; Dobhal, Mahabeer P; Gryshuk, Amy; Morgan, Janet; Dougherty, Thomas J; Oseroff, Allan; Pandey, Ravindra K

2005-06-02

Pyropheophorbides and their metal complexes were synthesized to investigate their applications as nonradioactive peripheral benzodiazepine receptor (PBR) binding probes and photosensitizers for use in photodynamic therapy. They were found to be localized in mitochondria and showed significant binding to PBR. In some cases, the PBR binding values were similar to that for 17 (PK11195, 1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)isoquinoline-3-carboxamide). However, no direct correlation between 17 displacement ability and photosensitizing efficacy of photosensitizers was observed.

Singlet oxygen luminescence kinetics under PDI relevant conditions of pathogenic dermatophytes and molds.

PubMed

Bornhütter, Tobias; Shamali, Nedaa; Saltsman, Irena; Mahammed, Atif; Gross, Zeev; Däschlein, Georg; Röder, Beate

2018-01-01

A treatment of onychomycosis using the photodynamic effect would be a favorable alternative to currently used antimycotic drugs. This study should be considered as a first step towards development and control of an efficient photodynamic inactivation of onychomycosis causative pathogens. Here, we evaluate the usage of time-resolved 2D singlet oxygen luminescence detection in combination with 2D fluorescence scanning as a tool to understand the behavior of the photosensitizer when applied to fungi on Petri dishes. To investigate the interaction of photosensitizer with fungi in various concentrations and in different stages of live, a photodynamic inactivation was avoided by keeping the samples in darkness. Scans of singlet oxygen luminescence and photosensitizer fluorescence were performed over a period of 24days. Two different photosensitizer, a cationic porphyrin and cationic corrole and two fungi strains, the dermatophyte Trichophyton rubrum and the mold Scopulariopsis brevicaulis, were investigated in this study. The two-dimensional correlation of photosensitizer fluorescence and singlet oxygen luminescence revealed differences in the diffusion of both photosensitizer. Even though the singlet oxygen luminescence was quenched with increasing growth of fungi, it was found that the kinetics of singlet oxygen luminescence could be detected on Petri dishes for both photosensitizers and both fungi strains for up to seven days. Copyright © 2017 Elsevier B.V. All rights reserved.

A new detector concept for silicon photomultipliers

NASA Astrophysics Data System (ADS)

Sadigov, A.; Ahmadov, F.; Ahmadov, G.; Ariffin, A.; Khorev, S.; Sadygov, Z.; Suleymanov, S.; Zerrouk, F.; Madatov, R.

2016-07-01

A new design and principle of operation of silicon photomultipliers are presented. The new design comprises a semiconductor substrate and an array of independent micro-phototransistors formed on the substrate. Each micro-phototransistor comprises a photosensitive base operating in Geiger mode and an individual micro-emitter covering a small part of the base layer, thereby creating, together with this latter, a micro-transistor. Both micro-emitters and photosensitive base layers are connected with two respective independent metal grids via their individual micro-resistors. The total value of signal gain in the proposed silicon photomultiplier is a result of both the avalanche gain in the base layer and the corresponding gain in the micro-transistor. The main goals of the new design are: significantly lower both optical crosstalk and after-pulse effects at high signal amplification, improve speed of single photoelectron pulse formation, and significantly reduce the device capacitance.

Tooth color change caused by photosensitizers after photodynamic therapy: An in vitro study.

PubMed

Costa, Larissa Menezes; Matos, Felipe de Souza; Correia, Ayla Macyelle de Oliveira; Carvalho, Nayane Chagas; Faria-E-Silva, André Luís; Paranhos, Luiz Renato; Ribeiro, Maria Amália Gonzaga

2016-07-01

This study aimed to perform an in vitro evaluation of the effect of photosensitizers used in photodynamic therapy (PDT) on tooth color change when used in combination with conventional endodontic treatment. Forty extracted human mandibular premolars were accessed and underwent root canal therapy and PDT. Photosensitizers were used in accordance with the experimental groups: MB (n=10) - PDT with Methylene Blue at 0.01%; TB (n=10) - PDT with Toluidine Blue at 0.01%; MG (n=10) - PDT with Malachite Green at 0.01%, at the concentration of 0.1mg/mL; and PC (n=10) - positive control, PDT with Endo-PTC cream stained with Methylene Blue at 25%. The samples were irradiated with 660-nm diode laser by means of a 330-μm-diameter optical fiber cable at a power density of 40mW for 120s. After light curing, the photosensitizers were removed from the specimens with 10mL sodium hypochlorite at 1%. A reflectance spectrometer was used for evaluation of color prior to and 60days after the experimental procedure based on the CIE L*a*b* system. According to ANOVA test, there were statistically significant differences between the experimental groups (p=0.003). Tukey's test showed a significant difference between PC and TB (p=0.008), as well as between MG and TB (p=0.009). However, there was no statistically significant difference between PC, MG (p=0.957) and MB (p=0.103). It was concluded that the use of PDT as an adjuvant to root canal therapy, using different photosensitizers, led to color change in tooth structure. Copyright © 2016 Elsevier B.V. All rights reserved.

Identification and Molecular Characterization of the Homogentisate Pathway Responsible for Pyomelanin Production, the Major Melanin Constituents in Aeromonas media WS

PubMed Central

Wang, He; Qiao, Yunqian; Chai, Baozhong; Qiu, Chenxi; Chen, Xiangdong

2015-01-01

The pigmentation of many Aeromonas species has been thought to be due to the production of a L-DOPA (L-3,4-dihydroxyphenylalanine) based melanin. However, in this study we found that although L-DOPA synthesis occurs in the high-melanin-yielding Aeromonas media strain WS, it plays a minor, if any, role in pigmentation. Instead, the pigmentation of A. media strain WS is due to the production of pyomelanin through HGA (homogentisate). Gene products of phhA (encodes phenylalanine hydroxylase), tyrB and aspC (both encode aromatic amino acid aminotransferase), and hppD (encodes 4-hydroxyphenylpyruvate dioxygenase) constitute a linear pathway of converting phenylalanine to HGA and disruption of any one of these genes impairs or blocks pigmentation of A. media strain WS. This HGA biosynthesis pathway is widely distributed in Aeromonas, but HGA is only detectable in the cultures of pigmented Aeromonas species. Heterologous expression of HppD from both pigmented and non-pigmented Aeromonas species in E. coli leads to the production of pyomelanin and thus pigmentation, suggesting that most Aeromonas species have the critical enzymes to produce pyomelanin through HGA. Taken together, we have identified a widely conserved biosynthesis pathway of HGA based pyomelanin in Aeromonas that may be responsible for pigmentation of many Aeromonas species. PMID:25793756

Combined photoultrasonic treatment of infected wounds

NASA Astrophysics Data System (ADS)

Zharov, Vladimir P.; Menyaev, Yulian A.; Kalinin, Konstantin L.; Zmievskoy, Gregory N.; Velsher, Leonid Z.; Podkolzin, Alexander A.; Stakhanov, Mikhail L.; Gorchak, Yury Y.; Sarantsev, V. P.

2001-05-01

A new combined photoultrasonic (CPUS) technology for the treatment of infected wounds is suggested. The CPUS principal operation is based on the topical application of a photosensitizer followed by light irradiation in combination with low frequency ultrasonic (US) treatment of wounds. In CPUS, two methods - photodynamic (PDT) and ultrasonic therapies supplement each other beneficially and in conjunction provide a significant effect of deep suppurative inflammatory wounds treatment. The main advantages of the new technology are the combined application of an antibiotic solution and photodynamic therapy to destroy antibiotic- resistant microorganisms, an effective mixing of a photosensitizer in the wound, the US enhancement of photosensitizer impregnation into the membranes of bacteria, the US clearing of wound surface from necrotic products, an increased effective light dose exposure in the whole volume of the deep wound when the light does not penetrate totally inside the wound, an additional bactericidal effect under the US impact, and the combined effect of CPUS activation of the immune system.

Investigation of photodynamic activity of water-soluble porphyrins in vitro and in vivo

NASA Astrophysics Data System (ADS)

Gyulkhandanyan, Grigor V.; Ghambaryan, Sona S.; Amelyan, Gayane V.; Ghazaryan, Robert K.; Arsenyan, Flora H.; Gyulkhandanyan, Aram G.

2006-02-01

Photodynamic therapy (PDT) is the method of photosensitized tumor treatment. It is based on the photosensitizer (PS) selective accumulation in tumors, its subsequent activation under the light influence and oxygen active form formation that results in tumor destruction. Photodynamic action of some new water-soluble porphyrins was investigated in our laboratory. Dose-dependent effect of these porphyrins was shown on PC-12 murine pheochromocytoma cell line. The results revealed that the efficiency of the investigated porphyrins decreased in the following way: TOEPyP (meso-tetra-(4-N-oxyethylpyridyl)porphyrin) > Zn-TOEPyP > Ag-TOEPyP. It was shown that TOEPyP possessed nearly the same photodynamic activity (LD50) as well-known photosensitizer chlorin e6. These porphyrins have also demonstrated quite high photodynamic activity in vivo. The results were obtained in the experiments on white mice with engrafted C-180 (Croker's sarcoma). Antitumor activity of these porphyrins in the dark was 30-40%, whereas photodynamic activity was 45-60%.

Development and photoelectric properties of In/p-Ag{sub 3}AsS{sub 3} surface-barrier structures

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rud', V. Yu., E-mail: rudvas@spbstu.ru; Rud', Yu. V.; Terukov, E. I.

2010-08-15

Homogeneous p-Ag{sub 3}AsS{sub 3} bulk single crystals with rhombic structure have been grown by planar crystallization from melts with atomic composition corresponding to this ternary compound. Photosensitive surface-barrier structures based on the interface between the surface of these crystals and thin films of pure indium are fabricated for the first time. The photosensitivity of fabricated structures is studied in natural and linearly polarized light. Photosensitivity spectra of In/p-Ag{sub 3}AsS{sub 3} structures are measured for the first time and used to determine the nature and energy of interband transitions in p-Ag{sub 3}AsS{sub 3} crystals. The phenomenon of natural photopleochroism is studiedmore » for surface-barrier structures grown on oriented p-Ag{sub 3}AsS{sub 3} single crystals. It is concluded that Ag{sub 3}AsS{sub 3} single crystals can be used in photoconverters of natural and linearly polarized light.« less

Endoplasmic Reticulum-Localized Two-Photon-Absorbing Boron Dipyrromethenes as Advanced Photosensitizers for Photodynamic Therapy.

PubMed

Zhou, Yimin; Cheung, Ying-Kit; Ma, Chao; Zhao, Shirui; Gao, Di; Lo, Pui-Chi; Fong, Wing-Ping; Wong, Kam Sing; Ng, Dennis K P

2018-05-10

Two advanced boron dipyrromethene (BODIPY) based photosensitizers have been synthesized and characterized. With a glibenclamide analogous moiety, these compounds can localize in the endoplasmic reticulum (ER) of HeLa human cervical carcinoma cells and HepG2 human hepatocarcinoma cells. The BODIPY π skeleton is conjugated with two styryl or carbazolylethenyl groups, which can substantially red-shift the Q-band absorption and fluorescence emission and impart two-photon absorption (TPA) property to the chromophores. The TPA cross section of the carbazole-containing analogue reaches a value of 453 GM at 1010 nm. These compounds also behave as singlet oxygen generators with high photostability. Upon irradiation at λ > 610 nm, these photosensitizers cause photocytotoxicity to these two cell lines with IC 50 values down to 0.09 μM, for which the cell death is triggered mainly by ER stress. The two-photon photodynamic activity of the distyryl derivative upon excitation at λ = 800 nm has also been demonstrated.

Intermolecular Structural Change for Thermoswitchable Polymeric Photosensitizer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Park, Wooram; Park, Sin-Jung; Cho, Soojeong

2016-08-17

A switchable photosensitizer (PS), which can be activated at a spe-cific condition beside light, has tremendous advantages for photo-dynamic therapy (PDT). Herein, we developed a thermo-switchable polymeric photosensitizer (T-PPS) by conjugating PS (Pheophor-bide-a, PPb-a) to a temperature-responsive polymer backbone of biocompatible hydroxypropyl cellulose (HPC). Self-quenched PS molecules linked in close proximity by pi-pi stacking in T-PPS were easily transited to an active monomeric state by the tempera-ture induced phase transition of polymer backbones. The tempera-ture responsive inter-molecular interaction changes of PS molecules in T-PPS were demonstrated in synchrotron small-angle X-ray scattering (SAXS) and UV-Vis spectrophotometer analysis. The T-PPS allowed switchablemore » activation and synergistically enhanced cancer cell killing effect at the hyperthermia temperature (45 °C). Our developed T-PPS has the considerable potential not only as a new class of photomedicine in clinics but also as a biosensor based on temperature responsiveness.« less

A study of the interaction of thioindigo dye, with several inorganic host materials

NASA Astrophysics Data System (ADS)

Ramirez, Alejandra

Maya Blue has been the focus of numerous studies and is believed to be a mixture of palygorskite clay and indigo dye.1,2 Several derivatives of this pigment have been developed with intriguing properties. For instance, the dye thioindigo reacts with the palygorskite clay to exhibit a broad range of colors from red to blue under UV-Vis excitation. Based on FT-Raman and computer simulation, previous work performed in our group could relate indigo and thioindigo interaction to the aluminum sites in the framework. 3,4 The work performed with other inorganic host materials such as, layer structures and zeolites have displayed reversible acid indicator properties, similar to the ones observed in concentrated sulfuric acid. Spectroscopic analyses and computer modeling of the above mentioned interactions have been evaluated. Results obtained by these techniques showed that in dehydrated materials a disturbance of thioindigo C=O at 1655 cm-1 to lower frequencies occurs, due to the C=O---Lewis acid sites (LAS) interaction. In the presence of water, a smaller C=O shift due to C=O---HO(H)LAS was observed. Moreover, displacement of the 001 plane in some layer materials confirmed the effect of water on the color changes displayed by UV-Vis spectroscopy. Based on these premises, it was concluded that weak electron donor-acceptor interactions took place between thioindigo functional groups (electron donors) and LAS of the aluminum silicate framework (electron acceptor). LAS (extra-framework aluminum and exchangeable cations) high hydration enthalpy made them extremely susceptible to water molecules (electron donors); generating a hydrogen bond between the two sites. The reversibility of these chromatic hybrid materials could have potential applications as water sensors and charge transfer photosensitizers in nanocrystalline TiO2-based solar cells.

Potential Role of Carotenoids as Antioxidants in Human Health and Disease

PubMed Central

Fiedor, Joanna; Burda, Květoslava

2014-01-01

Carotenoids constitute a ubiquitous group of isoprenoid pigments. They are very efficient physical quenchers of singlet oxygen and scavengers of other reactive oxygen species. Carotenoids can also act as chemical quenchers undergoing irreversible oxygenation. The molecular mechanisms underlying these reactions are still not fully understood, especially in the context of the anti- and pro-oxidant activity of carotenoids, which, although not synthesized by humans and animals, are also present in their blood and tissues, contributing to a number of biochemical processes. The antioxidant potential of carotenoids is of particular significance to human health, due to the fact that losing antioxidant-reactive oxygen species balance results in “oxidative stress”, a critical factor of the pathogenic processes of various chronic disorders. Data coming from epidemiological studies and clinical trials strongly support the observation that adequate carotenoid supplementation may significantly reduce the risk of several disorders mediated by reactive oxygen species. Here, we would like to highlight the beneficial (protective) effects of dietary carotenoid intake in exemplary widespread modern civilization diseases, i.e., cancer, cardiovascular or photosensitivity disorders, in the context of carotenoids’ unique antioxidative properties. PMID:24473231

Magnesium phthalocyanine(MgPc) thin films as nanomaterials

NASA Astrophysics Data System (ADS)

Puri, Munish; Bedi, R. K.; Prakash, G. V.

2006-05-01

MgPc is a promising candidate for photovoltaic applications. It can be easily synthesized and is non-toxic to the envioronment. It is a self assembly molecule developed from deep-blue-green pigment. It exhibits a characteristic structural self organization which is reflected in an efficient energy migration in the form of extinction transport. MgPc relates to the similarity with chlorophyll. In the present work thin films of MgPc have been prepared on glass substrate under strict vacuum conditions(10 Â6 torr), thickness of few nanometers. Absorption spectra in Visible and IR regions have been observed which is good for fabrication of Photovoltaic cells and Nanostructures for Photodynamic Cancer Therapy. Appreciable amount of cytotoxicity can be observed while using MgPc as photosensitizers which is a promising PDT agent. The films thus prepared have been studied for their electrical and optical characterizations. Investigations have been made from different stacking positions of molecular MgPc thin films for studying their self-assembling nature that can be useful for their applications as Molecular-Recognition in Drug delivery and sensors which is one of the key features of Nanotechnology.

A novel function for the pineal organ in the control of swim depth in the Atlantic halibut larva

NASA Astrophysics Data System (ADS)

Novales Flamarique, Iñigo

2002-02-01

The pineal organ of vertebrates is a photo-sensitive structure that conveys photoperiod information to the brain. This information influences circadian rhythm and related metabolic processes such as thermoregulation, hatching time, body growth, and the timing of reproduction. This study demonstrates extra-ocular light responses that control swim depth in the larva of the Atlantic halibut, Hyppoglosus hyppoglosus. Young larvae without a functional eye (<29 days) swim upwards after an average delay of 5 s following the onset of a downwelling light stimulus, but sink downwards a few seconds later. Older larvae (>=29 days), which possess a functional eye, swim immediately downwards (microsecond delay) following the onset of the light stimulus, but proceed to swim upwards several seconds later. These two response patterns are thus opposite in polarity and have different time kinetics. Because the pineal organ of the Atlantic halibut develops during the embryonic stage, and because it is the only centre in the brain that expresses functional visual pigments (opsins) at early larval stages, it is the only photosensory organ capable of generating the extra-ocular responses observed.

Xeroderma Pigmentosum.

PubMed

Black, Jennifer O

2016-06-01

Xeroderma pigmentosum (XP) is a rare disorder of defective UV-radiation induced damage repair that is characterized by photosensitivity with easy skin burning following minimal sun exposure, early freckling and development of lentiginous pigmentation along with other features of poikiloderma and a propensity for developing skin cancer at an early age. In this short review, the clinical, pathological, genetic and molecular aspects of XP are reviewed in the current literature. XP encompasses a spectrum of disease that overlaps with other diseases of DNA repair systems. In addition to cutaneous complications, patients are susceptible to eye conditions, neurodegenerative processes, central nervous system tumors and other tumors as a result of UV radiation exposure and its byproducts. Patients with XP frequently experience a shorter life span due to skin cancer and neurodegenerative sequelae, but aggressive preventative measures to minimize UV radiation exposure and damage can improve the course of disease and prolong life. The disease has served as a model for photoaging and UV radiation-induced cancer and has led to a better understanding of cell processes that prevent development of these disease features in normal individuals.

Effective photosensitization-based inactivation of Gram (-) food pathogens and molds using the chlorophyllin-chitosan complex: towards photoactive edible coatings to preserve strawberries.

PubMed

Buchovec, Irina; Lukseviciute, Viktorija; Marsalka, Arunas; Reklaitis, Ignas; Luksiene, Zivile

2016-04-01

This study is focused on the novel approaches to enhance the inactivation of the Gram (-) food pathogen Salmonella enterica and harmful molds in vitro and on the surface of strawberries using the chlorophyllin-chitosan complex. Salmonella enterica (∼1 × 10(7) CFU mL(-1)) was incubated with chlorophyllin 1.5 × 10(-5) M (Chl, food additive), chitosan 0.1% (CHS, food supplement) or the chlorophyllin-chitosan complex (1.5 × 10(-5) M Chl-0.1% CHS) and illuminated with visible light (λ = 405 nm, light dose 38 J cm(-2)) in vitro. Chlorophyllin (Chl)-based photosensitization inactivated Salmonella just by 1.8 log. Chitosan (CHS) alone incubated for 2 h with Salmonella reduced viability 2.15 log, whereas photoactivated Chl-CHS diminished bacterial viability by 7 log. SEM images indicate that the Chl-CHS complex under these experimental conditions covered the entire bacterial surface. Significant cell membrane disintegration was the main lethal injury induced in Gram (-) bacteria by this treatment. Analysis of strawberry decontamination from surface-inoculated Salmonella indicated that photoactivated Chl-CHS (1.5 × 10(-5) M Chl-0.1% CHS, 30 min incubation, light dose 38 J cm(-2)) coatings diminished the pathogen population on the surface of strawberries by 2.2 log. Decontamination of strawberries from naturally distributed yeasts/molds revealed that chitosan alone reduced the population of yeasts/molds just by 0.4 log, Chl-based photosensitization just by 0.9 log, whereas photoactivated Chl-CHS coatings reduced yeasts/molds on the surface of strawberries by 1.4 log. Electron paramagnetic resonance spectroscopy confirmed that no additional photosensitization-induced free radicals have been found in the strawberry matrix. Visual quality (color, texture) of the treated strawberries was not affected either. In conclusion, photoactive Chl-CHS exhibited strong antimicrobial action against more resistant to photosensitization Gram (-) Salmonella enterica in comparison with Gram (+) bacteria in vitro. It reduced significantly the viability of strawberry surface-attached yeasts/molds and inoculated Salmonella without any negative impact on the visual quality of berries. Experimental data support the idea that photoactivated Chl-CHS can be a useful tool for the future development of edible photoactive antimicrobial coatings which can preserve strawberries and prolong their shelf-life according to requirements of "clean green technology".

Preparation of nearly monodisperse nanoscale inorganic pigments.

PubMed

Wang, Dingsheng; Liang, Xin; Li, Yadong

2006-07-17

Many different important commercial pigments have been synthesized based on the liquid-solid-solution (LSS) phase-transfer and separation process. Transmission electron microscopy (TEM) measurement results show that they are very small in size and have a narrow size distribution. Visible absorption spectra were taken to examine the very pure and brilliant colors of the pigments. They can be well-dispersed in cyclohexane and remain non-agglomerated, even over several months. These nearly monodisperse nanoscale inorganic pigments may have wide applications in many important fields and could bring about new developments in the pigment industry.

Action spectrum and mechanisms of UV radiation-induced injury in lupus erythematosus

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kochevar, I.E.

1985-07-01

Photosensitivity associated with lupus erythematosus (LE) is well established. The photobiologic basis for this abnormal response to ultraviolet radiation, however, has not been determined. This paper summarizes the criteria for elucidating possible photobiologic mechanisms and reviews the literature relevant to the mechanism of photosensitivity in LE. In patients with LE, photosensitivity to wavelengths shorter than 320 nm has been demonstrated; wavelengths longer than 320 nm have not been adequately evaluated. DNA is a possible chromophore for photosensitivity below 320 nm. UV irradiation of skin produces thymine photodimers in DNA. UV-irradiated DNA is more antigenic than native DNA and the antigenicitymore » of UV-irradiated DNA has been proposed, but not proven, to be involved in the development of clinical lesions. UV irradiation of mice previously injected with anti-UV-DNA antibodies produces Ig deposition and complement fixation that appears to be similar to the changes seen in lupus lesions. Antibodies to UV-irradiated DNA occur in the serum of LE patients although a correlation between antibody titers and photosensitivity was not observed. Defective repair of UV-induced DNA damage does not appear to be a mechanism for the photosensitivity in LE. Other mechanisms must also be considered. The chromophore for photosensitivity induced by wavelengths longer than 320 nm has not been investigated in vivo. In vitro studies indicate that 360-400 nm radiation activates a photosensitizing compound in the lymphocytes and serum of LE patients and causes chromosomal aberrations and cell death. The mechanism appears to involve superoxide anion.« less

Organic photosensitive devices

DOEpatents

Rand, Barry P; Forrest, Stephen R

2013-11-26

The present invention generally relates to organic photosensitive optoelectronic devices. More specifically, it is directed to organic photosensitive optoelectronic devices having a photoactive organic region containing encapsulated nanoparticles that exhibit plasmon resonances. An enhancement of the incident optical field is achieved via surface plasmon polariton resonances. This enhancement increases the absorption of incident light, leading to a more efficient device.

Mechanism of colon cancer cell apoptosis mediated by pyropheophorbide-a methylester photosensitization.

PubMed

Matroule, J Y; Carthy, C M; Granville, D J; Jolois, O; Hunt, D W; Piette, J

2001-07-05

Pyropheophorbide-a methylester (PPME) is a second generation of photosensitizers used in photodynamic therapy (PDT). We demonstrated that PPME photosensitization triggered apoptosis of colon cancer cells as measured by using several classical parameters such as DNA laddering, PARP cleavage, caspase activation and mitochondrial release of cytochrome c. Preincubation of cells with N-acetyl cysteine (NAC) or pyrolidine dithiocarbamate (PDTC) protected against apoptosis mediated by PPME photosensitization showing that reactive oxygen species (ROS) are involved as second messengers. On the other hand, photosensitization carried out in the presence of deuterium oxide (D2O) which enhances singlet oxygen (1O2) lifetime only increases necrosis without affecting apoptosis. Since PPME was localized in the endoplasmic reticulum (ER)/Golgi system and lysosomes, other messengers than ROS were tested such as calcium, Bid, Bap31, phosphorylated Bcl-2 and caspase-12 but none was clearly identified as being involved in triggering cytochrome c release from mitochondria. On the other hand, we demonstrated that the transduction pathways leading to NF-kappaB activation and apoptosis were clearly independent although NF-kappaB was shown to counteract apoptosis mediated by PPME photosensitization.

Non-provocative diagnostics of photosensitivity using visual evoked potentials.

PubMed

Vermeulen, Joost; Kalitzin, Stiliyan; Parra, Jaime; Dekker, Erwin; Vossepoel, Albert; da Silva, Fernando Lopes

2008-04-01

Photosensitive epilepsy (PSE) is the most common form of reflex epilepsy. Usually, to find out whether a patient is sensitive, he/she is stimulated visually with, e.g. a stroboscopic light stimulus at variable frequency and intensity until a photo paroxysmal response (PPR) occurs. The research described in this work aims to find whether photosensitivity can be detected without provoking a PPR. Twenty-two subjects, 15 with known photosensitivity, were stimulated with visual stimuli that did not provoke a PPR. Using an "evoked response representation", 18 features were analytically derived from EEG signals. Single- and multi-feature classification paradigms were applied to extract those features that separate best subjects with PSE from controls. Two variables in the "evoked response representation", a frequency term and a goodness of fit term to a particular template, appeared to be best suited to make a prediction about the photosensitivity of a subject. Evoked responses appear to carry information about potential PSE. This result can be useful for screening patients for photosensitivity and it may also help to assess in a quantitative way the effectiveness of medical therapy.

New insights into the red and green pigments in the illuminated foral charter of Setubal (1515) by combined use of μ-Raman and X-ray fluorescence spectrometry

NASA Astrophysics Data System (ADS)

Guerra, M.; Carvalho, M. L.; Le Gac, A.; Manso, M.; Mortari, C.; Longelin, S.; Pessanha, S.

2016-03-01

The richly decorated foral charter attributed by D. Manuel I of Portugal, in 1515, to the village of Setubal, was studied using Energy Dispersive X-ray Fluorescence spectrometry and Raman micro-spectroscopy. An in situ characterization of the pigments used in the production of this masterpiece showed a very different pigment palette choice when compared to other similar Manueline charters. The red and green pigments are particularly puzzling, as the widely used mercury- and copper-based pigments, vermillion and malachite, respectively, were not found in the illuminated frontispiece. Instead, the cheaper lead-based pigment minium was used in the King's flag, while a mixture of copper sulfates was found for the green color, identified by means of micro-Raman spectroscopy. This result led to a new look at the conception that only one Royal workshop existed for the elaboration of Manueline foral charters.

Efficacy and safety of topical depigmenting agent in healthy human fair skin female volunteers: A single-arm study.

PubMed

Shah, Saurabh; Chew, Soon-Keong

2017-11-28

Skin hyperpigmentation is the darkening of skin due to the increased production of melanin in the body. To evaluate the efficacy and safety of a botanical-based Rosa E pigmentation serum in healthy fair skin female volunteers with wrinkles, skin tone, and pigmentation. This was a single-arm, open label study conducted in healthy Indian females; 18 subjects aged 30-55, having fair Caucasian-like skin with at least 2 dark skin pigments with facial wrinkles diagnosed by dermatologist were selected. Rosa E pigmentation serum was applied twice a day for 84 days. Effect was evaluated by (i) instrumental technique (spectrophotometer ® 2600D), (ii) clinically by dermatologist regarding product efficacy (skin tone, antiwrinkle, pigmentation), and (iii) volunteers self-evaluation. The L* value of spectrophotometer reading represents lightness in the skin pigment. Reduction in the pigment was reported from day 14, with significant reductions observed till day 84 compared with baseline. Significant (P < .0001) skin pigmentation lightening was seen on day 14 (1.11) vastly improving on day 84 (1.94) based on photographic assessments. The significant reduction in skin pigment was 76.85%, Felix von Luschan skin color score was 30.24% (P < .0001) with a 7.38-fold reduction in skin tone and 57% reduction in facial wrinkles at day 84 from baseline. Rosa E pigmentation serum was found safe and effective in significant reduction in skin pigments, improvement of skin tone, and antiwrinkle properties instrumentally, clinically, and self-evaluation by volunteers. In these evaluations, best results were seen the longer the Rosa E was used. © 2017 Wiley Periodicals, Inc.

Sugarcane bagasse hydrolysate as a potential feedstock for red pigment production by Monascus ruber.

PubMed

Terán Hilares, Ruly; de Souza, Rebeca Andrade; Marcelino, Paulo Franco; da Silva, Silvio Silvério; Dragone, Giuliano; Mussatto, Solange I; Santos, Júlio César

2018-04-15

Sugarcane bagasse (SCB) hydrolysate could be an interesting source for red pigment production by Monascus ruber Tieghem IOC 2225. The influence of different wavelength of light-emitting diode (LED) at 250 μmol.m -2 .s -1 of photon flux density on red pigment production by M. ruber in glucose-based medium was evaluated. Then, SCB hydrolysate was used as carbon source under the previously selected light incidence conditions. In glucose-based medium, the highest pigment production was achieved in fermentation assisted with orange LED light (8.28 UA 490nm ), white light (8.26 UA 490nm ) and under dark condition (7.45 UA 490nm ). By using SCB hydrolysate-based medium, the highest red pigment production (18.71 AU 490nm ) was achieved under dark condition and the glucose and cellobiose present in the hydrolysate were metabolized. SCB enzymatic hydrolysate was demonstrated to be a promising carbon source for high thermal stability red pigment production (activation energy of 10.5 kcal.mol -1 ), turning an interesting alternative for implementation in biorefineries. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Analysis of pigments from Rhodotorula glutinis by Raman spectroscopy and thin layer chromatography].

PubMed

Yuan, Yu-feng; Tao, Zhan-hua; Wang, Xue; Li, Yong-qing; Liu, Jun-xian

2012-03-01

The pigments from Rhodotorula glutinis were separated by using thin layer chromatography, and the result showed that Rhodotorula glutinis cells could synthesize at least three kinds of pigments, which were beta-carotene, torulene, and torularhodin. The Raman spectra based on the three pigments were acquired, and original spectra were preprocessed by background elimination, baseline correction, and three-point-smoothing, then the averaged spectra from different pigments were investigated, and the result indicated that Raman shift which represents C-C bond was different, and the wave number of beta-carotene demonstrated the largest deviation, finally torulene and torularhodin in Rhodotorula glutinis had more content than beta-carotene. Quantitative analysis of Raman peak height ratio revealed that peak height ratio of pigments showed little difference, which could be used as parameters for further research on living cells, providing reference content of pigments. The above results suggest that Raman spectroscopy combined with thin layer chromatography can be applied to analyze pigments from Rhodotorula glutinis, provides abundant information about pigments, and serves as an effective method to study pigments.

The in vitro photodynamic effect of laser activated gallium, indium and iron phthalocyanine chlorides on human lung adenocarcinoma cells.

PubMed

Maduray, K; Odhav, B

2013-11-05

Metal-based phthalocyanines currently are utilized as a colorant for industrial applications but their unique properties also make them prospective photosensitizers. Photosensitizers are non-toxic drugs, which are commonly used in photodynamic therapy (PDT), for the treatment of various cancers. PDT is based on the principle that, exposure to light shortly after photosensitizer administration predominately leads to the production of reactive oxygen species for the eradication of cancerous cells and tissue. This in vitro study investigated the photodynamic effect of gallium (GaPcCl), indium (InPcCl) and iron (FePcCl) phthalocyanine chlorides on human lung adenocarcinoma cells (A549). Experimentally, 2 × 10(4)cells/ml were seeded in 24-well tissue culture plates and allowed to attach overnight, after which cells were treated with different concentrations of GaPcCl, InPcCl and FePcCl ranging from 2 μg/ml to 100 μg/ml. After 2h, cells were irradiated with constant light doses of 2.5 J/cm(2), 4.5 J/cm(2) and 8.5 J/cm(2) delivered from a diode laser (λ = 661 nm). Post-irradiated cells were incubated for 24h before cell viability was measured using the MTT Assay. At 24h after PDT, irradiation with a light dose of 2.5 J/cm(2) for each photosensitizing concentration of GaPcCl, InPcCl and FePcCl produced a significant decrease in cell viability, but when the treatment light dose was further increased to 4.5 J/cm(2) and 8.5 J/cm(2) the cell survival was less than 40%. Results also showed that photoactivated FePcCl decreased cell survival of A549 cells to 0% with photosensitizing concentrations of 40 μg/ml and treatment light dose of 2.5 J/cm(2). A 20 μg/ml photosensitizing concentration of FePcCl in combination with an increased treatment light dose of either 4.5 J/cm(2) or 8.5 J/cm(2) also resulted in 0% cell survival. This PDT study concludes that low concentrations on GaPcCl, InPcCl and FePcCl activated with low level light doses can be used for the effective in vitro killing of lung cancer cells. Copyright © 2013 Elsevier B.V. All rights reserved.

Voltage-sensitive styryl dyes as singlet oxygen targets on the surface of bilayer lipid membrane.

PubMed

Sokolov, V S; Gavrilchik, A N; Kulagina, A O; Meshkov, I N; Pohl, P; Gorbunova, Yu G

2016-08-01

Photosensitizers are widely used as photodynamic therapeutic agents killing cancer cells by photooxidation of their components. Development of new effective photosensitive molecules requires profound knowledge of possible targets for reactive oxygen species, especially for its singlet form. Here we studied photooxidation of voltage-sensitive styryl dyes (di-4-ANEPPS, di-8-ANEPPS, RH-421 and RH-237) by singlet oxygen on the surface of bilayer lipid membranes commonly used as cell membrane models. Oxidation was induced by irradiation of a photosensitizer (aluminum phthalocyanine tetrasulfonate) and monitored by the change of dipole potential on the surface of the membrane. We studied the drop of the dipole potential both in the case when the dye molecules were adsorbed on the same side of the lipid bilayer as the photosensitizer (cis-configuration) and in the case when they were adsorbed on the opposite side (trans-configuration). Based on a simple model, we determined the rate of oxidation of the dyes from the kinetics of change of the potential during and after irradiation. This rate is proportional to steady-state concentration of singlet oxygen in the membrane under irradiation. Comparison of the oxidation rates of various dyes reveals that compounds of ANEPPS series are more sensitive to singlet oxygen than RH type dyes, indicating that naphthalene group is primarily responsible for their oxidation. Copyright © 2016 Elsevier B.V. All rights reserved.

Photophysical and Photochemical Properties of 3-methylpterin as a New and More Stable Pterin-type Photosensitizer.

PubMed

Estébanez, Sandra; Lorente, Carolina; Kaufman, Teodoro S; Larghi, Enrique L; Thomas, Andrés H; Serrano, Mariana P

2018-05-04

Pterin derivatives are heterocyclic compounds which are present in different biological systems. Neutral aqueous solutions of pterins presents acid-base and keto-enol equilibria. These compounds under UV-A radiation fluoresce, undergo photooxidation, generate reactive oxygen species, and photoinduce the oxidation of biological substrates. As photosensitizers, they may act through different mechanisms; mainly through an electron-transfer initiated process (type I mechanism), but they also produce singlet molecular oxygen ( 1 O 2 ) upon irradiation (type II mechanism). In general, upon UV-A excitation two triplet states, corresponding to the lactim and lactam tautomers, are formed, but only the last one is the responsible for the photosensitized reactions of biomolecules. We present a study of the photochemical properties of 3-methylpterin (3-Mep) which, in contrast to most pterin derivatives, exists only in the lactam form. Also an improvement in the synthesis of 3-Mep is reported. The spectroscopic properties 3-Mep in aqueous solution were similar to those of the unsubstituted pterin derivative (Ptr) in its acid form, such as absorption, fluorescent and phosphorescent emission spectra. Experiments using 2'-deoxyguanosine 5'-monophosphate (dGMP) as oxidizable target, demonstrated that methylation at C-3 position of the pterin moiety does not affect significantly the efficiency of photosensitization, but results in a more photostable sensitizer. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

An investigation of multispectral imaging for the mapping of pigments in paintings

NASA Astrophysics Data System (ADS)

Zhao, Yonghui; Berns, Roy S.; Taplin, Lawrence A.; Coddington, James

2008-02-01

Compared with colorimetric imaging, multispectral imaging has the advantage of retrieving spectral reflectance factor of each pixel of a painting. Using this spectral information, pigment mapping is concerned with decomposing the spectrum into its constituent pigments and their relative contributions. The output of pigment mapping is a series of spatial concentration maps of the pigments comprising the painting. This approach was used to study Vincent van Gogh's The Starry Night. The artist's palette was approximated using ten oil pigments, selected from a large database of pigments used in oil paintings and a priori analytical research on one of his self portraits, executed during the same time period. The pigment mapping was based on single-constant Kubelka-Munk theory. It was found that the region of blue sky where the stars were located contained, predominantly, ultramarine blue while the swirling sky and region surrounding the moon contained, predominantly, cobalt blue. Emerald green, used in light bluish-green brushstrokes surrounding the moon, was not used to create the dark green in the cypresses. A measurement of lead white from Georges Seurat's La Grande Jatte was used as the white when mapping The Starry Night. The absorption and scattering properties of this white were replaced with a modern dispersion of lead white in linseed oil and used to simulate the painting's appearance before the natural darkening and yellowing of lead white oil paint. Pigment mapping based on spectral imaging was found to be a viable and practical approach for analyzing pigment composition, providing new insight into an artist's working method, the possibility for aiding in restorative inpainting, and lighting design.

Anchoring energy of photo-sensitive polyimide alignment film containing methoxy cinnamate

NASA Astrophysics Data System (ADS)

Kim, Suyoung; Shin, Sung Eui; Shin, DongMyung

2010-02-01

Photosensitive polyimide containing 2-methoxy cinnamate was synthesized for photo-alignment layer of liquid crystals (LCs). 2-Methoxy cinnamic acid was confirmed photo-sensitive material by linearly polarized UV light. We studied that effect of polarized UV light on rubbed polyimide film. Anchoring energy of liquid crystal with aligning surface was measured. Irradiation of depolarized UV light on rubbed Polyimide film suppressed effective anchoring energy. Linearly polarized UV light on rubbed polyimide film controlled anchoring energy effectively. Polyimide film containing 2-methoxy cinnamate can control the photo-alignment layer easily due to its photo-sensitivity.

Pigmentation Phenotype, Photosensitivity, and Skin Neoplasms in Patients with Myotonic Dystrophy

PubMed Central

Gadalla, Shahinaz M.; Hilbert, James E.; Martens, William B.; Givens, Shannon; Moxley, Richard T.; Greene, Mark H.

2017-01-01

Background Recent studies have suggested a possible excess risk of skin neoplasms in patients with myotonic dystrophy (DM). Risk factors related to this observation have not been defined. Method We collected information regarding personal history of skin tumors, pigmentation phenotype, and skin reaction to sun exposure from 266 DM patients who were enrolled in the US NIH National Registry of Myotonic Dystrophy and Facioscapulohumeral Muscular Dystrophy Patients and Family Members. Results Seventy-seven subjects reported having skin tumors that were either benign (n=31), malignant (n=32), or both (n=14). Female gender (OR=2.27, 95%CI=1.02–5.05, p=0.04), older age (OR=1.10, 95%CI=1.05–1.16, p<0.001), and DM1 subtype (OR=3.42, 95%CI=1.27–9.26, p=0.02) were associated with a malignant skin tumor. The association between malignant skin tumors and known risk factors [light eye color (OR=1.62, 95%CI=0.78–3.39, p=0.20); light skin complexion (OR=1.31, 95% CI=0.63–2.73, p=0.48), moderate/extensive face freckles (OR=1.47, 95% CI=0.50–4.34, p=0.49)] were modest. Strong, but not statistically significant, associations were noted with sunburn reactions when exposed to sunlight (OR=4.28, 95%CI=0.91–19.95, p=0.06, and 2.19, 95%CI=0.67–7.09, p=0.19 for sunburns with and without blistering, respectively). Conclusions Although our study was limited by small sample size, the risk factors for malignant skin tumors in DM strongly resemble the general population. We recommend that DM patients adhere to sun exposure protective behavior. PMID:28317292

A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells.

PubMed

Prima, Eka Cahya; Hidayat, Novianto Nur; Yuliarto, Brian; Suyatman; Dipojono, Hermawan Kresno

2017-01-15

This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulata and Musa acuminata fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31+G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet-visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31+G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulata) will be further investigated compared to the gallocatechin (Musa acuminata) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulata cell under continuous light exposure of 100mW·cm -2 yields a short-circuit current density (J sc ) of 3.23mA/cm 2 , a photovoltage (V oc ) of 0.48V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (η) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dye's absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2μm, the fastest electron transit of 0.22ms, and the longest electron lifetime of 4.29ms. Copyright © 2016 Elsevier B.V. All rights reserved.

A combined spectroscopic and TDDFT study of natural dyes extracted from fruit peels of Citrus reticulata and Musa acuminata for dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Prima, Eka Cahya; Hidayat, Novianto Nur; Yuliarto, Brian; Suyatman; Dipojono, Hermawan Kresno

2017-01-01

This study reports the novel spectroscopic investigations and enhanced the electron transfers of Citrus reticulata and Musa acuminata fruit peels as the photosensitizers for the dye-sensitized solar cells. The calculated TD-DFT-UB3LYP/6-31 + G(d,p)-IEFPCM(UAKS), experiment spectra of ultra-violet-visible spectroscopy, and Fourier transform infrared spectroscopy studies indicate the main flavonoid (hesperidin and gallocatechin) structures of the dye extracts. The optimized flavonoid structures are calculated using Density functional theory (DFT) at 6-31 + G(d,p) level. The rutinosyl group of the hesperidin pigment (Citrus reticulata) will be further investigated compared to the gallocatechin (Musa acuminata) pigment. The acidity of the dye extract is treated by adding 2% acetic acid. The energy levels of the HOMO-LUMO dyes are measured by a combined Tauc plot and cyclic voltammetry contrasted with the DFT data. The electrochemical impedance spectroscopy will be performed to model the dye electron transfer. As for the rutinosyl group presence and the acidic treatment, the acidified Citrus reticulata cell under continuous light exposure of 100 mW·cm- 2 yields a short-circuit current density (Jsc) of 3.23 mA/cm2, a photovoltage (Voc) of 0.48 V, and a fill factor of 0.45 corresponding to an energy conversion efficiency (η) of 0.71% because the shifting down HOMO-LUMO edges and the broadening dye's absorbance evaluated by a combined spectroscopic and TD-DFT method. The result also leads to the longest diffusion length of 32.2 μm, the fastest electron transit of 0.22 ms, and the longest electron lifetime of 4.29 ms.

Violaxanthin de-epoxidase is rate-limiting for non-photochemical quenching under subsaturating light or during chilling in Arabidopsis.

PubMed

Chen, Zhong; Gallie, Daniel R

2012-09-01

In response to conditions of excess light energy, plants induce non-photochemical quenching (NPQ) as a protective mechanism to prevent over reduction of photosystem II and the generation of reactive oxygen species (ROS). The xanthophyll cycle, which contributes significantly to reversible NPQ to thermally dissipate excess absorbed light energy, involves de-epoxidation of violaxanthin and antheraxanthin to zeaxanthin in response to excess light energy. The activation of violaxanthin de-epoxidase (VDE), which catalyzes the de-epoxidation reaction, requires the generation of a light-induced, transthylakoid pH gradient. In this work, we overexpressed or repressed the expression of VDE in Arabidopsis (Arabidopsis thaliana) to examine whether VDE is rate-limiting for the induction of NPQ. Increasing VDE expression increased the de-epoxidation state of xanthophyll pigments, the rate of NPQ induction, and the level of NPQ achieved under subsaturating light. In saturating light, however, overexpression of VDE did not increase the xanthophyll pigment de-epoxidation state, the level of NPQ achieved following its initial induction, or substantially improve tolerance to high light. Only under chilling, which reduces VDE activity, did an increase in VDE expression provide slightly greater phototolerance. Repression of VDE expression impaired violaxanthin de-epoxidation, reduced the generation of NPQ, and lowered the level of NPQ achieved while increasing photosensitivity. These results demonstrate that the endogenous level of VDE is rate-limiting for NPQ in Arabidopsis under subsaturating but not saturating light and can become rate-limiting under chilling conditions. These results also show that increasing VDE expression confers greater phototolerance mainly under conditions which limit endogenous VDE activity. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Anti-corrosion properties of coatings with manganese compounds pigmentation

NASA Astrophysics Data System (ADS)

Ziganshina, M.; Nurislamova, E.

2018-02-01

Work investigates properties of corrosion-resistant coatings based on organic-aqueous emulsion and pigmented compounds of manganese, obtained by ceramic method. It is found that the inclusion of synthesized pigments in the composition of the coating increases their ability to inhibit underfilm corrosion of steel.

Pigment production on L-tryptophan medium by Cryptococcus gattii and Cryptococcus neoformans.

PubMed

Chaskes, Stuart; Cammer, Michael; Nieves, Edward; Casadevall, Arturo

2014-01-01

In recent years strains previously grouped within Cryptococcus neoformans have been divided into two species C. neoformans and C. gattii, with Cryptococcus neoformans comprising serotypes A, D, and AD and C. gattii comprising serotypes B and C. Cryptococcus neoformans have also been subdivided into two varieties C. neoformans var. grubii, serotype A, and C. neoformans var. neoformans, serotype D. We analyzed the growth and pigment production characteristics of 139 strains of Cryptococcus spp. in L-tryptophan containing media. Nearly all strains of Cryptococcus, including each variety and serotype tested produced a pink water-soluble pigment (molecular weight of 535.2 Da) from L-tryptophan. Consequently, the partial separation of the species was based on whether the pink pigment was secreted into the medium (extracellular) or retained as an intracellular pigment. On L-tryptophan medium C. neoformans var. grubii and serotype AD produced a pink extracellular pigment. In contrast, for C. gattii, the pink pigment was localized intracellularly and masked by heavy production of brown pigments. Pigment production by C. neoformans var. neoformans was variable with some strains producing the pink extracellular pigment and others retained the pink pigment intracellularly. The pink intracellular pigment produced by strains of C. neoformans var. neoformans was masked by production of brown pigments. Cryptococcus laccase mutants failed to produce pigments from L-tryptophan. This is the first report that the enzyme laccase is involved in tryptophan metabolism. Prior to this report Cryptococcus laccase produced melanin or melanin like-pigments from heterocyclic compounds that contained ortho or para diphenols, diaminobenzenes and aminophenol compounds. The pigments produced from L-tryptophan were not melanin.

PDT dose dosimetry for Photofrin-mediated pleural photodynamic therapy (pPDT)

NASA Astrophysics Data System (ADS)

Ong, Yi Hong; Kim, Michele M.; Finlay, Jarod C.; Dimofte, Andreea; Singhal, Sunil; Glatstein, Eli; Cengel, Keith A.; Zhu, Timothy C.

2018-01-01

Photosensitizer fluorescence excited by photodynamic therapy (PDT) treatment light can be used to monitor the in vivo concentration of the photosensitizer and its photobleaching. The temporal integral of the product of in vivo photosensitizer concentration and light fluence is called PDT dose, which is an important dosimetry quantity for PDT. However, the detected photosensitizer fluorescence may be distorted by variations in the absorption and scattering of both excitation and fluorescence light in tissue. Therefore, correction of the measured fluorescence for distortion due to variable optical properties is required for absolute quantification of photosensitizer concentration. In this study, we have developed a four-channel PDT dose dosimetry system to simultaneously acquire light dosimetry and photosensitizer fluorescence data. We measured PDT dose at four sites in the pleural cavity during pleural PDT. We have determined an empirical optical property correction function using Monte Carlo simulations of fluorescence for a range of physiologically relevant tissue optical properties. Parameters of the optical property correction function for Photofrin fluorescence were determined experimentally using tissue-simulating phantoms. In vivo measurements of photosensitizer fluorescence showed negligible photobleaching of Photofrin during the PDT treatment, but large intra- and inter-patient heterogeneities of in vivo Photofrin concentration are observed. PDT doses delivered to 22 sites in the pleural cavity of 8 patients were different by 2.9 times intra-patient and 8.3 times inter-patient.

Relative Pigment Composition and Remote Sensing Reflectance of Caribbean Shallow-Water Corals

PubMed Central

Torres-Pérez, Juan L.; Guild, Liane S.; Armstrong, Roy A.; Corredor, Jorge; Zuluaga-Montero, Anabella; Polanco, Ramón

2015-01-01

Reef corals typically contain a number of pigments, mostly due to their symbiotic relationship with photosynthetic dinoflagellates. These pigments usually vary in presence and concentration and influence the spectral characteristics of corals. We studied the variations in pigment composition among seven Caribbean shallow-water Scleractinian corals by means of High Performance Liquid Chromatography (HPLC) analysis to further resolve the discrimination of corals. We found a total of 27 different pigments among the coral species, including some alteration products of the main pigments. Additionally, pigments typically found in endolithic algae were also identified. A Principal Components Analysis and a Hierarchical Cluster Analysis showed the separation of coral species based on pigment composition. All the corals were collected under the same physical environmental conditions. This suggests that pigment in the coral’s symbionts might be more genetically-determined than influenced by prevailing physical conditions of the reef. We further investigated the use of remote sensing reflectance (Rrs) as a tool for estimating the total pigment concentration of reef corals. Depending on the coral species, the Rrs and the total symbiont pigment concentration per coral tissue area correlation showed 79.5–98.5% confidence levels demonstrating its use as a non-invasive robust technique to estimate pigment concentration in studies of coral reef biodiversity and health. PMID:26619210

Relative Pigment Composition and Remote Sensing Reflectance of Caribbean Shallow-Water Corals.

PubMed

Torres-Pérez, Juan L; Guild, Liane S; Armstrong, Roy A; Corredor, Jorge; Zuluaga-Montero, Anabella; Polanco, Ramón

2015-01-01

Reef corals typically contain a number of pigments, mostly due to their symbiotic relationship with photosynthetic dinoflagellates. These pigments usually vary in presence and concentration and influence the spectral characteristics of corals. We studied the variations in pigment composition among seven Caribbean shallow-water Scleractinian corals by means of High Performance Liquid Chromatography (HPLC) analysis to further resolve the discrimination of corals. We found a total of 27 different pigments among the coral species, including some alteration products of the main pigments. Additionally, pigments typically found in endolithic algae were also identified. A Principal Components Analysis and a Hierarchical Cluster Analysis showed the separation of coral species based on pigment composition. All the corals were collected under the same physical environmental conditions. This suggests that pigment in the coral's symbionts might be more genetically-determined than influenced by prevailing physical conditions of the reef. We further investigated the use of remote sensing reflectance (Rrs) as a tool for estimating the total pigment concentration of reef corals. Depending on the coral species, the Rrs and the total symbiont pigment concentration per coral tissue area correlation showed 79.5-98.5% confidence levels demonstrating its use as a non-invasive robust technique to estimate pigment concentration in studies of coral reef biodiversity and health.

An unusual photosensitizer: dyad of eosin-tris(2,2'-bipyridine)Ru(II).

PubMed

Jing, Bingwen; Zhang, Manhua; Shen, Tao

2003-10-02

[structure: see text] A dyad of eosin and tris(2,2'-bipyridine)Ru(II) was prepared, and its photophysical properties were investigated. The photosensitization of eosin is greatly enhanced by introduction of tris(2,2'-bipyridine)Ru(II), which is verified via photooxygenation of anthracene derivatives. The electron-transfer mechanism of photosensitization is also discussed.

Stimulation of microtubule-based transport by nucleation of microtubules on pigment granules

PubMed Central

Semenova, Irina; Gupta, Dipika; Usui, Takeo; Hayakawa, Ichiro; Cowan, Ann; Rodionov, Vladimir

2017-01-01

Microtubule (MT)-based transport can be regulated through changes in organization of MT transport tracks, but the mechanisms that regulate these changes are poorly understood. In Xenopus melanophores, aggregation of pigment granules in the cell center involves their capture by the tips of MTs growing toward the cell periphery, and granule aggregation signals facilitate capture by increasing the number of growing MT tips. This increase could be explained by stimulation of MT nucleation either on the centrosome or on the aggregate of pigment granules that gradually forms in the cell center. We blocked movement of pigment granules to the cell center and compared the MT-nucleation activity of the centrosome in the same cells in two signaling states. We found that granule aggregation signals did not stimulate MT nucleation on the centrosome but did increase MT nucleation activity of pigment granules. Elevation of MT-nucleation activity correlated with the recruitment to pigment granules of a major component of MT-nucleation templates, γ-tubulin, and was suppressed by γ-tubulin inhibitors. We conclude that generation of new MT transport tracks by concentration of the leading pigment granules provides a positive feedback loop that enhances delivery of trailing granules to the cell center. PMID:28381426

Time-resolved singlet-oxygen luminescence detection with an efficient and practical semiconductor single-photon detector

PubMed Central

Boso, Gianluca; Ke, Damei; Korzh, Boris; Bouilloux, Jordan; Lange, Norbert; Zbinden, Hugo

2015-01-01

In clinical applications, such as PhotoDynamic Therapy, direct singlet-oxygen detection through its luminescence in the near-infrared range (1270 nm) has been a challenging task due to its low emission probability and the lack of suitable single-photon detectors. Here, we propose a practical setup based on a negative-feedback avalanche diode detector that is a viable alternative to the current state-of-the art for different clinical scenarios, especially where geometric collection efficiency is limited (e.g. fiber-based systems, confocal microscopy, scanning systems etc.). The proposed setup is characterized with Rose Bengal as a standard photosensitizer and it is used to measure the singlet-oxygen quantum yield of a new set of photosensitizers for site-selective photodynamic therapy. PMID:26819830

Modified polymethylmethacrylate as a base for thermostable optical recording media

NASA Astrophysics Data System (ADS)

Krul, L. P.; Matusevich, V.; Hoff, D.; Kowarschik, R.; Matusevich, Yu. I.; Butovskaya, G. V.; Murashko, E. A.

2007-07-01

A possibility to improve the thermal properties of holographic gratings in a photosensitive system based on polymethylmethacrylate (PMMA) and to enhance simultaneously the adhesion of the photopolymer to soda-lime glass is demonstrated. The modified PMMA was prepared by radical copolymerisation of methylmethacrylate (MMA) with acrylic acid (AA). Polymer films deposited from samples of the copolymer of MMA with AA containing 9,10-phenanthrenequinone additives were used as a photosensitive material for the recording of holographic gratings. It is possible to generate gratings that are thermally stable up to 200ºC using this modified PMMA. Dynamic thermogravimetry, differential thermal analysis and thermal mechanic analyses were used to determine the dependence of the thermal stability of the modified PMMA on the composition and the structure of its macromolecules.

Photodynamic characterization and optimization using multifunctional nanoparticles for brain cancer treatment

NASA Astrophysics Data System (ADS)

Herrmann, Kristen; Lee Koo, Yong-Eun; Orringer, Daniel A.; Sagher, Oren; Philbert, Martin; Kopelman, Raoul

2013-03-01

Photosensitizer-conjugated polyacrylamide nanoparticles were prepared for in vivo characterization of the minimally invasive and localized treatment of photodynamic therapy (PDT) on brain tumors. By incorporating a variety of nanoparticle matrixes, choosing methylene blue as a photosensitizer, and targeting the nanoparticle by the use of F3 peptide we have made nanoparticle-based PDT improvements to current PDT efficiency. Quantitative growth patterns were determined through visual observation of the tumorigenic response to various treatments by the use of an animal cranial window model. PDT treatments with methylene blue-polyacrylamide (MB-PAA) nanoparticles produced significant adjournment of tumor growth over control groups, clearly demonstrating the advantages of nanoparticle-based PDT agents for the eradication of local tumors, leading to the potential palliation of the advancing disease.

Silica Integrated Optical Circuits Based on Glass Photosensitivity

NASA Technical Reports Server (NTRS)

Abushagur, Mustafa A. G.

1999-01-01

Integrated optical circuits play a major rule in the new photonics technology both in communication and sensing due to their small size and compatibility with integrated circuits. Currently integrated optical circuits (IOCs) are fabricated using similar manufacturing to those used in the semiconductor industry. In this study we are considering a new technique to fabricate IOCs which does not require layers of photolithography, depositing and etching. This method is based on the photosensitivity of germanosilicate glasses. Waveguides and other IOC devises can be patterned in these glasses by exposing them using UV lasers. This exposure by UV light changes the index of refraction of the germanosilicate glass. This technique enjoys both the simplicity and flexibility of design and fabrication with also the potential of being fast and low cost.

Photodynamic inactivation of Staphylococcus aureus and Escherichia coli biofilms by malachite green and phenothiazine dyes: an in vitro study.

PubMed

Vilela, Simone Furgeri Godinho; Junqueira, Juliana Campos; Barbosa, Junia Oliveira; Majewski, Marta; Munin, Egberto; Jorge, Antonio Olavo Cardoso

2012-06-01

The organization of biofilms in the oral cavity gives them added resistance to antimicrobial agents. The action of phenothiazinic photosensitizers on oral biofilms has already been reported. However, the action of the malachite green photosensitizer upon biofilm-organized microorganisms has not been described. The objective of the present work was to compare the action of malachite green with the phenothiazinic photosensitizers (methylene blue and toluidine blue) on Staphylococcus aureus and Escherichia coli biofilms. The biofilms were grown on sample pieces of acrylic resin and subjected to photodynamic therapy using a 660-nm diode laser and photosensitizer concentrations ranging from 37.5 to 3000 μM. After photodynamic therapy, cells from the biofilms were dispersed in a homogenizer and cultured in Brain Heart Infusion broth for quantification of colony-forming units per experimental protocol. For each tested microorganism, two control groups were maintained: one exposed to the laser radiation without the photosensitizer (L+PS-) and other treated with the photosensitizer without exposure to the red laser light (L-PS+). The results were subjected to descriptive statistical analysis. The best results for S. aureus and E. coli biofilms were obtained with photosensitizer concentrations of approximately 300 μM methylene blue, with microbial reductions of 0.8-1.0 log(10); 150 μM toluidine blue, with microbial reductions of 0.9-1.0 log(10); and 3000 μM malachite green, with microbial reductions of 1.6-4.0 log(10). Greater microbial reduction was achieved with the malachite green photosensitizer when used at higher concentrations than those employed for the phenothiazinic dyes. Copyright © 2011 Elsevier Ltd. All rights reserved.

Mechanism to preserve phrenic nerve function during photosensitization reaction: drug uptake and photosensitization reaction effect on electric propagation

NASA Astrophysics Data System (ADS)

Takahashi, Haruka; Hamada, Risa; Ogawa, Emiyu; Arai, Tsunenori

2018-02-01

To study a mechanism of phrenic nerve preservation phenomena during a photosensitization reaction, we investigated an uptake of talaporfin sodium and photosensitization reaction effect on an electric propagation. Right phrenic nerve was completely preserved after superior vena cava isolations using the photosensitization reaction in canine animal experiments, in spite of adjacent myocardium was electrically blocked. We predicted that low drug uptake and/or low photosensitization reaction effect on the nerve might be a mechanism of that phenomena. To investigate uptake to various nerve tissue, a healthy extracted crayfish ventral nerve cord and an extracted porcine phrenic nerve were immersed in 20 μg/ml talaporfin sodium solution for 0-240 min. The mean talaporfin sodium fluorescence brightness increased depending on the immersion time. This brightness saturated around the immersion time of 120 min. We found that talaporfin sodium uptake inside the perineurium which directly related to the electric propagation function was lower than that of outside in the porcine phrenic nerve. To investigate photosensitization reaction effect on electric propagation, the crayfish nerve was immersed into the same solution for 15 min and irradiated by a 663 nm laser light with 120 mW/cm2. Since we found the action potential disappeared when the irradiation time was 25-65 s, we consider that the crayfish nerve does not tolerant to the photosensitization reaction on electric propagation function at atmospheric pressure. From these results, we think that the low uptake of talaporfin sodium inside the perineurium and low oxygen partial pressure of nerve might be the possible mechanism to preserve phrenic nerve in vivo.

Identification of Organic Colorants in Art Objects by Solution Spectrophotometry: Pigments.

ERIC Educational Resources Information Center

Billmeyer, Fred W., Jr.; And Others

1981-01-01

Describes solution spectrophotometry as a simple, rapid identification technique for organic paint pigments. Reports research which includes analytical schemes for the extraction and separation of organic pigments based on their solubilities, and the preparation of an extensive reference collection of spectral curves allowing their identification.…

In vitro investigation of efficient photodynamic therapy using a nonviral vector; hemagglutinating virus of Japan envelope

NASA Astrophysics Data System (ADS)

Sakai, Makoto; Fujimoto, Naohiro; Ishii, Katsunori; Nakamura, Hiroyuki; Kaneda, Yasufumi; Awazu, Kunio

2012-07-01

Photodynamic therapy (PDT) is a photochemical modality approved for cancer treatment. PDT has demonstrated efficacy in early stage lung cancer and esophageal cancer. The accumulation of photosensitizers in cancer cells is necessary to enhance the therapeutic benefits of PDT; however, photosensitizers have low uptake efficiency. To overcome this limitation, a drug delivery system, such as the hemagglutinating virus of Japan envelope (HVJ-E) vector, is required. In this study, the combination of PDT and HVJ-E was investigated for enhancing the efficacy of PDT. The photosensitizers that were evaluated included 5-aminolaevulinic acid (5-ALA), protoporphyrin IX (PPIX), and HVJ-PPIX. The uptake of the photosensitizers as increased twenty-fold with the addition of HVJ-E. The cytotoxicity of conventional 5-ALA was enhanced by the addition of HVJ-E vector. In conclusion, HVJ-E vector improved the uptake of photosensitizers and the PDT effect.

HPLC pigment profiles of 31 harmful algal bloom species isolated from the coastal sea areas of China

NASA Astrophysics Data System (ADS)

Liu, Shuxia; Yao, Peng; Yu, Zhigang; Li, Dong; Deng, Chunmei; Zhen, Yu

2014-12-01

Chemotaxonomy based on diagnostic pigments is now a routine tool for macroscopic determination of the composition and abundance of phytoplankton in various aquatic environments. Since the taxonomic capability of this method depends on the relationships between diagnostic pigments and chlorophyll a of classified groups, it is critical to calibrate it by using pigment relationships obtained from representative and/or dominant species local to targeted investigation area. In this study, pigment profiles of 31 harmful algal bloom (HAB) species isolated from the coastal sea areas of China were analyzed with high performance liquid chromatography (HPLC). Pigment compositions, cellular pigment densities and ratios of pigments to chlorophyll a were determined and calculated. Among all these species, 25 kinds of pigments were detected, of which fucoxanthin, peridinin, 19'-butanoyloxyfucoxanthin, 19'-hexanoyloxyfucoxanthin, violaxanthin, and antheraxanthin were diagnostic pigments. Cellular pigment density was basically independent of species and environmental conditions, and therefore was recommended as a bridge to compare the results of HPLC-CHEMTAX technique with the traditional microscopy method. Pigment ratios of algal species isolated from the coast of China, especially the diagnostic pigment ratios, were higher than those from other locations. According to these results, pigment ratio ranges of four classes of phytoplankton common off the coast of China were summarized for using in the current chemotaxonomic method. Moreover, the differences of pigments ratios among different species under the same culturing conditions were consistent with their biological differences. Such differences have the potential to be used to classify the phytoplankton below class, which is meaningful for monitoring HABs by HPLC-CHEMTAX.

Effective photodynamic therapy in drug-resistant prostate cancer cells utilizing a non-viral antitumor vector (a secondary publication).

PubMed

Yamauchi, Masaya; Honda, Norihiro; Hazama, Hisanao; Tachikawa, Shoji; Nakamura, Hiroyuki; Kaneda, Yasufumi; Awazu, Kunio

2016-03-31

There is an urgent need to develop an efficient strategy for the treatment of drug-resistant prostate cancer. Photodynamic therapy (PDT), in which low incident levels of laser energy are used to activate a photosensitizer taken up by tumor cells, is expected as a novel therapy for the treatment of prostate cancer because of the minimal invasive nature of PDT. The present study was designed to assess the efficacy of a novel vector approach combined with a conventional porphyrin-based photosensitizer. Our group focused on a non-viral vector (hemagglutinating virus of Japan envelope; HVJ-E) combined with protoporphyrin IX (PpIX) lipid, termed the porphyrus envelope (PE). It has been previously confirmed that HVJ-E has drug-delivering properties and can induce cancer-specific cell death. The PE (HVJ-E contained in PpIX lipid) was developed as a novel photosensitizer. In this study, the antitumor and PDT efficacy of the PE against hormone-antagonistic human prostate cancer cells (PC-3) were evaluated. Our results demonstrated that, under specific circumstances, PDT using the PE was very effective against PC-3 cells. A novel therapy for drug-resistant prostate cancer based on this vector approach is eagerly anticipated.

Cardiovascular photodynamic therapy: state of the art

NASA Astrophysics Data System (ADS)

Woodburn, Kathryn W.; Rockson, Stanley G.

2000-05-01

Photodynamic therapy (PDT) has been used traditionally for oncologic and ophthalmic indications. In addition, the enormous potential for the use of PDT agents in cardiovascular diseases is currently being translated into reality. Preclinical studies with various photosensitizers have demonstrated reduction in atheromatous plaque and prevention of intimal hyperplasia. With recent advances in light-based vascular devices and laser diode technology, the clinical use of cardiovascular photodynamic therapy is even more likely. Two photosensitizers, 5-aminolevulinic acid (ALA) and AntrinR (motexafin lutetium) Injection, are under clinical evaluation with many other agents in preclinical testing. Here, preclinical studies are reviewed and the clinical viability of cardiovascular photodynamic therapy is discussed.

Excited triplet state of N-(9-methylpurin-6-yl)pyridinium cation as an efficient photosensitizer in the oxidation of sulfur-containing amino acids. Laser flash and steady-state photolysis studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marciniak, B.; Hug, G.L.; Bobrowski, K.

1995-01-11

In this paper, we present and discuss the results of a detailed mechanistic study of the photosensitized oxidation of sulfur-containing amino acids by N-(9-methylpurin-6-yl)pyridinium cations in aqueous solution. The results provide data on the photoreactivity of the pyridinium salts (derived from the purine bases) in the presence of the electron donors such as sulfur-containing organic compounds and give new experimental evidence for the general mechanism of the sensitized photooxidation of thioethers proposed previously. 39 refs., 6 figs., 2 tabs.

Liquid chromatographic separation of terpenoid pigments in foods and food products.

PubMed

Cserháti, T; Forgács, E

2001-11-30

The newest achievements in the use of various liquid chromatographic techniques such as adsorption and reversed-phase thin-layer chromatography and HPLC employed for the separation and quantitative determination of terpenoid-based color substances in foods and food products are reviewed. The techniques applied for the analysis of individual pigments and pigments classes are surveyed and critically evaluated. Future trends in the separation and identification of pigments in foods and food products are delineated.

Multispectral imaging determination of pigment concentration profiles in meat

NASA Astrophysics Data System (ADS)

Sáenz Gamasa, Carlos; Hernández Salueña, Begoña; Alberdi Odriozola, Coro; Alfonso Ábrego, Santiago; Berrogui Arizu, Miguel; Diñeiro Rubial, José Manuel

2006-01-01

The possibility of using multispectral techniques to determine the concentration profiles of myoglobin derivatives as a function of the distance to the meat surface during meat oxygenation is demonstrated. Reduced myoglobin (Mb) oxygenated oxymyoglobin (MbO II) and oxidized Metmyoglobin (MMb) concentration profiles are determined with a spatial resolutions better than of 0.01235 mm/pixel. Pigment concentrations are calculated using (K/S) ratios at isobestic points (474, 525, 572 and 610 nm) of the three forms of myoglobin pigments. This technique greatly improves previous methods, based on visual determination of pigment layers by their color, which allowed only estimations of pigment layer position and width. The multispectral technique avoids observer and illumination related bias in the pigment layer determination.

Use of chloro-aluminum sulfonated phthalocyanine as a photosensitizer in the treatment of malignant tumors in dogs and cats

NASA Astrophysics Data System (ADS)

Peavy, George M.; Klein, Mary K.; Newman, H. C.; Roberts, Walter G.; Berns, Michael W.

1991-05-01

Chloro-aluminum sulfonated phthalocyanine (CASPc) has been proposed as a photosensitizing agent for photodynamic therapy (PDT) of neoplasia. This paper reviews the results of PDT treatment using CASPc as a photosensitizing agent in the treatment of 15 cats representing 23 sites of facial, solar induced squamous cell carcinoma, 4 dogs with hemangiopericytomas, 3 dogs with fibrosarcomas, and 1 dog with multiple cutaneous mast cell tumors. The results of this study to date suggest that CASPc is a good photosensitizing agent for the treatment of some forms of spontaneously occurring malignant neoplasia and should be more thoroughly evaluated for this purpose.

Reflex epilepsy and reflex seizures of the visual system: a clinical review.

PubMed

Zifkin, B G; Kasteleijn-Nolst Trenité, D

2000-09-01

Reflex epilepsy of the visual system is charecterised by seizures precipitated by visual stimuli. EEG responses to intermittent photic stimulation depend on the age and sex of the subject and on how stimulation is performed: abnormalities are commonest in children and adolescents, especially girls. Only generalised paroxysmal epileptiform discharges are clearly linked to epilepsy. Abnormal responses may occur in asymptomatic subjects, especially children. Photosensitivity has an important genetic component. Some patients are sensitive to patterns, suggesting an occipital trigger for these events. Myoclonus and generalised convulsive and nonconvulsive seizures may be triggered by visual stimuli. Partial seizures occur less often and can be confused with migraine. Although usually idiopathic, photosensitive epilepsy may occur in degenerative diseases and some patients with photosensitive partial seizures have brain lesions. Sunlight and video screens, including television, video games, and computer displays, are the commonest environmental triggers of photosensitive seizures. Outbreaks of triggered seizures have occurred when certain flashing or patterned images have been broadcast. There are regulations to prevent this in some countries only. Pure photosensitive epilepsy has a good prognosis. There is a role for treatment with and without antiepileptic drugs, but photosensitivity usually does not disappear spontaneously, and then typically in the third decade.

The nature, fabrication, and applications of photosensitive, bulk, germano-silicate glass

NASA Astrophysics Data System (ADS)

Heaney, Alan Douglas

2000-08-01

The photosensitive nature of germano-silicate glass is widely used to create fiber-optic devices. This thesis examines the cause of photosensitivity in germano- silicate glass. The results of this research elucidate the role that germanium oxygen deficient defects play in the photosensitivity of hydrogen-loaded, germano-silicate glass. We find that defects are not vital to the photosensitivity of hydrogen-loaded, germano-silicate glass but they do enhance the effect. Quantitative measurements show that germanium oxygen deficient defects promote the formation of OH, GeH, and GeH2 when hydrogen-loaded, germano-silicate glass is exposed to ultraviolet light. A sol-gel process for fabricating germano-silicate glass in bulk samples has been developed. The sol-gel process produces high-quality, germano-silicate glass which can be tailored to contain defects or be relatively free of defects. Control over the glass defect concentration allows us to use sol-gel derived glass for comparative studies of the photosensitive process and for device applications. The unique properties of germano-silicate glass make it a likely choice for use in optical applications. To prove the feasibility of bulk devices, chirped-pulse amplification is demonstrated using gratings written in bulk germano-silicate glass.

Pigment Production on L-Tryptophan Medium by Cryptococcus gattii and Cryptococcus neoformans

PubMed Central

Chaskes, Stuart; Cammer, Michael; Nieves, Edward; Casadevall, Arturo

2014-01-01

In recent years strains previously grouped within Cryptococcus neoformans have been divided into two species C. neoformans and C. gattii, with Cryptococcus neoformans comprising serotypes A, D, and AD and C. gattii comprising serotypes B and C. Cryptococcus neoformans have also been subdivided into two varieties C. neoformans var. grubii, serotype A, and C. neoformans var. neoformans, serotype D. We analyzed the growth and pigment production characteristics of 139 strains of Cryptococcus spp. in L-tryptophan containing media. Nearly all strains of Cryptococcus, including each variety and serotype tested produced a pink water-soluble pigment (molecular weight of 535.2 Da) from L-tryptophan. Consequently, the partial separation of the species was based on whether the pink pigment was secreted into the medium (extracellular) or retained as an intracellular pigment. On L-tryptophan medium C. neoformans var. grubii and serotype AD produced a pink extracellular pigment. In contrast, for C. gattii, the pink pigment was localized intracellularly and masked by heavy production of brown pigments. Pigment production by C. neoformans var. neoformans was variable with some strains producing the pink extracellular pigment and others retained the pink pigment intracellularly. The pink intracellular pigment produced by strains of C. neoformans var. neoformans was masked by production of brown pigments. Cryptococcus laccase mutants failed to produce pigments from L-tryptophan. This is the first report that the enzyme laccase is involved in tryptophan metabolism. Prior to this report Cryptococcus laccase produced melanin or melanin like-pigments from heterocyclic compounds that contained ortho or para diphenols, diaminobenzenes and aminophenol compounds. The pigments produced from L-tryptophan were not melanin. PMID:24736553

Temperature effect of natural organic extraction upon light absorbance in dye-sensitized solar cells

NASA Astrophysics Data System (ADS)

Suhaimi, Suriati; Mohamed Siddick, Siti Zubaidah; Retnasamy, Vithyacharan; Abdul Wahid, Mohamad Halim; Ahmad Hambali, Nor Azura Malini; Mohamad Shahimin, Mukhzeer

2017-02-01

Natural organic dyes contain pigments which when safely extracted from plants have the potential to be used as a sensitizer while promising a low-cost fabrication, environmental friendly dye-sensitized solar cells (DSSCs). Ardisia, Bawang Sabrang, Harum Manis mango, Oxalis Triangularis and Rosella showed different absorption peaks when the extraction process were carried out at different temperatures. Hence, these were used as the basis to determine the conversion efficiency against the dyes extracting temperature. In this study, all dyes extracted in water have shown the best performance at a temperature of 100°C except for Harum Manis mango, while in ethanol, the optimum temperature was obtained between the room temperature, 25°C and 50°C. The absorption spectrum in water showed a broader absorption wavelength vis-à-vis ethanol solvent that resulted in the absorption peak for Ardisia, Harum Manis mango and Rosella between 450 nm and 550 nm. The highest conversion efficiency is observed to be achieved by Oxalis Triangularis extracted in water solution at 100°C, which was approximately 0.96% which corresponds to the broader absorbance trends in the literature. Thus, the optimum condition for extracting temperature for dyes in water and ethanol is room temperature and boiling points of water. Hence, Ardisia, Bawang Sabrang, Harum Manis mango, Oxalis Triangularis and Rosella can be an as alternative source for photosensitizer, and the impacts of temperature upon the light absorbance can be further investigated to produce the ultimate natural dye based solar cells.

The role of natural and UV-induced skin pigmentation on low-fluence IPL-induced side effects: a randomized controlled trial.

PubMed

Thaysen-Petersen, Daniel; Lin, Jennifer Y; Nash, Jf; Beerwerth, Frank; Wulf, Hans C; Philipsen, Peter A; Haedersdal, Merete

2014-02-01

The risk of adverse skin effects following light-based hair removal is greater in pigmented skin based on the theory of selective photothermolysis. Thus sunlight-induced pigment i.e., facultative pigmentation, increases the risk of adverse skin effects, perhaps disproportionately. The aim of this study was to evaluate the influence of constitutive and facultative skin pigmentation on low-fluence intense pulsed light (IPL)-induced adverse skin effects. Twenty-one subjects with Fitzpatrick skin type II-IV were enrolled. Two buttock blocks were randomized to receive 0 or 8 solar simulated ultraviolet radiation (UVR) exposures of consecutively increasing Standard Erythema Doses (2-4 SED). Each block was subdivided into four sites, randomized to receive IPL of 0, 7, 8, or 10 J/cm(2) , once a week for 3 weeks. Biopsies were taken 16-24 hours after the first IPL exposure and subjects were seen 1 and 4 weeks after the last IPL exposure. Outcome measures were: (i) skin reactions, (ii) pain, (iii) mRNA expression of pigment-markers microphthalmia-associated transcription factor (MITF) and pro-opiomelanocortin (POMC), and (iv) clinical appearance of biopsy wounds. Skin pigmentation increased after UVR (baseline median 13.8%, after UVR 28.1%, P = 0.0001) in all skin types. Subjects reported low pain intensities (median 1.5, scale 0-10) and experienced transient erythema immediately after IPL exposure. No persistent erythema, blisters, crusting, textual, or pigment changes were observed. The risk of erythema and pain intensities increased with IPL dose and skin pigmentation (P < 0.03). There was no difference in pain or skin reactions in skin with similar degree of natural and facultative pigmentation (P ≥ 0.104). Expression of cellular pigment-markers was not influenced by IPL exposure, neither in constitutive nor in facultative pigmented skin. Clinical appearance of biopsy wounds was unaffected by IPL exposure. The prevalence and intensity of low-fluence IPL-induced adverse skin effects depended on IPL dose and skin pigmentation regardless of the origin, i.e., constitutive versus UV induced. © 2013 Wiley Periodicals, Inc.

The remote sensing of ocean primary productivity - Use of a new data compilation to test satellite algorithms

NASA Technical Reports Server (NTRS)

Balch, William; Evans, Robert; Brown, Jim; Feldman, Gene; Mcclain, Charles; Esaias, Wayne

1992-01-01

Global pigment and primary productivity algorithms based on a new data compilation of over 12,000 stations occupied mostly in the Northern Hemisphere, from the late 1950s to 1988, were tested. The results showed high variability of the fraction of total pigment contributed by chlorophyll, which is required for subsequent predictions of primary productivity. Two models, which predict pigment concentration normalized to an attenuation length of euphotic depth, were checked against 2,800 vertical profiles of pigments. Phaeopigments consistently showed maxima at about one optical depth below the chlorophyll maxima. CZCS data coincident with the sea truth data were also checked. A regression of satellite-derived pigment vs ship-derived pigment had a coefficient of determination. The satellite underestimated the true pigment concentration in mesotrophic and oligotrophic waters and overestimated the pigment concentration in eutrophic waters. The error in the satellite estimate showed no trends with time between 1978 and 1986.

Dose-dependent photochemical/photothermal toxicity of indocyanine green-based therapy on three different cancer cell lines.

PubMed

Ruhi, Mustafa Kemal; Ak, Ayşe; Gülsoy, Murat

2018-03-01

The Food and Drug Administration-approved Indocyanine Green can be used as a photosensitizer to kill cancer cells selectively. Although indocyanine green is advantageous as a photosensitizer in terms of strong absorption in the near-infrared region, indocyanine green-based cancer treatment is still not approved as a clinical method. Some reasons for this are aggregation at high concentrations, rapid clearance of the photosensitizer from the body, low singlet oxygen quantum yield, and the uncertainty concerning its action mechanism. This in vitro study focuses on two of these points: "what is the cell inhibition mechanism of indocyanine green-based therapy?" and "how the dose-dependent aggregation problem of indocyanine green alters its cell inhibition efficiency?" The following experiments were conducted to provide insight into these points. Nontoxic doses of indocyanine green and near-infrared laser were determined. The aggregation behavior of indocyanine green was verified through experiments. The singlet oxygen quantum yield of indocyanine green at different concentrations were calculated. Various indocyanine green and energy densities of near-infrared light were applied to prostate cancer, neuroblastoma, and colon cancer cells. An MTT assay was performed at the end of the first, second, and third days following the treatments to determine the cell viability. Temperature changes in the medium during laser exposure were recorded. ROS generation following the treatment was verified by using a Total Reactive Oxygen Species detection kit. An apoptosis detection test was performed to establish the cell death mechanism and, finally, the cellular uptakes of the three different cells were measured. According to the results, indocyanine green-based therapy causes cell viability decrease for three cancer cell lines by means of excessive reactive oxygen species production. Different cells have different sensitivities to the therapy possibly because of the differentiation level and structural differences. The singlet oxygen generation of indocyanine green decreases at high concentrations because of aggregation. Nevertheless, better cancer cell killing effect was observed at higher photosensitizer concentrations. This result reveals that the cellular uptake of indocyanine green was determinant for better cancer cell inhibition. Copyright © 2018 Elsevier B.V. All rights reserved.

Bactericidal effect of visible light in the presence of erythrosine on Porphyromonas gingivalis and Fusobacterium nucleatum compared with diode laser, an in vitro study.

PubMed

Habiboallah, Ghanbari; Mahdi, Zakeri; Mahbobeh, Naderi Nasab; Mina, Zareian Jahromi; Sina, Faghihi; Majid, Zakeri

2014-12-27

Recently, photodynamic therapy (PDT) has been introduced as a new modality in oral bacterial decontamination. Besides, the ability of laser irradiation in the presence of photosensitizing agent to lethal effect on oral bacteria is well documented. Current research aims to evaluate the effect of photodynamic killing of visible blue light in the presence of plaque disclosing agent erythrosine as photosensitizer on Porphyromonas gingivalis associated with periodontal bone loss and Fusobacterium nucleatum associated with soft tissue inflammation, comparing with the near-infrared diode laser. Standard suspension of P. gingivalis and F. nucleatum were exposed to Light Emitting Diode (LED) (440-480 nm) used to photopolymerize composite resine dental restoration in combination with erythrosine (22 µm) up to 5 minutes. Bacterial sample were also exposed to a near-infrared diode laser (wavelength, 830 nm), using identical irradiation parameters for comparison. Bacterial samples from each treatment groups (radiation-only group, erythrosine-only group and light or laser with erythrosine group) were subcultured onto the surface of agar plates. Survival of these bacteria was determined by counting the number of colony forming units (CFU) after incubation. Exposure to visible blue light and diode laser in conjugation with erythrosine significantly reduced both species examined viability, whereas erythrosine-treated samples exposed to visible light suggested a statically meaningful differences comparing to diode laser. In addition, bactericidal effect of visible light or diode laser alone on P. gingivalis as black-pigmented bacteria possess endogenous porphyrins was noticeably. Our result suggested that visible blue light source in the presence of plaque disclosing agent erythrosine could can be consider as potential approach of PDT to kill the main gram-negative periodontal pathogens. From a clinical standpoint, this regimen could be established as an additional minimally invasive antibacterial treatment of plaque induced periodontal pathologies.

Arabidopsis ROOT PHOTOTROPISM2 Contributes to the Adaptation to High-Intensity Light in Phototropic Responses

PubMed Central

Haga, Ken; Tsuchida-Mayama, Tomoko; Yamada, Mizuki; Sakai, Tatsuya

2015-01-01

Living organisms adapt to changing light environments via mechanisms that enhance photosensitivity under darkness and attenuate photosensitivity under bright light conditions. In hypocotyl phototropism, phototropin1 (phot1) blue light photoreceptors mediate both the pulse light-induced, first positive phototropism and the continuous light-induced, second positive phototropism, suggesting the existence of a mechanism that alters their photosensitivity. Here, we show that light induction of ROOT PHOTOTROPISM2 (RPT2) underlies photosensory adaptation in hypocotyl phototropism of Arabidopsis thaliana. rpt2 loss-of-function mutants exhibited increased photosensitivity to very low fluence blue light but were insensitive to low fluence blue light. Expression of RPT2 prior to phototropic stimulation in etiolated seedlings reduced photosensitivity during first positive phototropism and accelerated second positive phototropism. Our microscopy and biochemical analyses indicated that blue light irradiation causes dephosphorylation of NONPHOTOTROPIC HYPOCOTYL3 (NPH3) proteins and mediates their release from the plasma membrane. These phenomena correlate closely with the desensitization of phot1 signaling during the transition period from first positive phototropism to second positive phototropism. RPT2 modulated the phosphorylation of NPH3 and promoted reconstruction of the phot1-NPH3 complex on the plasma membrane. We conclude that photosensitivity is increased in the absence of RPT2 and that this results in the desensitization of phot1. Light-mediated induction of RPT2 then reduces the photosensitivity of phot1, which is required for second positive phototropism under bright light conditions. PMID:25873385

Identification of singlet oxygen photosensitizes in lambs drinking water in an alveld risk area in West Norway.

PubMed

Tønnesen, Hanne Hjorth; Mysterud, Ivar; Karlsen, Jan; Skulberg, Olav M; Laane, Carl M M; Schumacher, Trond

2013-02-05

Alveld is a hepatogenous photosensitivity disorder in lambs. Although alveld has been known in Norway for more than 100years, there are still questions related to the cause of the disease. Phytoporphyrin has long been incriminated as the photosensitizer in hepatogenous photosensitivity diseases but previous findings suggest that the photosensitizing mechanism in alveld is more complex, possibly involving other co-factors. The current work investigates the presence of non-hepatogenous photosensitizers originating in lamb's drinking water from various sources. In addition samples of two of the predominent cyanobacteria found in a representative biofilm (i.e. aggregates of microbes) were identified and isolated in axenic (i.e. pure) cultures. Information from the absorption-, fluorescence emission-, and -excitation spectra and the action spectrum for the formation of singlet oxygen was combined in order to identify the chromophores responsible for the formation of singlet oxygen, e.g. phycocyanins from the cyanobacteria. The highest level of singlet oxygen formation was detected in lotic (i.e. flowing) water in the period consistent with the outbreak of the alveld disease in the area. Meteorological data indicate a warm and wet May with a high radiation exposure leading up to a colder and wet June with an even higher solar irradiance. The seasonal variation in the amount of photosensitizers in lamb's drinking water combined meteorological data can be important to predict the outbreak of alveld. Copyright © 2012 Elsevier B.V. All rights reserved.

21 CFR 73.3128 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Mica-based pearlescent pigments. 73.3128 Section 73.3128 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3128 Mica-based pearlescent...

21 CFR 73.3128 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Mica-based pearlescent pigments. 73.3128 Section 73.3128 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3128 Mica-based pearlescent...

21 CFR 73.3128 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Mica-based pearlescent pigments. 73.3128 Section 73.3128 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3128 Mica-based pearlescent...

21 CFR 73.3128 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Mica-based pearlescent pigments. 73.3128 Section 73.3128 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3128 Mica-based pearlescent...

21 CFR 73.3128 - Mica-based pearlescent pigments.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Mica-based pearlescent pigments. 73.3128 Section 73.3128 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3128 Mica-based pearlescent...

Serological characterization of black-pigmented Bacteroides endodontalis.

PubMed Central

van Winkelhoff, A J; Kippuw, N; de Graaff, J

1986-01-01

Serological studies on the black-pigmented Bacteroides species B. endodontalis revealed three serotypes based on capsular determinants. A common antigen (O-antigen) could be demonstrated after decapsulation. Weak cross-reactivity was found with B. asaccharolyticus, but not with B. gingivalis. Similarity between the serology of Enterobacteriaceae and black-pigmented Bacteroides spp. is discussed. PMID:3949388

Adsorption of ethoxylated styrene oxide and polyacrylic acid and mixtures there of on organic pigment.

PubMed

Wijting, W K; Laven, J; van Benthem, R A T M; de With, G

2008-11-01

The adsorption of two polymeric surfactants on an organic pigment was investigated. As surfactants the anionic polyacrylic acid sodium salt (PANa, M(W)=15,000) and a non-ionic block copolymer surfactant based on styrene oxide (SO) and ethylene oxide (EO) (M(W)=1500) were used. The adsorption behavior was analyzed by size exclusion chromatography of the supernatant after centrifugation of the pigment dispersions. It was found that PANa has no affinity to the pigment, whereas SO-EO has a strong affinity to the pigment surface. Competitive adsorption of PANa and SO-EO was not observed. Addition of SO-EO yields stable dispersions.

Phosphorescence dynamics of singlet oxygen and Radachlorin photosensitizer in aqueous solution

NASA Astrophysics Data System (ADS)

Belik, V. P.; Beltukova, D. M.; Gadzhiev, I. M.; Semenova, I. V.; Vasyutinskii, O. S.

2017-07-01

The luminescence spectrum of aqueous solution of Radachlorin photosensitizer in the near IR spectral range (950-1350 nm) has been determined at the excitation in both the Soret and Q absorption bands. Major sources of the recorded luminescence were analyzed. Kinetics of photosensitizer and singlet oxygen phosphorescence signals were studied by means of time-resolved spectroscopy. The corresponding characteristic lifetimes were determined.

Singlet oxygen-sensitized delayed fluorescence of common water-soluble photosensitizers.

PubMed

Scholz, Marek; Dědic, Roman; Breitenbach, Thomas; Hála, Jan

2013-10-01

Six common water-soluble singlet oxygen ((1)O2) photosensitizers - 5,10,15,20-tetrakis(1-methyl-4-pyridinio) porphine (TMPyP), meso-tetrakis(4-sulfonathophenyl)porphine (TPPS4), Al(III) phthalocyanine chloride tetrasulfonic acid (AlPcS4), eosin Y, rose bengal, and methylene blue - were investigated in terms of their ability to produce delayed fluorescence (DF) in solutions at room temperature. All the photosensitizers dissolved in air-saturated phosphate buffered saline (PBS, pH 7.4) exhibit easily detectable DF, which can be nearly completely quenched by 10 mM NaN3, a specific (1)O2 quencher. The DF kinetics has a biexponential rise-decay character in a microsecond time domain. Therefore, we propose that singlet oxygen-sensitized delayed fluorescence (SOSDF), where the triplet state of a photosensitizer reacts with (1)O2 giving rise to an excited singlet state of the photosensitizer, is the prevailing mechanism. It was confirmed by additional evidence, such as a monoexponential decay of triplet-triplet transient absorption kinetics, dependence of SOSDF kinetics on oxygen concentration, absence of SOSDF in a nitrogen-saturated sample, or the effect of isotopic exchange H2O-D2O. Eosin Y and AlPcS4 show the largest SOSDF quantum yield among the selected photosensitizers, whereas rose bengal possesses the highest ratio of SOSDF intensity to prompt fluorescence intensity. The rate constant for the reaction of triplet state with (1)O2 giving rise to the excited singlet state of photosensitizer was estimated to be ~/>1 × 10(9) M(-1) s(-1). SOSDF kinetics contains information about both triplet and (1)O2 lifetimes and concentrations, which makes it a very useful alternative tool for monitoring photosensitizing and (1)O2 quenching processes, allowing its detection in the visible spectral region, utilizing the photosensitizer itself as a (1)O2 probe. Under our experimental conditions, SOSDF was up to three orders of magnitude more intense than the infrared (1)O2 phosphorescence and by far the most important pathway of DF. SOSDF was also detected in a suspension of 3T3 mouse fibroblast cells, which underlines the importance of SOSDF and its relevance for biological systems.

Photodynamic therapy: a promising alternative in oncology

NASA Astrophysics Data System (ADS)

Nelius, Thomas; de Riese, Werner T. W.; Filleur, Stephanie

2004-07-01

Photodynamic Therapy (PDT) is a treatment modality that is based on the administration of a photosensitizer and the following application of light in a wavelength range matching the absorption spectrum of the photosensitizer. Ideally the photosensitizer retains in the tumor tissue more than in normal tissue and thus allows targeted destruction of cancerous tissue. The use of PDT is slowly being accepted as a standard treatment for certain types of cancer. This includes mainly treatment strategies with only palliative intentions (obstructive esophageal cancer and advanced lung cancer) while for certain malignant conditions new applications exists that are already intended for cure (e.g. early stage of lung cancer). The main advantage of PDT is that the treatment can be repeated multiple times safely without major side effects. PDT can be safely combined with already established treatment options like surgery, chemotherapy or radiotherapy. A disadvantage of PDT is the only localized effect of the therapy, which usually cannot significantly alter the outcome of a systemic disease. In this paper we review the history of PDT as well as current clinical applications in oncology and future directions.

Reactive oxygen species explicit dosimetry (ROSED) of a type 1 photosensitizer

NASA Astrophysics Data System (ADS)

Ong, Yi Hong; Kim, Michele M.; Huang, Zheng; Zhu, Timothy C.

2018-02-01

Type I photodynamic therapy (PDT) is based on the use of photochemical reactions mediated through an interaction between a tumor-selective photosensitizer, photoexcitation with a specific wavelength of light, and production of reactive oxygen species (ROS). The goal of this study is to develop a model to calculate reactive oxygen species concentration ([ROS]rx) after Tookad®-mediated vascular PDT. Mice with radiation-induced fibrosarcoma (RIF) tumors were treated with different light fluence and fluence rate conditions. Explicit measurements of photosensitizer drug concentration were made via diffuse reflective absorption spectrum using a contact probe before and after PDT. Blood flow and tissue oxygen concentration over time were measured during PDT as a mean to validate the photochemical parameters for the ROSED calculation. Cure index was computed from the rate of tumor regrowth after treatment and was compared against three calculated dose metrics: total light fluence, PDT dose, reacted [ROS]rx. The tumor growth study demonstrates that [ROS]rx serves as a better dosimetric quantity for predicting treatment outcome, as a clinically relevant tumor growth endpoint.

Photodynamic antimicrobial chemotherapy using zinc phthalocyanine derivative for bacterial skin infection

NASA Astrophysics Data System (ADS)

Chen, Zhuo; Zhang, Yaxin; Li, Linsen; Zhou, Shanyong; Chen, Jincan; Hu, Ping; Huang, Mingdong

2014-09-01

Folliculitis, furunculosis and acne vulgaris are very common skin disorders of the hair follicles and are associated with large grease-producing (sebaceous) glands. Although the detailed mechanisms involved these skin disorders are not fully understood, it is believed that the bacteria Propionibacterium acnes and Staphylococcus aureus are the key pathogenic factors involved. Conventional treatments targeting the pathogenic factors include a variety of topical and oral medications such as antibiotics. The wide use of antibiotics leads to bacterial resistance, and hence there is a need for new alternatives in above bacterial skin treatment. Photodynamic antimicrobial chemotherapy (PACT) is based on an initial photosensitization of the infected area, followed by irradiation with visible light, producing singlet oxygen which is cytotoxic to bacteria. Herein we reported a zinc phthalocyanine derivative, pentalysine β-carbonylphthalocyanine zinc (ZnPc-(Lys)5) and its PACT effect for the bacteria involved in these skin infections. Our results demonstrated strong bactericidal effects of this photosensitizer on both strains of the bacteria, suggesting ZnPc-(Lys)5 as a promising antimicrobial photosensitizer for the treatment of infectious diseases caused by these bacteria.

cRGD Peptide-Conjugated Pyropheophorbide-a Photosensitizers for Tumor Targeting in Photodynamic Therapy.

PubMed

Li, Wenjing; Tan, Sihai; Xing, Yutong; Liu, Qian; Li, Shuang; Chen, Qingle; Yu, Min; Wang, Fengwei; Hong, Zhangyong

2018-04-02

Pyropheophorbide-a (Pyro) is a highly promising photosensitizer for tumor photodynamic therapy (PDT), although its very limited tumor-accumulation ability seriously restricts its clinical applications. A higher accumulation of photosensitizers is very important for the treatment of deeply seated and larger tumors. The conjugation of Pyro with tumor-homing peptide ligands could be a very useful strategy to optimize the physical properties of Pyro. Herein, we reported our studies on the conjugation of Pyro with a cyclic cRGDfK (cRGD) peptide, an integrin binding sequence, to develop highly tumor-specific photosensitizers for PDT application. To further reduce the nonspecific uptake and, thus, reduce the background distribution of the conjugates in normal tissues, we opted to add a highly hydrophilic polyethylene glycol (PEG) chain and an extra strongly hydrophilic carboxylic acid group as the linker to avoid the direct connection of the strongly hydrophobic Pyro macrocycle and cRGD ligand. We reported here the synthesis and characterization of these conjugates, and the influence of the hydrophilic modification on the biological function of the conjugates was carefully studied. The tumor-accumulation ability and photodynamic-induced cell-killing ability of these conjugates were evaluated through both in vitro cell-based experiment and in vivo distribution and tumor therapy experiments with tumor-bearing mice. Thus, the synthesized conjugate significantly improved the tumor enrichment and tumor selectivity of Pyro, as well as abolished the xenograft tumors in the murine model through a one-time PDT treatment.

Activatable albumin-photosensitizer nanoassemblies for triple-modal imaging and thermal-modulated photodynamic therapy of cancer.

PubMed

Hu, Dehong; Sheng, Zonghai; Gao, Guanhui; Siu, Fungming; Liu, Chengbo; Wan, Qian; Gong, Ping; Zheng, Hairong; Ma, Yifan; Cai, Lintao

2016-07-01

Photodynamic therapy (PDT) is a noninvasive and effective approach for cancer treatment. The main bottlenecks of clinical PDT are poor selectivity of photosensitizer and inadequate oxygen supply resulting in serious side effects and low therapeutic efficiency. Herein, a thermal-modulated reactive oxygen species (ROS) strategy using activatable human serum albumin-chlorin e6 nanoassemblies (HSA-Ce6 NAs) for promoting PDT against cancer is developed. Through intermolecular disulfide bond crosslinking and hydrophobic interaction, Ce6 photosensitizer is effectively loaded into the HSA NAs, and the obtained HSA-Ce6 NAs exhibit excellent reduction response, as well as enhanced tumor accumulation and retention. By the precision control of the overall body temperature instead of local tumor temperature increasing from 37 °C to 43 °C, the photosensitization reaction rate of HSA-Ce6 NAs increases 20%, and the oxygen saturation of tumor tissue raise 52%, significantly enhancing the generation of ROS for promoting PDT. Meanwhile, the intrinsic fluorescence and photoacoustic properties, and the chelating characteristic of porphyrin ring can endow the HSA-Ce6 NAs with fluorescence, photoacoustic and magnetic resonance triple-modal imaging functions. Upon irradiation of low-energy near-infrared laser, the tumors are completely suppressed without tumor recurrence and therapy-induced side effects. The robust thermal-modulated ROS strategy combined with albumin-based activatable nanophotosensitizer is highly potential for multi-modal imaging-guided PDT and clinical translation. Copyright © 2016 Elsevier Ltd. All rights reserved.

Blue light induced reactive oxygen species from flavin mononucleotide and flavin adenine dinucleotide on lethality of HeLa cells.

PubMed

Yang, Ming-Yeh; Chang, Chih-Jui; Chen, Liang-Yü

2017-08-01

Photodynamic therapy (PDT) is a safe and non-invasive treatment for cancers and microbial infections. Various photosensitizers and light sources have been developed for clinical cancer therapies. Flavin mononucleotide (FMN) and flavin adenine dinucleotide (FAD) are the cofactor of enzymes and are used as photosensitizers in this study. Targeting hypoxia and light-triggering reactive oxygen species (ROS) are experimental strategies for poisoning tumor cells in vitro. HeLa cells are committed to apoptosis when treated with FMN or FAD and exposed to visible blue light (the maximum emitted wavelength of blue light is 462nm). Under blue light irradiation at 3.744J/cm 2 (=0.52mW/cm 2 irradiated for 2h), the minimal lethal dose is 3.125μM and the median lethal doses (LD 50 ) for FMN and FAD are 6.5μM and 7.2μM, respectively. Individual exposure to visible blue light irradiation or riboflavin photosensitizers does not produce cytotoxicity and no side effects are observed in this study. The western blotting results also show that an intrinsic apoptosis pathway is activated by the ROS during photolysis of riboflavin analogues. Blue light triggers the cytotoxicity of riboflavins on HeLa cells in vitro. Based on these results, this is a feasible and efficient of PDT with an intrinsic photosensitizer for cancer research. Copyright © 2017 Elsevier B.V. All rights reserved.

Photosensitized cleavage of some olefins as potential linkers to be used in drug delivery

NASA Astrophysics Data System (ADS)

Dinache, Andra; Smarandache, Adriana; Simon, Agota; Nastasa, Viorel; Tozar, Tatiana; Pascu, Alexandru; Enescu, Mironel; Khatyr, Abderrahim; Sima, Felix; Pascu, Mihail-Lucian; Staicu, Angela

2017-09-01

A study of photosensitized cleavage of different olefins as potential linkers for drug carrier complexes is reported. The role of singlet oxygen and the kinetic rates for light induced reactions were estimated by time-resolved measurements of singlet oxygen phosphorescence (at 1270 nm) obtained via 532 nm pulse laser excitation of a photosensitizer. The mixture of each studied olefin with verteporfin (used as photosensitizer) were exposed to low energy visible radiation. The rate constants for singlet oxygen quenching by studied olefins were determined. The irradiated solutions were investigated by FTIR spectroscopy and potential photoproducts were suggested. The experimental results were compared with simulations made by DFT method.

Novel visible light activated type 1 photosensitizers

NASA Astrophysics Data System (ADS)

Rajagopalan, Raghavan; Karwa, Amolkumar; Poreddy, Amruta R.; Lusiak, Przemyslaw M.; Pandurangi, Raghoottama S.; Cantrell, Gary L.; Dorshow, Richard B.

2010-02-01

Photodynamic therapy of tumors involving Type 2 photosenstizers has been conspicuously successful, but the Type 1 process, in contrast, has not received much attention despite its considerable potential. Accordingly, several classes of molecules containing fragile bonds such as azido (-N=N=N), azo (-N=N-), and oxaza (-N-O-) functional groups that produce reactive intermediates such as radicals and nitrenes upon photoexcitation with visible light were prepared and tested for cell viability using U397 leukemia cell line. The cells were incubated with the photosensitizer at various concentrations, and were illuminated for 5, 10, and 20 minutes. The results show that all the photosensitizers caused cell death compared to the controls when exposed to both the photosensitizers and light.

The influence of excitation radiation parameters on photosensitized generation of singlet oxygen in water

NASA Astrophysics Data System (ADS)

Il'ina, A. D.; Glazov, A. L.; Semenova, I. V.; Vasyutinskii, O. S.

2016-06-01

Photosensitized generation of singlet oxygen with the aid of Radahlorin® photosensitizer has been investigated. The dependences of the intensity of singlet oxygen phosphorescence and photosensitizer fluorescence on the excitation radiation wavelength in the range of 350-440 nm and on the irradiation dose have been obtained. The dependence of the ratio of the sensitizer fluorescence intensity at about 670 nm to the singlet oxygen phosphorescence intensity at a wavelength of 1270 nm on the excitation radiation wavelength is found to be nonmonotonic and have a minimum near the center of the absorption band on its red wing. The results obtained can be used to monitor the singlet oxygen concentration in solutions.

Upregulation of mucin glycoprotein MUC1 in the progression to esophageal adenocarcinoma and therapeutic potential with a targeted photoactive antibody-drug conjugate

PubMed Central

Haidry, Rehan J.; Oukrif, Dahmane; Khan, Saif-U-Rehman; Puccio, Ignazio; Gandy, Michael; Reinert, Halla W.; Bloom, Ellie; Rashid, Mohammed; Yahioglu, Gokhan; Deonarain, Mahendra P.; Hamoudi, Rifat; Rodriguez-Justo, Manuel; Novelli, Marco R.; Lovat, Laurence B.

2017-01-01

Background Mucin glycoprotein 1 (MUC1) is a glycosylated transmembrane protein on epithelial cells. We investigate MUC1 as a therapeutic target in Barrett’s epithelium (BE) and esophageal adenocarcinoma (EA) and provide proof of concept for a light based therapy targeting MUC1. RESULTS MUC1 was present in 21% and 30% of significantly enriched pathways comparing BE and EA to squamous epithelium respectively. MUC1 gene expression was x2.3 and x2.2 higher in BE (p=<0.001) and EA (p=0.03). MUC1 immunohistochemical expression increased during progression to EA and followed tumor invasion. HuHMFG1 based photosensitive antibody drug conjugates (ADC) showed cell internalization, MUC1 selective and light-dependent cytotoxicity (p=0.0006) and superior toxicity over photosensitizer alone (p=0.0022). Methods Gene set enrichment analysis (GSEA) evaluated pathways during BE and EA development and quantified MUC1 gene expression. Immunohistochemistry and flow cytometry evaluated the anti-MUC1 antibody HuHMFG1 in esophageal cells of varying pathological grade. Confocal microscopy examined HuHMFG1 internalization and HuHMFG1 ADCs were created to deliver a MUC1 targeted phototoxic payload. Conclusions MUC1 is a promising target in EA. Molecular and light based targeting of MUC1 with a photosensitive ADC is effective in vitro and after development may enable treatment of locoregional tumors endoscopically. PMID:28212575

Photophysical and antibacterial properties of complex systems based on smectite, a cationic surfactant and methylene blue.

PubMed

Donauerová, Alena; Bujdák, Juraj; Smolinská, Miroslava; Bujdáková, Helena

2015-10-01

Solid or colloidal materials with embedded photosensitizers are promising agents from the medical or environmental perspective, where the direct use of photoactive solutions appears to be problematic. Colloids based on layered silicates of the saponite (Sap) and montmorillonite (Mon) type, including those modified with dodecylammonium cations (C12) and photosensitizer--methylene blue (MB) were studied. Two representatives of bacteria, namely Enterobacter cloacae and Escherichia coli, were selected for this work. A spectral study showed that MB solutions and also colloids with Sap including C12 exhibited the highest photoactivities. The antimicrobial properties of the smectite colloids were not directly linked to the photoactivity of the adsorbed MB cations. They were also influenced by other parameters, such as light vs. dark conditions, the spectrum, power and duration of the light used for the irradiation; growth phases, and the pre-treatment of microorganisms. Both the photoactivity and antimicrobial properties of the colloids were improved upon pre-modification with C12. Significantly higher antimicrobial properties were observed for the colloids based on Mon with MB in the form of molecular aggregates without significant photoactivities. The MB/Mon colloids, both modified and non-modified with C12 cations, exhibited higher antimicrobial effects than pure MB solution. Besides the direct effect of photosensitization, the surface properties of the silicate particles likely played a crucial role in the interactions with microorganisms. Copyright © 2015 Elsevier B.V. All rights reserved.

Two rapid pigmentation tests for identification of Cryptococcus neoformans.

PubMed Central

Kaufmann, C S; Merz, W G

1982-01-01

Two tests were developed for the rapid identification of Cryptococcus neoformans based on pigment produced by the organism's phenoloxidase activity. Caffeic acid was incorporated into cornmeal agar, a medium used routinely for yeast identification. When tested on this medium, only C. neoformans isolates produced brown pigment. All other yeasts maintained their normal morphology and did not produce the reaction product. A non-medium-based test was developed for same-day identification of C. neoformans isolates. Paper strips saturated with a buffered L-beta-3,4-dihydroxyphenylalanine-ferric citrate solution were inoculated with isolates and incubated at 37 degrees C. Pigment production occurred only with C. neoformans isolates, many within 60 to 90 min. All other yeasts remained negative. PMID:7040452

DOSE-RESPONSE FOR UV-INDUCED IMMUNE SUPPRESSION IN PEOPLE OF COLOR: DIFFERENCES BASED ON ERYTHEMAL REACTIVITY RATHER THAN SKIN PIGMENTATION

EPA Science Inventory

Ultraviolet radiation (UVR) is known to suppress immune responses in human subjects. The purpose of this study was to develop dose responses across a broad range of skin pigmentation in order to facilitate risk assessment. UVR was administered using FS 20 bulbs. Skin pigmentation...

Solid state photosensitive devices which employ isolated photosynthetic complexes

DOEpatents

Peumans, Peter; Forrest, Stephen R.

2009-09-22

Solid state photosensitive devices including photovoltaic devices are provided which comprise a first electrode and a second electrode in superposed relation; and at least one isolated Light Harvesting Complex (LHC) between the electrodes. Preferred photosensitive devices comprise an electron transport layer formed of a first photoconductive organic semiconductor material, adjacent to the LHC, disposed between the first electrode and the LHC; and a hole transport layer formed of a second photoconductive organic semiconductor material, adjacent to the LHC, disposed between the second electrode and the LHC. Solid state photosensitive devices of the present invention may comprise at least one additional layer of photoconductive organic semiconductor material disposed between the first electrode and the electron transport layer; and at least one additional layer of photoconductive organic semiconductor material, disposed between the second electrode and the hole transport layer. Methods of generating photocurrent are provided which comprise exposing a photovoltaic device of the present invention to light. Electronic devices are provided which comprise a solid state photosensitive device of the present invention.

Off-Resonance Photosensitization of a Photorefractive Polymer Composite Using PbS Nanocrystals

DOE PAGES

Moon, Jong-Sik; Liang, Yichen; Stevens, Tyler E.; ...

2015-05-26

The photosensitization of photorefractive polymeric composites for operation at 633 nm is accomplished through the inclusion of narrow band gap semiconductor nanocrystals composed of PbS. Unlike previous studies involving photosensitization of photorefractive polymer composites with inorganic nanocrystals, we employ an off-resonance approach where the first excitonic transition associated with the PbS nanocrystals lies at ~1220 nm and not the wavelength of operation. Using this methodology, internal diffraction efficiencies exceeding 82%, two-beam-coupling gain coefficients of 211 cm –1, and response times of 34 ms have been observed, representing some of the best figures of merit reported for this class of materials.more » Furthermore, these data demonstrate the ability of semiconductor nanocrystals to compete effectively with traditional organic photosensitizers. In addition to superior performance, this approach also offers an inexpensive and easy means by which to photosensitize composite materials. Additionally, the photoconductive characteristics of the composites used for this study will also be considered.« less

Novel type 1 photosensitizers: viability of leukemia cells exposed to reactive intermediates generated in situ by in vitro photofragmentation

NASA Astrophysics Data System (ADS)

Rajagopalan, Raghavan; Karwa, Amol; Lusiak, Przemyslaw M.; Srivastava, Kripa; Poreddy, Amruta R.; Pandurangi, Raghootama S.; Galen, Karen P.; Neumann, William L.; Cantrell, Gary E.; Dorshow, Richard B.

2009-06-01

Photodynamic therapy of tumors involving Type 2 photosenstizers has been conspicuously successful, but the Type 1 process, in contrast, has not received much attention despite its considerable potential. Accordingly, several classes of molecules containing fragile bonds such as azido (-N=N=N), azo (-N=N-), sulfenato (-S-O-) and oxaza (-N-O-) functional groups that produce reactive intermediates such as radicals and nitrenes upon photoexcitation were prepared and tested for cell viability using U397 leukemia cell line. The azido photosensitizer was conjugated to leukemia cell binding peptide, SFFWRLS, for targeted cell viability study. The cells were incubated with the photosensitizer at various concentrations, and were illuminated for 5, 10, and 20 minutes. The results show that all the photosensitizers caused cell death compared to the controls when exposed to both the photosensitizers and light. Most importantly, selective cell death was observed with the azido peptide conjugate 6, which clearly demonstrates that these Type 1 sensitizers are useful for phototherapeutic applications.

78 FR 54758 - Listing of Color Additives Exempt From Certification; Mica-Based Pearlescent Pigments...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-09-06

... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration 21 CFR Part 73 [Docket No. FDA-2012-C-0224] Listing of Color Additives Exempt From Certification; Mica-Based Pearlescent Pigments...). The final rule amended the color additive regulations to provide for the safe use of mica-based...

Positive selection of a duplicated UV-sensitive visual pigment coincides with wing pigment evolution in Heliconius butterflies

PubMed Central

Briscoe, Adriana D.; Bybee, Seth M.; Bernard, Gary D.; Yuan, Furong; Sison-Mangus, Marilou P.; Reed, Robert D.; Warren, Andrew D.; Llorente-Bousquets, Jorge; Chiao, Chuan-Chin

2010-01-01

The butterfly Heliconius erato can see from the UV to the red part of the light spectrum with color vision proven from 440 to 640 nm. Its eye is known to contain three visual pigments, rhodopsins, produced by an 11-cis-3-hydroxyretinal chromophore together with long wavelength (LWRh), blue (BRh) and UV (UVRh1) opsins. We now find that H. erato has a second UV opsin mRNA (UVRh2)—a previously undescribed duplication of this gene among Lepidoptera. To investigate its evolutionary origin, we screened eye cDNAs from 14 butterfly species in the subfamily Heliconiinae and found both copies only among Heliconius. Phylogeny-based tests of selection indicate positive selection of UVRh2 following duplication, and some of the positively selected sites correspond to vertebrate visual pigment spectral tuning residues. Epi-microspectrophotometry reveals two UV-absorbing rhodopsins in the H. erato eye with λmax = 355 nm and 398 nm. Along with the additional UV opsin, Heliconius have also evolved 3-hydroxy-DL-kynurenine (3-OHK)-based yellow wing pigments not found in close relatives. Visual models of how butterflies perceive wing color variation indicate this has resulted in an expansion of the number of distinguishable yellow colors on Heliconius wings. Functional diversification of the UV-sensitive visual pigments may help explain why the yellow wing pigments of Heliconius are so colorful in the UV range compared to the yellow pigments of close relatives lacking the UV opsin duplicate. PMID:20133601

Positive selection of a duplicated UV-sensitive visual pigment coincides with wing pigment evolution in Heliconius butterflies.

PubMed

Briscoe, Adriana D; Bybee, Seth M; Bernard, Gary D; Yuan, Furong; Sison-Mangus, Marilou P; Reed, Robert D; Warren, Andrew D; Llorente-Bousquets, Jorge; Chiao, Chuan-Chin

2010-02-23

The butterfly Heliconius erato can see from the UV to the red part of the light spectrum with color vision proven from 440 to 640 nm. Its eye is known to contain three visual pigments, rhodopsins, produced by an 11-cis-3-hydroxyretinal chromophore together with long wavelength (LWRh), blue (BRh) and UV (UVRh1) opsins. We now find that H. erato has a second UV opsin mRNA (UVRh2)-a previously undescribed duplication of this gene among Lepidoptera. To investigate its evolutionary origin, we screened eye cDNAs from 14 butterfly species in the subfamily Heliconiinae and found both copies only among Heliconius. Phylogeny-based tests of selection indicate positive selection of UVRh2 following duplication, and some of the positively selected sites correspond to vertebrate visual pigment spectral tuning residues. Epi-microspectrophotometry reveals two UV-absorbing rhodopsins in the H. erato eye with lambda(max) = 355 nm and 398 nm. Along with the additional UV opsin, Heliconius have also evolved 3-hydroxy-DL-kynurenine (3-OHK)-based yellow wing pigments not found in close relatives. Visual models of how butterflies perceive wing color variation indicate this has resulted in an expansion of the number of distinguishable yellow colors on Heliconius wings. Functional diversification of the UV-sensitive visual pigments may help explain why the yellow wing pigments of Heliconius are so colorful in the UV range compared to the yellow pigments of close relatives lacking the UV opsin duplicate.

Pyropheophorbide-a methyl ester-mediated photosensitization activates transcription factor NF-kappaB through the interleukin-1 receptor-dependent signaling pathway.

PubMed

Matroule, J Y; Bonizzi, G; Morlière, P; Paillous, N; Santus, R; Bours, V; Piette, J

1999-01-29

Pyropheophorbide-a methyl ester (PPME) is a second generation of photosensitizers used in photodynamic therapy. We demonstrated that PPME photosensitization activated NF-kappaB transcription factor in colon cancer cells. Unexpectedly, this activation occurred in two separate waves, i.e. a rapid and transient one and a second slower but sustained phase. The former was due to photosensitization by PPME localized in the cytoplasmic membrane which triggered interleukin-1 receptor internalization and the transduction pathways controlled by the interleukin-1 type I receptor. Indeed, TRAF6 dominant negative mutant abolished NF-kappaB activation by PPME photosensitization, and TRAF2 dominant negative mutant was without any effect, and overexpression of IkappaB kinases increased gene transcription controlled by NF-kappaB. Oxidative stress was not likely involved in the activation. On the other hand, the slower and sustained wave could be the product of the release of ceramide through activation of the acidic sphingomyelinase. PPME localization within the lysosomal membrane could explain why ceramide acted as second messenger in NF-kappaB activation by PPME photosensitization. These data will allow a better understanding of the molecular basis of tumor eradication by photodynamic therapy, in particular the importance of the host cell response in the treatment.

Genetic (idiopathic) epilepsy with photosensitive seizures includes features of both focal and generalized seizures.

PubMed

Xue, Jiao; Gong, Pan; Yang, Haipo; Liu, Xiaoyan; Jiang, Yuwu; Zhang, Yuehua; Yang, Zhixian

2018-04-19

Clinically, some patients having genetic (idiopathic) epilepsy with photosensitive seizures were difficult to be diagnosed. We aimed to discuss whether the genetic (idiopathic) epilepsy with photosensitive seizures is a focal entity, a generalized entity or a continuum. Twenty-two patients with idiopathic epilepsies and photoconvulsive response (PCR) were retrospectively recruited. In the medical records, the seizure types included "generalized tonic-clonic seizures (GTCS)" in 15, "partial secondarily GTCS (PGTCS)" in 3, partial seizures (PS) in 3, myoclonic seizures in 2, eyelid myoclonus in one, and only febrile seizures in one. Seizure types of PCR included GTCS (1/22), PGTCS (6/22), PS (9/22), electrical seizures (ES) (3/22) and GTCS/PGTCS (3/22). Combined the medical history with PCR results, they were diagnosed as: idiopathic (photosensitive) occipital lobe epilepsy (I(P)OE) in 12, genetic (idiopathic) generalized epilepsy (GGE) in one, GGE/I(P)OE in 5, pure photosensitive seizure in one, and epilepsy with undetermined generalized or focal seizure in 3. So, the dichotomy between generalized and focal seizures might have been out of date regarding to pathophysiological advances in epileptology. To some extent, it would be better to recognize the idiopathic epilepsy with photosensitive seizures as a continuum between focal and generalized seizures.

Exogenous indirect photoinactivation of bacterial pathogens and indicators in water with natural and synthetic photosensitizers in simulated sunlight with reduced UVB.

PubMed

Maraccini, P A; Wenk, J; Boehm, A B

2016-08-01

To investigate the UVB-independent and exogenous indirect photoinactivation of eight human health-relevant bacterial species in the presence of photosensitizers. Eight bacterial species were exposed to simulated sunlight with greatly reduced UVB light intensity in the presence of three synthetic photosensitizers and two natural photosensitizers. Inactivation curves were fit with shoulder log-linear or first-order kinetic models, from which the presence of a shoulder and magnitude of inactivation rate constants were compared. Eighty-four percent reduction in the UVB light intensity roughly matched a 72-95% reduction in the overall bacterial photoinactivation rate constants in sensitizer-free water. With the UVB light mostly reduced, the exogenous indirect mechanism contribution was evident for most bacteria and photosensitizers tested, although most prominently with the Gram-positive bacteria. Results confirm the importance of UVB light in bacterial photoinactivation and, with the reduction of the UVB light intensity, that the Gram-positive bacteria are more vulnerable to the exogenous indirect mechanism than Gram-negative bacteria. UVB is the most important range of the sunlight spectrum for bacterial photoinactivation. In aquatic environments where photosensitizers are present and there is high UVB light attenuation, UVA and visible wavelengths can contribute to exogenous indirect photoinactivation. © 2016 The Society for Applied Microbiology.

Metal-based phthalocyanines as a potential photosensitizing agent in photodynamic therapy for the treatment of melanoma skin cancer

NASA Astrophysics Data System (ADS)

Maduray, Kaminee; Odhav, B.

2014-03-01

Photodynamic therapy (PDT) is an emerging medical treatment that uses photosensitizers (drug) which are activated by laser light for the generation of cytotoxic free radicals and singlet oxygen molecules that cause tumor cell death. In the recent years, there has been a focus on using and improving an industrial colorant termed phthalocyanines as a prospective photosensitizer because of its unique properties. This in vitro study investigated the photodynamic effect of indium (InPcCl) and iron (FePcCl) phthalocyanine chlorides on human skin cancer cells (melanoma). Experimentally, 2 x 104 cells/ml were seeded in 24-well tissue culture plates and allowed to attach overnight, after which cells were treated with different concentrations (2 μg/ml - 100 μg/ml) of InPcCl and FePcCl. After 2 h, cells were irradiated with constant light doses of 2.5 J/cm2, 4.5 J/cm2 and 8.5 J/cm2 delivered from a diode laser. Post-irradiated cells were incubated for 24 h before cell viability was measured using the MTT Assay. At 24 h after PDT, irradiation with a light dose of 2.5 J/cm2 for each photosensitizing concentration of InPcCl and FePcCl produced a significant decrease in cell viability, but when the treatment light dose was further increased to 4.5 J/cm2 and 8.5 J/cm2 the cell survival was less than 55% for photosensitizing concentrations of InPcCl and FePcCl from 4 μg/ml to 100 μg/ml. This PDT study concludes that low concentrations on InPcCl and FePcCl activated with low level light doses can be used for the effective in vitro killing of melanoma cancer cells.

The influence of visible light and inorganic pigments on fluorescence excitation emission spectra of egg-, casein- and collagen-based painting media

NASA Astrophysics Data System (ADS)

Nevin, A.; Anglos, D.; Cather, S.; Burnstock, A.

2008-07-01

Spectrofluorimetric analysis of proteinaceous binding media is particularly promising because proteins employed in paintings are often fluorescent and media from different sources have significantly different fluorescence spectral profiles. Protein-based binding media derived from eggs, milk and animal tissue have been used for painting and for conservation, but their analysis using non-destructive techniques is complicated by interferences with pigments, their degradation and their low concentration. Changes in the fluorescence excitation emission spectra of films of binding media following artificial ageing to an equivalent of 50 and 100 years of museum lighting include the reduction of bands ascribed to tyrosine, tryptophan and Maillard reaction products and an increase in fluorescent photodegradation. Fluorescence of naturally aged paint is dependent on the nature of the pigment present and, with egg-based media, in comparison with un-pigmented films, emissions ascribed to amino acids are more pronounced.

Arabidopsis ROOT PHOTOTROPISM2 Contributes to the Adaptation to High-Intensity Light in Phototropic Responses.

PubMed

Haga, Ken; Tsuchida-Mayama, Tomoko; Yamada, Mizuki; Sakai, Tatsuya

2015-04-01

Living organisms adapt to changing light environments via mechanisms that enhance photosensitivity under darkness and attenuate photosensitivity under bright light conditions. In hypocotyl phototropism, phototropin1 (phot1) blue light photoreceptors mediate both the pulse light-induced, first positive phototropism and the continuous light-induced, second positive phototropism, suggesting the existence of a mechanism that alters their photosensitivity. Here, we show that light induction of ROOT PHOTOTROPISM2 (RPT2) underlies photosensory adaptation in hypocotyl phototropism of Arabidopsis thaliana. rpt2 loss-of-function mutants exhibited increased photosensitivity to very low fluence blue light but were insensitive to low fluence blue light. Expression of RPT2 prior to phototropic stimulation in etiolated seedlings reduced photosensitivity during first positive phototropism and accelerated second positive phototropism. Our microscopy and biochemical analyses indicated that blue light irradiation causes dephosphorylation of NONPHOTOTROPIC HYPOCOTYL3 (NPH3) proteins and mediates their release from the plasma membrane. These phenomena correlate closely with the desensitization of phot1 signaling during the transition period from first positive phototropism to second positive phototropism. RPT2 modulated the phosphorylation of NPH3 and promoted reconstruction of the phot1-NPH3 complex on the plasma membrane. We conclude that photosensitivity is increased in the absence of RPT2 and that this results in the desensitization of phot1. Light-mediated induction of RPT2 then reduces the photosensitivity of phot1, which is required for second positive phototropism under bright light conditions. © 2015 American Society of Plant Biologists. All rights reserved.

Effects of glycolic acid chemical peeling on facial pigment deposition: evaluation using novel computer analysis of digital-camera-captured images.

PubMed

Kakudo, Natsuko; Kushida, Satoshi; Suzuki, Kenji; Kusumoto, Kenji

2013-12-01

Chemical peeling is becoming increasingly popular for skin rejuvenation in dermatological cosmetic medicine. However, the improvements seen with chemical peeling are often very minor, and it is difficult to conduct a quantitative assessment of pre- and post-treatment appearance. We report the pre- and postpeeling effects for facial pigment deposition using a novel computer analysis method for digital-camera-captured images. Glycolic acid chemical peeling was performed a total of 5 times at 2-week intervals in 23 healthy women. We conducted a computer image analysis by utilizing Robo Skin Analyzer CS 50 and Clinical Suite 2.1 and then reviewed each parameter for the area of facial pigment deposition pre- and post-treatment. Parameters were pigmentation size and four pigmentation categories: little pigmentation and three levels of marked pigmentation (Lv1, 2, and 3) based on detection threshold. Each parameter was measured, and the total area of facial pigmentation was calculated. The total area of little pigmentation and marked pigmentation (Lv1) was significantly reduced. On the other hand, a significant difference was not observed for the total area of marked pigmentation Lv2 and Lv3. This suggests that glycolic acid chemical peeling has an effect on small facial pigment disposition or has an effect on light pigment deposition. As the Robo Skin Analyzer is useful for objectively quantifying and analyzing minor changes in facial skin, it is considered to be an effective tool for accumulating treatment evidence in the cosmetic and esthetic skin field. © 2013 Wiley Periodicals, Inc.

Real-Time Visualization of Active Species in a Single-Site Metal–Organic Framework Photocatalyst

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Sizhuo; Pattengale, Brian; Lee, Sungsik

In this work, we report a new single-site photocatalyst (Co-Ru-UIO- 67(bpy)) based on a metal-organic framework platform with incorporated molecular photosensitizer and catalyst. We show that this catalyst not only demonstrates exceptional activity for light-driven H2 production but also can be recycled without loss of activity. Using the combination of optical transient absorption spectroscopy and in situ X-ray absorption spectroscopy, we not only captured the key CoI intermediate species formed after ultrafast charge transfer from the incorporated photosensitizer but also identified the rate-limiting step in the catalytic cycle, providing insight into the catalysis mechanism of these single-site metal-organic framework photocatalysts.

Synthesis, bioanalysis and biodistribution of photosensitizer conjugates for photodynamic therapy

PubMed Central

Denis, Tyler GSt; Hamblin, Michael R

2013-01-01

Photodynamic therapy (PDT) was discovered in 1900 by Raab, and has since emerged as a promising tool for treating diseases characterized by unwanted cells or hyperproliferating tissue (e.g., cancer or infectious disease). PDT consists of the light excitation of a photosensitizer (PS) in the presence of O2 to yield highly reactive oxygen species. In recent years, PDT has been improved by the synthesis of targeted bioconjugates between monoclonal antibodies and PS, and by investigating PS biodistribution and PD. Here, we provide a comprehensive review of major developments in PS-immunoconjugate-based PDT and the bioanalysis of these agents, with a specific emphasis on anticancer and antimicrobial PDT. PMID:23641699

Separation of porphyrin-based photosensitizer isomers by laser-induced fluorescence capillary electrophoresis.

PubMed

Peng, Xuejun; Sternberg, Ethan; Dolphin, David

2005-10-01

Methods for the separation of photosensitizer isomers, such as benzoporphyrin derivative monoacid, benzoporphyrin ethyl monoacid, 2-[1-hexyloxyethyl]-2-devinylpyropheophorbide-a, diethyleneglycol diester benzoporphyrin derivative, tin ethyl etiopurpurin, and phthalocyanine tetrasulfonate, have been systematically developed by CE. Detection was accomplished by UV absorption at 214 nm or by LIF with excitation at 442/488 nm and emission at 690 nm. The effects of three major experimental parameters of buffer types, organic solvents, and surfactant additives are described. The optimized separation conditions were determined so as to provide satisfactory separation efficiency and analysis time. The methods are shown to be suitable for the separation and determination of porphyrin and phthalocyanines regioisomers, diastereoisomers, and enantiomers.

Synthesis and characterization of black ceramic pigments by recycling of two hazardous wastes

NASA Astrophysics Data System (ADS)

Du, Minxing; Du, Yi; Chen, Zhongtao; Li, Zhongfu; Yang, Kai; Lv, Xingjie; Feng, Yibing

2017-09-01

In this study, two different industrial wastes, namely vanadium tailing and leather sludge, were used as less expensive alternative raw materials for the synthesis of black ceramic pigments to be used in commercial glazes. The pigments were based on hematite structure (FexCr1-x)2O3 and prepared by the common solid-state reaction method, under optimal formulation and processing conditions. The synthesized pigments were characterized in typical ceramic glazes and ceramic tile bodies. Optimal color development was achieved when the Fe/Cr mole ratios were 2.0 with 40 wt% content of vanadium tailing at 1200 °C. The coloring properties were similar to those imparted by a commercial black pigment.

Colour and toxic characteristics of metakaolinite–hematite pigment for integrally coloured concrete, prepared from iron oxide recovered from a water treatment plant of an abandoned coal mine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sadasivam, Sivachidambaram, E-mail: sadasivams@cardiff.ac.uk; Thomas, Hywel Rhys

A metakaolinite-hematite (KH) red pigment was prepared using an ocherous iron oxide sludge recovered from a water treatment plant of an abandoned coal mine. The KH pigment was prepared by heating the kaolinite and the iron oxide sludge at kaolinite's dehydroxylation temperature. Both the raw sludge and the KH specimen were characterised for their colour properties and toxic characteristics. The KH specimen could serve as a pigment for integrally coloured concrete and offers a potential use for the large volumes of the iron oxide sludge collected from mine water treatment plants. - Graphical abstract: A kaolinite based red pigment wasmore » prepared using an ocherous iron oxide sludge recovered from an abandoned coal mine water treatment plant. Display Omitted - Highlights: • A red pigment was prepared by heating a kaolinite and an iron oxide sludge. • The iron oxide and the pigment were characterised for their colour properties. • The red pigment can be a potential element for integrally coloured concrete.« less

Statistical optimization and anticancer activity of a red pigment isolated from Streptomyces sp. PM4

PubMed Central

Karuppiah, Valliappan; Aarthi, Chandramohan; Sivakumar, Kannan; Kannan, Lakshmanan

2013-01-01

Objective To enhance the pigment production by Streptomyces sp. PM4 for evaluating its anticancer activity. Methods Response surface methodology was employed to enhance the production of red pigment from Streptomyces sp. PM4. Optimized pigment was purified and evaluated for the anticancer activity against HT1080, Hep2, HeLa and MCF7 cell lines by MTT assay. Results Based on the response surface methodology, it could be concluded that maltose (4.06 g), peptone (7.34 g), yeast extract (4.34 g) and tyrosine (2.89 g) were required for the maximum production of pigment (1.68 g/L) by the Streptomyces sp. PM4. Optimization of the medium with the above tested features increased the pigment yield by 4.6 fold. Pigment showed the potential anticancer activity against HT1080, HEp-2, HeLa and MCF-7cell lines with the IC50 value of 18.5, 15.3, 9.6 and 8.5 respectively. Conclusions The study revealed that the maximum amount of pigment could be produced to treat cancer. PMID:23905024

Statistical optimization and anticancer activity of a red pigment isolated from Streptomyces sp. PM4.

PubMed

Karuppiah, Valliappan; Aarthi, Chandramohan; Sivakumar, Kannan; Kannan, Lakshmanan

2013-08-01

To enhance the pigment production by Streptomyces sp. PM4 for evaluating its anticancer activity. Response surface methodology was employed to enhance the production of red pigment from Streptomyces sp. PM4. Optimized pigment was purified and evaluated for the anticancer activity against HT1080, Hep2, HeLa and MCF7 cell lines by MTT assay. Based on the response surface methodology, it could be concluded that maltose (4.06 g), peptone (7.34 g), yeast extract (4.34 g) and tyrosine (2.89 g) were required for the maximum production of pigment (1.68 g/L) by the Streptomyces sp. PM4. Optimization of the medium with the above tested features increased the pigment yield by 4.6 fold. Pigment showed the potential anticancer activity against HT1080, HEp-2, HeLa and MCF-7 cell lines with the IC50 value of 18.5, 15.3, 9.6 and 8.5 respectively. The study revealed that the maximum amount of pigment could be produced to treat cancer.

Recreating a functional ancestral archosaur visual pigment.

PubMed

Chang, Belinda S W; Jönsson, Karolina; Kazmi, Manija A; Donoghue, Michael J; Sakmar, Thomas P

2002-09-01

The ancestors of the archosaurs, a major branch of the diapsid reptiles, originated more than 240 MYA near the dawn of the Triassic Period. We used maximum likelihood phylogenetic ancestral reconstruction methods and explored different models of evolution for inferring the amino acid sequence of a putative ancestral archosaur visual pigment. Three different types of maximum likelihood models were used: nucleotide-based, amino acid-based, and codon-based models. Where possible, within each type of model, likelihood ratio tests were used to determine which model best fit the data. Ancestral reconstructions of the ancestral archosaur node using the best-fitting models of each type were found to be in agreement, except for three amino acid residues at which one reconstruction differed from the other two. To determine if these ancestral pigments would be functionally active, the corresponding genes were chemically synthesized and then expressed in a mammalian cell line in tissue culture. The expressed artificial genes were all found to bind to 11-cis-retinal to yield stable photoactive pigments with lambda(max) values of about 508 nm, which is slightly redshifted relative to that of extant vertebrate pigments. The ancestral archosaur pigments also activated the retinal G protein transducin, as measured in a fluorescence assay. Our results show that ancestral genes from ancient organisms can be reconstructed de novo and tested for function using a combination of phylogenetic and biochemical methods.

Optimizing conditions for the extraction of pigments in cochineals (Dactylopius coccus Costa) using response surface methodology.

PubMed

González, Mónica; Méndez, Jesús; Carnero, Aurelio; Lobo, M Gloria; Afonso, Ana

2002-11-20

A simple method was developed for the extraction and determination of color pigments in cochineals (Dactylopius coccus Costa). The procedure was based on the solvent extraction of pigments in insect samples using methanol:water (65:35, v:v) as extractant. Two-level factorial design was used in order to optimize the solvent extraction parameters: temperature, time, methanol concentration in the extractant mixture, and the number of extractions. The results suggest that the number of extractions is statistically the most significant factor. The separation and determination of the pigments was carried out by high-performance liquid chromatography with UV-visible detection. Because the absorption spectra of different pigments are different in the visible region, it is convenient to use a diode array detector to obtain chromatographic profiles that allow for the characterization of the extracted pigments.

Ag nanoparticles agargel nanocomposites for SERS detection of cultural heritage interest pigments

NASA Astrophysics Data System (ADS)

Amato, F.; Micciche', C.; Cannas, M.; Gelardi, F. M.; Pignataro, B.; Li Vigni, M.; Agnello, S.

2018-02-01

Agarose gel (agargel) composites with commercial and laboratory made silver nanoparticles were prepared by a wet solution method at room temperature. The gel composites were used for pigment extraction and detection by Raman spectroscopy. Red (alizarin) and violet (crystal violet) pigments deposited on paper were extracted by the composites and were investigated by micro-Raman spectroscopy. Evaluation was carried out of the surface-enhanced Raman spectroscopy (SERS) effect induced by the silver nanoparticles embedded in the gel. A kinetic approach as a function of time was used to determine the efficiency of pigments extraction by composites deposition. A non-invasive extraction process of few minutes is demonstrated. This process induces active SERS for both used pigments. The reported results show the full exploitability of agargel silver nanoparticle composites for the extraction of pigments from paper based artworks.

An analytical Raman spectroscopic study of an important english oil painting of the 18th Century

NASA Astrophysics Data System (ADS)

Edwards, Howell G. M.; Vandenabeele, Peter; Jehlicka, Jan; Benoy, Timothy J.

2014-01-01

An opportunity was afforded to analyse pigment specimens from an unrestored oil painting in the style of the English School of the mid-18th Century prior to conservation being undertaken. Raman spectroscopy was adopted to characterise the pigments and indicated the presence of a novel red pigment which was assigned to the complex chromium mineral, hemihedrite, in addition to other interesting materials found in combination. This is the first recorded identification of hemihedrite spectral signals in an art context in a range of mineral pigments that are otherwise typical of this period and some hypotheses are presented to explain its presence based on its occurrence with associated mineral pigments. It is suggested that the presence of powdered glass identified in certain areas of the painting enhanced the reflectivity of the pigment matrix.

Photomedicine with laser drug delivery technologies

NASA Astrophysics Data System (ADS)

Zharov, Vladimir P.; Latyshev, Alexei S.; Leviev, Dmitry O.

1999-07-01

This paper presents a new technology, which consists in utilizing laser drug delivery methods for the purposes of photodrug therapy. According to this technology, photosensitizer is applied onto the treated surface and then the solution is either impregnated or injected into the medium, with it being suggested to employ laser drug delivery techniques for the impregnation and injection of the photosensitizer. After introducing the photosensitizer, the area is illuminated by a matrix of light-emission diodes.

Assessment of the actual light dose in photodynamic therapy.

PubMed

Schaberle, Fabio A

2018-06-09

Photodynamic therapy (PDT) initiates with the absorption of light, which depends on the spectral overlap between the light source emission and the photosensitizer absorption, resulting in the number of photons absorbed, the key parameter starting PDT processes. Most papers report light doses regardless if the light is only partially absorbed or shifted relatively to the absorption peak, misleading the actual light dose value and not allowing quantitative comparisons between photosensitizers and light sources. In this manuscript a method is presented to calculate the actual light dose delivered by any light source for a given photosensitizer. This method allows comparing light doses delivered for any combination of light source (broad or narrow band or daylight) and photosensitizer. Copyright © 2018. Published by Elsevier B.V.

Stable powders made from photosensitive polycrystalline complexes of heterocyclic monomers and their polymers

NASA Technical Reports Server (NTRS)

Murphy, Oliver J. (Inventor); Hitchens, G. Duncan (Inventor); Hodko, Dalibor (Inventor)

1999-01-01

The present invention relates to a low electronic conductivity polymer composition having well dispersed metal granules, a stable powder made from photosensitive polycrystalline complexes of pyrrole, or its substituted derivatives and silver cations for making the polymer composition, and methods of forming the stable powder and polymer composition, respectively. A polycrystalline complex of silver and a monomer, such as pyrrole, its substituted derivatives or combinations thereof, is precipitated in the form of a stable photosensitive powder upon addition of the monomer to a solvent solution, such as toluene containing an electron acceptor. The photosensitive powder can be stored in the dark until needed. The powder may be dissolved in a solvent, cast onto a substrate and photopolymerized.

Establishment of an in vitro photoassay using THP-1 cells and IL-8 to discriminate photoirritants from photoallergens.

PubMed

Martínez, V; Galbiati, V; Corsini, E; Martín-Venegas, R; Vinardell, M P; Mitjans, M

2013-09-01

At present, there are no in vivo or in vitro methods developed which has been adopted by regulatory authorities to assess photosensitization induced by chemicals. Recently, we have proposed the use of THP-1 cells and IL-8 release to identify the potential of chemicals to induce skin sensitization. Based on the assumption that sensitization and photosensitization share common mechanisms, the aim of this work was to explore the THP-1 model as an in vitro model to identify photoallergenic chemicals. THP-1 cells were exposed to 7 photoallergens and 3 photoirritants and irradiated with UVA light or kept in dark. Non phototoxic allergens or irritants were also included as negative compounds. Following 24h of incubation, cytotoxicity and IL-8 release were measured. At subtoxic concentrations, photoallergens produced a dose-related increase in IL-8 release after irradiation. Some photoirritants also produced a slight increase in IL-8 release. However, when the overall stimulation indexes of IL-8 were calculated for each chemical, 6 out of 7 photoallergens tested reached a stimulation index above 2, while the entire set of negative compounds had stimulation indexes below 2. Our data suggest that this assay may become a useful cell-based in vitro test for evaluating the photosensitizing potential of chemicals. Copyright © 2013 Elsevier Ltd. All rights reserved.

Enhanced Photodynamic Therapy by Reduced Levels of Intracellular Glutathione Obtained By Employing a Nano-MOF with CuII as the Active Center.

PubMed

Zhang, Wei; Lu, Jun; Gao, Xiaonan; Li, Ping; Zhang, Wen; Ma, Yu; Wang, Hui; Tang, Bo

2018-02-16

In photodynamic therapy (PDT), the level of reactive oxygen species (ROS) produced in the cell directly determines the therapeutic effect. Improvement in ROS concentration can be realized by reducing the glutathione (GSH) level or increasing the amount of photosensitizer. However, excessive amounts photosensitizer may cause side effects. Therefore, the development of photosensitizers that reduce GSH levels through synergistically improving ROS concentration in order to strengthen the efficacy of PDT for tumor is important. We report a nano-metal-organic framework (Cu II -metalated nano-MOF {CuL-[AlOH] 2 } n (MOF-2, H 6 L=mesotetrakis(4-carboxylphenyl)porphyrin)) based on Cu II as the active center for PDT. This MOF-2 is readily taken up by breast cancer cells, and high levels of ROS are generated under light irradiation. Meanwhile, intracellular GSH is considerably decreased owing to absorption on MOF-2; this synergistically increases ROS concentration and accelerates apoptosis, thereby enhancing the effect of PDT. Notably, based on the direct adsorption of GSH, MOF-2 showed a comparable effect with the commercial antitumor drug camptothecin in a mouse breast cancer model. This work provides strong evidence for MOF-2 as a promising new PDT candidate and anticancer drug. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bioproduction and characterization of extracellular melanin-like pigment from industrially polluted metagenomic library equipped Escherichia coli.

PubMed

Amin, Shivani; Rastogi, Rajesh P; Sonani, Ravi R; Ray, Arabinda; Sharma, Rakesh; Madamwar, Datta

2018-04-15

To explore the potential genes from the industrially polluted Amlakhadi canal, located in Ankleshwar, Gujarat, India, its community genome was extracted and cloned into E. coli EPI300™-T1 R using a fosmid vector (pCC2 FOS™) generating a library of 3,92,000 clones with average size of 40kb of DNA-insert. From this library, the clone DM1 producing brown colored melanin-like pigment was isolated and characterized. For over expression of the pigment, further sub-cloning of the clone DM1 was done. Sub-clone containing 10kb of the insert was sequenced for gene identification. The amino acids sequence of a protein 4-Hydroxyphenylpyruvate dioxygenase (HPPD), which is know to be involved in melanin biosynthesis was obtained from the gene sequence. The sequence-homology based 3D structure model of HPPD was constructed and analyzed. The physico-chemical nature of pigment was further analysed using 1 H and 13 C NMR, LC-MS, FTIR and UV-visible spectroscopy. The pigment was readily soluble in DMSO with an absorption maximum around 290nm. Based on the genetic and chemical characterization, the compound was confirmed as melanin-like pigment. The present results indicate that the metagenomic library from industrially polluted environment generated a microbial tool for the production of melanin-like pigment. Copyright © 2018 Elsevier B.V. All rights reserved.

Fast Profiling of Natural Pigments in Different Spirulina (Arthrospira platensis) Dietary Supplements by DI-FT-ICR and Evaluation of their Antioxidant Potential by Pre-Column DPPH-UHPLC Assay.

PubMed

Sommella, Eduardo; Conte, Giulio Maria; Salviati, Emanuela; Pepe, Giacomo; Bertamino, Alessia; Ostacolo, Carmine; Sansone, Francesca; Prete, Francesco Del; Aquino, Rita Patrizia; Campiglia, Pietro

2018-05-11

Arthrospira platensis , better known as Spirulina, is one of the most important microalgae species. This cyanobacterium possesses a rich metabolite pattern, including high amounts of natural pigments. In this study, we applied a combined strategy based on Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and Ultra High-Performance Liquid Chromatography (UHPLC) for the qualitative/quantitative characterization of Spirulina pigments in three different commercial dietary supplements. FT-ICR was employed to elucidate the qualitative profile of Spirulina pigments, in both direct infusion mode (DIMS) and coupled to UHPLC. DIMS showed to be a very fast (4 min) and accurate (mass accuracy ≤ 0.01 ppm) tool. 51 pigments were tentatively identified. The profile revealed different classes, such as carotenes, xanthophylls and chlorophylls. Moreover, the antioxidant evaluation of the major compounds was assessed by pre-column reaction with the DPPH radical followed by fast UHPLC-PDA separation, highlighting the contribution of single analytes to the antioxidant potential of the entire pigment fraction. β-carotene, diadinoxanthin and diatoxanthin showed the highest scavenging activity. The method took 40 min per sample, comprising reaction. This strategy could represent a valid tool for the fast and comprehensive characterization of Spirulina pigments in dietary supplements, as well as in other microalgae-based products.

Changes in pigment, spectral transmission and element content of pink chicken eggshells with different pigment intensity during incubation.

PubMed

Yu, Yue; Li, Zhanming; Pan, Jinming

2016-01-01

Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells. Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0-21 d), the values of the eggshell pigment (ΔE, L (∗), a (∗), b (∗)) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380-780 nm. Result. Three measured indicators of eggshell color, ΔE, L (∗) and a (∗), did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0.001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation. Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity.

Changes in pigment, spectral transmission and element content of pink chicken eggshells with different pigment intensity during incubation

PubMed Central

Yu, Yue; Li, Zhanming

2016-01-01

Objective. The objective of this study was to investigate changes in pigment, spectral transmission and element content of chicken eggshells with different intensities of pink pigment during the incubation period. We also investigated the effects of the region (small pole, equator and large pole) and pink pigment intensity of the chicken eggshell on the percent transmission of light passing through the chicken eggshells. Method. Eggs of comparable weight from a meat-type breeder (Meihuang) were used, and divided based on three levels of pink pigment (light, medium and dark) in the eggshells. During the incubation (0–21 d), the values of the eggshell pigment (ΔE, L∗, a∗, b∗) were measured. The percent transmission of light for different regions and intensities of eggshell pigmentation was measured by using the visible wavelength range of 380–780 nm. Result. Three measured indicators of eggshell color, ΔE, L∗ and a∗, did not change significantly during incubation. Compared with other regions and pigment intensities, eggshell at the small pole and with light pigmentation intensity showed the highest percent transmission of light. The transmission value varied significantly (P < 0.001) with incubation time. The element analysis of eggshells with different levels of pink pigment showed that the potassium content of the eggshells for all pigment levels decreased significantly during incubation. Conclusion. In summary, pigment intensity and the region of the eggshell influenced the percent transmission of light of eggshell. Differences in the spectral characteristics of different eggshells may influence the effects of photostimulation during the incubation of eggs. All of these results will be applicable for perfecting the design of light intensity for lighted incubation to improve productivity. PMID:27019785

Quenching of porous silicon photoluminescence by molecular oxygen and dependence of this phenomenon on storing media and method of preparation of pSi photosensitizer

NASA Astrophysics Data System (ADS)

Balaguer, María; Matveeva, Eugenia

2010-10-01

The quenching of porous silicon photoluminescence (pSi PL) by molecular oxygen has been studied in different storing media in an attempt to clarify the mechanism of the energy transfer from the silicon photosensitizer to the oxygen acceptor. Luminescent materials have been prepared by two methods: electrochemical anodizing and chemical etching. Different structural forms were used: porous layers on silicon wafer and two kinds of differently prepared powder. Dry air and liquid water were employed as storing media; quenching behaviour was under observation until total degradation of quenching properties. Singlet oxygen molecules generation through energy transfer from photoluminescent pSi was the only photosensitizing mechanism observed under dry gas conditions. This PL quenching process was preferentially developed at 760 nm (1.63 eV) that corresponds to the formation of the 1Σ singlet oxygen state. Oxidation of the pSi photosensitizer was the main factor that led to its total deactivation in a time scale of few weeks. Regarding water medium, different photosensitizing behaviour was observed. In watery conditions, two preferred energy levels were found: the one detected in dry gas and another centred at approximately 2.2 eV (550 nm). Formation of reactive oxygen species (ROS) different from singlet oxygen, such as superoxide anion or superoxide radical, can be responsible for the second one. This second quenching process developed gradually after the initial contact of pSi photosensitizer with water and then degraded. The process lasted only several hours. Therefore, functionalization of the pSi photosensitizer is probably required to stabilize its PL and quenching properties in the watery physiological conditions required for biomedical applications.

Differentiation of pigmented Spitz nevi and Reed nevi by integration of dermatopathologic and dermatoscopic findings

PubMed Central

Bär, Michael; Tschandl, Philipp; Kittler, Harald

2012-01-01

Background: It is unclear whether pigmented Spitz and Reed nevi are distinct morphologic entities or part of the spectrum of Spitz nevi. Methods: In a retrospective observational study we analyzed dermatopathologic slides of 22 cases with clinical and dermatoscopic features indicative of pigmented Spitz or Reed nevus in a blinded fashion according to predefined criteria and subsequently correlated dermatopathologic with clinical and dermatoscopic findings. Results: We differentiated pigmented Spitz and Reed nevus dermatopathologically by their capacity of melanin production and a vertical versus horizontal growth pattern. Based on histopathology 20 nevi (91%) could be reliably diagnosed as Reed nevus (68%, n=15) or as pigmented Spitz nevus (23%, n=5). In two cases (9%, n=2) it was not possible to make a clear distinction from a dermatopathologic point of view. Dermatopathologic-dermatoscopic correlation showed that Reed nevi were characterized by a dermatoscopic pattern of peripheral radial lines or pseudopods (fascicular growth pattern), whereas pigmented Spitz nevi were typified by a pattern consisting of clods (nested growth pattern). “Spitz cells” (large epithelioid melanocytes) were more commonly found in Spitz nevi (100%, n = 5) but were also present in Reed nevi (n=6, 40%). Spindle cells were found in both types of nevi. Conclusions: Pigmented Spitz and Reed nevi can be reliably distinguished based on their dermatopathologic and dermatoscopic patterns. The specific dermatopathologic patterns of pigmented Spitz and Reed nevi correspond well to their dermatoscopic patterns. The presence of “Spitz cells” or spindle cells should not be regarded as the decisive criterion to differentiate between these two entities. PMID:24765545

Smart textile framework: Photochromic and fluorescent cellulosic fabric printed by strontium aluminate pigment.

PubMed

Khattab, Tawfik A; Rehan, Mohamed; Hamouda, Tamer

2018-09-01

Smart clothing can be defined as textiles that respond to a certain stimulus accompanied by a change in their properties. A specific class herein is the photochromic and fluorescent textiles that change color with light. A photochromic and fluorescent cotton fabric based on pigment printing is obtained. Such fabric is prepared by aqueous-based pigment-binder printing formulation containing inorganic pigment phosphor characterized by good photo- and thermal stability. It exhibits optimal excitation wavelength (365 nm) results in color and fluorescence change of the fabric surface. To prepare the transparent pigment-binder composite film, the phosphor pigment must be well-dispersed via physical immobilization without their aggregation. The pigment-binder paste is applied successfully onto cotton fabric using screen printing technique followed by thermal fixation. After screen-printing, a homogenous photochromic film is assembled on a cotton substrate surface, which represents substantial greenish-yellow color development as indicated by CIE Lab color space measurements under ultraviolet light, even at a pigment concentration of 0.08 wt% of the printing paste. The photochromic cotton fabric exhibit three excitation peaks at 272, 325 and 365 nm and three emission peaks at 418, 495 and 520 nm. The fluorescent optical microscope, scanning electron microscope, elemental mapping, energy dispersive X-ray spectroscopy, fluorescence emission and UV/Vis absorption spectroscopic data of the printed cotton fabric are described. The printed fabric showed a reversible and rapid photochromic response during ultra-violet excitation without fatigue. The fastness properties including washing, crocking, perspiration, sublimation/heat, and light are described. Copyright © 2018 Elsevier Ltd. All rights reserved.

Efficacy of antioxidants in human hair.

PubMed

Fernández, Estibalitz; Martínez-Teipel, Blanca; Armengol, Ricard; Barba, Clara; Coderch, Luisa

2012-12-05

Hair is exposed every day to a range of harmful effects such as sunlight, pollution, cosmetic treatments, grooming practices and cleansing. The UV components of sunlight damage human hair, causing fibre degradation. UV-B attacks the melanin pigments and the protein fractions (keratin) of hair and UV-A produces free radical/reactive oxygen species (ROS) through the interaction of endogenous photosensitizers. Hair was dyed and the efficacy of two antioxidant formulations was demonstrated after UV exposure by evaluating, surface morphology, protein and amino acid degradation, lipidic peroxidation, colour and shine changes and strength/relaxation properties. UV treatment resulted in an increase in protein and lipid degradation, changes in colour and shine and in adverse consequences for the mechanical properties. Natural antioxidants obtained from artichoke and rice applied to pretreated hair improved mechanical properties and preserved colour and shine of fibres, coating them and protecting them against UV. Furthermore, the lipidic peroxidation of the protein degradation caused by UV was reduced for some treated fibres, suggesting an improvement in fibre integrity. This was more marked in the case of the fibres treated using the artichoke extract, whereas the rice extract was better preserving shine and colour of hair fibres. Copyright © 2012 Elsevier B.V. All rights reserved.

Carotenoids, versatile components of oxygenic photosynthesis.

PubMed

Domonkos, Ildikó; Kis, Mihály; Gombos, Zoltán; Ughy, Bettina

2013-10-01

Carotenoids (CARs) are a group of pigments that perform several important physiological functions in all kingdoms of living organisms. CARs serve as protective agents, which are essential structural components of photosynthetic complexes and membranes, and they play an important role in the light harvesting mechanism of photosynthesizing plants and cyanobacteria. The protection against reactive oxygen species, realized by quenching of singlet oxygen and the excited states of photosensitizing molecules, as well as by the scavenging of free radicals, is one of the main biological functions of CARs. X-ray crystallographic localization of CARs revealed that they are present at functionally and structurally important sites of both the PSI and PSII reaction centers. Characterization of a CAR-less cyanobacterial mutant revealed that while the absence of CARs prevents the formation of PSII complexes, it does not abolish the assembly and function of PSI. CAR molecules assist in the formation of protein subunits of the photosynthetic complexes by gluing together their protein components. In addition to their aforementioned indispensable functions, CARs have a substantial role in the formation and maintenance of proper cellular architecture, and potentially also in the protection of the translational machinery under stress conditions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Formation of bulk refractive index structures

DOEpatents

Potter, Jr., Barrett George; Potter, Kelly Simmons; Wheeler, David R.; Jamison, Gregory M.

2003-07-15

A method of making a stacked three-dimensional refractive index structure in photosensitive materials using photo-patterning where first determined is the wavelength at which a photosensitive material film exhibits a change in refractive index upon exposure to optical radiation, a portion of the surfaces of the photosensitive material film is optically irradiated, the film is marked to produce a registry mark. Multiple films are produced and aligned using the registry marks to form a stacked three-dimensional refractive index structure.

A comprehensive evaluation of the toxicology of monogram inks added to experimental cigarettes.

PubMed

Smith, Donna C; Wiecinski, Paige N; Coggins, Christopher R E; Banty, Tamara H; Oldham, Michael J

2013-01-01

Cigarettes often have a small identifying mark (monogram) printed either on the cigarette paper toward the filter end of the cigarette or on the tipping paper. A battery of tests was used to compare the toxicology of mainstream smoke from experimental cigarettes manufactured with different monogram inks. Cigarettes with different concentrations of different pigments were compared with cigarettes without ink, and with a control ink. Smoke from each of the experimental cigarettes was evaluated using analytical chemistry and in vitro bacterial mutagenicity (Salmonella, five strains, ± S9) and cytotoxicity (neutral red uptake) assays. No differences were observed between experimental cigarettes printed with three different pigment loads of iron oxide-based Black pigment and non-printed cigarettes. In general, no dose response was observed. However, increases in certain smoke constituents were found to correlate with Pigment Yellow 14 (also known as benzidine yellow) and Pigment Blue 15 (copper phthalocyanine). Increases in bacterial mutagenicity were observed for high-level print of Pigment Yellow 14 in TA98 and TA1537 and the high-level print of Pigment Blue 15 in TA98. In vitro cytotoxicity of mainstream smoke was unaffected by the presence of monogram ink on cigarettes. Statistically significant dose-responsive constituent changes and an increase in mutagenicity were observed with inclusion of Pigment Yellow 14 and Pigment Blue 15. Other pigments showed minimal toxicological activity.

Photoluminescence of cerium fluoride and cerium-doped lanthanum fluoride nanoparticles and investigation of energy transfer to photosensitizer molecules.

PubMed

Cooper, Daniel R; Kudinov, Konstantin; Tyagi, Pooja; Hill, Colin K; Bradforth, Stephen E; Nadeau, Jay L

2014-06-28

CexLa1-xF3 nanoparticles have been proposed for use in nanoscintillator-photosensitizer systems, where excitation of nanoparticles by ionizing radiation would result in energy transfer to photosensitizer molecules, effectively combining the effects of radiotherapy and photodynamic therapy. Thus far, there have been few experimental investigations of such systems. This study reports novel synthesis methods for water-dispersible Ce0.1La0.9F3/LaF3 and CeF3/LaF3 core/shell nanoparticles and an investigation of energy transfer to photosensitizers. Unbound deuteroporphyrin IX 2,4-disulfonic acid was found to substantially quench the luminescence of large (>10 nm diameter) aminocaproic acid-stabilized nanoparticles at reasonable concentrations and loading amounts: up to 80% quenching at 6% w/w photosensitizer loading. Energy transfer was found to occur primarily through a cascade, with excitation of "regular" site Ce(3+) at 252 nm relayed to photosensitizer molecules at the nanoparticle surface through intermediate "perturbed" Ce(3+) sites. Smaller (<5 nm) citrate-stabilized nanoparticles were coated with the bisphosphonate alendronate, allowing covalent conjugation to chlorin e6 and resulting in static quenching of the nanoparticle luminescence: ∼50% at ∼0.44% w/w. These results provide insight into energy transfer mechanisms that may prove valuable for optimizing similar systems.

How predictive are photosensitive epilepsy models as proof of principle trials for epilepsy?

PubMed

Yuen, Eunice S M; Sims, John R

2014-06-01

Human photosensitive epilepsy models have been used as proof of principle (POP) trials for epilepsy. Photosensitive patients are exposed to intermittent photic stimulation and the reduction in sensitivity to the number of standard visual stimulation frequencies is used as an endpoint. The aim of this research was to quantify the predictive capabilities of photosensitive POP trials, through a survey of current literature. A literature search was undertaken to identify articles describing photosensitive POP trials. Minimally efficacious doses (MEDs) in epilepsy were compared to doses in the POP trials that produced 50-100% response (ED50-100). Ratios of these doses were calculated and summarised statistically. The search identified ten articles describing a total of 17 anti-epileptic drugs. Of these, data for both MED and ED50-100 were available for 13 anti-epileptic drugs. The average ratio of MED to ED50-100 was 0.95 (95% CI 0.60-1.30). The difference in MED to ED50-100 ratios between partial epilepsy (0.82) was not significantly different from that of generalised epilepsy (1.08) (p=0.51). Photosensitive POP trials are a useful tool to quantitatively predict efficacy in epilepsy, and can be useful as early and informative indicators in anti-epileptic drug discovery and development. Copyright © 2014 British Epilepsy Association. Published by Elsevier Ltd. All rights reserved.

Silver-halide photographic materials based on nanoporous glasses

NASA Astrophysics Data System (ADS)

Andreeva, O. V.; Obyknovennaya, I. E.; Gavrilyuk, E. R.; Paramonov, A. A.; Kushnarenko, A. P.

2005-12-01

This paper discusses the results of an investigation of the recording of composite nanoporous photographic materials with a photosensitive composite made from silver halide in gelatin, developed and created at S. I. Vavilov State Optical Institute.

Direct Fabrication of the Graphene-Based Composite for Cancer Phototherapy through Graphite Exfoliation with a Photosensitizer.

PubMed

Liu, Gang; Qin, Hongmei; Amano, Tsukuru; Murakami, Takashi; Komatsu, Naoki

2015-10-28

We report on the application of pristine graphene as a drug carrier for phototherapy (PT). The loading of a photosensitizer, chlorin e6 (Ce6), was achieved simply by sonication of Ce6 and graphite in an aqueous solution. During the loading process, graphite was gradually exfoliated to graphene to give its composite with Ce6 (G-Ce6). This one-step approach is considered to be superior to the graphene oxide (GO)-based composites, which required pretreatment of graphite by strong oxidation. Additionally, the directly exfoliated graphene ensured a high drug loading capacity, 160 wt %, which is about 10 times larger than that of the functionalized GO. Furthermore, the Ce6 concentration for killing cells by G-Ce6 is 6-75 times less than that of the other Ce6 composites including GO-Ce6.

Singlet oxygen-based electrosensing by molecular photosensitizers

NASA Astrophysics Data System (ADS)

Trashin, Stanislav; Rahemi, Vanoushe; Ramji, Karpagavalli; Neven, Liselotte; Gorun, Sergiu M.; de Wael, Karolien

2017-07-01

Enzyme-based electrochemical biosensors are an inspiration for the development of (bio)analytical techniques. However, the instability and reproducibility of the reactivity of enzymes, combined with the need for chemical reagents for sensing remain challenges for the construction of useful devices. Here we present a sensing strategy inspired by the advantages of enzymes and photoelectrochemical sensing, namely the integration of aerobic photocatalysis and electrochemical analysis. The photosensitizer, a bioinspired perfluorinated Zn phthalocyanine, generates singlet-oxygen from air under visible light illumination and oxidizes analytes, yielding electrochemically-detectable products while resisting the oxidizing species it produces. Compared with enzymatic detection methods, the proposed strategy uses air instead of internally added reactive reagents, features intrinsic baseline correction via on/off light switching and shows C-F bonds-type enhanced stability. It also affords selectivity imparted by the catalytic process and nano-level detection, such as 20 nM amoxicillin in μl sample volumes.

High photoresponse of individual WS2 nanowire-nanoflake hybrid materials

NASA Astrophysics Data System (ADS)

Asres, Georgies Alene; Järvinen, Topias; Lorite, Gabriela S.; Mohl, Melinda; Pitkänen, Olli; Dombovari, Aron; Tóth, Geza; Spetz, Anita Lloyd; Vajtai, Robert; Ajayan, Pulickel M.; Lei, Sidong; Talapatra, Saikat; Kordas, Krisztian

2018-06-01

van der Waals solids have been recognized as highly photosensitive materials that compete conventional Si and compound semiconductor based devices. While 2-dimensional nanosheets of single and multiple layers and 1-dimensional nanowires of molybdenum and tungsten chalcogenides have been studied, their nanostructured derivatives with complex morphologies are not explored yet. Here, we report on the electrical and photosensitive properties of WS2 nanowire-nanoflake hybrid materials we developed lately. We probe individual hybrid nanostructured particles along the structure using focused ion beam deposited Pt contacts. Further, we use conductive atomic force microscopy to analyze electrical behavior across the nanostructure in the transverse direction. The electrical measurements are complemented by in situ laser beam illumination to explore the photoresponse of the nanohybrids in the visible optical spectrum. Photodetectors with responsivity up to ˜0.4 AW-1 are demonstrated outperforming graphene as well as most of the other transition metal dichalcogenide based devices.

Optical sensor based on a single CdS nanobelt.

PubMed

Li, Lei; Yang, Shuming; Han, Feng; Wang, Liangjun; Zhang, Xiaotong; Jiang, Zhuangde; Pan, Anlian

2014-04-23

In this paper, an optical sensor based on a cadmium sulfide (CdS) nanobelt has been developed. The CdS nanobelt was synthesized by the vapor phase transportation (VPT) method. X-Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) results revealed that the nanobelt had a hexagonal wurtzite structure of CdS and presented good crystal quality. A single nanobelt Schottky contact optical sensor was fabricated by the electron beam lithography (EBL) technique, and the device current-voltage results showed back-to-back Schottky diode characteristics. The photosensitivity, dark current and the decay time of the sensor were 4 × 10⁴, 31 ms and 0.2 pA, respectively. The high photosensitivity and the short decay time were because of the exponential dependence of photocurrent on the number of the surface charges and the configuration of the back to back Schottky junctions.

Visualization of Porphyrin-Based Photosensitizer Distribution from Fluorescence Images In Vivo Using an Optimized RGB Camera

NASA Astrophysics Data System (ADS)

Liu, L.; Huang, Zh.; Qiu, Zh.; Li, B.

2018-01-01

A handheld RGB camera was developed to monitor the in vivo distribution of porphyrin-based photosensitizer (PS) hematoporphyrin monomethyl ether (HMME) in blood vessels during photodynamic therapy (PDT). The focal length, f-number, International Standardization Organization (ISO) sensitivity, and shutter speed of the camera were optimized for the solution sample with various HMME concentrations. After the parameter optimization, it was found that the red intensity value of the fluorescence image was linearly related to the fluorescence intensity under investigated conditions. The RGB camera was then used to monitor the in vivo distribution of HMME in blood vessels in a skin-fold window chamber model. The red intensity value of the recorded RGB fluorescence image was found to be linearly correlated to HMME concentrations in the range 0-24 μM. Significant differences in the red to green intensity ratios were observed between the blood vessels and the surrounding tissue.

Smart photovoltaics based on dye-sensitized solar cells using photochromic spiropyran derivatives as photosensitizers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, Shengbo; Ting, Hungkit; Ma, Yingzhuang

2015-05-15

In this paper, smart photovoltaic (SPV) devices, integrating both functions of solar cells and smart windows, was fabricated based on dye-sensitized solar cells using photochromic spiropyran derivatives SIBT as photosensitizers. SPV devices have self-regulated power conversion efficiency (PCE) and light transmission responding to the incident spectra due to the photoisomerization of SIBT. SIBT isomerize from closed-ring form to open-ring form under UV illumination, accompanied with enhanced visible light absorption and electron delocalization. Therefore, increased PCE and absorption in SPV devices were observed under UV treatment and the devices can be restored gradually to the initial status when kept in dark.more » The SPV devices have self-regulation of PCE and sunlight transmission responding to the changing sun spectra in different times of a day, providing a proper energy usage and a better sun-shading.« less

Singlet oxygen-based electrosensing by molecular photosensitizers

PubMed Central

Trashin, Stanislav; Rahemi, Vanoushe; Ramji, Karpagavalli; Neven, Liselotte; Gorun, Sergiu M.; De Wael, Karolien

2017-01-01

Enzyme-based electrochemical biosensors are an inspiration for the development of (bio)analytical techniques. However, the instability and reproducibility of the reactivity of enzymes, combined with the need for chemical reagents for sensing remain challenges for the construction of useful devices. Here we present a sensing strategy inspired by the advantages of enzymes and photoelectrochemical sensing, namely the integration of aerobic photocatalysis and electrochemical analysis. The photosensitizer, a bioinspired perfluorinated Zn phthalocyanine, generates singlet-oxygen from air under visible light illumination and oxidizes analytes, yielding electrochemically-detectable products while resisting the oxidizing species it produces. Compared with enzymatic detection methods, the proposed strategy uses air instead of internally added reactive reagents, features intrinsic baseline correction via on/off light switching and shows C-F bonds-type enhanced stability. It also affords selectivity imparted by the catalytic process and nano-level detection, such as 20 nM amoxicillin in μl sample volumes.

Optimization of Photosensitized Tryptophan Oxidation in the Presence of Dimegin-Polyvinylpyrrolidone-Chitosan Systems.

PubMed

Solovieva, Anna B; Kardumian, Valeria V; Aksenova, Nadezhda A; Belovolova, Lyudmila V; Glushkov, Mikhail V; Bezrukov, Evgeny A; Sukhanov, Roman B; Kotova, Svetlana L; Timashev, Peter S

2018-05-23

By the example of a model process of tryptophan photooxidation in the aqueous medium in the presence of a three-component photosensitizing complex (porphyrin photosensitizer-polyvinylpyrrolidone- chitosan, PPS-PVP-CT) in the temperature range of 20-40 °С, we have demonstrated a possibility of modification of such a process by selecting different molar ratios of the components in the reaction mixture. The actual objective of this selection is the formation of a certain PPS-PVP-CT composition in which PVP macromolecules would coordinate with PPS molecules and at the same time practically block the complex binding of PPS molecules with chitosan macromolecules. Such blocking allows utilization of the bactericidal properties of chitosan to a greater extent, since chitosan is known to depress the PPS photosensitizing activity in PPS-PVP-CT complexes when using those in photodynamic therapy (PDT). The optimal composition of photosensitizing complexes appears to be dependent on the temperature at which the PDT sessions are performed. We have analyzed the correlations of the effective rate constants of tryptophan photooxidation with the photophysical characteristics of the formed complexes.

Time-resolved spectral analysis of Radachlorin luminescence in water

NASA Astrophysics Data System (ADS)

Belik, V. P.; Gadzhiev, I. M.; Semenova, I. V.; Vasyutinskii, O. S.

2017-05-01

We report results of spectral- and time-resolved study of Radachlorin photosensitizer luminescence in water in the spectral range of 950-1350nm and for determination of the photosensitizer triplet state and the singlet oxygen lifetimes responsible for singlet oxygen generation and degradation. At any wavelength within the explored spectral range the luminescence decay contained two major contributions: a fast decay at the ns time scale and a slow evolution at the μs time scale. The fast decay was attributed to electric dipole fluorescence transitions in photosensitizer molecules and the slow evolution to intercombination phosphorescence transitions in singlet oxygen and photosensitizer molecules. Relatively high-amplitude ns peak observed at all wavelengths suggests that singlet oxygen monitoring with spectral isolation methods alone, without additional temporal resolution can be controversial. In the applied experimental conditions the total phosphorescence signal at any wavelength contained a contribution from the photosensitizer triplet state decay, while at 1274nm the singlet oxygen phosphorescence dominated. The results obtained can be used for optimization of the methods of singlet oxygen monitoring and imaging.

Uptake of photosensitizers by bacteria is influenced by the presence of cations

NASA Astrophysics Data System (ADS)

Kishen, A.; George, S.

2007-05-01

This investigation studies the influence of cations on photosensitizer uptake by Enterococcus faecalis (gram positive) and Actinobacillus actinomycetemcomitans (gram negative). Methods- The uptake of Methylene blue (MB) and Indocyanine Green (ICG), by bacteria were studied under the influence of divalent cations (CaCl II & MgCl II) and EDTA. Further, E. faecalis cells subjected to trypsinisation and calcium channel blocker (verapamil) were also analysed for MB and ICG uptake inorder to understand the mechanism of photosensitizer uptake. Results- Uptake of ICG was enhanced in the presence of divalent cations in E. faecalis and A. actinomycetemcomitans. Treating cells with EDTA had no significant effect on the photosensitizer uptake, although the highest concentration tested showed an enhancement of uptake. In contrast to ICG, MB showed a decreased uptake by bacterial cells on subjecting them to divalent cations and EDTA. Calcium channel blocker had no significant inhibitory effect on photosensitizers uptake. However, trypsin treatment resulted in significant reduction of ICG uptake. The result suggested that ICG uptake by bacteria is mediated through specific transporter protein while MB is associated with the outer surface structures of bacterial cells.

Stable Benzacridine Pigments by Oxidative Coupling of Chlorogenic Acid with Amino Acids and Proteins: Toward Natural Product-Based Green Food Coloring.

PubMed

Iacomino, Mariagrazia; Weber, Fabian; Gleichenhagen, Maike; Pistorio, Valeria; Panzella, Lucia; Pizzo, Elio; Schieber, Andreas; d'Ischia, Marco; Napolitano, Alessandra

2017-08-09

The occasional greening of sweet potatoes and other plant tissues observed during cooking or other food processing has been shown to arise from the autoxidative coupling of chlorogenic acid (CGA, 5-caffeoylquinic acid) with amino acid components, leading to trihydroxybenzacridine pigments. To explore the potential of this reaction for food coloring, we report herein the optimized biomimetic preparation of trihydroxybenzacridine pigments from CGA and amino acids such as glycine and lysine, their straightforward purification by gel filtration chromatography, the UHPLC-MS/MS analysis of the purified pigment fraction, and a detailed characterization of the pH-dependent trihydroxybenzacridine chromophore. Similar green pigments were also obtained by analogous reaction of CGA with a low-cost protein, bovine serum albumin, and by simply adding CGA to chicken egg white (CEW) under stirring. Neither the purified pigments from amino acids nor the pigmented CEW exerted significant toxicity against two human cell lines, Caco-2 and HepG2, at doses compatible with common use in food coloring. Additions of the pure pigments or pigmented CEW to different food matrices imparted intense green hues, and the thermal stability of these preparations proved satisfactory up to 90 °C. The potential application of the greening reaction for the sensing of fish deterioration is also disclosed.

Nonphotosynthetic Pigments as Potential Biosignatures

PubMed Central

Cockell, Charles S.; Meadows, Victoria S.

2015-01-01

Abstract Previous work on possible surface reflectance biosignatures for Earth-like planets has typically focused on analogues to spectral features produced by photosynthetic organisms on Earth, such as the vegetation red edge. Although oxygenic photosynthesis, facilitated by pigments evolved to capture photons, is the dominant metabolism on our planet, pigmentation has evolved for multiple purposes to adapt organisms to their environment. We present an interdisciplinary study of the diversity and detectability of nonphotosynthetic pigments as biosignatures, which includes a description of environments that host nonphotosynthetic biologically pigmented surfaces, and a lab-based experimental analysis of the spectral and broadband color diversity of pigmented organisms on Earth. We test the utility of broadband color to distinguish between Earth-like planets with significant coverage of nonphotosynthetic pigments and those with photosynthetic or nonbiological surfaces, using both 1-D and 3-D spectral models. We demonstrate that, given sufficient surface coverage, nonphotosynthetic pigments could significantly impact the disk-averaged spectrum of a planet. However, we find that due to the possible diversity of organisms and environments, and the confounding effects of the atmosphere and clouds, determination of substantial coverage by biologically produced pigments would be difficult with broadband colors alone and would likely require spectrally resolved data. Key Words: Biosignatures—Exoplanets—Halophiles—Pigmentation—Reflectance spectroscopy—Spectral models. Astrobiology 15, 341–361. PMID:25941875

Light-Emitting Photon-Upconversion Nanoparticles in the Generation of Transdermal Reactive-Oxygen Species.

PubMed

Prieto, Martin; Rwei, Alina Y; Alejo, Teresa; Wei, Tuo; Lopez-Franco, Maria Teresa; Mendoza, Gracia; Sebastian, Victor; Kohane, Daniel S; Arruebo, Manuel

2017-12-06

Common photosensitizers used in photodynamic therapy do not penetrate the skin effectively. In addition, the visible blue and red lights used to excite such photosensitizers have shallow penetration depths through tissue. To overcome these limitations, we have synthesized ultraviolet- and visible-light-emitting, energy-transfer-based upconversion nanoparticles and coencapsulated them inside PLGA-PEG (methoxy poly(ethylene glycol)-b-poly(lactic-co-glycolic acid)) nanoparticles with the photosensitizer protoporphyrin IX. Nd 3+ has been introduced as a sensitizer in the upconversion nanostructure to allow its excitation at 808 nm. The subcytotoxic doses of the hybrid nanoparticles have been evaluated on different cell lines (i.e., fibroblasts, HaCaT, THP-1 monocytic cell line, U251MG (glioblastoma cell line), and mMSCs (murine mesenchymal stem cells). Upon NIR (near infrared)-light excitation, the upconversion nanoparticles emitted UV and VIS light, which consequently activated the generation of reactive-oxygen species (ROS). In addition, after irradiating at 808 nm, the resulting hybrid nanoparticles containing both upconversion nanoparticles and protoporphyrin IX generated 3.4 times more ROS than PLGA-PEG nanoparticles containing just the same dose of protoporphyrin IX. Their photodynamic effect was also assayed on different cell cultures, demonstrating their efficacy in selectively killing treated and irradiated cells. Compared to the topical application of the free photosensitizer, enhanced skin permeation and penetration were observed for the nanoparticulate formulation, using an ex vivo human-skin-permeation experiment. Whereas free protoporphyrin IX remained located at the outer layer of the skin, nanoparticle-encapsulated protoporphyrin IX was able to penetrate through the epidermal layer slightly into the dermis.

Two-photon excitation photodynamic therapy with Photofrin

NASA Astrophysics Data System (ADS)

Karotki, Aliaksandr; Khurana, Mamta; Lepock, James R.; Wilson, Brian C.

2005-09-01

Photodynamic therapy (PDT) based on simultaneous two-photon (2-γ) excitation has a potential advantage of highly targeted treatment by means of nonlinear localized photosensitizer excitation. One of the possible applications of 2-γ PDT is a treatment of exodus age-related macular degeneration where highly targeted excitation of photosensitizer in neovasculature is vital for reducing collateral damage to healthy surrounding tissue. To investigate effect of 2-γ PDT Photofrin was used as an archetypal photosensitizer. First, 2-γ absorption properties of Photofrin in the 750 - 900 nm excitation wavelength range were investigated. It was shown that above 800 nm 2-γ interaction was dominant mode of excitation. The 2-γ cross section of Photofrin was rather small and varied between 5 and 10 GM (1 GM = 10-50 cm4s/photon) in this wavelength range. Next, endothelial cells treated with Photofrin were used to model initial effect of 2-γ PDT on neovasculature. Ultrashort laser pulses provided by mode-locked Ti:sapphire laser (pulse duration at the sample 300 fs, repetition rate 90 MHz, mean laser power 10 mW, excitation wavelength 850 nm) were used for the excitation of the photosensitizer. Before 2-γ excitation of the Photofrin cells formed a single continuous sheet at the bottom of the well. The tightly focused laser light was scanned repeatedly over the cell layer. After irradiation the cell layer of the control cells stayed intact while cells treated with photofrin became clearly disrupted. The light doses required were high (6300 Jcm(-2) for ~ 50% killing), but 2-γ cytotoxicity was unequivocally demonstrated.

Topically applied hypericin exhibits skin penetrability on nude mice.

PubMed

Li, Zhuo-Heng; Li, Yuan-Yuan; Hou, Min; Yang, Tao; Lu, Lai-Chun; Xu, Xiao-Yu

2018-06-13

Hypericin, a powerful natural photosensitizer in photodynamic therapy (PDT), is suitable for treating skin diseases involving excess capillary proliferation. In the present study, we aimed to evaluate the skin penetrability of topically applied hypericin, expecting a reduced risk of prolonged skin photosensitivity, which often occurs after systemic administration. Firstly, the Franz diffusion cell assays were performed to evaluate the penetration effects of different enhancers, including menthol, propylene glycol, camphanone, azone, and carbamide. In view of above evaluation results, we selected menthol as the enhancer in the subsequent in vivo studies. The setting groups were as follows: the blank control group, the light-exposure control group, the gel-base control group, the hypericin gel group, and a hypericin gel-containing menthol group. Except for the blank control, all other animals were irradiated by a LED light. Then, fluorescence microscopy was performed to examine the distribution of hypericin in the skin of nude mouse. Macroscopic and microscopic analyses were also carried out to detect pathological changes in the skin after topical hypericin-PDT treatment. Immunohistochemistry was used to determine the expression change of PECAM-1. As shown in the results, menthol facilitated hypericin penetrate the skin of nude mice most. The results of in vivo assays revealed that hypericin penetrated nude mouse skin, spread to the dermis, and resulted in obvious photosensitivity reaction on the dermal capillaries. Moreover, skin injured by the photosensitive reaction induced by hypericin-PDT treatment was replaced by normal skin within 7 days. We concluded that topical applied hypericin could penetrate nude mouse skin well and has a great potential in PDT treatment of skin diseases.

Permeability of DOPC bilayers under photoinduced oxidation: Sensitivity to photosensitizer.

PubMed

Bacellar, Isabel O L; Baptista, Mauricio S; Junqueira, Helena C; Wainwright, Mark; Thalmann, Fabrice; Marques, Carlos M; Schroder, André P

2018-06-07

The modification of lipid bilayer permeability is one of the most striking yet poorly understood physical transformations that follow photoinduced lipid oxidation. We have recently proposed that the increase of permeability of photooxidized 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayers is controlled by the time required by the oxidized lipid species to diffuse and aggregate into pores. Here we further probe this mechanism by studying photosensitization of DOPC membranes by methylene blue (MB) and DO15, a more hydrophobic phenothiazinium photosensitizer, under different irradiation powers. Our results not only reveal the interplay between the production rate and the diffusion of the oxidized lipids, but highlight also the importance of photosensitizer localization in the kinetics of oxidized membrane permeability. Copyright © 2018. Published by Elsevier B.V.

Light trapping architecture for photovoltaic and photodector applications

DOEpatents

Forrest, Stephen R.; Lunt, Richard R.; Slootsky, Michael

2016-08-09

There is disclosed photovoltaic device structures which trap admitted light and recycle it through the contained photosensitive materials to maximize photoabsorption. For example, there is disclosed a photosensitive optoelectronic device comprising: a first reflective layer comprising a thermoplastic resin; a second reflective layer substantially parallel to the first reflective layer; a first transparent electrode layer on at least one of the first and second reflective layer; and a photosensitive region adjacent to the first electrode, wherein the first transparent electrode layer is substantially parallel to the first reflective layer and adjacent to the photosensitive region, and wherein the device has an exterior face transverse to the planes of the reflective layers where the exterior face has an aperture for admission of incident radiation to the interior of the device.

Analysis of pigments in polychromes by use of laser induced breakdown spectroscopy and Raman microscopy

NASA Astrophysics Data System (ADS)

Castillejo, M.; Martín, M.; Silva, D.; Stratoudaki, T.; Anglos, D.; Burgio, L.; Clark, R. J. H.

2000-09-01

Two laser-based analytical techniques, Laser Induced Breakdown Spectroscopy (LIBS) and Raman microscopy, have been used for the identification of pigments on a polychrome from the Rococo period. Detailed spectral data are presented from analyses performed on a fragment of a gilded altarpiece from the church of Escatrón, Zaragoza, Spain. LIBS measurements yielded elemental analytical data which suggest the presence of certain pigments and, in addition, provide information on the stratigraphy of the paint layers. Identification of most pigments and of the materials used in the preparation layer was performed by Raman microscopy.

Rapid Retinal Release from a Cone Visual Pigment Following Photoactivation*

PubMed Central

Chen, Min-Hsuan; Kuemmel, Colleen; Birge, Robert R.; Knox, Barry E.

2012-01-01

As part of the visual cycle, the retinal chromophore in both rod and cone visual pigments undergoes reversible Schiff base hydrolysis and dissociation following photobleaching. We characterized light-activated retinal release from a short-wavelength sensitive cone pigment (VCOP) in 0.1% dodecyl maltoside using fluorescence spectroscopy. The half-time (t1/2) of retinal release from VCOP was 7.1 s, 250-fold faster than rhodopsin. VCOP exhibited pH-dependent release kinetics, with the t1/2 decreasing from 23 s to 4 s with pH 4.1 to 8, respectively. However, the Arrhenius activation energy (Ea) for VCOP derived from kinetic measurements between 4° and 20°C was 17.4 kcal/mol, similar to 18.5 kcal/mol for rhodopsin. There was a small kinetic isotope (D2O) effect in VCOP, but less than that observed in rhodopsin. Mutation of the primary Schiff base counterion (VCOPD108A) produced a pigment with an unprotonated chromophore (⌊max = 360 nm) and dramatically slowed (t1/2 ~ 6.8 min) light-dependent retinal release. Using homology modeling, a VCOP mutant with two substitutions (S85D/ D108A) was designed to move the counterion one alpha helical turn into the transmembrane region from the native position. This double mutant had a UV-visible absorption spectrum consistent with a protonated Schiff base (⌊max = 420 nm). Moreover, VCOPS85D/D108A mutant had retinal release kinetics (t1/2 = 7 s) and Ea (18 kcal/mol) similar to the native pigment exhibiting no pH-dependence. By contrast, the single mutant VCOPS85D had a ~3-fold decrease in retinal release rate compared to the native pigment. Photoactivated VCOPD108A had kinetics comparable to a rhodopsin counterion mutant, RhoE113Q, both requiring hydroxylamine to fully release retinal. These results demonstrate that the primary counterion of cone visual pigments is necessary for efficient Schiff base hydrolysis. We discuss how the large differences in retinal release rates between rod and cone visual pigments arise, not from inherent differences in the rate of Schiff base hydrolysis, but rather from differences in the non-covalent binding properties of the retinal chromophore to the protein. PMID:22217337

Self-assembled nanoparticles based on PEGylated conjugated polyelectrolyte and drug molecules for image-guided drug delivery and photodynamic therapy.

PubMed

Yuan, Youyong; Liu, Bin

2014-09-10

A drug delivery system based on poly(ethylene glycol) (PEG) grafted conjugated polyelectrolyte (CPE) has been developed to serve as a polymeric photosensitizer and drug carrier for combined photodynamic and chemotherapy. The amphiphilic brush copolymer can self-assemble into micellar nanopaticles (NPs) in aqueous media with hydrophobic conjugated polyelectrolyte backbone as the core and hydrophilic PEG as the shell. The NPs have an average diameter of about 100 nm, with the absorption and emission maxima at 502 and 598 nm, respectively, making them suitable for bioimaging applications. Moreover, the CPE itself can serve as a photosensitizer, which makes the NPs not only a carrier for drug but also a photosensitizing unit for photodynamic therapy, resulting in the combination of chemo- and photodynamic therapy for cancer. The half-maximal inhibitory concentration (IC50) value for the combination therapy to U87-MG cells is 12.7 μg mL(-1), which is much lower than that for the solely photodynamic therapy (25.5 μg mL(-1)) or chemotherapy (132.8 μg mL(-1)). To improve the tumor specificity of the system, cyclic arginine-glycine-aspartic acid (cRGD) tripeptide as the receptor to integrin αvβ3 overexpressed cancer cells was further incorporated to the surface of the NPs. The delivery system based on PEGylated CPE is easy to fabricate, which integrates the merits of targeted cancer cell image, chemotherapeutic drug delivery, and photodynamic therapy, making it promising for cancer treatment.

Higher-efficiency photoelectrochemical electrodes of titanium dioxide-based nanoarrays sensitized simultaneously with plasmonic silver nanoparticles and multiple metal sulfides photosensitizers

NASA Astrophysics Data System (ADS)

Guo, Keying; Liu, Zhifeng; Han, Jianhua; Zhang, Xueqi; Li, Yajun; Hong, Tiantian; Zhou, Cailou

2015-07-01

This paper describes a novel design of high-efficiency photoelectrochemical water splitting electrode, i.e., ordered TiO2 nanorod arrays (NRs) sensitized simultaneously with noble metal (Ag), binary metal sulfides (Ag2S) and ternary metal sulfides (Ag3CuS2) multiple photosensitizers for the first time. The TiO2/Ag/Ag2S/Ag3CuS2 NRs heterostructure is successfully synthesized through successive ion layer adsorption and reaction (SILAR) and a simple ion-exchange process based on ionic reaction mechanism. On the basis of an optimal quantity of Ag, Ag2S and Ag3CuS2 nanoparticles, such TiO2/Ag/Ag2S/Ag3CuS2 NRs exhibit a higher photoelectrochemical activity ever reported for TiO2-based nanoarrays in PEC water splitting, the photocurrent density is up to 9.82 mA cm-2 at 0.47 V versus Ag/AgCl, respectively. This novel architecture is able to increase electron collection efficiency and suppress carrier recombination via (i) a higher efficiency of light-harvesting through these multiple photosensitizers (Ag, Ag2S and Ag3CuS2); (ii) the efficient separation of photo-induced electrons and holes due to the direct electrical pathways; (iii) the surface plasmon resonance (SPR) effect of Ag nanoparticles, which enhances the efficient charge separation and high carrier mobility. This work is useful to explore feasible routes to further enhance the performance of oxide semiconductors for PEC water splitting to produce clean H2 energy.

Effect of Monascus purpureus inoculum concentration on pigment production in jackfruit seed flour substrate

NASA Astrophysics Data System (ADS)

Hamdiyati, Yanti; Kusnadi, Yuliani, Lia Amelia

2016-02-01

The used of synthetic dyes have various negative effects on human health. Roomates pigment produced by Monascus purpureus mold can be used as an alternative natural food coloring. The research on the effect of inoculum concentration's M. purpureus to pigment production on the jackfruit seed flour has been done. The objective of research to is to investigate the effect of inoculum concentration's M. purpureus to the production of red, yellow and orange pigment on the jackfruit seed flour. The concentrations used were 0%, 5%, 10%, and 15% (v/w). The result of the data analysed using One-Way ANOVA showed that the inoculum concentration affected the production of red pigment M. purpureus, as well as the data analysis using the Kruskal-Wallis showed that inoculum concentration has influence on the production of yellow and orange pigments. Inoculum concentration of 15% is the optimum concentration for the production of red, yellow and orange pigments with 0:10, 0:50 and 0:20 absorbance units per gram of sample respectively. Based on the results of the research, it can be concluded that inoculum concentration of M. purpureus influenced the production of red, yellow and orange pigments.

[Study of scavenging activity of sorghum pigment to hydroxyl free radicals by fluorimetry].

PubMed

Zhang, Hai-rong; Wang, Wen-yan

2007-03-01

A natural product, sorghum pigment, consists of a number of important flavonoid derivatives, occurrs on the seed capsules or in the stems of many sorghums, and is widely applied in different fields of food, cosmetic and dyeing industries, It is important for scavenging hydroxyl free radicals and protection of human healthiness. Scavenging capacities of hydroxyl free radicals with sodium nitrite, quercetin and sorghum pigment were comparatively researched by fluorimetry, and the model of hydroxyl free radicals produced is based on the reaction of Cu2+ -catalyzed oxidation of ascorbic acid in the presence of hydrogen peroxide. The hydroxyl radicals react with benzoic acid, forming a fluorescent product, and the fluorescence intensity was determined by the concentration of hydroxybenzoic acid. The experimental results show that the sodium nitrite, quercetin and sorghum pigment have a quantity-effect relationship for scavenging hydroxyl free radicals, and sodium nitrite and quercetin in comparison with sorghum pigment have high antioxidant capacity. Finally, the quenching mechanisms were explored with sodium nitrite, sorghum pigment, and quercetin respectively. The sorghum pigment and sodium nitrite feature a dynamic quenching processes, while quercetin shows a static quenching processes. A reference method was provided for reasonable exploitation and utilization of sorghum pigment.

Spectral properties of singlet-oxygen luminescence in the IR Region at the 1Δ g → 3Σ g transition in the presence of fullerene as a photosensitizer

NASA Astrophysics Data System (ADS)

Kiselev, V. M.; Bagrov, I. V.

2017-10-01

The spectral properties of singlet-oxygen luminescence at the 1Δ g → 3Σ g transition observed using fullerene as a photosensitizer are analyzed. It is shown that the use of C60 and C70 fullerenes for singlet-oxygen generation exhibits all the main spectral regularities observed for other photosensitizers. The results of investigations in this field are summarized.

New Generation of Photosensitizers: Conjugates of Chlorin e 6 With Diamond Nanoparticles

NASA Astrophysics Data System (ADS)

Lapina, V. A.; Bushuk, S. B.; Pavich, T. A.; Vorobey, A. V.

2016-07-01

Conjugates of chlorin e 6 with diamond nanoparticles were synthesized by two methods. The spectral and luminescent properties of the obtained conjugates were studied. It was shown that chlorin e 6 retained its photosensitizing activity in the conjugate. It was established that chlorin e 6 immobilized directly on diamond nanoparticles had higher photosensitizing activity than that conjugated using a spacer. It was observed that chlorin e 6 in the conjugate had higher photolytic stability than the free form.

Acceleration Of Wound Healing Ny Photodynamic Therapy

DOEpatents

Hasan, Tayyaba; Hamblin, Michael R.; Trauner, Kenneth

2000-08-22

Disclosed is a method for accelerating wound healing in a mammal. The method includes identifying an unhealed wound site or partially-healed wound site in a mammal; administering a photosensitizer to the mammal; waiting for a time period wherein the photosensitizer reaches an effective tissue concentration at the wound site; and photoactivating the photosensitizer at the wound site. The dose of photodynamic therapy is selected to stimulate the production of one or more growth factor by cells at the wound site, without causing tissue destruction.

The effect of thermal treatment on antioxidant capacity and pigment contents in separated betalain fractions.

PubMed

Mikołajczyk-Bator, Katarzyna; Pawlak, Sylwia

2016-01-01

Increased consumption of fruits and vegetables significantly reduces the risk of cardio-vascular disease. This beneficial effect on the human organism is ascribed to the antioxidant compounds these foods contain. Unfortunately, many products, particularly vegetables, need to be subjected to thermal processing before consumption. The aim of this study was to determine the effect of such thermal treatment on the antioxidant capacity and pigment contents in separated fractions of violet pigments (betacyanins) and yellow pigments (betaxanthins and betacyanins). Fractions of violet and yellow pigments were obtained by separation of betalain pigments from fresh roots of 3 red beet cultivars using column chromatography and solid phase extraction (SPE). The betalain pigment content was determined in all samples before and after thermal treatment (90°C/30 min) by spectrophotometry, according to Nilsson's method [1970] and antioxidant capacity was assessed based on ABTS. Betalain pigments in the separated fractions were identified using HPLC-MS. After thermal treatment of betacyanin fractions a slight, but statistically significant degradation of pigments was observed, while the antioxidant capacity of these fractions did not change markedly. Losses of betacyanin content amounted to 13-15% depending on the cultivar, while losses of antioxidant capacity were approx. 7%. HPLC/MS analyses showed that before heating, betanin was the dominant pigment in the betacyanin fraction, while after heating it was additionally 15-decarboxy-betanin. Isolated fractions of yellow pigments in red beets are three times less heat-resistant than betacyanin fractions. At losses of yellow pigment contents in the course of thermal treatment reaching 47%, antioxidant capacity did not change markedly (a decrease by approx. 5%). In the yellow pigment fractions neobetanin was the dominant peak in the HPLC chromatogram, while vulgaxanthin was found in a much smaller area, whereas after heating additionally 2-decarboxy-2,3-dehydro-neobetanin was detected. Both groups of betalain pigments (betacyanins and betaxanthins) exhibit antioxidant capacity before and after heating. Violet beatacyjanins are 3 times more stable when heated than yellow betaxanthins.

Tracking of pigment accumulation and secretion in extractive fermentation of Monascus anka GIM 3.592.

PubMed

Chen, Gong; Bei, Qi; Huang, Tao; Wu, Zhenqiang

2017-10-04

Monascus pigments are promising sources for food and medicine due to their natural food-coloring functions and pharmaceutical values. The innovative technology of extractive fermentation is used to promote pigment productivity, but reports of pigment trans-membrane secretion mechanism are rare. In this study, tracking of pigment accumulation and secretion in extractive fermentation of Monascus anka GIM 3.592 was investigated. The increased vacuole size in mycelia correlated with fluorescence intensity (r > 0.85, p < 0.05), which indicates that intracellular pigments with strong fluorescence accumulated in the cytoplasmic vacuole. After adding nonionic surfactant Triton X-100, the uptake of rhodamine123 (Rh123) and 1-N-phenylnaphthylamine (NPN) and the release of K + and Na + rapidly increased, demonstrating that the physiological performances of the cell membrane varied upon damaging the integrity, increasing the permeability, and changing the potential. Simultaneously, the fatty acid composition also varied, which caused a weak fluidity in the membrane lipids. Therefore, the intracellular pigments embedded in Triton X-100 were secreted through the ion channels of the cell membrane. Dense, spherical pigment-surfactant micelles with an average size of 21 nm were distributed uniformly in the extraction broth. Based on the different pigment components between extractive fermentation and batch fermentation, a threefold decrease in the NAD + /NADH ratio in mycelia and a more than 200-fold increase in glucose-6-phosphate dehydrogenase (G6PDH) activity in extracellular broth occurred, further suggesting that a reduction reaction for pigment conversion from orange pigments to yellow pigments occurred in non-aqueous phase solution. A putative model was established to track the localization of Monascus pigment accumulation and its trans-membrane secretion in extractive fermentation. This finding provides a theoretical explanation for microbial extractive fermentation of Monascus pigments, as well as other non-water-soluble products.

[Photosensitizing properties and antioxidant activity of furagin--an antimicrobial drug that is a derivative of nitrofuran].

PubMed

Makareeva, E N; Lozovskaia, E L; Tatikolov, A S; Sapezhinskiĭ, I I

1997-01-01

Photosensitizing effect of antimicrobial drug nitrofuran derivative--furagin N-(5-nitro-2-furil)-allylidencamino-hydantoin) under irradiation with light longer than 280 nm was found. The method of investigation is based on photochemiluminescence of Gly-Trp peptide in aqueous solution. Maximum photosensitizing efficiency was observed at the furagin concentration 0.08 mM when chemiluminescence yield was 33 times greater than photochemiluminescence of Gly-Trp peptide in absence of drug. It was shown that photochemiluminescence sensitized by furagin occurred via free radical way. Life time of the triplet state of furagin determined by flash photolysis was 40 microseconds. A comparison of experimental data with kinetic calculation allowed us to estimate the rate constant of triplet quenching by oxygen ((2.2 +/- 0.3)10(8) M-1.s-1) and the total rate constants of physical quenching and chemical reaction with Gly-Trp peptide ((2.0 +/- 0.4)10(8) M-1.s-1). It was also found in experiments with photochemiluminescence of Gly-Trp peptide sensitized by riboflavin (irradiation with monochromatic light 436 nm) that furagin possesses antioxidant properties twice reducing the intensity of chemiluminescence at the drug concentration 0.029 mM.

Predictive analysis of photodynamic therapy applied to esophagus cancer

NASA Astrophysics Data System (ADS)

Fanjul-Vélez, F.; del Campo-Gutiérrez, M.; Ortega-Quijano, N.; Arce-Diego, J. L.

2008-04-01

The use of optical techniques in medicine has revolutionized in many cases the medical praxis, providing new tools for practitioners or improving the existing ones in the fight against diseases. The application of this technology comprises mainly two branches, characterization and treatment of biological tissues. Photodynamic Therapy (PDT) provides a solution for malignant tissue destruction, by means of the inoculation of a photosensitizer and irradiation by an optical source. The key factor of the procedure is the localization of the damage to avoid collateral harmful effects. The volume of tissue destroyed depends on the type of photosensitizer inoculated, both on its reactive characteristics and its distribution inside the tissue, and also on the specific properties of the optical source, that is, the optical power, wavelength and exposition time. In this work, a model for PDT based on the one-dimensional diffusion equation, extensible to 3D, to estimate the optical distribution in tissue, and on photosensitizer parameters to take into account the photobleaching effect is proposed. The application to esophagus cancer allows the selection of the right optical source parameters, like irradiance, wavelength or exposition time, in order to predict the area of tissue destruction.

Targeted two-photon PDT photo-sensitizers for the treatment of subcutaneous tumors

NASA Astrophysics Data System (ADS)

Spangler, C. W.; Rebane, A.; Starkey, J.; Drobizhev, M.

2009-06-01

New porphyrin-based photo-sensitizers have been designed, synthesized and characterized that exhibit greatly enhanced intrinsic two-photon absorption. These new photo-sensitizers have been incorporated into triad formulations that also incorporate Near-infrared (NIR) imaging agents, and small-molecule targeting agents that direct the triads to cancerous tumors' over-expressed receptor sites. PDT can be initiated deep into the tissue transparency window at 780-800 nm utilizing a regeneratively amplified Ti:sapphire laser using 100-150 fs pulses of 600-800 mW. Human tumor xenografts of human breast cancer (MDA-MB-231) and both small SCLC (NCI-H69) and NSCLC (A-459) have been successfully treated using octreotate targeting of over-expressed SST2 receptors. In particular, the lung cancer xenografts can be successfully treated by irradiating from the side of the mouse opposite the implanted tumor, thereby passing through ca. 2 cm of mouse skin, tissue and organs with no discernible damage to healthy tissue while causing regression in the tumors. These results suggest a new PDT paradigm for the noninvasive treatment of subcutaneous tumors, including the possibility that the targeting moiety could be matched to individual patient genetic profiles (patient-specific therapeutics).

Hybrid TiO2 -Ruthenium Nano-photosensitizer Synergistically Produces Reactive Oxygen Species in both Hypoxic and Normoxic Conditions.

PubMed

Gilson, Rebecca C; Black, Kvar C L; Lane, Daniel D; Achilefu, Samuel

2017-08-28

Photodynamic therapy (PDT) is widely used to treat diverse diseases, but its dependence on oxygen to produce cytotoxic reactive oxygen species (ROS) diminishes the therapeutic effect in a hypoxic environment, such as solid tumors. Herein, we developed a ROS-producing hybrid nanoparticle-based photosensitizer capable of maintaining high levels of ROS under both normoxic and hypoxic conditions. Conjugation of a ruthenium complex (N3) to a TiO 2 nanoparticle afforded TiO 2 -N3. Upon exposure of TiO 2 -N3 to light, the N3 injected electrons into TiO 2 to produce three- and four-fold more hydroxyl radicals and hydrogen peroxide, respectively, than TiO 2 at 160 mmHg. TiO 2 -N3 maintained three-fold higher hydroxyl radicals than TiO 2 under hypoxic conditions via N3-facilitated electron-hole reduction of adsorbed water molecules. The incorporation of N3 transformed TiO 2 from a dual type I and II PDT agent to a predominantly type I photosensitizer, irrespective of the oxygen content. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Light-driven photosensitizer uptake increases Candida albicans photodynamic inactivation.

PubMed

Romano, Renan A; Pratavieira, Sebastião; Silva, Ana P da; Kurachi, Cristina; Guimarães, Francisco E G

2017-11-01

Photodynamic Inactivation (PDI) is based on the use of a photosensitizer (PS) and light that results mainly in the production of reactive oxygen species, aiming to produce microorganism cell death. PS incubation time and light dose are key protocol parameters that influence PDI response; the correct choice of them can increase the efficiency of inactivation. The results of this study show that a minor change in the PDI protocol, namely light-driven incubation leads to a higher photosensitizer and more uniform cell uptake inside the irradiated zone. Furthermore, as the uptake increases, the damage caused by PDI also increases. The proposed light-driven incubation prior to the inactivation illumination dose has advantages when compared to the traditional PDI treatments since it can be more selective and effective. Using a violet light as pre-illumination (light-driven incubation) source and a red-light system as PDI source, it was possible to demonstrate that when compared to the traditional protocol of dark incubation, the pre-illuminated cell culture showed an inactivation increase of 7 log units. These in vitro results performed in Candida albicans cells may result in the introduction of a new protocol for PDI. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Kaolin-based foliar reflectant and water deficit influence Malbec leaf and berry temperature, pigments, and photosynthesis

USDA-ARS?s Scientific Manuscript database

The effects of a kaolin-based foliar reflectant on traits of commercial interest in the red-skinned wine grape cultivar Malbec (Vitis vinifera L.) were evaluated over three growing seasons by measuring the surface temperatures of leaves and clusters, leaf-level assimilation, leaf and berry pigment c...

Modified developer increases line resolution in photosensitive resist

NASA Technical Reports Server (NTRS)

1965-01-01

Standard developer solution is mixed with dipropyl carbonate. This reduces swelling in the photosensitive resist and permits application of relatively thick films with minimal pinhole formation and increased line resolution.

Phytoalexin Phenalenone Derivatives Inactivate Mosquito Larvae and Root-knot Nematode as Type-II Photosensitizer

NASA Astrophysics Data System (ADS)

Song, Runjiang; Feng, Yian; Wang, Donghui; Xu, Zhiping; Li, Zhong; Shao, Xusheng

2017-02-01

Phytoalexins phenalenones (PNs) are phytochemicals biosynthesized inside the plant in responsive to exterior threat. PNs are excellent type-II photosensitizers, which efficiently produce singlet oxygen upon light irradiation. Based on the core functional structure of PNs, novel PN derivatives were synthesized here and their singlet oxygen generating abilities and their phototoxicity were evaluated. At the presence of light, these PNs have photoinduced toxicity towards Aedes albopictus larvae and nematode Meloidogyne incognita, while the activity lost in the dark. The obvious tissue damage was observed on the treated mosquito larvae and nematode due to the generation of singlet oxygen. Our results revealed the potential of phenalenones as photoactivated agents for mosquito and root-knot nematode management together with light.

Patterns of coccolithophore pigment change under global acidification conditions based on in-situ observations at BATS site between July 1990-Dec 2008

NASA Astrophysics Data System (ADS)

Lv, Jianhai; Kuang, Yaoqiu; Zhao, Hui; Andersson, Andreas

2017-06-01

Coccolith production is an important part of the biogenic carbon cycle as the largest source of calcium carbonate on earth, accounting for about 75% of the deposition of carbon on the sea floor. Recent studies based on laboratory experiment results indicated that increasing anthropogenic CO2 in the atmosphere triggered global ocean acidification leading to a decrease of calcite or aragonite saturation and calcium carbonate, and to decreasing efficiency of carbon export/pumping to deep layers. In the present study, we analyzed about 20 years of field observations of coccolithophore pigment, dissolved inorganic carbon (DIC), nutrients, and temperatures from the Bermuda Atlantic Time-series Study (BATS) site and satellite remote sensing to investigate the variable tendency of the coccolithophore pigment, and to evaluate the influence of ocean acidification on coccolithophore biomass. The results indicated that there was a generally increasing tendency of coccolithophore pigment, coupled with increasing bicarbonate concentrations or decreasing carbonate ion concentration. The change of coccolithophore pigment was also closely associated with pH, nutrients, mixed layer depth (MLD), and temperature. Correlation analyses between coccolithophores and abiotic parameter imply that coccoliths production or coccolithophore pigment has increased with increasing acidification in the recent 20 years.

Ocular toxicity of beta-blockers and benzalkonium chloride in pigmented rabbits: electrophysiological and morphological studies.

PubMed

Chou, A; Hori, S; Takase, M

1985-01-01

Subconjunctival injection of 0.2 ml of the following solutions was carried out once a day for two weeks in the albino and pigmented rabbit: commercial 0.5% timolol or 1% befunolol ophthalmic solutions, both containing benzalkonium chloride, and also these drug solutions containing no preservative, ophthalmic base solutions containing benzalkonium chloride, physiological saline solution or phosphate buffer solution. One week after daily injections of the commercial drug solutions or base solutions with benzalkonium chloride, the electroretinogram (ERG) showed a marked reduction in the a- and b-wave amplitudes in the pigmented rabbit, but the ERG changes were slight in the albino rabbit. After two weeks of injections, histological studies of the pigmented rabbit eyes revealed retinal detachment, visual cell loss and atrophy of the retinal pigment epithelium and choroid; the changes in the albino rabbit eyes were minimal. Injections of the beta-blockers containing no benzalkonium resulted in no significant changes in the ERG or in the tissue structures of all rabbits. Injections of only physiological saline or phosphate buffer had no deleterious effects. Therefore, the ocular toxicity of the beta-blockers was thought to be minor and the toxic effects seen in this study were thought to be due to benzalkonium chloride, which possibly accumulates in the ocular pigments.

Diversities in Virulence, Antifungal Activity, Pigmentation and DNA Fingerprint among Strains of Burkholderia glumae

PubMed Central

Karki, Hari S.; Shrestha, Bishnu K.; Han, Jae Woo; Groth, Donald E.; Barphagha, Inderjit K.; Rush, Milton C.; Melanson, Rebecca A.; Kim, Beom Seok; Ham, Jong Hyun

2012-01-01

Burkholderia glumae is the primary causal agent of bacterial panicle blight of rice. In this study, 11 naturally avirulent and nine virulent strains of B. glumae native to the southern United States were characterized in terms of virulence in rice and onion, toxofalvin production, antifungal activity, pigmentation and genomic structure. Virulence of B. glumae strains on rice panicles was highly correlated to virulence on onion bulb scales, suggesting that onion bulb can be a convenient alternative host system to efficiently determine the virulence of B. glumae strains. Production of toxoflavin, the phytotoxin that functions as a major virulence factor, was closely associated with the virulence phenotypes of B. glumae strains in rice. Some strains of B. glumae showed various levels of antifungal activity against Rhizoctonia solani, the causal agent of sheath blight, and pigmentation phenotypes on casamino acid-peptone-glucose (CPG) agar plates regardless of their virulence traits. Purple and yellow-green pigments were partially purified from a pigmenting strain of B. glumae, 411gr-6, and the purple pigment fraction showed a strong antifungal activity against Collectotrichum orbiculare. Genetic variations were detected among the B. glumae strains from DNA fingerprinting analyses by repetitive element sequence-based PCR (rep-PCR) for BOX-A1R-based repetitive extragenic palindromic (BOX) or enterobacterial repetitive intergenic consensus (ERIC) sequences of bacteria; and close genetic relatedness among virulent but pigment-deficient strains were revealed by clustering analyses of DNA fingerprints from BOX-and ERIC-PCR. PMID:23028972

Aptamer-based multifunctional ligand-modified UCNPs for targeted PDT and bioimaging.

PubMed

Hou, Weijia; Liu, Yuan; Jiang, Ying; Wu, Yuan; Cui, Cheng; Wang, Yanyue; Zhang, Liqin; Teng, I-Ting; Tan, Weihong

2018-06-14

We designed an aptamer-based multifunctional ligand which, upon conjugation to the surface of upconversion nanoparticles (UCNPs), could realize phase transfer, covalent photosensitizer (PS) loading, and cancer cell targeting in one simple step. The as-built PDT nanodrug is selectively internalized into cancer cells and it exhibits highly efficient and selective cytotoxicity.

Nanotechnology-Based Drug Delivery Systems for Photodynamic Therapy of Cancer: A Review.

PubMed

Calixto, Giovana Maria Fioramonti; Bernegossi, Jéssica; de Freitas, Laura Marise; Fontana, Carla Raquel; Chorilli, Marlus

2016-03-11

Photodynamic therapy (PDT) is a promising alternative approach for improved cancer treatment. In PDT, a photosensitizer (PS) is administered that can be activated by light of a specific wavelength, which causes selective damage to the tumor and its surrounding vasculature. The success of PDT is limited by the difficulty in administering photosensitizers (PSs) with low water solubility, which compromises the clinical use of several molecules. Incorporation of PSs in nanostructured drug delivery systems, such as polymeric nanoparticles (PNPs), solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs), gold nanoparticles (AuNPs), hydrogels, liposomes, liquid crystals, dendrimers, and cyclodextrin is a potential strategy to overcome this difficulty. Additionally, nanotechnology-based drug delivery systems may improve the transcytosis of a PS across epithelial and endothelial barriers and afford the simultaneous co-delivery of two or more drugs. Based on this, the application of nanotechnology in medicine may offer numerous exciting possibilities in cancer treatment and improve the efficacy of available therapeutics. Therefore, the aim of this paper is to review nanotechnology-based drug delivery systems for photodynamic therapy of cancer.

Preclinical evaluation of zinc phthalocyanine tetrasulfonate-based PDT

NASA Astrophysics Data System (ADS)

Borgatti-Jeffreys, Antonella; Hooser, Stephen B.; Miller, Margaret A.; Thomas, Rose M.; deGortari, Amalia; Lucroy, Michael D.

2005-04-01

Photodynamic therapy (PDT) involves the light activation of a drug within a tumor causing selective tumor cell death. Unfortunately, some photosensitizing drugs have been associated with adverse reactions in veterinary patients. Zinc phthalocyanine tetrasulfonate (ZnPcS4) is a promising second-generation photosensitizer for use in veterinary medicine, however, it cannot be applied clinically until safety and efficacy data are available. ZnPcS4 was given to Swiss Webster mice to assess acute toxicity. Doses >100 mg/kg were associated with acute toxicity and mortality, and doses >100 mg/kg resulted in renal tubular nephrosis, suggesting that the minimum toxic dose is approximately 100 mg/kg. Based on these data, a Phase I clinical trial of ZnPcS4-based PDT in tumor-bearing dogs is underway, with ZnPcS4 doses up to 2 mg/kg producing no apparent toxicity. Tumor response has been observed after ZnPcS4-based PDT using doses as low as 0.25 mg/kg, suggesting that conventional phase I clinical trials may not be appropriate for PDT protocols.

Cultural studies coupled with DNA based sequence analyses and its implication on pigmentation as a phylogenetic marker in Pestalotiopsis taxonomy.

PubMed

Liu, Ai-Rong; Chen, Shuang-Chen; Wu, Shang-Ying; Xu, Tong; Guo, Liang-Dong; Jeewon, Rajesh; Wei, Ji-Guang

2010-11-01

Previous phylogenetic studies based on DNA sequence data have partially resolved taxonomic relationships among Pestalotiopsis species. There are still some morphological characters whose phylogenetic significance have not been assessed properly due to limited taxon sampling, in particular the degree of pigmentation of median cells. In this study, the stability of pigmentation of median cells of conidia in Pestalotiopsis species was evaluated in subculture, and a molecular phylogenetic analysis was conducted on 45 strains belonging to 26 species in order to reappraise the pigmentation of median cells for its significance in the taxonomy of Pestalotiopsis. Phylogenetic relationships were inferred from nucleotide sequences in ITS regions (ITS1, 5.8S and ITS2) and β-tubulin 2 gene (tub2). The results showed that pigmentation of median cells was stable and it could be a key character in the taxonomy of Pestalotiopsis species. Instead of "concolorous" and "versicolor" proposed by Steyeart (1949), "brown to olivaceous" and "umber to fuliginous" are described and proposed in this paper. Copyright © 2010. Published by Elsevier Inc.

Beech wood Fagus sylvatica dilute-acid hydrolysate as a feedstock to support Chlorella sorokiniana biomass, fatty acid and pigment production.

PubMed

Miazek, Krystian; Remacle, Claire; Richel, Aurore; Goffin, Dorothee

2017-04-01

This work evaluates the possibility of using beech wood (Fagus sylvatica) dilute-acid (H 2 SO 4 ) hydrolysate as a feedstock for Chlorella sorokiniana growth, fatty acid and pigment production. Neutralized wood acid hydrolysate, containing organic and mineral compounds, was tested on Chlorella growth at different concentrations and compared to growth under phototrophic conditions. Chlorella growth was improved at lower loadings and inhibited at higher loadings. Based on these results, a 12% neutralized wood acid hydrolysate (Hyd12%) loading was selected to investigate its impact on Chlorella growth, fatty acid and pigment production. Hyd12% improved microalgal biomass, fatty acid and pigment productivities both in light and in dark, when compared to photoautotrophic control. Light intensity had substantial influence on fatty acid and pigment composition in Chlorella culture during Hyd12%-based growth. Moreover, heterotrophic Chlorella cultivation with Hyd12% also showed that wood hydrolysate can constitute an attractive feedstock for microalgae cultivation in case of lack of light. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production and chemical characterization of pigments in filamentous fungi.

PubMed

Souza, Patrícia Nirlane da Costa; Grigoletto, Tahuana Luiza Bim; de Moraes, Luiz Alberto Beraldo; Abreu, Lucas M; Guimarães, Luís Henrique Souza; Santos, Cledir; Galvão, Luciano Ribeiro; Cardoso, Patrícia Gomes

2016-01-01

Production of pigments by filamentous fungi is gaining interest owing to their use as food colourants, in cosmetics and textiles, and because of the important biological activities of these compounds. In this context, the objectives of this study were to select pigment-producing fungi, identify these fungi based on internal transcribed spacer sequences, evaluate the growth and pigment production of the selected strains on four different media, and characterize the major coloured metabolites in their extracts. Of the selected fungal strains, eight were identified as Aspergillus sydowii (CML2967), Aspergillus aureolatus (CML2964), Aspergillus keveii (CML2968), Penicillium flavigenum (CML2965), Penicillium chermesinum (CML2966), Epicoccum nigrum (CML2971), Lecanicillium aphanocladii (CML2970) and Fusarium sp. (CML2969). Fungal pigment production was influenced by medium composition. Complex media, such as potato dextrose and malt extract, favoured increased pigment production. The coloured compounds oosporein, orevactaene and dihydrotrichodimerol were identified in extracts of L. aphanocladii (CML2970), E. nigrum (CML2971), and P. flavigenum (CML2965), respectively. These results indicate that the selected fungal strains can serve as novel sources of pigments that have important industrial applications.

Crystalline Organic Pigment-Based Field-Effect Transistors.

PubMed

Zhang, Haichang; Deng, Ruonan; Wang, Jing; Li, Xiang; Chen, Yu-Ming; Liu, Kewei; Taubert, Clinton J; Cheng, Stephen Z D; Zhu, Yu

2017-07-05

Three conjugated pigment molecules with fused hydrogen bonds, 3,7-diphenylpyrrolo[2,3-f]indole-2,6(1H,5H)-dione (BDP), (E)-6,6'-dibromo-[3,3'-biindolinylidene]-2,2'-dione (IIDG), and 3,6-di(thiophen-2-yl)-2,5-dihydropyrrolo-[3,4-c]pyrrole-1,4-dione (TDPP), were studied in this work. The insoluble pigment molecules were functionalized with tert-butoxylcarbonyl (t-Boc) groups to form soluble pigment precursors (BDP-Boc, IIDG-Boc, and TDPP-Boc) with latent hydrogen bonding. The single crystals of soluble pigment precursors were obtained. Upon simple thermal annealing, the t-Boc groups were removed and the soluble pigment precursor molecules with latent hydrogen bonding were converted into the original pigment molecules with fused hydrogen bonding. Structural analysis indicated that the highly crystalline soluble precursors were directly converted into highly crystalline insoluble pigments, which are usually only achievable by gas-phase routes like physical vapor transport. The distinct crystal structure after the thermal annealing treatment suggests that fused hydrogen bonding is pivotal for the rearrangement of molecules to form a new crystal in solid state, which leads to over 2 orders of magnitude enhancement in charge mobility in organic field-effect transistor (OFET) devices. This work demonstrated that crystalline OFET devices with insoluble pigment molecules can be fabricated by their soluble precursors. The results indicated that a variety of commercially available conjugated pigments could be potential active materials for high-performance OFETs.

EDXRF analysis of the Pentecost Triptych from the "São Pedro de Miragaia" church (Porto, Portugal)

NASA Astrophysics Data System (ADS)

Roldán, Clodoaldo; Ferrero, José; Juanes, David; Carballo, Jorgelina; Calvo, Ana; Aguiar, Maria

2013-01-01

EDXRF spectrometry was used to determine the pigment composition of the Pentecost Triptych, a Flemish masterpiece located at the Church of São Pedro de Miragaia (Porto, Portugal). The triptych was restored at the beginning of the 20th century and presents a great number of zones with repaints and colour alterations that can be observed on the whole of their surface. The identification of the original pigments and restoration pigments was based on their characteristic colour and the correlation between the detected elements and the named "key elements" of ancient pigments (Ca, Fe, Cu, Hg, Pb,…) and modern pigments (Ti, Ba, Cr, Zn, Co, Cd,…). The analysis of the triptych has been carried out in situ by means of portable instrumentation.

The efficiency of micro-Raman spectroscopy in the analysis of complicated mixtures in modern paints: Munch's and Kupka's paintings under study

NASA Astrophysics Data System (ADS)

Košařová, Veronika; Hradil, David; Hradilová, Janka; Čermáková, Zdeňka; Němec, Ivan; Schreiner, Manfred

2016-03-01

Twenty one mock-up samples containing inorganic pigments primarily used at the turn of the 19th and 20th century were selected for comparative study and measured by micro-Raman and portable Raman spectrometers. They included pure grounds (chalk-based, earth-based and lithopone-based), grounds covered by resin-based varnish, and different paint layers containing mixtures of white, yellow, orange, red, green, blue and black pigments, usually in combination with white pigments (titanium, zinc and barium whites or chalk). In addition, ten micro-samples obtained from seven paintings of two world-famous modern painters Edvard Munch and František Kupka have been investigated. Infrared reflection spectroscopy (FTIR), portable X-ray fluorescence (XRF) and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were used as supplementary methods. The measurements showed that blue pigments (ultramarine, Prussian blue and azurite), vermilion and ivory black in mixture with whites provided characteristic Raman spectra, while Co-, Cd- and Cr- pigments' bands were suppressed by fluorescence. The best success rate of micro-Raman spectroscopy has been achieved using the 780 nm excitation, however, the sensitivity of this excitation laser in a portable Raman instrument significantly decreased. The analyses of micro-samples of paintings by E. Munch and F. Kupka showed that micro-Raman spectroscopy identified pigments which would remain unidentified if analyzed only by SEM-EDS (zinc yellow, Prussian blue). On the other hand, chromium oxide green and ultramarine were not detected together in a sample due to overlap of their main bands. In those cases, it is always necessary to complement Raman analysis with other analytical methods.

Evolution, Development and Function of Vertebrate Cone Oil Droplets

PubMed Central

Toomey, Matthew B.; Corbo, Joseph C.

2017-01-01

To distinguish colors, the nervous system must compare the activity of distinct subtypes of photoreceptors that are maximally sensitive to different portions of the light spectrum. In vertebrates, a variety of adaptations have arisen to refine the spectral sensitivity of cone photoreceptors and improve color vision. In this review article, we focus on one such adaptation, the oil droplet, a unique optical organelle found within the inner segment of cone photoreceptors of a diverse array of vertebrate species, from fish to mammals. These droplets, which consist of neutral lipids and carotenoid pigments, are interposed in the path of light through the photoreceptor and modify the intensity and spectrum of light reaching the photosensitive outer segment. In the course of evolution, the optical function of oil droplets has been fine-tuned through changes in carotenoid content. Species active in dim light reduce or eliminate carotenoids to enhance sensitivity, whereas species active in bright light precisely modulate carotenoid double bond conjugation and concentration among cone subtypes to optimize color discrimination and color constancy. Cone oil droplets have sparked the curiosity of vision scientists for more than a century. Accordingly, we begin by briefly reviewing the history of research on oil droplets. We then discuss what is known about the developmental origins of oil droplets. Next, we describe recent advances in understanding the function of oil droplets based on biochemical and optical analyses. Finally, we survey the occurrence and properties of oil droplets across the diversity of vertebrate species and discuss what these patterns indicate about the evolutionary history and function of this intriguing organelle. PMID:29276475

Raman microspectroscopy of Hematoporphyrins. Imaging of the noncancerous and the cancerous human breast tissues with photosensitizers

NASA Astrophysics Data System (ADS)

Brozek-Pluska, B.; Kopec, M.

2016-12-01

Raman microspectroscopy combined with fluorescence were used to study the distribution of Hematoporphyrin (Hp) in noncancerous and cancerous breast tissues. The results demonstrate the ability of Raman spectroscopy to distinguish between noncancerous and cancerous human breast tissue and to identify differences in the distribution and photodegradation of Hematoporphyrin, which is a photosensitizer in photodynamic therapy (PDT), photodynamic diagnosis (PDD) and photoimmunotherapy (PIT) of cancer. Presented results show that Hematoporphyrin level in the noncancerous breast tissue is lower compared to the cancerous one. We have proved also that the Raman intensity of lipids and proteins doesn't change dramatically after laser light irradiation, which indicates that the PDT treatment destroys preferably cancer cells, in which the photosensitizer is accumulated. The specific subcellular localization of photosensitizer for breast tissues samples soaked with Hematoporphyrin was not observed.

In Vitro Antimicrobial Photodynamic Therapy Against Trichophyton mentagrophytes Using New Methylene Blue as the Photosensitizer.

PubMed

López-Chicón, P; Gulías, Ò; Nonell, S; Agut, M

2016-11-01

Antimicrobial photodynamic therapy combines the use of a photosensitizing drug with light and oxygen to eradicate pathogens. Trichophyton mentagrophytes is a dermatophytic fungus able to invade the skin and keratinized tissues. We have investigated the use of new methylene blue as the photosensitizing agent for antimicrobial photodynamic therapy to produce the in vitro inactivation of T mentagrophytes. A full factorial design was employed to optimize the parameters for photoinactivation of the dermatophyte. The parameters studied were new methylene blue concentration, contact time between the photosensitizing agent and the fungus prior to light treatment, and the fluence of red light (wavelength, 620-645nm) applied. The minimum concentration of new methylene blue necessary to induce the death of all T. mentagrophytes cells in the initial suspension (approximate concentration, 10 6 colony forming units per milliliter) was 50μM for a fluence of 81J/cm 2 after a contact time of 10minutes with the photosensitizing-agent. Increasing the concentration to 100μM allowed the fluence to be decreased to 9J/cm 2 . Comparison of our data with other published data shows that the susceptibility of T. mentagrophytes to antimicrobial photodynamic therapy with new methylene blue is strain-dependent. New methylene blue is a photosensitizing agent that should be considered for the treatment of fungal skin infections caused by this dermatophyte. Copyright © 2016 AEDV. Publicado por Elsevier España, S.L.U. All rights reserved.

Suppression of T24 human bladder cancer cells by ROS from locally delivered hematoporphyrin-containing polyurethane films.

PubMed

Kim, Dohyun; Lee, Mi Hee; Koo, Min-Ah; Kwon, Byeong-Ju; Kim, Min Sung; Seon, Gyeung Mi; Hong, Seung Hee; Park, Jong-Chul

2018-06-13

Systemic injection of a photosensitizer is a general method in photodynamic therapy, but it has complications due to the unintended systemic distribution and remnants of photosensitizers. This study focused on the possibility of suppressing luminal proliferative cells by excessive reactive oxygen species from locally delivered photosensitizer with biocompatible polyurethane, instead of the systemic injection method. We used human bladder cancer cells, hematoporphyrin as the photosensitizer, and polyurethane film as the photosensitizer-delivering container. The light source was a self-made LED (510 nm, 5 mW cm-2) system. The cancer cells were cultured on different doses of hematoporphyrin-containing polyurethane film and irradiated with LED for 15 minutes and 30 minutes each. After irradiating with LED and incubating for 24 hours, cell viability analysis, cell cycle analysis, apoptosis assay, intracellular and extracellular ROS generation study and western blot were performed. The cancer cell suppression effects of different concentrations of the locally delivered hematoporphyrin with PDT were compared. Apoptosis dominant cancer cell suppressions were shown to be hematoporphyrin dose-dependent. However, after irradiation, intracellular ROS amounts were similar in all the groups having different doses of hematoporphyrin, but these values were definitely higher than those in the control group. Excessive extracellular ROS from the intended, locally delivered photosensitizer for photodynamic treatment application had an inhibitory effect on luminal proliferative cancer cells. This method can be another possibility for PDT application on contactable or attachable lesions.

Development of Improved and Novel Thermal Control Coatings (Preprint)

DTIC Science & Technology

2007-05-01

a ZnO-based coating (Figure 5). A product offered by the 3M Corporation composed of hollow soda - lime borosilicate spheres with diameters ranging...as well as the current zinc oxide based coatings. In addition, a novel pigment concept based on hollow silica particles is continuing to be explored...coatings. In addition, a novel pigment concept based on hollow silica particles is continuing to be explored as an extremely space durable and

Frequency domain, time-resolved and spectroscopic investigations of photosensitizers encapsulated in liposomal phantoms

NASA Astrophysics Data System (ADS)

Mermut, Ozzy; Bouchard, Jean-Pierre; Cormier, Jean-Francois; Diamond, Kevin R.; Noiseux, Isabelle; Vernon, Marcia L.; Patterson, Michael S.

2007-07-01

A broadband frequency domain fluorescence lifetime system (from ns to ms time scale) has been developed to study the photochemical and photodynamic behavior of model, well-controlled photosensitizer-encapsulating liposomes. Liposomes are known to be efficient and selective photosensitizer (PS) drug delivery vesicles, however, their chemical and physical effects on the photochemical properties of the photosensitizer have not been well characterized. The liposomes employed in this study (both blank and photosensitizer-complexed) were characterized to determine their: a) size distribution (dynamic light scattering), b) image (scanning electron microscope, confocal fluorescence microscopy), c) concentration of particles (flow cytometry), d) temperature-dependant phase transition behavior (differential scanning calorimetry, and e) spectrofluorescent spectrophotometric properties, e.g. aggregation, in the confined environment. The fluorescence decay behavior of two families of encapsulated photosensitizers, di-and tetrasulfonated metallophthalocyanines, and 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH), has been examined as a function of the liposome's physical properties (size-scale, distribution and concentration of scatterer) and the impact of the photosensitizer spatial confinement determined. It is found that the achievable size range and distribution of the PS-liposomes is controlled by the chemical nature of the PS for large liposomes (1000 nm), and is PS independent for small PS-liposomes (~140nm). The lifetime decay behavior was studied for all three photosensitizer-liposome systems and compared before and after confinement. We found the nature of the decay to be similar before and after encapsulation for the sulfonated phthalocyanines containing ionic moieties (primarily monoexponential) but not for HPPH. In the latter, the decay transitioned from multi- to monoexponential decay upon localizing lypophilic HPPH to the liposomal membrane. This behavior was confirmed by obtaining a similar change in lifetime response with an independent timedomain system. We also varied the environment in temperature and oxygen content to examine the effects on the fluorescent lifetimes of the liposomal complexes. The fluorescence decay of all three PS-containing liposomes showed that the local spatial confinement of PS (dictated by the PS chemistry) into different domains within the liposome directly controls the temperature-response. Membrane-bound photosensitizers were less sensitive to temperature effects as illustrated by the decay dynamics observed in solu, that is, they developed a unique decay behavior that correlated with the phase transition of the membrane. The fluorescent lifetime of PS-encapsulated liposomes in deoxygenated environments, relevant to oxygen independent type I phototoxicity, was also probed in the frequency-domain revealing that liposome-confined PS display very different trends than those observed in solu.

Dissecting pigment architecture of individual photosynthetic antenna complexes in solution

DOE PAGES

Wang, Quan; Moerner, W. E.

2015-10-05

Oligomerization plays a critical role in shaping the light-harvesting properties of many photosynthetic pigment-protein complexes, but a detailed understanding of this process at the level of individual pigments is still lacking. To study the effects of oligomerization, we designed a single-molecule approach to probe the photophysical properties of individual pigment sites as a function of protein assembly state. Our method, based on the principles of anti-Brownian electrokinetic trapping of single fluorescent proteins, step-wise photobleaching, and multiparameter spectroscopy, allows pigment-specific spectroscopic information on single multipigment antennae to be recorded in a nonperturbative aqueous environment with unprecedented detail. We focus on themore » monomer-to-trimer transformation of allophycocyanin (APC), an important antenna protein in cyanobacteria. Here, our data reveal that the two chemically identical pigments in APC have different roles. One (α) is the functional pigment that red-shifts its spectral properties upon trimer formation, whereas the other (β) is a "protective" pigment that persistently quenches the excited state of α in the prefunctional, monomer state of the protein. These results show how subtleties in pigment organization give rise to functionally important aspects of energy transfer and photoprotection in antenna complexes. Finally, the method developed here should find immediate application in understanding the emergent properties of other natural and artificial light-harvesting systems.« less

Studies of a novel photosensitizer Pd-bacteriopheophorbide (Tookad) for the prostate cancer PDT in canine model

NASA Astrophysics Data System (ADS)

Huang, Zheng; Chen, Qun; Brun, Pierre-Herve; Wilson, Brian C.; Scherz, Avigdor; Salomon, Yoram; Luck, David L.; Beckers, Jill; Hetzel, Fred W.

2003-12-01

Photodynamic therapy (PDT) mediated with vascular acting photosensitizer pd-bacteriopheophorbide (Tookad), is investigated as an alternative modality for the total ablation of prostate cancer. In vivo normal canine prostate is used as the animal model. Interstitial PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the i.v. infused photosensitizer drug. The effects of two-session PDT were evaluated. The prostate and its adjacent tissues were harvested and subjected to histopathological examination. At one-week, post second-session PDT, the animals recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. Two-session PDT or one single session PDT induced a similar extent of damage. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis. Maximum lesion size of over 3 cm in dimension could be achieved with a single 1-cm interstitial treatment, suggesting the therapy is very effective in ablating prostatic tissue. Pharmacokinetic studies show that the photosensitizer is cleared rapidly from the circulation. In conclusion, the novel photosensitizer Tookad mediated PDT may provide an effective alternative to treat prostate cancer.

Smart Photosensitizer: Tumor-Triggered Oncotherapy by Self-Assembly Photodynamic Nanodots.

PubMed

Jia, Yuhua; Li, Jinyu; Chen, Jincan; Hu, Ping; Jiang, Longguang; Chen, Xueyuan; Huang, Mingdong; Chen, Zhuo; Xu, Peng

2018-05-09

Clinical photosensitizers suffer from the disadvantages of fast photobleaching and high systemic toxicities because of the off-target photodynamic effects. To address these problems, we report a self-assembled pentalysine-phthalocyanine assembly nanodots (PPAN) fabricated by an amphipathic photosensitizer-peptide conjugate. We triggered the photodynamic therapy effects of photosensitizers by precisely controlling the assembly and disintegration of the nanodots. In physiological aqueous conditions, PPAN exhibited a size-tunable spherical conformation with a highly positive shell of the polypeptides and a hydrophobic core of the π-stacking Pc moieties. The assembly conformation suppressed the fluorescence and the reactive oxygen species generation of the monomeric photosensitizer molecules (mono-Pc) and thus declined the photobleaching and off-target photodynamic effects. However, tumor cells disintegrated PPAN and released the mono-Pc molecules, which exhibited fluorescence for detection and the photodynamic effects for the elimination of the tumor tissues. The molecular dynamics simulations revealed the various assembly configurations of PPAN and illustrated the assembly mechanism. At the cellular level, PPAN exhibited a remarkable phototoxicity to breast cancer cells with the IC 50 values in a low nanomolar range. By using the subcutaneous and orthotopic breast cancer animal models, we also demonstrated the excellent antitumor efficacies of PPAN in vivo.

Photosensitized Formation of Secondary Organic Aerosols above the Air/Water Interface

PubMed Central

2016-01-01

In this study, we evaluated photosensitized chemistry at the air–sea interface as a source of secondary organic aerosols (SOA). Our results show that, in addition to biogenic emissions, abiotic processes could also be important in the marine boundary layer. Photosensitized production of marine secondary organic aerosol was studied in a custom-built multiphase atmospheric simulation chamber. The experimental chamber contained water, humic acid (1–10 mg L–1) as a proxy for dissolved organic matter, and nonanoic acid (0.1–10 mM), a fatty acid proxy which formed an organic film at the air–water interface. Dark secondary reaction with ozone after illumination resulted in SOA particle concentrations in excess of 1000 cm–3, illustrating the production of unsaturated compounds by chemical reactions at the air–water interface. SOA numbers via photosensitization alone and in the absence of ozone did not exceed background levels. From these results, we derived a dependence of SOA numbers on nonanoic acid surface coverage and dissolved organic matter concentration. We present a discussion on the potential role of the air–sea interface in the production of atmospheric organic aerosol from photosensitized origins. PMID:27434860

Photosensitivity of layered semiconductor propolis heterocontact

NASA Astrophysics Data System (ADS)

Drapak, Stepan I.; Orletskii, Volodymyr B.; Bahtinov, Anatolii P.; Kovalyuk, Zakhar D.; Fotiy, Vasyl D.

2003-03-01

Room temperature photosensitivity and its spectral distribution are investigated for a hetercontact between a layered semiconductor (p-InSe) and a biological entity (propolis). The obtained heterocontacts has a maximum photosensitivity >= 10^4 V/W. It is shown that the form of spectral sensitivity curve depends on the way of the heterocontact preparation. The long-wave edge of relative quantum efficiency varies from hν =1.2 eV (the energy gap for InSe at T=300 K) to 1.6 eV depending on a state of aggregation of propolis. The maximum photosensitivity in the long-wave spectral range takes place when the propolis layer is under illumination. The obtained peculiarities of the photoelectrical properties cannot be explained in the framework of the classical description of photosensitivity spectral description (the window effect) what follows from the optical absorption measurements for InSe and propolis in the range hν <= 1.2 eV. Impurity states in the energy gap of InSe and states at the heterocontact interface (a classical case of isotype p-p heterojunction) also do not give an appropriate explanation. To interpret the obtained results the complexity of the chemical composition of propolis, a product from honey bee, must be taken into account.

The effect of UV exposure and heat treatment on crystallization behavior of photosensitive glasses

NASA Astrophysics Data System (ADS)

Kıbrıslı, Orhan; Ersundu, Ali Erçin

2018-05-01

In this study, photosensitive glasses in the Na2O-ZnO-Al2O3-SiO2 system with photosensitizing agents (cerium, silver, tin, antimony) and halogenides (NaF and KBr) were synthesized through a conventional melt-quenching technique. The crystallization mechanism was investigated for solely heat-treated and UV-exposed + heat-treated samples using differential thermal analysis (DTA), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) techniques to understand the effect of UV exposure on crystallization behavior of photosensitive glasses. Accordingly, non-isothermal DTA measurements were performed at different heating rates to determine crystallization peak, T p, and onset, T c, temperatures. For solely heat-treated samples, the kinetic parameters such as the Avrami constant, n, and morphology index, m, were calculated as 1 from the Ozawa method indicating surface crystallization and the value of crystallization activation energy was calculated as 944 kJ/mol using modified Kissinger method. On the contrary, bulk crystallization was found to be predominant for UV exposed + heat-treated samples revealing that UV exposure is the primary cause of bulk crystallization in photosensitive glasses.

Augmenting the antibiofilm efficacy of advanced noninvasive light activated disinfection with emulsified oxidizer and oxygen carrier.

PubMed

George, Saji; Kishen, Anil

2008-09-01

In this study, we tested the hypothesis that the inclusion of an oxidizer and oxygen carrier in the photosensitization formulation would facilitate comprehensive disinfection of matured endodontic biofilm by light-activated disinfection (LAD). Photosensitizing formulations containing methylene blue (MB) and an oxygen carrier alone (perfluorodecahydronaphthalene) (PF1) or in combination with oxidizer (H(2)O(2)) (PF2) or their emulsions formed with triton-X100 (Bio-Rad Laboratories, Hercules, CA) in different proportions (PF3 and PF4) were tested for photochemical properties and damage to the biofilm structure using confocal laser scanning microscopy. Conventional chemomechanical preparation, LAD using MB in water, and LAD using MB in emulsion (PF4) were also conducted on 10-week-old Enterococcus faecalis biofilm within root canals. MB in emulsion (PF4) was overall the most effective photosensitizer formulation for photooxidation, generation of singlet oxygen (p = 0.001), and in disinfecting biofilm bacteria. Advanced noninvasive LAD using a photosensitizer formulation containing oxidizer and oxygen carrier disrupted the biofilm matrix and facilitated comprehensive inactivation of biofilm bacteria. This modified photosensitizer formulation will have potential advantages in endodontic disinfection.

[Spectral properties of new photosensitizers for photodynamic diagnosis and therapy].

PubMed

Li, Bu-hong; Xie, Shu-sen; Lu, Zu-kang

2002-12-01

The spectral properties of new photosensitizer ZnPcS2P2, PsD-007 and HMME, as well as traditional photosensitizer HpD have been studied by comparing their spectra in physiological saline and in physiological saline with 10 percent serum. Experimental results show that the maximum absorption peaks for PsD-007, HMME and HpD in the physiological saline with 10 percent serum appear at 400 nm in the soret region, while at 670 nm for ZnPcS2P2. The fluorescence excitation spectra closely resemble the absorption spectra. When excited by the light at the wavelengths of 413 and 514.5 nm, the fluorescence emission peaks for PsD-007, HMME and HpD appear at 625 and 690 nm, respectively. The fluorescent excitation efficiency of the same photosensitizer with the same concentration excited by the light at the wavelength of 413 nm is about three fold higher than that at 514.5 nm. Furthermore, the fluorescent excitation efficiency is the highest for HMME, but is lower for HpD and lowest for PsD-007. These results are significant in the selection of photosensitizers for photodynamic diagnosis and therapy.

Clinical status of benzoporphyrin derivative

NASA Astrophysics Data System (ADS)

Levy, Julia G.; Chan, Agnes H.; Strong, H. Andrew

1996-01-01

Benzoporphyrin derivative monoacid ring A (BPD) is currently in Phase II clinical trials for the treatment of cutaneous malignancies (basal cell carcinoma and cutaneous metastases) and psoriasis. Results to date suggest that this photosensitizer has potential in both of these areas. Recently, a clinical trial with BPD was initiated for the treatment of age related macular degeneration, a neovascular condition in the eye which leads to blindness. BPD is a lipophilic photosensitizer which is rapidly taken up by activated cells and the vascular endothelium of neovasculature. The PDT effects seen with BPD appear to be a combination of vascular occlusion and direct killing of target cells. Since many diseases involve either activated cells and/or neovasculature, PDT with photosensitizer with characteristics like those of BPD, has applications far wider than oncology. A new area of interest involving photosensitizers is that of immune modulation. A number of photosensitizers have been shown to effect immune modulation in animal models of immune dysfunction including autoimmunity (rheumatoid arthritis, lupus), cutaneous hypersensitivity and allografts. BPD and PHOTOFRINR have both been shown to be effective in ameliorating arthritic symptoms in a number of animal models. The mechanisms by which immune modulation is affected in these studies still remains to be resolved.

Larval, pre-juvenile and juvenile development of Diapterus peruvianus (Perciformes: Gerreidae).

PubMed

Jiménez Rosenberg, Sylvia Patricia; González Navarro, Enrique; Saldierna Martínez, Ricardo Javier

2003-06-01

The development of Diapterus peruvianus (Sauvage 1879) is based on 60 larvae collected in superficial tows made in Bahía Concepción, and on 16 pre-juvenile and juvenile organisms collected in Bahía de La Paz, B. C. S., México, using a standard plankton net and a rectangular epibenthonic net, respectively. Larvae of D. peruvianus show three large blotches on the dorsum of the gut that can fuse together and give the appearance of one large continuous blotch. There are two to three pre-anal pigments and 16 post-anal pigments in the ventral midline; cephalic pigments are present from the postflexion stage, as well as a serrated preoperculum. The pre-juvenile and juvenile organisms are distinguished by their body depth, the anal-fin formula, the serrated pre-operculum and the base pigments in the dorsal and anal fins.

Natural pigments: carotenoids, anthocyanins, and betalains--characteristics, biosynthesis, processing, and stability.

PubMed

Delgado-Vargas, F; Jiménez, A R; Paredes-López, O

2000-05-01

Pigments are present in all living matter and provide attractive colors and play basic roles in the development of organisms. Human beings, like most animals, come in contact with their surroundings through color, and things can or cannot be acceptable based on their color characteristics. This review presents the basic information about pigments focusing attention on the natural ones; it emphasizes the principal plant pigments: carotenoids, anthocyanins, and betalains. Special considerations are given to their salient characteristics; to their biosynthesis, taking into account the biochemical and molecular biology information generated in their elucidation; and to the processing and stability properties of these compounds as food colorants.

Polycrystalline BiFeO{sub 3} thin film synthesized via sol-gel assisted spin coating technique for photosensitive application

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogle, K. A., E-mail: kashinath.bogle@gmail.com; Narwade, R. D.; Mahabole, M. P.

2016-05-06

We are reporting photosensitivity property of BiFeO{sub 3} thin film under optical illumination. The thin film used for photosensitivity work was fabricated via sol-gel assisted spin coating technique. I-V measurements on the Cu/BiFeO{sub 3}/Al structure under dark condition show a good rectifying property and show dramatic blue shit in threshold voltage under optical illumination. The microstructure, morphology and elemental analysis of the films were characterized by using XRD, UV-Vis, FTIR, SEM and EDS.

Transport modalities of photodynamic agents for tumors

NASA Astrophysics Data System (ADS)

Reddi, Elena

1994-03-01

Systemically injected porphyrins and other tetrapyrrolic compounds associate with serum proteins. Highly hydrophobic photosensitizers are mainly associated with lipoproteins and are deposited in intracellular loci of the neoplastic tissue. Hydrophilic photosensitizers are preferentially bound by serum albumin that releases the dye in the vascular stroma of the tumor. As a consequence the type of photosensitizer carrier determines different mechanisms of PDT-induced tumor necrosis. Low-density lipoproteins (LDL) may increase the selectivity of tumor targeting by releasing the bound dye to the neoplastic cells by a receptor-mediated endocytotic mechanism.

Quenching-induced deactivation of photosensitizer by nanoencapsulation to improve phototherapy of cancer.

PubMed

Zeisser-Labouèbe, Magali; Mattiuzzo, Marc; Lange, Norbert; Gurny, Robert; Delie, Florence

2009-09-01

Photodynamic therapy has emerged as a promising alternative to current cancer treatment. However, conventional photosensitizers have several limitations due to their unsuitable pharmaceutical formulations and lack of selectivity. Our strategy was to exploit the advantages of nanoparticles and the quenching-induced deactivation of the model photosensitizer hypericin to produce "activatable" drug delivery systems. Efficient fluorescence and activity quenching were achieved by increasing the drug-loading rate of nanoparticles. In vitro assays confirmed the reversibility of hypericin deactivation, as the hypericin fluorescence and photodynamic activity were recovered upon cell internalization.

Photodynamic activity of pyropheophorbide methyl ester and pyropheophorbide a in dimethylformamide solution.

PubMed

Al-Omari, Saleh; Ali, Ahmad

2009-03-01

Comparative spectroscopic study including the photosensitizers of pyropheophorbide methyl ester (PPME) and pyropheophorbide a (PPa) was performed to study their photodynamic activity. The investigated photosensitizers in a homogeneous system of dimethylformamide (DMF) are not photostable upon irradiation. The photobleaching efficiency of PPa is higher than that of PPME. Combining these results with the data obtained by measuring the singlet oxygen quantum yield and the hydroxyl group generation, it was revealed that the photobleaching efficiency could be correlated with the singlet oxygen quantum yield and the hydroxyl group production of the photosensitizer.

Laser inactivation of periodontal bacteria using photosensitizing dyes

NASA Astrophysics Data System (ADS)

Golding, Paul S.; Maddocks, L.; King, Terence A.; Drucker, D. B.

1996-12-01

We demonstrate the killing of the oral bacteria Prevotella nigrescens using a photosensitizer and light from a 10 Hz, frequency doubled, Q-switched Nd:YAG pumped dye laser, with modified oscillator to increase output power. This system produced light at wavelengths close to 620 nm, the absorption maximum of the photosensitizing agent, malachite green isothiocyanate, a wavelength that is not significantly absorbed by tissue. A bacterial reduction of 97.5 percent was achieved at an energy density of 0.67 J/cm2 and exposure times of 300 seconds.

Organic Aerosol Formation Photoenhanced by the Formation of Secondary Photo-sensitizers in ageing Aerosols

NASA Astrophysics Data System (ADS)

Aregahegn, Kifle; Nozière, Barbara; George, Christian

2013-04-01

Humankind is facing a changing environment possibly due to anthropogenic stress on the atmosphere. In this context, aerosols play a key role by affecting the radiative climate forcing, hydrological cycle, and by their adverse effect on health. The role of organic compounds in these processes is however still poorly understood because of their massive chemical complexity and numerous transformations. This is particularly true for Secondary Organic Aerosol (SOA), which are produced in the atmosphere by organic gases. Traditionally, the driving forces for SOA growth is believed to be the partitioning onto aerosol seeds of condensable gases, either emitted primarily or resulting from the gas phase oxidation of organic gases. However, even the most up-to-date models based on such mechanisms can not account for the SOA mass observed in the atmosphere, suggesting the existence of other, yet unknown formation processes. The present study shows experimental evidence that particulate phase chemistry produces photo-sensitizers that lead to photo-induced formation and growth of secondary organic aerosol in the near UV and the presence of volatile organic compounds (VOC) such as terpenes. By means of an aerosol flow tube reactor equipped with Scanning Mobility Particle Sizer (SMPS) having Kr-85 source aerosol neutralizer, Differential Mobility Analyser (DMA) and Condensation Particle Sizer (CPC), we identified that traces of the aerosol phase product of glyoxal chemistry as is explained in Gallway et al., and Yu et al., namely imidazole-2-carboxaldehyde (IC) is a strong photo-sensitizer when irradiated by near-UV in the presence of volatile organic compounds such as terpenes. Furthermore, the influence of pH, type and concentration of VOCs, composition of seed particles, relative humidity and irradiation intensity on particle growth were studied. This novel photo-sensitizer contributed to more than 30% of SOA growth in 19min irradiation time in the presence of terpenes in the system and has linear relationship with the irradiation intensity. These results demonstrate that, upon ageing, organic aerosols can produce photo-sensitizers which auto-photo-catalyses their SOA growth.

Surface-enhanced Raman spectroscopy studies of yellow organic dyestuffs and lake pigments in oil paint.

PubMed

Mayhew, Hannah E; Fabian, David M; Svoboda, Shelley A; Wustholz, Kristin L

2013-08-21

Identifying natural, organic dyes and pigments is important for the conservation, preservation, and historical interpretation of works of art. Although previous SERS studies have demonstrated high sensitivity and selectivity for red lake pigments using various pretreatment conditions, corresponding investigations of yellow lake pigments and paints are relatively sparse. Here, surface-enhanced Raman scattering (SERS) spectroscopy is used to identify a variety of yellow organic dyestuffs and lake pigments in oil paint. High-quality SERS spectra of yellow dyestuffs (i.e., turmeric, old fustic, Buckthorn berries) and corresponding paints could be obtained with or without sample pretreatment using microliter quantities of HCl and methanol at room temperature. However, the SERS spectra of yellow lake pigments (i.e., Stil de Grain, Reseda lake) and their corresponding oil paints were only observed upon sample pretreatment. Ultimately, we demonstrate a reliable sample treatment protocol for SERS-based identification of turmeric, old fustic, Buckthorn berries, Stil de Grain, and Reseda lake as well as for microscopic samples of the corresponding oil paints.

Screening of Marine Actinomycetes from Segara Anakan for Natural Pigment and Hydrolytic Activities

NASA Astrophysics Data System (ADS)

Asnani, A.; Ryandini, D.; Suwandri

2016-02-01

Marine actinomycetes have become sources of great interest to natural product chemistry due to their new chemical entities and bioactive metabolites. Since April 2010, we have screened actinobacteria from five sites that represent different ecosystems of Segara Anakan lagoon. In this present study we focus on specific isolates, K-2C which covers 1) actinomycetes identification based on morphology observation and 16S rRNA gene; 2) fermentation and isolation of pigment; 3) structure determination of pigment; and 4) hydrolytic enzymes characterization; Methodologies relevant to the studies were implemented accordingly. The results indicated that K-2C was likely Streptomyces fradiae strain RSU15, and the best fermentation medium should contain starch and casein with 21 days of incubation. The isolate has extracellular as well as intracellular pigments. Isolated pigments gave purple color with λmax of 529.00 nm. The pigment was structurally characterized. Interestingly, Streptomyces K-2C was able to produce potential hydrolytic enzymes such as amylase, cellulase, protease, lipase, urease, and nitrate reductase.

Study on the Spectral Mixing Model for Mineral Pigments Based on Derivative of Ratio Spectroscopy-Take Vermilion and Stone Yellow for Example

NASA Astrophysics Data System (ADS)

Zhao, H.; Hao, Y.; Liu, X.; Hou, M.; Zhao, X.

2018-04-01

Hyperspectral remote sensing is a completely non-invasive technology for measurement of cultural relics, and has been successfully applied in identification and analysis of pigments of Chinese historical paintings. Although the phenomenon of mixing pigments is very usual in Chinese historical paintings, the quantitative analysis of the mixing pigments in the ancient paintings is still unsolved. In this research, we took two typical mineral pigments, vermilion and stone yellow as example, made precisely mixed samples using these two kinds of pigments, and measured their spectra in the laboratory. For the mixing spectra, both fully constrained least square (FCLS) method and derivative of ratio spectroscopy (DRS) were performed. Experimental results showed that the mixing spectra of vermilion and stone yellow had strong nonlinear mixing characteristics, but at some bands linear unmixing could also achieve satisfactory results. DRS using strong linear bands can reach much higher accuracy than that of FCLS using full bands.

Transcriptomic analysis of skin pigmentation variation in the Virginia opossum (Didelphis virginiana).

PubMed

Nigenda-Morales, Sergio F; Hu, Yibo; Beasley, James C; Ruiz-Piña, Hugo A; Valenzuela-Galván, David; Wayne, Robert K

2018-06-01

Skin pigmentation and coat pigmentation are two of the best-studied examples of traits under natural selection given their quantifiable fitness interactions with the environment (e.g., camouflage) and signalling with other organisms (e.g., warning coloration). Previous morphological studies have found that skin pigmentation variation in the Virginia opossum (Didelphis virginiana) is associated with variation in precipitation and temperatures across its distribution range following Gloger's rule (lighter pigmentation in temperate environments). To investigate the molecular mechanism associated with skin pigmentation variation, we used RNA-Seq and quantified gene expression of wild opossums from tropical and temperate populations. Using differential expression analysis and a co-expression network approach, we found that expression variation in genes with melanocytic and immune functions is significantly associated with the degree of skin pigmentation variation and may be underlying this phenotypic difference. We also found evidence suggesting that the Wnt/β-catenin signalling pathway might be regulating the depigmentation observed in temperate populations. Based on our study results, we present several alternative hypotheses that may explain Gloger's rule pattern of skin pigmentation variation in opossum, including changes in pathogen diversity supporting a pathogen-resistant hypothesis, thermal stress associated with temperate environments, and pleiotropic and epistatic interactions between melanocytic and immune genes. © 2018 John Wiley & Sons Ltd.

A new room temperature gas sensor based on pigment-sensitized TiO2 thin film for amines determination.

PubMed

Yanxiao, Li; Xiao-bo, Zou; Xiao-wei, Huang; Ji-yong, Shi; Jie-wen, Zhao; Holmes, Mel; Hao, Limin

2015-05-15

A new room temperature gas sensor was fabricated with pigment-sensitized TiO2 thin film as the sensing layer. Four natural pigments were extracted from spinach (Spinacia oleracea), red radish (Raphanus sativus L), winter jasmine (Jasminum nudiflorum), and black rice (Oryza sativa L. indica) by ethanol. Natural pigment-sensitized TiO2 sensor was prepared by immersing porous TiO2 films in an ethanol solution containing a natural pigment for 24h. The hybrid organic-inorganic formed films here were firstly exposed to atmospheres containing methylamine vapours with concentrations over the range 2-10 ppm at room temperature. The films sensitized by the pigments from black-rice showed an excellent gas-sensitivity to methylamine among the four natural pigments sensitized films due to the anthocyanins. The relative change resistance, S, of the films increased almost linearly with increasing concentrations of methylamine (r=0.931). At last, the black rice pigment sensitized TiO2 thin film was used to determine the biogenic amines generated by pork during storage. The developed films had good sensitivity to analogous gases such as putrscine, and cadaverine that will increase during storage. Copyright © 2014 Elsevier B.V. All rights reserved.

Sunlight Promotes Fast Release of Hazardous Cadmium from Widely-Used Commercial Cadmium Pigment.

PubMed

Liu, Huiting; Gao, Han; Long, Mingce; Fu, Heyun; Alvarez, Pedro J J; Li, Qilin; Zheng, Shourong; Qu, Xiaolei; Zhu, Dongqiang

2017-06-20

Cadmium pigments are widely used in the polymer and ceramic industry. Their potential environmental risk is under debate, being the major barrier for appropriate regulation. We show that 83.0 ± 0.2% of hazardous cadmium ion (Cd 2+ ) was released from the commercial cadmium sulfoselenide pigment (i.e., cadmium red) in aqueous suspension within 24 h under simulated sunlit conditions. This photodissolution process also generated sub-20 nm pigment nanoparticles. Cd 2+ release is attributed to the reactions between photogenerated holes and the pigment lattices. The photodissolution process can be activated by both ultraviolet and visible light in the solar spectrum. Irradiation under alkaline conditions or in the presence of phosphate and carbonate species resulted in reduced charge carrier energy or the formation of insoluble and photostable cadmium precipitates on pigment surfaces, mitigating photodissolution. Tannic acid inhibited the photodissolution process by light screening and scavenging photogenerated holes. The fast release of Cd 2+ from the pigment was further confirmed in river water under natural sunlight, with 38.6 ± 0.1% of the cadmium released within 4 h. Overall, this study underscores the importance to account for photochemical effects to inform risk assessments and regulations of cadmium pigments which are currently based on their low solubility.

High lenticular tolerance to ultraviolet radiation-B by pigmented guinea-pig; application of a safety limit strategy for UVR-induced cataract.

PubMed

Mody, Vino C; Kakar, Manoj; Söderberg, Per G; Löfgren, Stefan

2012-05-01

The purpose of this study was to determine a threshold measure, maximum tolerable dose (MTD), for avoidance of UVR-B-induced cataract in the pigmented guinea-pig. Thirty pupil-dilated anesthetized young female guinea-pigs, divided into five equal groups, received between 0 and 84.9 kJ/m(2) unilateral UVR-B. Lens extraction and in vitro lens photography occurred 24 hr after exposure. Measurement of intensity of lens light scattering served as quantifying tool for the degree of cataract. Data analysis included regression, using a second order polynomial model. The applied MTD concept was based on the UVR-B dose-response curve obtained for the pigmented guinea-pig. A smaller number of pigmented guinea-pigs, pigmented rats and albino rats underwent morphometric analysis of the anterior segment geometry. All eyes exposed to UVR-B developed cataract in the anterior subcapsular region. MTD for avoidance of UVR-B-induced cataract was 69.0 kJ/m(2) in the pigmented guinea-pig. Iris was considerably thicker in the guinea-pig than in the rats. Lens blockage by the dilated iris was lowest in the guinea-pig. Maximum tolerable dose for avoidance of UVR-B-induced cataract in the pigmented guinea-pig was 69.0 kJ/m(2), over 10-fold higher than the threshold 5 kJ/m(2) obtained by Pitts et al. in the pigmented rabbit. Maximum tolerable dose is an appropriate method for estimation of toxicity for UVR-B-induced cataract in the guinea-pig. The pigmented guinea-pig is significantly less sensitive to UVR-B exposure than the pigmented rabbit and pigmented rat. © 2010 The Authors. Journal compilation © 2010 Acta Ophthalmol.

Serum levels of pigment epithelium-derived factor (PEDF) are positively associated with acanthosis nigricans in obese adolescents.

PubMed

Galhardo, J; Hunt, L P; Shield, J P H

2012-07-01

Circulating pigment epithelium-derived factor, or serine protease inhibitor F1, is upregulated during adipogenesis, contributing to obesity-induced insulin resistance. Furthermore, pigment epithelium-derived factor is abundant in stage I melanosomes and has been reported to increase pigment granules and the appearance of mature melanosomes in retinal pigment epithelium. As acanthosis nigricans is a well-recognized clinical marker of insulin resistance, we hypothesized that increased pigment epithelium-derived factor might be associated with the generation of acanthosis nigricans. Acanthosis nigricans, anthropometric measurements, circulating total PEDF and metabolic profiles were assessed in 28 obese adolescents in a hospital-based obesity clinic. Subjects with acanthosis nigricans (n = 10) showed greater plasma levels of pigment epithelium-derived factor (PEDF) than those without [geometric mean 23.55 (range 15.2-40.2) vs. 9.01 (range 5.5-18.7) μg/ml; P < 0.001]. Although pigment epithelium-derived factor was positively correlated with the homeostasis model assessment for insulin resistance (HOMA-IR) (r = 0.779, P < 0.001; 95% CI 0.573-0.892), as previously reported, for the same degree of insulin resistance, those with acanthosis nigricans exhibited a 2.1-fold (95%CI 2.0-2.3) higher level of pigment epithelium-derived factor. While acanthosis nigricans is undoubtedly associated with insulin resistance, its appearance is not ubiquitous in patients at any given level of HOMA-IR. The higher levels of pigment epithelium-derived factor in those with acanthosis nigricans compared with those without, with similar levels of resistance, suggest that pigment epithelium-derived factor levels are associated with acanthosis nigricans. © 2012 The Authors. Diabetic Medicine © 2012 Diabetes UK.

Comparison of Clinicopathologic Features and Survival of Histopathologically Amelanotic and Pigmented Melanomas: A Population-Based Study

PubMed Central

Thomas, Nancy E.; Kricker, Anne; Waxweiler, Weston T.; Dillon, Patrick M.; Busam, Klaus J.; From, Lynn; Groben, Pamela A.; Armstrong, Bruce K.; Anton-Culver, Hoda; Gruber, Stephen B.; Marrett, Loraine D.; Gallagher, Richard P.; Zanetti, Roberto; Rosso, Stefano; Dwyer, Terence; Venn, Alison; Kanetsky, Peter A.; Orlow, Drs. Irene; Paine, Susan; Ollila, David W.; Reiner, Anne S.; Luo, Li; Hao, Honglin; Frank, Jill S.; Begg, Colin B.; Berwick, Marianne

2014-01-01

Importance Previous studies have reported that histopathologically amelanotic melanoma is associated with poorer survival than pigmented melanoma; however, small numbers of amelanotic melanomas, selected populations, lack of centralized pathology review, or no adjustment for stage limit interpretation or generalization of results from prior studies. Objective To compare melanoma-specific survival between patients with histopathologically amelanotic and those with pigmented melanoma in a large international population-based study. Design Survival analysis with median follow-up of 7.6 years. Setting The Genes, Environment, and Melanoma study enrolled incident cases of melanoma diagnosed in 1998-2003 from international population-based cancer registries. Participants A total of 2,995 patients with 3,486 invasive primary melanomas centrally scored for histologic pigmentation. Main Outcomes and Measurements Clinicopathologic predictors and melanoma-specific survival of histologically amelanotic and pigmented melanoma were compared using generalized estimating equations and Cox regression models, respectively. Results Eight percent of melanomas (275 of 3,467) were histopathologically amelanotic. Female sex, nodular and unclassified or other histologic subtypes, increased Breslow thickness, presence of mitoses, severe solar elastosis, and lack of a co-existing nevus were independently associated with amelanotic melanoma (each P < .05). Amelanotic melanoma was generally of a higher American Joint Committee on Cancer (AJCC) tumor stage at diagnosis (P for trend <.001) than pigmented melanoma. Hazard of death from melanoma was higher for amelanotic than pigmented melanoma [hazard ratio (HR), 2.0; 95% confidence interval (CI), 1.4-3.0; P< .001], adjusted for age, sex anatomic site, and study design variables; but survival did not differ once AJCC tumor stage was also taken into account, (HR, 0.8; 95% CI, 0.5-1.2; P = .36). Conclusions and Relevance At the population level, survival after diagnosis of amelanotic melanoma is poorer than after pigmented melanoma because of its more advanced stage at diagnosis. It is probable that amelanotic melanomas present at more advanced tumor stages because they are difficult to diagnose. The association of amelanotic melanoma with presence of mitoses independently of Breslow thickness and other clinicopathologic characteristics suggests that amelanotic melanomas might also grow faster than pigmented melanomas. New strategies for early diagnosis and investigation of the biology of amelanotic melanoma are warranted. PMID:25162299

Glucose-functionalized amino-OPEs as biocompatible photosensitizers in PDT.

PubMed

Deni, Elisa; Zamarrón, Alicia; Bonaccorsi, Paola; Carmen Carreño, M; Juarranz, Ángeles; Puntoriero, Fausto; Sciortino, Maria Teresa; Ribagorda, María; Barattucci, Anna

2016-03-23

Photodynamic therapy (PDT) is a minimally invasive procedure that can provide a selective eradication of neoplastic diseases by the combined effect of a photosensitizer, light and oxygen. New amino oligo(phenylene-ethynylene)s (OPEs), bearing hydrophilic glucoside terminations, have been prepared, characterized and tested as photosensitizers in PDT. The effectiveness of these compounds in combination with UVA light has been checked on two tumor cell lines (HEp-2 and HeLa cells, derived from a larynx carcinoma and a cervical carcinoma, respectively). The compounds triggered a mitotic blockage that led to the cell death, being the effect active up to 3 μm concentration. The photophysical properties of OPEs, such as high quantum yield, stability, singlet oxygen production, biocompatibility, easy cell-internalization and very good response even at low concentration, make them promising photosensitizers in the application of PDT. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Methods and Devices for Micro-Isolation, Extraction, and/or Analysis of Microscale Components

NASA Technical Reports Server (NTRS)

Wade, Lawrence A. (Inventor); Kartalov, Emil P. (Inventor); Taylor, Clive (Inventor); Shibata, Darryl (Inventor)

2014-01-01

Provided herein are devices and methods for the micro-isolation of biological cellular material. A micro-isolation apparatus described can comprise a photomask that protects regions of interest against DNA-destroying illumination. The micro-isolation apparatus can further comprise photosensitive material defining access wells following illumination and subsequent developing of the photosensitive material. The micro-isolation apparatus can further comprise a chambered microfluidic device comprising channels providing access to wells defined in photosensitive material. The micro-isolation apparatus can comprise a chambered microfluidic device without access wells defined in photosensitive material where valves control the flow of gases or liquids through the channels of the microfluidic device. Also included are methods for selectively isolating cellular material using the apparatuses described herein, as are methods for biochemical analysis of individual regions of interest of cellular material using the devices described herein. Further included are methods of making masking arrays useful for the methods described herein.

A review of photodiagnostic investigations over 26 years: experience of the National Scottish Photobiology Service (1989-2015).

PubMed

Nassan, H; Dawe, R S; Moseley, H; Ibbotson, S H

2017-12-01

Background The Scottish Photobiology Service is the national referral pathway for patients with cutaneous photosensitivity diseases in Scotland. We reviewed the pattern of diagnosis of photosensitivity diseases and investigations performed between 1989 and 2015. Methods and Results Data were collected from the Photodiagnostic Database, annual reports and paper records. The total number of patients assessed each year was stable over the period studied (median 242 [range 231-266]), with most being new patients (median 69 [range 62-73]%). Monochromator phototesting was the most utilised investigation, although the use of provocation testing and photopatch testing has increased. The most common diagnosis was polymorphic light eruption, and there was a trend to increasing diagnosis of photoaggravated atopic eczema. Conclusions The pattern of diagnosis of photosensitivity diseases remains fairly stable in Scotland and we wish to emphasise the importance of this Scottish specialist service for patients with photosensitivity diseases and referrers.

Role of polymer matrix on photo-sensitivity of CdSe polymer nanocomposites

NASA Astrophysics Data System (ADS)

Kaur, Ramneek; Tripathi, S. K.

2018-04-01

This paper reports the effect of three different polymer matrices (PVP, PMMA and PVK) and Ag doping on the photo-sensitivity of CdSe polymer nanocomposites. The results reveal that the photoconductivity is high for linear chain polymer nanocomposites as compared to aromatic ones with decreasing trend as: CdSe-PMMA > CdSe-PVP > CdSe-PVK. The large substituents or branches along the polymer backbone hinder the stacking sequences in CdSe-PVK nanocomposites resulting in lowest photoconductivity. On contrary, CdSe-PVK nanocomposite exhibit highest photosensitivity. The reason behind it is the low value of dark conductivity in CdSe-PVK nanocomposite and photoconductive PVK matrix. With Ag doping, no considerable effect on the value of photosensitivity has been observed. The obtained results indicate that the photo-conducting properties of these polymer nanocomposites can be tuned by using different polymer matrices.

Polymer-Immobilized Photosensitizers for Continuous Eradication of Bacteria

PubMed Central

Valkov, Anton; Nakonechny, Faina; Nisnevitch, Marina

2014-01-01

The photosensitizers Rose Bengal (RB) and methylene blue (MB), when immobilized in polystyrene, were found to exhibit high antibacterial activity in a continuous regime. The photosensitizers were immobilized by dissolution in chloroform, together with polystyrene, with further evaporation of the solvent, yielding thin polymeric films. Shallow reservoirs, bottom-covered with these films, were used for constructing continuous-flow photoreactors for the eradication of Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli and wastewater bacteria under illumination with visible white light using a luminescent lamp at a 1.8 mW·cm−2 fluence rate. The bacterial concentration decreased by two to five orders of magnitude in separate reactors with either immobilized RB or MB, as well as in three reactors connected in series, which contained one of the photosensitizers. Bacterial eradication reached more than five orders of magnitude in two reactors connected in series, where the first reactor contained immobilized RB and the second contained immobilized MB. PMID:25158236

Evaluation of toxicological properties and photodynamic activity of Photolon ointment: an experimental study

NASA Astrophysics Data System (ADS)

Shliakhtsin, Siarhei V.; Trukhachova, Tatsiana V.; Istomin, Yuriy P.; Dunetz, Ludmila N.; Kuvshinov, Andrey V.; Naumovich, Semen A.

2009-06-01

The purpose of the present study was to evaluate toxicological properties and photodynamic activity of a new ready form of the photosensitizer Photolon (Fotolon) - an ointment for topical use. The data obtained show the use of topicaly applied photosensitizer provides sufficient penetration and accumulation of the active compound in tumor tissue as well as in affected periodontal tissues for the effective PDT. There are several advantages of PDT with topical application of the photosensitizer such as absence of systemic toxic and photosensitive reactions, relatively low cost of the treatment and etc. We have shown that PDT of affected periodontal tissues with local application of Photolon/Fotolon ointment provides an ability of local destruction of microbial cell, located as on the gum surface as in the spatium intercellulare what is extremely important for successful treatment of acute and chronic periodontitis.

Effect of variation in indium concentration on the photosensitivity of chlorine doped In{sub 2}S{sub 3} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cherian, Angel Susan; Kartha, C. Sudha; Vijayakumar, K. P.

2014-01-28

Consequence of variation in Indium concentration in chlorine doped In2S{sub 3} thin films deposited by spray pyrolysis technique was studied. Chlorine was incorporated in the spray solution, using HCl and Indium concentration was varied by adjusting In/S ratio Interestingly, the photo response of all chlorine doped samples augmented compared to pristine samples; but the highest photosensitivity value of ∼2300 was obtained only when 36ml 0.5M HCl was added to the solution of In{sub 2}S{sub 3} having In/S=2/8. It was also observed that samples with high photosensitivity possess higher band gap and variation in sub band gap absoption levels were observedmore » with increase in Indium concentration. The present study proved that concentration of Indium plays an important role in controlling the crystallinity and photosensitivity of chlorine doped samples.« less

Raman microspectroscopy of Hematoporphyrins. Imaging of the noncancerous and the cancerous human breast tissues with photosensitizers.

PubMed

Brozek-Pluska, B; Kopec, M

2016-12-05

Raman microspectroscopy combined with fluorescence were used to study the distribution of Hematoporphyrin (Hp) in noncancerous and cancerous breast tissues. The results demonstrate the ability of Raman spectroscopy to distinguish between noncancerous and cancerous human breast tissue and to identify differences in the distribution and photodegradation of Hematoporphyrin, which is a photosensitizer in photodynamic therapy (PDT), photodynamic diagnosis (PDD) and photoimmunotherapy (PIT) of cancer. Presented results show that Hematoporphyrin level in the noncancerous breast tissue is lower compared to the cancerous one. We have proved also that the Raman intensity of lipids and proteins doesn't change dramatically after laser light irradiation, which indicates that the PDT treatment destroys preferably cancer cells, in which the photosensitizer is accumulated. The specific subcellular localization of photosensitizer for breast tissues samples soaked with Hematoporphyrin was not observed. Copyright © 2016 Elsevier B.V. All rights reserved.

SU-D-16A-07: Photobleaching Predicts Necrosis in Interstitial PDT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, M; Finlay, J; Liu, B

Purpose: Dosimetry for PDT has proven to be a challenge thus far, and for prediction of PDT outcome, a singlet oxygen model based on fundamental photophysical parameters has been developed. Previously, the photobleaching effect of photosensitizers was taken into account in the singlet oxygen explicit dosimetry model; here we report of direct measurements of photobleaching in the same model to assess the conditions under which implicit dosimetry using photobleaching can serve as an intermediate surrogate for PDT damage. Methods: Fluorescence spectra were measured interstitially in sensitized mouse tumors prior to after irradiation via a cylindrical diffuser. Photobleaching was determined bymore » the relative decrease in fluorescence amplitude from the initial pre-treatment measurement. Spectra were analyzed by singular value decomposition to determine the photosensitizer concentration. Different photosensitizers were used to see the effect of photobleaching on PDT outcome and the impact of fluence on photobleaching. The drugs used were BPD (at two drug-light intervals), HPPH, and Photofrin. PDT outcome was determined by tumor necrosis radii measured upon sectioning and staining of treated tumors. Results: Post-PDT photosentizer concentrations were compared to initial pre-PDT photosensitizer concentrations, and the decrease was greater with a higher fluence measured during treatment. Furthermore, photobleaching and necrosis radius were found to be positively correlated. The relationship between photobleaching and necrosis radius is sensitizer-dependent, however the differences among sensitizers can be understood in terms of their respective photophysical parameters. Conclusions: Photobleaching is predictive of PDT outcome, but a comprehensive singlet oxygen model, has the potential to further improve the prediction of PDT outcome and the understanding of implicit dosimetry.« less

Efficacy of gallium phthalocyanine as a photosensitizing agent in photodynamic therapy for the treatment of cancer

NASA Astrophysics Data System (ADS)

Maduray, Kaminee; Odhav, Bharti

2012-12-01

Photodynamic therapy is a revolutionary treatment aimed at treating cancers without surgery or chemotherapy. It is based on the discovery that certain chemicals known as photosensitizing agents (e.g. porphyrins, phthalocyanines, etc.) can kill cancerous cells when exposed to low level laser light at a specific wavelength. The present study investigates the cellular uptake and photodynamic effect of gallium (III) phthalocyanine chloride (GaPcCl) on Caco-2 cancer cells. Caco-2 cells were treated with different concentrations of GaPcCl for 2 h before treatment with a diode laser (λ = 661 nm, laser power = 90 mW) delivering a light dose of 2.5 J/cm2, 4.5 J/cm2 or 8.5 J/cm2. After 24 h, the cell viability of post-irradiated cells was measured using the MTT assay. Cellular uptake studies were performed by photosensitizing cells with GaPcCl for 30 min, 2 h, 10 h, 12 h, 18 h and 24 h before lysing the treated cells into solution to measure the GaPcCl fluorescence emission at an excitation wavelength of 600 nm. Results showed an increase in fluorescence intensity of emission peaks at longer incubation times, indicating a greater cellular uptake of GaPcCl by Caco-2 cells at 24 h in comparison to 30 min. GaPcCl at a concentration of 100 μg/ml activated with a laser light dose of 8.5 J/cm2 reduced the cell viability of Caco-2 cells to 27%. This concludes that GaPcCl activated with low level laser light can be used as a photosensitizing agent for the in vitro PDT treatment of colon cancer.

On the factors influencing the performance of solar reactors for water disinfection with photosensitized singlet oxygen.

PubMed

Manjón, Francisco; Villén, Laura; García-Fresnadillo, David; Orellana, Guillermo

2008-01-01

Two solar reactors based on compound parabolic collectors (CPCs) were optimized for water disinfection by photosensitized singlet oxygen (1O2) production in the heterogeneous phase. Sensitizing materials containing Ru(II) complexes immobilized on porous silicone were produced, photochemically characterized, and successfully tested for the inactivation of up to 10(4) CFU mL(-1) of waterborne Escherichia coli (gram-negative) or Enterococcus faecalis (gram-positive) bacteria. The main factors determining the performance of the solar reactors are the type of photosensitizing material, the sensitizer loading, the CPC collector geometry (fin- vs coaxial-type), the fluid rheology, and the balance between concurrent photothermal--photolytic and 1O2 effects on the microorganisms' inactivation. In this way, at the 40 degrees N latitude of Spain, water can be disinfected on a sunny day (0.6-0.8 MJ m(-2) L(-1) accumulated solar radiation dose in the 360-700 nm range, typically 5-6 h of sunlight) with a fin-type reactor containing 0.6 m2 of photosensitizing material saturated with tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (ca. 2.0 g m(-2)). The optimum rheological conditions require laminar-to-transitional water flow in both prototypes. The fin-type system showed better inactivation efficiency than the coaxial reactor due to a more important photolytic contribution. The durability of the sensitizing materials was tested and the operational lifetime of the photocatalyst is at least three months without any reduction in the bacteria inactivation efficiency. Solar water disinfection with 1O2-generating films is demonstrated to be an effective technique for use in isolated regions of developing countries with high yearly average sunshine.

Immunophototherapy for the treatment of AIDS and AIDS-related infections

NASA Astrophysics Data System (ADS)

Schlager, Kenneth J.

1992-06-01

Immunophototherapy (IPT) is an experimental method of medical treatment that seeks to provide for the selective destruction of diseased cells and microbes such as human immunodeficiency virus (HIV)-T4 cells and the rapid elimination of their toxic by-products from the human body. Photosensitive monoclonal or polyclonal antibody fragments, which are specific to the diseased cell or microbe, will be used to treat acquired immunodeficiency syndrome (AIDS) and related infections. These antibody fragments are tagged with photosensitive compounds and metal colloids and then intravenously injected into the patient. The tagged antibodies quickly and selectively bind to the diseased cells or microbes in the blood stream and affected organs. These cells or microbes are then selectively destroyed by irradiation of these complexes with light of the proper wavelength. This light activates the photosensitive material which then creates singlet oxygen that destroys the microbe or cell. Toxic products of lysis are quickly discharged from the body by activation of the reticuloendothelial system. IPT has been demonstrated by Biotronics to be very effective in the in vitro selective destruction of specified cell types. In a proposed AIDS-treatment research program, IPT will be first demonstrated in vitro for a set of infected blood samples using commercially-available antibodies labeled with appropriate photosensitizers. Efficacy will be determined by a p24 antigen immunodiagnostic test that will indicate the % inhibition in comparison to controls and samples treated with the drug AZT. Subcontracted animal efficacy studies will use a SCID-hu mouse model and PCR/DNA-RNA for endpoint analysis. Toxicity studies of animal (rat) models will be based on post-treatment investigations of lymph nodes, spleen, liver and other organs.

[Brownish coloration of the left nipple in a 60-year-old woman].

PubMed

Blum, A; Hartmann, K W; Rütten, A

2010-01-01

Pigmented Paget disease of the nipple is a rare disease. We report on a 60-year-old woman in whom this diagnosis was made based on clinical findings, dermoscopy, histology and immunohistology. Circumscribed pigmentation of the nipple includes a wide spectrum of benign and malignant differential diagnostic considerations. Dermoscopy can enhance the clinical diagnosis. Biopsies should always be performed on unclear pigmentation of the nipple in both women and men. On histology, rare melanocytic tumors must be differentiated from pigmented Paget disease and pigmented Bowen disease. Pagetoid intraepithelial cells of a melanocytic tumor are positive for S100, HMB45 or melan A, but not for cytokeratins. Intraepithelial tumor cells of Paget disease are positive for cytokeratin 7. The clear cells in Bowen diseases are usually not positive for cytokeratin 7 and are also negative for all melanocytic markers.

Fumed metallic oxides and conventional pigments for glossy inkjet paper

NASA Astrophysics Data System (ADS)

Lee, Hyunkook

Product development activity in the area of inkjet printing papers has accelerated greatly to meet the rapidly growing market for inkjet papers. Advancements in inkjet printing technology have also placed new demands on the paper substrate due to faster printing rates, greater resolution through increased drop volumes, and colorants added to the ink. To meet these requirements, papermakers are turning to pigmented size press formulations or pigmented coating systems. For inkjet coating applications, both the internal porosity of the pigment particles as well as the packing porosity of the coating affect print quality and dry time. Pores between the pigment particles allow for rapid diffusion of ink fluids into the coating structure, while also providing capacity for ink fluid uptake. Past research has shown the presence of coating cracks to increase the microroughness of the papers, consequently reducing the gloss of the silica/polyvinyl alcohol based coating colors. Coating cracks were not observed, at the same level of magnification, in the scanning electron microscopy images of alumina/polyvinyl alcohol coated papers. Studies are therefore needed to understand the influence of coating cracking on the microroughening of silica/polyvinyl alcohol based coatings and consequences to coating and ink gloss. Since micro roughening is known to be linked to shrinkage of the coating layer, studies are needed to determine if composite pigments can be formulated, which would enable the coating solids of the formulations to be increased to minimize the shrinkage of coating layer during drying. Coating solids greater than 55% solids are needed to reduce the difference between application solids and the coating's immobilization solids point in order to reduce shrinkage. The aim of this research was to address the above mentioned needed studies. Studies were performed to understand the influence of particle packing on gloss and ink jet print quality. Composite pigment structures were built using well-characterized pigments to determine the influence of particle size and particle size distribution on coating application solids, coatings immobilization solids on coating gloss and print attributes. This research consists of five articles which have all been accepted for publication: (1) Influence of Pigment Particles on the Gloss and Printability of Inkjet Coated Papers, (2) Influence of Silica and Alumina Oxide Pigments on Coating Structure and Print Quality of Inkjet Papers, (3) Production of a Single Coated Glossy Inkjet Paper Using Conventional Coating and Calendering Methods, (4) Influence of Pigment Particle Size and Packing Volume on the Printability of Glossy Inkjet Paper Coatings-Part I, and (5) Influence of Pigment Selection on Printability of Glossy Inkjet Paper Coatings-Part II.

In vivo magnetic resonance measures of dark cytotoxicity of photosensitizers in a Murine tumor model

NASA Astrophysics Data System (ADS)

Ramaprasad, Subbaraya; Ripp, Elzbieta; Pi, Jiaxiong; Joshi, Shantaram S.; Pandey, Suresh K.; Missert, Joseph; Pandey, Ravindra K.

2005-04-01

Photodynamic therapy (PDT) is a novel cancer treatment modality where the therapeutic action is controlled by light and the potency of the photosensitizer used. Development of new potent photosensitizers (PS) for clinical applications requires that the PDT effects are maximized while minimizing dark cytotoxicity. The dark toxicity of photosensitizers is generally confirmed using cell lines. Photososensitizers that appear promising from in vitro assays need further investigations under in vivo conditions. As in vivo MR methods have the potential to provide information on the tumor status, they can be very effective tools to study dark toxicity of tumors. The tumor produced on the mouse foot dorsum was tested on two newly synthesized photosensitizers along with Photofrin as a control. The MR studies consisted of serial 31P spectral measurements both before and after PS injection. The results show significant changes in the tumor metabolism with increased inorganic phosphate while using new photosensitizers. However these changes slowly approached control levels several hours later. The studies performed while using Photofrin did not show any significant changes indicating minimal or no dark cytotoxicity. Similar studies performed on normal tissue such as the muscle indicated that the energy metabolism was minimally compromised. Our studies demonstrate that the effects of dark cytotoxicity can be observed by 31P MR. The growth profiles of tumors treated with PS alone indicate that the metabolic changes are temporary and do not interfere with the tumor growth. The studies suggest that MR is a new method of monitoring the effect of PS administered toxicity in an in vivo model.

Epileptic spasms and early-onset photosensitive epilepsy in Patau syndrome: An EEG study.

PubMed

Spagnoli, Carlotta; Kugathasan, Umaiyal; Brittain, Helen; Boyd, Stewart G

2015-08-01

Patau syndrome, trisomy 13, is the third commonest autosomal trisomy. It is associated with a 25-50% prevalence of epilepsy, but detailed electroclinical descriptions are rare. The occurrence of early-onset photosensitivity has recently been reported in single patients. We collected electroclinical data on 8 infants (age range from 2 months to 3 years and 9 months, median: 17 months) with Patau syndrome referred for an EEG in our Clinical Neurophysiology Department between 1991 and 2011. All EEGs, case-notes, cytogenetic diagnosis and neuroimaging when available were reviewed; data on the occurrence of seizures, epileptiform discharges, photoparoxysmal response and their characteristics in terms of positive frequencies, latencies, grade and duration were noted and analysed. Two patients had been previously diagnosed with epilepsy (one with tonic spasms and one with multiple seizure types). We found 3 patients with photosensitive myoclonic epilepsy (37.5%), and one with non-photosensitive myoclonic epilepsy. We also recorded non-epileptic myoclonic jerks in one patient known to suffer from epileptic spasms. Among photosensitive patients we found self-limited, Waltz's grade 2-4, spike-wave/polyspike-wave discharges in low, medium and high frequency ranges in two patients and in the high frequency range in the third patient, with latencies and duration from less than 1s to a maximum of 9s. In our cohort of Patau syndrome patients, we found a high prevalence of spasms and photic-induced myoclonic jerks. Photosensitivity shows an unusual early age of onset. Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.

Photosensitized H2 Production Using a Zinc Porphyrin-Substituted Protein, Platinum Nanoparticles, and Ascorbate with No Electron Relay: Participation of Good's Buffers.

PubMed

Clark, Emily R; Kurtz, Donald M

2017-04-17

Development of efficient light-driven splitting of water, 2H 2 O → 2H 2 + O 2 , often attempts to optimize photosensitization of the reductive and oxidative half-reactions individually. Numerous homogeneous and heterogeneous systems have been developed for photochemical stimulation of the reductive half reaction, 2H + + 2e - → H 2 . These systems generally consist of various combinations of a H + reduction catalyst, a photosensitizer (PS), and a "sacrificial" electron donor. Zinc(II)-porphyrins (ZnPs) have frequently been used as PSs for H 2 generation, but they are subject to various self-quenching processes in aqueous solutions. Colloidal platinum in nanoparticle form (Pt NP) is a classical H + reduction catalyst using ZnP photosensitizers, but efficient photosensitized H 2 generation requires an electron relay molecule between ZnP and Pt NP. The present report describes an aqueous system for visible (white) light-sensitized generation of H 2 using a protein-embedded Zn(II)-protoporphyrin IX as PS and Pt NP as H + reduction catalyst without an added electron relay. This system operated efficiently in piperazino- and morpholino-alkylsulfonic acid (Good's buffers), which served as sacrificial electron donors. The system also required ascorbate at relatively modest concentrations, which stabilized the Zn(II)-protoporphyrin IX against photodegradation. In the absence of an electron relay molecule, the photosensitized H 2 generation must involve formation of at least a transient complex between a protein-embedded Zn(II)-protoporphyrin IX species and Pt NP.

The NPe6 fluorescence measurements by using a fluorescence sensing system for skin photosensitivity risk assessment after photodynamic therapy

NASA Astrophysics Data System (ADS)

Ohtani, Keishi; Usuda, Jitsu; Ogawa, Emiyu; Maehara, Sachio; Imai, Kentaro; Inoue, Tatsuya; Hagiwara, Masaru; Kakihana, Masatoshi; Kajiwara, Naohiro; Ohira, Tatsuo; Arai, Tsunenori; Ikeda, Norihiko

2018-02-01

Background: Skin photosensitivity is a major side effect of photodynamic therapy (PDT). It is induced by the photosensitizer remaining in the skin. It is usually rapidly metabolized by the liver, but the pharmacokinetic profile varies widely among individuals. This makes it difficult to predict the incidence of skin photosensitivity. Therefore, we conducted a prospective study to investigate whether the NPe6 fluorescence intensity in skin after NPe6-PDT could be measured safely in human patients using a fluorescence sensing system for judging the risk of skin photosensitivity. Methods: The NPe6 fluorescence measurements using a constructed fluorescence sensing system at the inside of the arm were acquired prior to and 5 and 10 minutes after NPe6 administration as well as at the time of PDT (4-5 hours after administration), at discharge (2 or 3 days after PDT), and at 1 or 2 weeks after PDT. Participants were interviewed as to whether they had any complications at 2 weeks after PDT. Results: Nine male patients and one female patient entered this study. All of the measurements of NPe6 fluorescence in the skin could be obtained without any complications. The spectral peak was detected at the time of discharge (2-3 days after administration) in most cases and it decreased at 1 or 2 weeks after PDT. Conclusions: The fluorescence of NPe6 in the skin could be detected feasibly using the fluorescence sensing system in human patients. Measuring fluorescence intensity in the skin might be useful to predict the incidence of skin photosensitivity after PDT.

Topical delivery of a preformed photosensitizer for photodynamic therapy of cutaneous lesions

NASA Astrophysics Data System (ADS)

Oleinick, Nancy L.; Kenney, Malcolm E.; Lam, Minh; McCormick, Thomas; Cooper, Kevin D.; Baron, Elma D.

2012-02-01

Photosensitizers for photodynamic therapy (PDT) are most commonly delivered to patients or experimental animals via intravenous injection. After initial distribution throughout the body, there can be some preferential accumulation within tumors or other abnormal tissue in comparison to the surrounding normal tissue. In contrast, the photosensitizer precursor, 5-aminolevulinic acid (ALA) or one of its esters, is routinely administered topically, and more specifically, to target skin lesions. Following metabolic conversion to protoporphyrin IX, the target area is photoilluminated, limiting peripheral damage and targeting the effective agent to the desired region. However, not all skin lesions are responsive to ALA-PDT. Topical administration of fully formed photosensitizers is less common but is receiving increased attention, and some notable advances with selected approved and experimental photosensitizers have been published. Our team has examined topical administration of the phthalocyanine photosensitizer Pc 4 to mammalian (human, mouse, pig) skin. Pc 4 in a desired formulation and concentration was applied to the skin surface at a rate of 5-10 μL/cm2 and kept under occlusion. After various times, skin biopsies were examined by confocal microscopy, and fluorescence within regions of interest was quantified. Early after application, images show the majority of the Pc 4 fluorescence within the stratum corneum and upper epidermis. As a function of time and concentration, penetration of Pc 4 across the stratum corneum and into the epidermis and dermis was observed. The data indicate that Pc 4 can be delivered to skin for photodynamic activation and treatment of skin pathologies.

A Dual Anticancer Efficacy Molecule: A Selective Dark Cytotoxicity Photosensitizer.

PubMed

Chen, Jyun-Wei; Chang, Cheng-Chung

2016-11-09

Unlike traditional binary nanostructures that construct chemotherapy drugs and photodynamic therapy photosensitizers, we introduce a molecule with a chemo-photodynamic dual therapy function. A water-soluble aggregation-induced emission enhancement (AIEE) fluorogen, NV-12P, was designed and synthesized based on asymmetric 1,6-disubstituted naphthalene and can generate particular reactive oxygen species to undergo type I photodynamic therapy under irradiation. Furthermore, this compound can specifically localize in mitochondria and, after biological evaluation, can cause mitochondrial dysfunction and potent cytotoxicity to cancer cells but not normal cells. We conclude that this compound is a potential dual-toxic efficacy molecule because it exhibits selective dark cytotoxicity and efficient photodamage in cancer cells. Additionally, we also supported the optimal combinational treatment course for the best chemo-phototherapy efficacy.

Thick photosensitive polyimide film side wall angle variability and scum improvement for IC packaging stress control

NASA Astrophysics Data System (ADS)

Mehta, Sohan Singh; Yeung, Marco; Mirza, Fahad; Raman, Thiagarajan; Longenbach, Travis; Morgan, Justin; Duggan, Mark; Soedibyo, Rio A.; Reidy, Sean; Rabie, Mohamed; Cho, Jae Kyu; Premachandran, C. S.; Faruqui, Danish

2018-03-01

In this paper, we demonstrate photosensitive polyimide (PSPI) profile optimization to effectively reduce stress concentrations and enable PSPI as protection package-induced stress. Through detailed package simulation, we demonstrate 45% reduction in stress as the sidewall angle (SWA) of PSPI is increased from 45 to 80 degrees in Cu pillar package types. Through modulation of coating and develop multi-step baking temperature and time, as well as dose energy and post litho surface treatments, we demonstrate a method for reliably obtaining PSPI sidewall angle >75 degree. Additionally, we experimentally validate the simulation findings that PSPI sidewall angle impacts chip package interaction (CPI). Finally, we conclude this paper with PSPI material and tool qualification requirements for future technology node based on current challenges.

A glycoporphyrin story: from chemistry to PDT treatment of cancer mouse models.

PubMed

Lupu, M; Maillard, Ph; Mispelter, J; Poyer, F; Thomas, C D

2018-06-01

Photodynamic therapy (PDT) represents a non-toxic and non-mutagenic antitumor therapy. The photosensitizer's (PS) chemo-physical properties are essential for the therapy, being responsible for the biological effects induced in the targeted tissues. In this study, we present the synthesis and development of some glycoconjugated porphyrins based on lectin-type receptor interaction. They were tested in vitro for finally choosing the most effective chemical structure for an optimum antitumor outcome. The most effective photosensitizer is substituted by three diethylene glycol α-d-mannosyl groups. In vivo studies allow firstly the determination of some characteristics of the biological processes triggered by the initial photochemical activation. Secondly, they make it possible to improve the therapeutic protocol in the function of the structural architecture of the targeted tumor tissue.

Issues and advances in the management and pathogenesis of cutaneous lupus erythematosus.

PubMed

Pelle, Michelle T

2006-01-01

Evidence-based therapy for cutaneous lupus is lacking. A new clinical assessment tool for cutaneous lupus, the CLASI score, will enable more standardized assessments of response to therapy. Anti-Ro autoantibodies are associated with photosensitive SLE and SCLE, and they play a role in cell survival following ultraviolet exposure. Ro also functions in quality control of small RNAs, important in the prevention of autoimmune disease. Drug-induced lupus erythematosus can be anti-Ro- or anti-dsDNA-associated; SCLE and photosensitivity are characteristic of Ro-positive drug-induced lupus. Biologic therapies and IVIg are being studied for the treatment of SLE and cutaneous lupus. Large, controlled trials are needed, not only to evaluate newer therapies, but also to substantiate and define the usage of traditional therapies for cutaneous lupus erythematosus.

Mechanistic quantitative structure-activity relationship model for the photoinduced toxicity of polycyclic aromatic hydrocarbons. 2: An empirical model for the toxicity of 16 polycyclic aromatic hydrocarbons to the duckweed Lemna gibba L. G-3

DOE Office of Scientific and Technical Information (OSTI.GOV)

Huang, X.D.; Krylov, S.N.; Ren, L.

1997-11-01

Photoinduced toxicity of polycyclic aromatic hydrocarbons (PAHs) occurs via photosensitization reactions (e.g., generation of singlet-state oxygen) and by photomodification (photooxidation and/or photolysis) of the chemicals to more toxic species. The quantitative structure-activity relationship (QSAR) described in the companion paper predicted, in theory, that photosensitization and photomodification additively contribute to toxicity. To substantiate this QSAR modeling exercise it was necessary to show that toxicity can be described by empirically derived parameters. The toxicity of 16 PAHs to the duckweed Lemna gibba was measured as inhibition of leaf production in simulated solar radiation (a light source with a spectrum similar to thatmore » of sunlight). A predictive model for toxicity was generated based on the theoretical model developed in the companion paper. The photophysical descriptors required of each PAH for modeling were efficiency of photon absorbance, relative uptake, quantum yield for triplet-state formation, and the rate of photomodification. The photomodification rates of the PAHs showed a moderate correlation to toxicity, whereas a derived photosensitization factor (PSF; based on absorbance, triplet-state quantum yield, and uptake) for each PAH showed only a weak, complex correlation to toxicity. However, summing the rate of photomodification and the PSF resulted in a strong correlation to toxicity that had predictive value. When the PSF and a derived photomodification factor (PMF; based on the photomodification rate and toxicity of the photomodified PAHs) were summed, an excellent explanatory model of toxicity was produced, substantiating the additive contributions of the two factors.« less

Photooxidation of d(TpG) by phthalocyanines and riboflavin. Isolation and characterization of dinucleoside monophosphates containing the 4R* and 4S* diastereoisomers of 4,8-dihydro-4-hydroxy-8-oxo-2'-deoxy-guanosine.

PubMed Central

Buchko, G W; Cadet, J; Berger, M; Ravanat, J L

1992-01-01

Phthalocyanine mediated photosensitization of 2'-deoxyguanosine (dG) in oxygen saturated aqueous solution has previously been shown to result in the addition of molecular oxygen to the guanine base generating the 4R* and 4S* diastereoisomers of 4,8-dihydro-4-hydroxy-8-oxo-2'-deoxyguanosine (dO) (the asterisk denotes unambiguous assignment of the 4R and 4S diastereoisomers). The data presented here show that the same guanine modified bases are generated in a 1:1 ratio when thymidylyl-(3',5')-2'-deoxyguanosine (d(TpG)) is similarly photo-oxidized. These modified dinucleoside monophosphates, labelled d(TpO)-A and -B, have been isolated by high performance liquid chromatography and characterized by proton NMR spectrometry, fast atom bombardment mass spectrometry, and enzymatic digestions. Photosensitization in D2O instead of H2O leads to an increase in the rate of d(TpO) formation that is consistent with a type II (singlet oxygen) reaction mechanism. Three interesting properties of these modified dinucleoside monophosphates are: i) the rate of their digestion with spleen phosphodiesterase is greatly reduced relative to d(TpG), ii) they are not digested by snake venom phosphodiesterase, and iii) they are stable to 1.0 M piperidine at 90 degrees C for 30 min. The latter observation indicates that 4,8-dihydro-4-hydroxy-8-oxoguanine is not a base lesion responsible for the strand breaks observed following hot piperidine treatment of DNA exposed to type II photosensitizers or chemically generated singlet oxygen. PMID:1329029

Effectiveness of partially soluble photosensitizer in photodynamic microbiological inactivation: a curcumin example

NASA Astrophysics Data System (ADS)

Pratavieira, Sebastião.; Matroodi, Fatima; Pinto-Júnior, Fabio Francisco; Rastelli, Alessandra Nara Souza; Bagnato, Vanderlei S.; Guimarães, Francisco E. G.

2017-07-01

We show that partial solubility of a photosensitizer is not necessarily a bad property when dealing with microbiological control. The presence of curcumin aggregates in solution may present advantages with respect the photoand chemical stability.

Technical note: comparing von Luschan skin color tiles and modern spectrophotometry for measuring human skin pigmentation.

PubMed

Swiatoniowski, Anna K; Quillen, Ellen E; Shriver, Mark D; Jablonski, Nina G

2013-06-01

Prior to the introduction of reflectance spectrophotometry into anthropological field research during the 1950s, human skin color was most commonly classified by visual skin color matching using the von Luschan tiles, a set of 36 standardized, opaque glass tiles arranged in a chromatic scale. Our goal was to establish a conversion formula between the tile-based color matching method and modern reflectance spectrophotometry to make historical and contemporary data comparable. Skin pigmentation measurements were taken on the forehead, inner upper arms, and backs of the hands using both the tiles and a spectrophotometer on 246 participants showing a broad range of skin pigmentation. From these data, a second-order polynomial conversion formula was derived by jackknife analysis to estimate melanin index (M-index) based on tile values. This conversion formula provides a means for comparing modern data to von Luschan tile measurements recorded in historical reports. This is particularly important for populations now extinct, extirpated, or admixed for which tile-based measures of skin pigmentation are the only data available. Copyright © 2013 Wiley Periodicals, Inc.

Photodynamic chlorophyll a metabolites, including phytoporphyrin (phylloerythrin), in the blood of photosensitive livestock: overview and measurement.

PubMed

Campbell, W M; Dombroski, G S; Sharma, I; Partridge, A C; Collett, M G

2010-06-01

To validate a spectrofluorometric method for measuring chlorophyll a metabolites, specifically phytoporphyrin (= phylloerythrin), as well as the chlorins, pheophorbide a and pyropheophorbide a, in the blood of photosensitive cattle and sheep. Standard methanolic solutions of pheophorbide a (25 microM), pyropheophorbide a (25 microM), and phytoporphyrin (<3.7 microM) were prepared. Serum and plasma samples were obtained from cattle (n=5), sheep (n=3), and one alpaca, with clinical facial eczema (i.e. photosensitive), as well as from clinically normal (n=2 of each) adult cows, recently weaned calves, and sheep (controls). Standard solutions of the three metabolites were characterised using high-performance liquid chromatography (HPLC), with mass spectrometry, in conjunction with absorption and emission spectral data, and were compared with sera from photosensitive animals. In the latter, phytoporphyrin was the only metabolite detected. Calibration curves were prepared by adding different ratios of methanol and standard solutions of phytoporphyrin in methanol to diluted serum from control animals. Peak areas of fluorescence spectra were determined in samples from photosensitive animals. Pheophorbide a and pyropheophorbide a produced typical chlorin spectra, and had excitation/emission maxima of 408/669 nm and 409/669 nm, respectively. Phytoporphyrin showed a typical porphyrin fluorescence spectrum, with excitation/ emission maxima of 425/644 nm. Pyropheophorbide a and phytoporphyrin had very similar chromatographic retention times, the same chemical formula and same mass, but were distinguishable by differences in their absorption spectra. In sera from photosensitive animals, the fluorescence emission at 644 nm was shown to arise solely from phytoporphyrin and not from any other chlorophyll a metabolites. Calibration curves using sera and plasma from control animals gave reliable measurements of phytoporphyrin in the range 0.4-6 microM. The sera of facial eczema-affected cattle and sheep had concentrations of phytoporphyrin ranging from 0.4 to 1.8 and 0.9 to 2.8 microM, respectively. Haemolysed serum samples were not suitable for determination of phytoporphyrin with this method. A spectrofluorometric method for the quantification of phytoporphyrin in the blood of photosensitive animals has been validated, and can be applied to the measurement of other chlorophyll a metabolites in blood. This will be a useful tool in the further investigation of the cause and pathogenesis of idiopathic photosensitivities of farm animals.

Novel Three-Dimensional Semiconducting Materials Based on Hybrid d10 Transition Metal Halogenides as Visible Light-Driven Photocatalysts.

PubMed

Yue, Cheng-Yang; Hu, Bing; Lei, Xiao-Wu; Li, Rui-Qing; Mi, Fu-Qi; Gao, Hui; Li, Yan; Wu, Fan; Wang, Chun-Lei; Lin, Na

2017-09-18

The development of new visible light-driven photocatalysts based on semiconducting materials remains a greatly interesting and challenging task for the purpose of solving the energy crisis and environmental issues. By using photosensitive [(Me) 2 -2,2'-bipy] 2+ (1,1'-dimethyl-2,2'-bipyridinium) cation as template, we synthesized one new type of inorganic-organic hybrid cuprous and silver halogenides of [(Me) 2 -2,2'-bipy]M 8 X 10 (M = Cu, Ag, X = Br, I). The compounds feature a three-dimensional anionic [M 8 X 10 ] 2- network composed of a one-dimensional [M 8 X 12 ] chain based on MX 4 tetrahedral units. The photosensitization of organic cationic templates results in narrow band gaps of hybrid compounds (1.66-2.06 eV), which feature stable visible light-driven photodegradation activities for organic pollutants. A detailed study of the photocatalytic mechanism, including the photoelectric response, photoluminescence spectra, and theoretical calculations, shows that the organic cationic template effectively inhibits the recombination of photoinduced electron-hole pairs leading to excellent photocatalytic activities and photochemical stabilities.

Fiber optic-based fluorescence detection system for in vivo studies of exogenous chromophore pharmacokinetics

NASA Astrophysics Data System (ADS)

Doiron, Daniel R.; Dunn, J. B.; Mitchell, W. L.; Dalton, Brian K.; Garbo, Greta M.; Warner, Jon A.

1995-05-01

The detection and quantification of the concentration of exogenous chromophores in-vivo by their fluorescence is complicated by many physical and geometrical parameters. Measurement of such signals is advantageous in determining the pharmacokinetics of photosensitizers such as those used in photodynamic therapy (PDT) or to assist in the diagnosis of tissue histological state. To overcome these difficulties a ratio based fiber optic contact fluorometer has been developed. This fluorescence detection system (FDS) uses the ratio of the fluorescence emission peak of the exogenous chromophore to that of endogenous chromophores, i.e. autofluorescence, to correct for a variety of parameters affecting the magnitude of the measured signals. By doing so it also minimizes the range of baseline measurements prior to exogenous drug injection, for various tissue types. Design of the FDS and results of its testing in animals and patients using the second generation photosensitizer Tin ethyletiopurpurin (SnET2) are presented. These results support the feasibility and usefulness of the Ratio FDS system.

Detection and Estimation of an Optical Image by Photon-Counting Techniques. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Wang, Lily Lee

1973-01-01

Statistical description of a photoelectric detector is given. The photosensitive surface of the detector is divided into many small areas, and the moment generating function of the photo-counting statistic is derived for large time-bandwidth product. The detection of a specified optical image in the presence of the background light by using the hypothesis test is discussed. The ideal detector based on the likelihood ratio from a set of numbers of photoelectrons ejected from many small areas of the photosensitive surface is studied and compared with the threshold detector and a simple detector which is based on the likelihood ratio by counting the total number of photoelectrons from a finite area of the surface. The intensity of the image is assumed to be Gaussian distributed spatially against the uniformly distributed background light. The numerical approximation by the method of steepest descent is used, and the calculations of the reliabilities for the detectors are carried out by a digital computer.

Semiconductive Copper(I)-Organic Frameworks for Efficient Light-Driven Hydrogen Generation Without Additional Photosensitizers and Cocatalysts.

PubMed

Shi, Dongying; Zheng, Rui; Sun, Ming-Jun; Cao, Xinrui; Sun, Chun-Xiao; Cui, Chao-Jie; Liu, Chun-Sen; Zhao, Junwei; Du, Miao

2017-11-13

As the first example of a photocatalytic system for splitting water without additional cocatalysts and photosensitizers, the comparatively cost-effective Cu 2 I 2 -based MOF, Cu-I-bpy (bpy=4,4'-bipyridine) exhibited highly efficient photocatalytic hydrogen production (7.09 mmol g -1  h -1 ). Density functional theory (DFT) calculations established the electronic structures of Cu-I-bpy with a narrow band gap of 2.05 eV, indicating its semiconductive behavior, which is consistent with the experimental value of 2.00 eV. The proposed mechanism demonstrates that Cu 2 I 2 clusters of Cu-I-bpy serve as photoelectron generators to accelerate the copper(I) hydride interaction, providing redox reaction sites for hydrogen evolution. The highly stable cocatalyst-free and self-sensitized Cu-I-bpy provides new insights into the future design of cost-effective d 10 -based MOFs for highly efficient and long-term solar fuels production. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Photosensitive filler minimizes internal stresses in epoxy resins

NASA Technical Reports Server (NTRS)

Dillon, J. N.

1967-01-01

Photosensitive filler is added to curable epoxy resins to minimize stress from internal shrinkage during curing or polymerization. Cinnamic acid resins and cinnamal ketones may be added in the amount of 1 to 3 percent by weight of the resin mixture.

Multispectral confocal microscopy images and artificial neural nets to monitor the photosensitizer uptake and degradation in Candida albicans cells

NASA Astrophysics Data System (ADS)

Romano, Renan A.; Pratavieira, Sebastião.; da Silva, Ana P.; Kurachi, Cristina; Guimarães, Francisco E. G.

2017-07-01

This study clearly demonstrates that multispectral confocal microscopy images analyzed by artificial neural networks provides a powerful tool to real-time monitoring photosensitizer uptake, as well as photochemical transformations occurred.

Investigation of photodynamic effect caused by MPPa-PDT on breast cancer Investigation of photodynamic effect caused by MPPa-PDT

NASA Astrophysics Data System (ADS)

Tian, Y. Y.; Hu, X. Y.; Leung, W. N.; Yuan, H. Q.; Zhang, L. Y.; Cui, F. A.; Tian, X.

2012-10-01

Breast cancer is the common malignant tumor, the incidence increases with age. Photodynamic therapy (PDT) is a new technique applied in tumors, which involves the administration of a tumor localizing photosensitizer and it is followed by the activation of a specific wavelength. Pyropheophorbide-a methyl ester (MPPa), a derivative of chlorophyll, is a novel potent photosensitizer. We are exploring the photodynamic effect caused by MPPa-PDT on breast cancer. The in vitro and in vivo experiments indicate that MPPa is a comparatively ideal photosensitizer which can induce apoptosis in breast cancer.

Recording polarization gratings with a standing spiral wave

NASA Astrophysics Data System (ADS)

Vernon, Jonathan P.; Serak, Svetlana V.; Hakobyan, Rafik S.; Aleksanyan, Artur K.; Tondiglia, Vincent P.; White, Timothy J.; Bunning, Timothy J.; Tabiryan, Nelson V.

2013-11-01

A scalable and robust methodology for writing cycloidal modulation patterns of optical axis orientation in photosensitive surface alignment layers is demonstrated. Counterpropagating circularly polarized beams, generated by reflection of the input beam from a cholesteric liquid crystal, direct local surface orientation in a photosensitive surface. Purposely introducing a slight angle between the input beam and the photosensitive surface normal introduces a grating period/orientation that is readily controlled and templated. The resulting cycloidal diffractive waveplates offer utility in technologies requiring diffraction over a broad range of angles/wavelengths. This simple methodology of forming polarization gratings offers advantages over conventional fabrication techniques.

Preclinical studies of vascular acting photosensitizer bacteriopheophorbide for the treatment of prostate cancer

NASA Astrophysics Data System (ADS)

Hetzel, Fred W.; Chen, Qun; Luck, David; Beckers, Jill; Huang, Zheng

2004-06-01

Photodynamic therapy (PDT) mediated with vascular acting photosensitizer pd-bacteriopheophorbide (Tookad), is investigated as an alternative modality for the total ablation of prostate cancer. In vivo normal canine prostate is used as the animal model. Interstitial PDT was performed by irradiating the surgically exposed prostates with a diode laser (763 nm, 150 mW/cm) to activate the IV infused photosensitizer drug. The prostate and its adjacent tissues were harvested and subjected to histopathological examination. At one-week post PDT, the animals recovered well with little or no urethral complications. Prostatic urethra and prostate adjacent tissues (bladder and underlying colon) were well preserved. PDT induced prostate lesions were characterized by marked hemorrhagic necrosis. Prostate lesions could be detected by MRI scan as early as 48 h post PDT. Maximum lesion size of 1.5 cm3 and 2.9 cm3 could be achieved at 50 J/cm and 100 J/cm, respectively, with interstitial treatment using a single 1-cm diffuser fiber, suggesting the Tookad-PDT is very effective in ablating prostatic tissue. Pharmacokinetic studies show that the photosensitizer is cleared rapidly from the circulation. In conclusion, the novel photosensitizer Tookad mediated PDT may provide an effective alternative to treat localized prostate cancer.

In vitro lethal photosensitization of S. mutans using methylene blue and toluidine blue O as photosensitizers.

PubMed

Araújo, Patrícia V; Teixeira, Karina I R; Lanza, Lincoln D; Cortes, Maria E; Poletto, Luiz T A

2009-01-01

The purpose of this in vitro study was to evaluate the antimicrobial effect of photodynamic therapy on Streptococcus mutans (A TCC 25175) suspensions, using a red laser for one minute in combination with toluidine blue O (TBO) or methylene blue (MB). Both photosensitizers were used in three concentrations (25, 10 and 5 mg/L). The activity ofphotosensitizers and laser irradiation were tested separately on the bacteria, as well as the irradiation of this light source in the presence of the TBO or MB. These groups were compared to a control group, in which the microorganism did not receive any treatment. The activity of both TBO and MB or laser irradiation, alone, were not able to reduce the number of S. mutans. In the groups of lethal photosensitization, a bacterial reduction of 70% for TBO and 73% for MB was observed when these photosensitizers were used at 25 mg/L and a reduction of 48% was observed for MB at 5mg/L. In other concentrations there were no significant differences in comparison to the control group. Both the TBO and the MB at 25 mg/L associated with a red laser had an excellent potential for use in PDT in lethal sensitization of S. mutans.

Hereditary polymorphic light eruption of American Indians: occurrence in non-Indians with polymorphic light eruption.

PubMed

Fusaro, R M; Johnson, J A

1996-04-01

Hereditary polymorphic light eruption (HPLE) occurs unique ly in the American Indian and Inuit and exhibits autosomal dominant transmission. Because the cutaneous expression of HPLE resembles that of polymorphic light eruption (PLE) and because many non-Indians in the United States have American Indian heritage, some instances of PLE may actually be HPLE. Our purpose was to determine whether non-Indian patients with PLE have characteristics suggestive of HPLE. We surveyed in Nebraska 25 European-Caucasian and 36 African-American patients with PLE for American Indian heritage and photosensitive relatives. Nonphotosensitive subjects (52 Caucasians and 40 African Americans) were surveyed for American Indian heritage. American Indian heritage occurred in 11 Caucasian patients (44%); of those, seven (64%) had photosensitive relatives. Likewise, 29 African Americans (81%) had American Indian heritage; 19 (66%) of those had photosensitive relatives. American Indian heritage occurred in 10 Caucasian control subjects (19%) and in 34 African-American control subjects (85%). If American Indian heritage and a family history of photosensitivity are definitive for HPLE, seven (28%) of our Caucasian patients and 19 (53%) of our African-American patients have HPLE rather than PLE. We urge physicians who suspect PLE in non-Indians to ask about American Indian heritage and photosensitive relatives and to screen their present patients with PLE for such characteristics.

Nanolabel for TNF-α determination

NASA Astrophysics Data System (ADS)

Say, Rıdvan; Diltemiz, Sibel Emir; Çelik, Suzan; Ersöz, Arzu

2013-06-01

Tumor necrosis factor-α (TNF-α), also known as cachectin, is one of the most important regulatory cytokines and mediates a variety of cell functions, including the stimulation of nitric oxide (NO) production which has been related to oxidative stress and diseases such as arthritis, diabetes, stroke, and chronic inflammation. Determination of TNF-α concentration in human serum might be helpful in the staging and prognosis of diseases. And it is also very important for the understanding of tumor biological processes, inherent mechanisms, and discovering drugs as well as having a therapeutic potential for the treatment of diseases. So, in this study, sensor systems based on Reflectometric Interference Spectroscopy (RIfS) have been prepared for selectively recognition and binding of TNF-α biomolecules. For this purpose, photosensitive nano structured TNF-α has been synthesized applying AmiNoAcid (monomer) Decorated and Light Underpining Conjugation Approach (ANADOLUCA) method using bis (2-2'-bipyridyl) MATyr-MATyr-ruthenium(II) (MATyr-Ru-MATyr) as a photosensitive monomer. Then, these photosensitive nano structured TNF-α have been used for TNF-α recognition as an alternative and unique sensor method. Also, the affinity constant of RIfS sensor has been calculated. The method has been showed high sensitivity, good precision and accuracy, and suited for the detection of TNF-α from aqueous solution.

Photodynamic killing of cancer cells by a Platinum(II) complex with cyclometallating ligand

NASA Astrophysics Data System (ADS)

Doherty, Rachel E.; Sazanovich, Igor V.; McKenzie, Luke K.; Stasheuski, Alexander S.; Coyle, Rachel; Baggaley, Elizabeth; Bottomley, Sarah; Weinstein, Julia A.; Bryant, Helen E.

2016-03-01

Photodynamic therapy that uses photosensitizers which only become toxic upon light-irradiation provides a strong alternative to conventional cancer treatment due to its ability to selectively target tumour material without affecting healthy tissue. Transition metal complexes are highly promising PDT agents due to intense visible light absorption, yet the majority are toxic even without light. This study introduces a small, photostable, charge-neutral platinum-based compound, Pt(II) 2,6-dipyrido-4-methyl-benzenechloride, complex 1, as a photosensitizer, which works under visible light. Activation of the new photosensitizer at low concentrations (0.1-1 μM) by comparatively low dose of 405 nm light (3.6 J cm-2) causes significant cell death of cervical, colorectal and bladder cancer cell lines, and, importantly, a cisplatin resistant cell line EJ-R. The photo-index of the complex is 8. We demonstrate that complex 1 induces irreversible DNA single strand breaks following irradiation, and that oxygen is essential for the photoinduced action. Neither light, nor compound alone led to cell death. The key advantages of the new drug include a remarkably fast accumulation time (diffusion-controlled, minutes), and photostability. This study demonstrates a highly promising new agent for photodynamic therapy, and attracts attention to photostable metal complexes as viable alternatives to conventional chemotherapeutics, such as cisplatin.

Photosensitized UVA-Induced Cross-Linking between Human DNA Repair and Replication Proteins and DNA Revealed by Proteomic Analysis

PubMed Central

2016-01-01

Long wavelength ultraviolet radiation (UVA, 320–400 nm) interacts with chromophores present in human cells to induce reactive oxygen species (ROS) that damage both DNA and proteins. ROS levels are amplified, and the damaging effects of UVA are exacerbated if the cells are irradiated in the presence of UVA photosensitizers such as 6-thioguanine (6-TG), a strong UVA chromophore that is extensively incorporated into the DNA of dividing cells, or the fluoroquinolone antibiotic ciprofloxacin. Both DNA-embedded 6-TG and ciprofloxacin combine synergistically with UVA to generate high levels of ROS. Importantly, the extensive protein damage induced by these photosensitizer+UVA combinations inhibits DNA repair. DNA is maintained in intimate contact with the proteins that effect its replication, transcription, and repair, and DNA–protein cross-links (DPCs) are a recognized reaction product of ROS. Cross-linking of DNA metabolizing proteins would compromise these processes by introducing physical blocks and by depleting active proteins. We describe a sensitive and statistically rigorous method to analyze DPCs in cultured human cells. Application of this proteomics-based analysis to cells treated with 6-TG+UVA and ciprofloxacin+UVA identified proteins involved in DNA repair, replication, and gene expression among those most vulnerable to cross-linking under oxidative conditions. PMID:27654267

Intrinsic photosensitizer fluorescence measured using multi-diameter single-fiber spectroscopy in vivo

NASA Astrophysics Data System (ADS)

van Leeuwen-van Zaane, Floor; Gamm, Ute A.; van Driel, Pieter B. A. A.; Snoeks, Thomas J.; de Bruijn, Henriette S.; van der Ploeg-van den Heuvel, Angelique; Sterenborg, Henricus J. C. M.; Löwik, Clemens W.; Amelink, Arjen; Robinson, Dominic J.

2014-01-01

Quantification of fluorescence in vivo is complicated by the influence of tissue optical properties on the collected fluorescence signal. When tissue optical properties in the measurement volume are quantified, one can obtain the intrinsic fluorescence, which equals the product of fluorophore absorption coefficient and quantum yield. We applied this method to in vivo single-fiber fluorescence spectroscopy measurements on mouse tongue, skin, liver, and oral squamous cell carcinoma, where we detected intrinsic fluorescence spectra of the photosensitizers chlorin e6 and Bremachlorin at t=[3,4.5,6,24,48] h incubation time. We observed a tissue-dependent maximum of 35% variation in the total correction factor over the visible wavelength range. Significant differences in spectral shape over time between sensitizers were observed. Although the wavelength position of the fluorescence intensity maximum for ce6 shifted to the red, Bremachlorin showed a blue shift. Furthermore, the Bremachlorin peak appeared to be broader than the ce6 fluorescence peak. Intrinsic fluorescence intensity, which can be related to photosensitizer concentration, was decreasing for all time points but showed significantly more Bremachlorin present compared to ce6 at long incubation times. Results from this study can be used to define an optimal treatment protocol for Bremachlorin-based photodynamic therapy.

Probing Photosensitization by Functionalized Carbon Nanotubes.

PubMed

Chen, Chia-Ying; Zepp, Richard G

2015-12-01

Carbon nanotubes (CNTs) photosensitize the production of reactive oxygen species that may damage organisms by biomembrane oxidation or mediate environmental transformations of CNTs. Photosensitization by derivatized carbon nanotubes from various synthetic methods, and thus with different intrinsic characteristics (e.g., diameter and electronic properties), has been investigated under environmentally relevant aquatic conditions. We used the CNT-sensitized photoisomerization of sorbic acid ((2E,4E)-hexa-2,4-dienoic acid) and singlet oxygen formation to quantify the triplet states ((3)CNT*) formed upon irradiation of selected single-walled carbon nanotubes (SWCNTs) and multiwalled carbon nanotubes (MWCNTs). The CNTs used in our studies were derivatized by carboxyl groups to facilitate their dispersion in water. Results indicate that high-defect-density (thus well-stabilized), small-diameter, and semiconducting-rich CNTs have higher-measured excited triplet state formation and therefore singlet oxygen ((1)O2) yield. Derivatized SWCNTs were significantly more photoreactive than derivatized MWCNTs. Moreover, addition of sodium chloride resulted in increased aggregation and small increases in (1)O2 production of CNTs. The most photoreactive CNTs exhibited comparable photoreactivity (in terms of (3)CNT* formation and (1)O2 yield) to reference natural organic matter (NOM) under sunlight irradiation with the same mass-based concentration. Selected reference NOM could therefore be useful in evaluating environmental photoreactivity or intended antibacterial applications of CNTs.

Photosensitizer-Loaded Branched Polyethylenimine-PEGylated Ceria Nanoparticles for Imaging-Guided Synchronous Photochemotherapy.

PubMed

Yang, Zhang-You; Li, Hong; Zeng, Yi-Ping; Hao, Yu-Hui; Liu, Cong; Liu, Jing; Wang, Wei-Dong; Li, Rong

2015-11-04

A multifunctional theranostic platform based on photosensitizer (chlorin e6, Ce6)-loaded branched polyethylenimine-PEGylated ceria nanoparticles (PPCNPs-Ce6) was created for the development of effective cancer treatments involving the use of imaging-guided synchronous photochemotherapy. PPCNPs-Ce6 with high Ce6 photosensitizer loading (Ce6: cerium ∼40 wt %) significantly enhanced the delivery of Ce6 into cells and its accumulation in lysosomes, remarkably improving photodynamic therapeutic (PDT) efficacy levels compared to those in the administration of free Ce6 at ultralow drug doses (∼200 nM). Interestingly, PPCNPs-Ce6 efficiently induced HeLa cell death even at low concentrations (∼10 μM) without the use of laser irradiation and exhibit chemocytotoxicity. Inductively coupled plasma mass spectrometry (ICP-MS) and biology transmission electron microscopy (Bio-TEM) analyses demonstrated that ceria nanoparticles enter cells abundantly and accumulate in lysosomes or large vesicles. We then evaluated the effects of the different materials on lysosomal integrity and function, which revealed that PPCNPs-Ce6 catastrophically impaired lysosomal function compared to results with PPCNPs and Ce6. Studies of apoptosis revealed greater induction of apoptosis by PPCNPs-Ce6 treatment. This multifunctional nanocarrier also exhibited a high degree of solubility and stability in aqueous solutions, suggesting its applicability for extensive biomedical application.

Iris pigmentation and photopic visual acuity: a preliminary study.

PubMed

Short, G B

1975-11-01

Visual acuity under varying conditions of light stress was tested in four human populations. It was found that the density of iris pigmentation had no significant effect on visual acuity under conditions of bright light. While some acclimatization to local light levels was observed, significant population differences in visual acuity were obtained. A hypothesis is advanced at to the adaptive value of varying densities of pigmentation of the iris based on the known heat absorption properties of melanin granules.

Detection of pigment network in dermatoscopy images using texture analysis

PubMed Central

Anantha, Murali; Moss, Randy H.; Stoecker, William V.

2011-01-01

Dermatoscopy, also known as dermoscopy or epiluminescence microscopy (ELM), is a non-invasive, in vivo technique, which permits visualization of features of pigmented melanocytic neoplasms that are not discernable by examination with the naked eye. ELM offers a completely new range of visual features. One such prominent feature is the pigment network. Two texture-based algorithms are developed for the detection of pigment network. These methods are applicable to various texture patterns in dermatoscopy images, including patterns that lack fine lines such as cobblestone, follicular, or thickened network patterns. Two texture algorithms, Laws energy masks and the neighborhood gray-level dependence matrix (NGLDM) large number emphasis, were optimized on a set of 155 dermatoscopy images and compared. Results suggest superiority of Laws energy masks for pigment network detection in dermatoscopy images. For both methods, a texel width of 10 pixels or approximately 0.22 mm is found for dermatoscopy images. PMID:15249068

Photocurrent generation by dye-sensitized solar cells using natural pigments.

PubMed

Armendáriz-Mireles, Eddie Nahúm; Rocha-Rangel, Enrique; Caballero-Rico, Frida; Ramírez-de-León, José Alberto; Vázquez, Manuel

2017-01-01

The development of photovoltaic panels has improved the conversion of solar radiation into electrical energy. This paper deals with the electrical and thermal characteristics (voltage, current, and temperature) of photovoltaic solar cells sensitized with natural pigments (dye-sensitized solar cell, DSSC) based on a titanium dioxide semiconductor. Several natural pigments (blackberry, beets, eggplant skin, spinach, flame tree flower, papaya leaf, and grass extracts) were evaluated to determine their sensitizing effect on titanium dioxide. The results showed the great potential of natural pigments for use in solar cells. The best results were obtained with the blackberry pigment, reaching a value of 7.1 mA current, open-circuit voltage (V oc ) of 0.72 V in 2 cm 2 , and fill factor (ff) of 0.51 in the DSSC. This performance is well above than that currently offers by actual cells. © 2015 International Union of Biochemistry and Molecular Biology, Inc.

Surgical Management of Iatrogenic Pigment Dispersion Glaucoma.

PubMed

Mierlo, Camille Van; Pinto, Luis Abegão; Stalmans, Ingeborg

2015-01-01

Iatrogenic pigment dispersion syndrome generally originates from a repetitive, mechanical trauma to the pigmented posterior epithelium of the iris. This trauma can arise after intraocular surgery, most commonly due to an abnormal contact between the intraocular lens (IOL) and the iris. Whether surgical removal of this primary insult can lead to a successful intraocular pressure (IOP) control remains unclear. Case-series. Patients with IOP elevation and clinical signs of pigment dispersion were screened for a diagnosis of iatrogenic IOL-related pigment dispersion. Three patients in which the IOL or the IOL-bag complex caused a pigment dispersion through a repetitive iris chafing were selected. In two cases, replacement of a sulcus-based single-piece IOL (patient 1) or a sub-luxated in-the-bag IOL (patient 2) by an anterior-chamber (AC) iris-fixed IOL led to a sustained decrease in IOP. In the third case, extensive iris atrophy and poor anatomical AC parameters for IOL implantation precluded further surgical intervention. IOL-exchange appears to be a useful tool in the management of iatrogenic pigment dispersion glaucoma due to inappropriate IOL implantation. This cause-oriented approach seems to be effective in controlling IOP, but should be offered only if safety criteria are met. How to cite this article: Van Mierlo C, Abegao Pinto L, Stalmans I. Surgical Management of Iatrogenic Pigment Dispersion Glaucoma. J Curr Glaucoma Pract 2015;9(1):28-32.

Artificial neural network model for photosynthetic pigments identification using multi wavelength chromatographic data

NASA Astrophysics Data System (ADS)

Prilianti, K. R.; Hariyanto, S.; Natali, F. D. D.; Indriatmoko, Adhiwibawa, M. A. S.; Limantara, L.; Brotosudarmo, T. H. P.

2016-04-01

The development of rapid and automatic pigment characterization method become an important issue due to the fact that there are only less than 1% of plant pigments in the earth have been explored. In this research, a mathematical model based on artificial intelligence approach was developed to simplify and accelerate pigment characterization process from HPLC (high-performance liquid chromatography) procedure. HPLC is a widely used technique to separate and identify pigments in a mixture. Input of the model is chromatographic data from HPLC device and output of the model is a list of pigments which is the spectrum pattern is discovered in it. This model provides two dimensional (retention time and wavelength) fingerprints for pigment characterization which is proven to be more accurate than one dimensional fingerprint (fixed wavelength). Moreover, by mimicking interconnection of the neuron in the nervous systems of the human brain, the model have learning ability that could be replacing expert judgement on evaluating spectrum pattern. In the preprocessing step, principal component analysis (PCA) was used to reduce the huge dimension of the chromatographic data. The aim of this step is to simplify the model and accelerate the identification process. Six photosynthetic pigments i.e. zeaxantin, pheophytin a, α-carotene, β-carotene, lycopene and lutein could be well identified by the model with accuracy up to 85.33% and processing time less than 1 second.

Probabilistic classification method on multi wavelength chromatographic data for photosynthetic pigments identification

NASA Astrophysics Data System (ADS)

Prilianti, K. R.; Setiawan, Y.; Indriatmoko, Adhiwibawa, M. A. S.; Limantara, L.; Brotosudarmo, T. H. P.

2014-02-01

Environmental and health problem caused by artificial colorant encourages the increasing usage of natural colorant nowadays. Natural colorant refers to the colorant that is derivate from living organism or minerals. Extensive research topic has been done to exploit these colorant, but recent data shows that only 0.5% of the wide range of plant pigments in the earth has been exhaustively used. Hence development of the pigment characterization technique is an important consideration. High-performance liquid chromatography (HPLC) is a widely used technique to separate pigments in a mixture and identify it. In former HPLC fingerprinting, pigment characterization was based on a single chromatogram from a fixed wavelength (one dimensional) and discard the information contained at other wavelength. Therefore, two dimensional fingerprints have been proposed to use more chromatographic information. Unfortunately this method leads to the data processing problem due to the size of its data matrix. The other common problem in the chromatogram analysis is the subjectivity of the researcher in recognizing the chromatogram pattern. In this research an automated analysis method of the multi wavelength chromatographic data was proposed. Principal component analysis (PCA) was used to compress the data matrix and Maximum Likelihood (ML) classification was applied to identify the chromatogram pattern of the existing pigments in a mixture. Three photosynthetic pigments were selected to show the proposed method. Those pigments are β-carotene, fucoxanthin and zeaxanthin. The result suggests that the method could well inform the existence of the pigments in a particular mixture. A simple computer application was also developed to facilitate real time analysis. Input of the application is multi wavelength chromatographic data matrix and the output is information about the existence of the three pigments.

Solid-state NMR Reveals the Carbon-based Molecular Architecture of Cryptococcus neoformans Fungal Eumelanins in the Cell Wall*

PubMed Central

Chatterjee, Subhasish; Prados-Rosales, Rafael; Itin, Boris; Casadevall, Arturo; Stark, Ruth E.

2015-01-01

Melanin pigments protect against both ionizing radiation and free radicals and have potential soil remediation capabilities. Eumelanins produced by pathogenic Cryptococcus neoformans fungi are virulence factors that render the fungal cells resistant to host defenses and certain antifungal drugs. Because of their insoluble and amorphous characteristics, neither the pigment bonding framework nor the cellular interactions underlying melanization of C. neoformans have yielded to comprehensive molecular-scale investigation. This study used the C. neoformans requirement of exogenous obligatory catecholamine precursors for melanization to produce isotopically enriched pigment “ghosts” and applied 2D 13C-13C correlation solid-state NMR to reveal the carbon-based architecture of intact natural eumelanin assemblies in fungal cells. We demonstrated that the aliphatic moieties of solid C. neoformans melanin ghosts include cell-wall components derived from polysaccharides and/or chitin that are associated proximally with lipid membrane constituents. Prior to development of the mature aromatic fungal pigment, these aliphatic moieties form a chemically resistant framework that could serve as the scaffold for melanin synthesis. The indole-based core aromatic moieties show interconnections that are consistent with proposed melanin structures consisting of stacked planar assemblies, which are associated spatially with the aliphatic scaffold. The pyrrole aromatic carbons of the pigments bind covalently to the aliphatic framework via glycoside or glyceride functional groups. These findings establish that the structure of the pigment assembly changes with time and provide the first biophysical information on the mechanism by which melanin is assembled in the fungal cell wall, offering vital insights that can advance the design of bioinspired conductive nanomaterials and novel therapeutics. PMID:25825492

Solid-state NMR Reveals the Carbon-based Molecular Architecture of Cryptococcus neoformans Fungal Eumelanins in the Cell Wall.

PubMed

Chatterjee, Subhasish; Prados-Rosales, Rafael; Itin, Boris; Casadevall, Arturo; Stark, Ruth E

2015-05-29

Melanin pigments protect against both ionizing radiation and free radicals and have potential soil remediation capabilities. Eumelanins produced by pathogenic Cryptococcus neoformans fungi are virulence factors that render the fungal cells resistant to host defenses and certain antifungal drugs. Because of their insoluble and amorphous characteristics, neither the pigment bonding framework nor the cellular interactions underlying melanization of C. neoformans have yielded to comprehensive molecular-scale investigation. This study used the C. neoformans requirement of exogenous obligatory catecholamine precursors for melanization to produce isotopically enriched pigment "ghosts" and applied 2D (13)C-(13)C correlation solid-state NMR to reveal the carbon-based architecture of intact natural eumelanin assemblies in fungal cells. We demonstrated that the aliphatic moieties of solid C. neoformans melanin ghosts include cell-wall components derived from polysaccharides and/or chitin that are associated proximally with lipid membrane constituents. Prior to development of the mature aromatic fungal pigment, these aliphatic moieties form a chemically resistant framework that could serve as the scaffold for melanin synthesis. The indole-based core aromatic moieties show interconnections that are consistent with proposed melanin structures consisting of stacked planar assemblies, which are associated spatially with the aliphatic scaffold. The pyrrole aromatic carbons of the pigments bind covalently to the aliphatic framework via glycoside or glyceride functional groups. These findings establish that the structure of the pigment assembly changes with time and provide the first biophysical information on the mechanism by which melanin is assembled in the fungal cell wall, offering vital insights that can advance the design of bioinspired conductive nanomaterials and novel therapeutics. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Upscaling from leaf to canopy chlorophyll/carotenoid pigment based vegetation indices reveal phenology of photosynthesis in temperate evergreen and deciduous trees

NASA Astrophysics Data System (ADS)

Wong, C. Y.; Bhathena, Y.; Arain, M. A.; Ensminger, I.

2017-12-01

Optically derived vegetation indices have been developed to provide information about plant status including photosynthetic activity. They reflect changes in leaf pigments, which vary seasonally in pigment composition, enabling them to be used as a proxy of photosynthetic phenology. Important pigments in photosynthetic activity are carotenoids and chlorophylls, which are associated with light harvesting and energy dissipation. In temperate forests, which consist of deciduous and evergreen trees, there are difficulties resolving evergreen phenology using the most widely used index, the normalized difference vegetation index (NDVI). NDVI works well in deciduous trees, which exhibit a "visible" phenological process of leaf growth in the spring, and leaf senescence and abscission in the autumn. Evergreen conifers stay green year-round and utilize "invisible" changes of overwintering pigment composition that NDVI cannot resolve, so carotenoid pigment sensitive vegetation indices have been suggested for evergreens. The aim of this study was to evaluate carotenoid based vegetation indices over the chlorophyll sensitive NDVI. For this purpose, we evaluated the greenness index, NDVI, and carotenoid pigment sensitive indices: photochemical reflectance index (PRI) and chlorophyll/carotenoid index (CCI) in red maple, white oak and eastern white pine for two years. We also measured leaf gas exchange and pigment concentrations. We observed that NDVI correlated with photosynthetic activity in deciduous trees, whereas PRI and CCI correlated with photosynthesis across both evergreen and deciduous trees. This pattern was consistent, upscaling from leaf- to canopy-scales indicating that the mechanisms involved in winter acclimation can be resolved at larger spatial scales. PRI and CCI detected seasonal changes in carotenoids and chlorophylls linked to photoprotection and are suitable as a proxy of photosynthetic activity. These findings have implications to improve our use and understanding of remotely sensed vegetation indices as proxies of photosynthetic activity in northern forests for long-term monitoring.

Triple-channel microreactor for biphasic gas-liquid reactions: Photosensitized oxygenations.

PubMed

Maurya, Ram Awatar; Park, Chan Pil; Kim, Dong-Pyo

2011-01-01

A triple-channel microreactor fabricated by means of a soft-lithography technique was devised for efficient biphasic gas-liquid reactions. The excellent performance of the microreactor was demonstrated by carrying out photosensitized oxygenations of α-terpinene, citronellol, and allyl alcohols.

Posterior chamber phakic intraocular lens sizing based on iris pigment layer measurements by anterior segment optical coherence tomography.

PubMed

Malyugin, Boris E; Shpak, Alexander A; Pokrovskiy, Dmitry F

2015-08-01

To use anterior segment optical coherence tomography (AS-OCT) to evaluate the clinical effectiveness of Implantable Collamer Lens posterior chamber phakic intraocular lens (PC pIOL) sizing based on measurement of the distance from the iris pigment end to the iris pigment end. S. Fyodorov Eye Microsurgery Federal State Institution, Moscow, Russia. Evaluation of diagnostic test or technology. Stage 1 was a prospective study. The sulcus-to-sulcus (STS) distance was measured using ultrasound biomicroscopy (UBM) (Vumax 2), and the distance from iris pigment end to iris pigment end was assessed using a proposed AS-OCT algorithm. Part 2 used retrospective data from patients after implantation of a PC pIOL with the size selected according to AS-OCT (Visante) measurements of the distance from iris pigment end to iris pigment end. The PC pIOL vault was measured by AS-OCT, and adverse events were assessed. Stage 1 comprised 32 eyes of 32 myopic patients (mean age 28.4 years ± 6.3 [SD]; mean spherical equivalent [SE] -13.11 ± 4.28 diopters [D]). Stage 2 comprised 29 eyes of 16 patients (mean age 27.7 ± 4.7 years; mean SE -16.55 ± 3.65 D). The mean STS distance (12.35 ± 0.47 mm) was similar to the mean distance from iris pigment end to iris pigment end distance (examiner 1: 12.36 ± 0.51 mm; examiner 2: 12.37 ± 0.53 mm). The PC pIOL sized using the new AS-OCT algorithm had a mean vault of 0.53 ± 0.18 mm and did not produce adverse events during the 12-month follow-up. In 16 of 29 eyes, the PC pIOL vault was within an optimum interval (0.35 to 0.70 mm). The new measurement algorithm can be effectively used for PC pIOL sizing. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2015 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Ground-State Electronic Structure of RC-LH1 and LH2 Pigment Assemblies of Purple Bacteria via the EBF-MO Method.

PubMed

Shrestha, Kushal; Jakubikova, Elena

2015-08-20

Light-harvesting antennas are protein-pigment complexes that play a crucial role in natural photosynthesis. The antenna complexes absorb light and transfer energy to photosynthetic reaction centers where charge separation occurs. This work focuses on computational studies of the electronic structure of the pigment networks of light-harvesting complex I (LH1), LH1 with the reaction center (RC-LH1), and light-harvesting complex II (LH2) found in purple bacteria. As the pigment networks of LH1, RC-LH1, and LH2 contain thousands of atoms, conventional density functional theory (DFT) and ab initio calculations of these systems are not computationally feasible. Therefore, we utilize DFT in conjunction with the energy-based fragmentation with molecular orbitals method and a semiempirical approach employing the extended Hückel model Hamiltonian to determine the electronic properties of these pigment assemblies. Our calculations provide a deeper understanding of the electronic structure of natural light-harvesting complexes, especially their pigment networks, which could assist in rational design of artificial photosynthetic devices.

Anticorrosion Properties of Pigments based on Ferrite Coated Zinc Particles

NASA Astrophysics Data System (ADS)

Benda, P.; Kalendová, A.

The paper deals with a new anticorrosion pigment, synthesized on a core-shell basis. For its syntheses a starting substance is used that forms the lamellar shaped core; namely lamellar zinc. The cover of the core is represented by zinc oxide, which is in fact partly oxidized lamellar zinc core, and is created during the calcination of the pigment. The compound that forms the top layer of the core, a ferrite, is also formed during calcination. The formula for the prepared pigment is then defined as MexZn1-xFe2O4/Zn and the formula of thin ferrite layer is MexZn1-xFe2O4 (where Me = Ca, Mg). Due to its shape, this anticorrosion pigment includes another anticorrosion effect, the so called "barrier effect". The mechanisms of anticorrosion effect, corrosion efficiency and mechanical properties were investigated for epoxy-ester paint systems with 10%pigment volume concentration (PVC). Mechanical tests were performed to determine the adhesiveness and mechanical resistance of paints and accelerated corrosion tests were carried out to evaluate efficiency against chemical degradation factors.

Surface modification of polyester fabrics by atmospheric-pressure air/He plasma for color strength and adhesion enhancement

NASA Astrophysics Data System (ADS)

Zhang, Chunming; Zhao, Meihua; Wang, Libing; Qu, Lijun; Men, Yajing

2017-04-01

Surface properties of water-based pigmented inks for ink-jet printed polyester fabrics were modified with atmospheric-pressure air/He plasma to improve the color strength and pigment adhesion of the treated surfaces. The influence of various parameters, including the surface morphology, chemical compositions, surface energy and dynamic contact angles of the control and plasma treated samples was studied. Color strength and edge definition were used to evaluate the ink-jet printing performance of fabrics. The change in pigment adhesion to polyester fibers was analyzed by SEM (scanning electron microscopy). AFM (Atomic force microscope) and XPS (X-ray photoelectron spectroscopy) analyses indicated the increase in surface roughness and the oxygen-containing polar groups(Cdbnd O, Csbnd OH and COOH) reinforced the fixation of pigments on the fiber surface. The result from this study suggested that the improved pigment color yield was clearly affected by alteration of pigment adhesion enhanced by plasma surface modification. Polyester fabrics exhibited better surface property and ink-jet printing performance after the air/He mixture plasma treatment comparing with those after air plasma treatment.

The effect of pigment matrix, temperature and amount of carrier on the yield and final color properties of spray dried purple corn (Zea mays L.) cob anthocyanin powders.

PubMed

Lao, Fei; Giusti, M Monica

2017-07-15

Spray drying is an economic technique to produce anthocyanin-based colorants. High pigments yields with minimum color degradation are desirable to maximize quality and profits. This study evaluated the impacts of purple corncob (PCC) anthocyanin extraction matrices (hot water, 40% ethanol, C18 purified), drying inlet temperature (130, 150, 170°C) and amount of carrier (2%, 5%, 10% maltodextrin) on the yields and quality of PCC anthocyanin powders. Monomeric and polymeric anthocyanins, color properties (CIELch, haze), and pigments composition before and after spray drying were determined. The yield and final color quality of spray dried PCC anthocyanins were affected (p<0.05) by all parameters evaluated. The pigment matrix, inlet temperature, and carrier amount had biggest impacts on product water solubility, pigments degradation and yield, respectively. The optimal combination of hot water extracts spray dried with 5% maltodextrin at 150°C gave the highest pigment yield (∼90%) with good solubility with the least color loss. Copyright © 2017 Elsevier Ltd. All rights reserved.

Single-sided lateral-field and phototransistor-based optoelectronic tweezers

NASA Technical Reports Server (NTRS)

Ohta, Aaron (Inventor); Chiou, Pei-Yu (Inventor); Hsu, Hsan-Yin (Inventor); Jamshidi, Arash (Inventor); Wu, Ming-Chiang (Inventor); Neale, Steven L. (Inventor)

2011-01-01

Described herein are single-sided lateral-field optoelectronic tweezers (LOET) devices which use photosensitive electrode arrays to create optically-induced dielectrophoretic forces in an electric field that is parallel to the plane of the device. In addition, phototransistor-based optoelectronic tweezers (PhOET) devices are described that allow for optoelectronic tweezers (OET) operation in high-conductivity physiological buffer and cell culture media.

Digging Deeper with Trees.

ERIC Educational Resources Information Center

Growing Ideas, 2001

2001-01-01

Describes hands-on science areas that focus on trees. A project on leaf pigmentation involves putting crushed leaves in a test tube with solvent acetone to dissolve pigment. In another project, students learn taxonomy by sorting and classifying leaves based on observable characteristics. Includes a language arts connection. (PVD)

Hydrothermally Processed Photosensitive Field-Effect Transistor Based on ZnO Nanorod Networks

NASA Astrophysics Data System (ADS)

Kumar, Ashish; Bhargava, Kshitij; Dixit, Tejendra; Palani, I. A.; Singh, Vipul

2016-11-01

Formation of a stable, reproducible zinc oxide (ZnO) nanorod-network-based photosensitive field-effect transistor using a hydrothermal process at low temperature has been demonstrated. K2Cr2O7 additive was used to improve adhesion and facilitate growth of the ZnO nanorod network over the SiO2/Si substrate. Transistor characteristics obtained in the dark resemble those of the n-channel-mode field-effect transistor (FET). The devices showed I on/ I off ratio above 8 × 102 under dark condition, field-effect mobility of 4.49 cm2 V-1 s-1, and threshold voltage of -12 V. Further, under ultraviolet (UV) illumination, the FET exhibited sensitivity of 2.7 × 102 in off-state (-10 V) versus 1.4 in on-state (+9.7 V) of operation. FETs based on such nanorod networks showed good photoresponse, which is attributed to the large surface area of the nanorod network. The growth temperature for ZnO nanorod networks was kept at 110°C, enabling a low-temperature, cost-effective, simple approach for high-performance ZnO-based FETs for large-scale production. The role of network interfaces in the FET performance is also discussed.

Spectrometric characteristics and tumor-affinity of a novel photosensitizer: mono-l-aspartyl aurochlorin e6 (Au-NPe6).

PubMed

Ishizumi, Taichiro; Aizawa, Katsuo; Tsuchida, Takaaki; Okunaka, Tetsuya; Kato, Harubumi

2004-12-01

Photodiagnosis and photodynamic therapy with photosensitizers can be indicated only for tumors of the superficial type, because these approaches utilizing visible light are limited by said light penetrability. To overcome this disadvantage, we innovated a novel photosensitizer, mono-l-aspartyl aurochlorin e6 (Au-NPe6), by incorporating a gold atom in the center of tetrapyrrole ring of NPe6 with a coordination bond. The gold atom in Au-NPe6 plays a role as an X-ray interceptor to detect deeply sited tumors. In this study, the absorption spectrum of novel Au-NPe6 in the diagnosis of deeply sited tumors was investigated, and the results were compared with the parent photosensitizer NPe6. Furthermore, the tumor-affinity of Au-NPe6 was evaluated using atomic absorption spectrometry. Despite the fact that both photosensitizers display a difference in the absorption spectrum, waveform changes of either photosensitizer with human serum albumin established a saturation point at a molar ratio of 1:1. The results indicate that it is highly possible that Au-NPe6 bound with albumin at a molar ratio (1:1) similar to NPe6. The accumulation rate of gold in tumor tissues was always significantly (p<0.05) higher than that in normal muscle tissues during the observation terms. Moreover, absorption spectra of tumor-tissue homogenates obtained from tumor-bearing mice after Au-NPe6 administration revealed a common peak with a wavelength equivalent to that of albumin-bond Au-NPe. This result suggests that the gold atom and NPe6 probably remained bonded even when Au-NPe6 was incorporated in tumor tissues.

Photosensitized enzyme deactivation and protein oxidation by axial-substituted phosphorus(V) tetraphenylporphyrins.

PubMed

Ouyang, Dongyan; Hirakawa, Kazutaka

2017-10-01

The activity for photodynamic therapy of water-soluble cationic porphyrins, tetraphenylporphyrin P(V) complexes, was investigated. Bis(cyclohexylmethoxy)P(V)tetraphenylporphyrin (DCHMP(V)TPP), dichloroP(V)tetraphenylporphyrin (Cl 2 P(V)TPP), and dimethoxyP(V)tetraphenylporphyrin (DMP(V)TPP) could cause the photosensitized deactivation of tyrosinase. The tryptophan residue of human serum albumin (HSA) and several kinds of amino acids could be damaged by these P(V)porphyrins under visible light irradiation. The photosensitized damage of these biomolecules was inhibited by sodium azide, a singlet oxygen ( 1 O 2 ) quencher, and enhanced in deuterium oxide, suggesting the contribution of 1 O 2 . However, an excess amount of sodium azide did not completely inhibit the photosensitized damage. In addition, the redox potential measurements demonstrated the possibility of electron transfer from tryptophan and tyrosine to photoexcited P(V)porphyrins. These results suggest that electron transfer-mediated oxidation of amino acids contributes to the photosensitized protein and amino acid damage by these P(V)porphyrins. Specifically, Cl 2 P(V)TPP showed the highest photodamaging activity in the P(V)porphyrins used in this study. Oxidized products of amino acids by photoexcited P(V)porphyrins were analyzed with a liquid chromatography-mass spectrometer. Because of the hypoxic condition of a tumor, photodynamic therapy through a 1 O 2 -mediated mechanism should be restricted, and the electron transfer-mediated mechanism may improve the photodynamic effect. In the cases of these P(V)porphyrins, redox potential is the most important factor for photosensitized protein and amino acid oxidation through photoinduced electron transfer. Copyright © 2017 Elsevier B.V. All rights reserved.

Surface processing and ageing behavior of silk fabrics treated with atmospheric-pressure plasma for pigment-based ink-jet printing

NASA Astrophysics Data System (ADS)

Zhang, Chunming; Wang, Libing; Yu, Miao; Qu, Lijun; Men, Yajing; Zhang, Xiangwu

2018-03-01

Pigment inkjet printing has highlighted the advantages of cost-effective, short production cycle and environment-friendly. However, patterns directly printed with pigment inks usually have low color yields and blurry images which are caused by bleeding phenomenon. This work presents an atmospheric-pressure plasma method for improving the pigment-based ink-jet printing performance of silk fabrics. The effects of surface changes induced are discussed, with data derived from morphological study by atomic force microscopy (AFM), chemical analysis using X-ray photoelectron spectroscopy (XPS) and contact angle measurement. Ink-jet printing experiments were conducted to study the influence of measured changes on anti-bleeding property and color strength of treated and original samples. The ageing experiment indicates that the modified silk fabrics should be printed within 24 h after plasma processing for maximum color yields. This study explores an effective approach for the atmospheric-pressure plasma, which can provide its significant use in improving the surface properties and ink-jet printing performance of fabrics.