Read by QxMD icon Read

Photochemical & Photobiological Sciences

Masoomeh Vafa, Khosrow Khalifeh, Vahab Jafarian
Mnemiopsin 2 from Mnemiopsis leidy has three Ca2+-binding motifs and has luminescence properties in the presence of calcium and coelenterazine. It has been reported that the pattern of calcium binding among EF-hand loops of various photoproteins is different. Here, we designed and constructed two variants of mnemiopsin 2 (E50G/D47N and E50G/E53T mutants) with modified EF-hand I in which the negative charge in the first loop was reduced. According to the activity measurements, the initial intensity of mutants decreases; while the decay rate increases in E50G/D47N...
May 17, 2018: Photochemical & Photobiological Sciences
Masami Enoki, Ryuzi Katoh
We studied the weak fluorescence from the dimer of eosin Y (EY) in aqueous solutions. We used a newly developed ultrathin optical cell with a thickness ranging from of the order of microns to several hundreds of microns to successfully measure the fluorescence spectra of highly concentrated aqueous solutions of EY without artifacts caused by the reabsorption of fluorescence. The spectra we obtained were similar to the fluorescence spectrum of the EY monomer; almost no fluorescence was observed from the EY dimer...
May 17, 2018: Photochemical & Photobiological Sciences
Yang Chen, Jine Wang, Yajie Zhang, Lijun Xu, Tian Gao, Bing Wang, Renjun Pei
Aptamers are short single-stranded DNA or RNA, which can be selected in vitro by systematic evolution of ligands by exponential enrichment (SELEX). In order to develop novel light-up probes to substitute G-quadruplex (G4), we selected a DNA aptamer for crystal violet (CV), a triphenylmethane light-up dye, by a modified affinity chromatography-based SELEX. The ssDNA pool was first coupled on streptavidin-coated agarose beads through a biotin labeled complementary oligonucleotide, and then the aptamer sequences would be released from agarose beads by CV affinity...
May 17, 2018: Photochemical & Photobiological Sciences
Hajime Maeda, Tsubasa Suzuki, Masahito Segi
1,3,6,8-Tetrasilylpyrenes and related germyl and stannyl derivatives were synthesized, and their absorption and fluorescence spectroscopic and structural properties were elucidated. The results show that the UV-vis absorption maxima of these substances in CH2Cl2 solutions shift to longer wavelengths as the size of the alkyl groups and numbers of phenyl groups on silicon increase. Fluorescence quantum yields of tetrasilylpyrenes in cyclohexane are larger than that of pyrene, and a pentamethyldisilyl derivative has an emission efficiency of 0...
May 9, 2018: Photochemical & Photobiological Sciences
H A Schwartz, U Ruschewitz, L Heinke
Smart, molecularly structured materials with remote-controllable properties and functionalities attract particular attention and may enable advanced applications. In this respect, the embedment of stimuli-responsive molecules, such as azobenzenes, spiropyrans or diarylethenes, in metal-organic frameworks (MOFs) is a very fascinating approach, resulting in easily accessible photoswitchable, nanoporous hybrid materials. It is an attractive alternative to the incorporation of the smart moieties in the MOF scaffold, which usually demands complex synthetic efforts...
May 8, 2018: Photochemical & Photobiological Sciences
Davis P Plasko, Christopher J Jordan, Brittney E Ciesa, Madison A Merrill, James M Hanna
A mild, redox-neutral, alkylation of imines with potassium alkyltrifluoroborates is described. The reaction proceeds under photoredox conditions at ∼30 °C with primary, secondary, and tertiary alkyltrifluoroborates, leading to alkylation products in moderate to good yield in most cases. Aryl-, vinyl-, and cyclopropyltrifluoroborates failed to react under the reported conditions.
May 3, 2018: Photochemical & Photobiological Sciences
Lorenzo Casimiro, Jessica Groppi, Massimo Baroncini, Marcello La Rosa, Alberto Credi, Serena Silvi
Among the plethora of photochromes reported so far, azobenzene has been proven to be the most suitable photoswitch for molecular systems and materials, due to its highly efficient and clean E-Z photoisomerization. Here we report two ammonium-based molecular axles bearing one or two p-cyanoazobenzene units at the extremities, able to form pseudorotaxanes with a crown ether macrocycle. The photochemistry of these compounds was studied in the isolated forms and in the pseudorotaxanes, showing that the functionalization speeds up the threading process without affecting the photochemical properties of the system...
May 3, 2018: Photochemical & Photobiological Sciences
(no author information available yet)
No abstract text is available yet for this article.
May 3, 2018: Photochemical & Photobiological Sciences
Johannes R Klein, Mirko Scholz, Kawon Oum, Thomas Lenzer
We present steady-state and time-resolved spectroscopic investigations combined with detailed kinetic modelling for the triarylamine derivatives X60 and PTAA which serve as hole transport materials (HTMs) in perovskite solar cells and represent model compounds for organic electronic materials. Photoexcitation of the spiro-fluorene-xanthene X60 populates its S1 state which decays via intersystem crossing (ISC) as well as fluorescence and internal conversion on a nanosecond time scale. Photoexcitation of the PTAA polymer leads to the formation of singlet excitons which relax and migrate in the time regime from a few to about a hundred picoseconds and decay to the ground state with a lifetime of ca...
May 3, 2018: Photochemical & Photobiological Sciences
R S Dawe, J Ferguson, S Ibbotson, L Lawrence, S Paulson, E Duffy, S Cammarata
AIMS: Delafloxacin is a fluoroquinolone antibiotic recently approved by the FDA for treatment of acute bacterial skin and skin structure infections (ABSSSI). Delafloxacin was assessed for phototoxicity potential compared with a known phototoxic fluoroquinolone. METHODS: A Phase 1, investigator-blind, placebo/active-controlled, randomized, parallel-group study was conducted in 52 healthy male and female volunteers who received 200 or 400 mg of oral delafloxacin, 400 mg oral lomefloxacin or placebo once daily for 6 days...
May 3, 2018: Photochemical & Photobiological Sciences
Dumitru Sirbu, Owen J Woodford, Andrew C Benniston, Anthony Harriman
Two Chromophore-Quencher Conjugates (CQCs) have been synthesized by covalent attachment of the anti-oxidant dibutylated-hydroxytoluene (BHT) to a pyrrole-BF2 chromophore (BOPHY) in an effort to protect the latter against photofading. In fluid solution, light-induced intramolecular charge transfer is favoured in polar solvents and helps to inhibit photo-bleaching of the chromophore. The rate of photo-fading, which scales with the number of BHT residues, is zero-order in polar solvents but shows a linear dependence on the number of absorbed photons...
May 2, 2018: Photochemical & Photobiological Sciences
Dohyun Kim, Mi Hee Lee, Min-Ah Koo, Byeong-Ju Kwon, Min Sung Kim, Gyeung Mi Seon, Seung Hee Hong, Jong-Chul Park
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...
May 2, 2018: Photochemical & Photobiological Sciences
Gabriela Ortega, Jesús Hernández, Teresa González, Romano Dorta, Alexander Briceño
The crystal engineering of hydrogen bonded organic assemblies based on 1,2,4,5-benzenetetracarboxylic acid (H4bta) and stilbazole derivatives (1-10) is exploited to provide regio-controlled [2 + 2] photocycloadditions in the solid state. Single crystal X-ray diffraction analyses have revealed that all the arrays are built-up from the self-assembly of the (H2bta)2- dianion with two stilbazolium cations via O-HO- and N+-HO- charge-assisted H-bonding synthons: (4-Hstilbazolium+)2(H2bta2-). The dianion displays an interesting diversity of H-bonding motifs...
May 2, 2018: Photochemical & Photobiological Sciences
Eduard Stadler, Anna Eibel, David Fast, Hilde Freißmuth, Christian Holly, Mathias Wiech, Norbert Moszner, Georg Gescheidt
We have developed a simple method for determining the quantum yields of photo-induced reactions. Our setup features a fibre coupled UV-Vis spectrometer, LED irradiation sources, and a calibrated spectrophotometer for precise measurements of the LED photon flux. The initial slope in time-resolved absorbance profiles provides the quantum yield. We show the feasibility of our methodology for the kinetic analysis of photochemical reactions and quantum yield determination. The typical chemical actinometers, ferrioxalate and ortho-nitrobenzaldehyde, as well as riboflavin, a spiro-compound, phosphorus- and germanium-based photoinitiators for radical polymerizations and the frequently utilized photo-switch azobenzene serve as paradigms...
May 1, 2018: Photochemical & Photobiological Sciences
M Paula Militello, Marcela S Altamirano, Sonia G Bertolotti, Carlos M Previtali
The interaction of the singlet and triplet excited states of the synthetic dye safranine-O with carboxyl-terminated poly(amidoamine) (PAMAM) dendrimers was investigated in a buffer solution at pH 8. Low half-generation PAMAM dendrimers (G -0.5; G +0.5: G 1.5) were employed. The UV-vis absorption spectrum of the dye presents only a very small red shift in the presence of dendrimers. Fluorescence quenching was detected and it was interpreted by a static mechanism in terms of the association of the dye with the dendrimer...
April 30, 2018: Photochemical & Photobiological Sciences
Liyi Huang, Min Wang, Ying-Ying Huang, Ahmed El-Hussein, Lawrence M Wolf, Long Y Chiang, Michael R Hamblin
It is known that multiple cationic charges are required to produce broad-spectrum antimicrobial photosensitizers (PS) for photodynamic inactivation (aPDI) or photodynamic therapy of bacteria and fungi. In the present study we describe the synthesis and aPDI testing of a set of derivatives prepared from the parent pheophytin molecule with different numbers of attached side arms (1-3) each consisting of five quaternized cationic groups (pentacationic), producing the corresponding [Zn2+]pheophorbide-a-N(C2N+C1C3)5 (Zn-Phe-N5+, 5 charges), [Zn2+]chlorin e6-[N(C2N+C1C3)5]2 (Zn-Chl-N10+, 10 charges) and [Zn2+]mesochlorin e6-[N(C2N+C1C3)5]3 (Zn-mChl-N15+, 15 charges)...
April 27, 2018: Photochemical & Photobiological Sciences
Haydar Ali, Nikhil R Jana
Bisphenol A is a well-known endocrine disruptor that comes from plastic/epoxy resin-based consumer products, pollutes our environment and is responsible for various human diseases. Thus, its removal from water/food/the environment is becoming a challenging issue. Here we report the visible light photocatalytic degradation of bisphenol A using a gold nanoparticle based composite with reduced graphene oxide. The nanocomposite captures visible light and produces hydroxyl radicals that oxidize bisphenol A into smaller organic fragments such as phenol derivatives and aliphatic aldehydes/ketones...
April 26, 2018: Photochemical & Photobiological Sciences
Toshiko Mizokuro, Aizitiaili Abulikemu, Yusuke Sakagami, Tetsuro Jin, Kenji Kamada
The room-temperature phosphorescence chromophore, Pt(ii) coproporphyrin I (PtCP), was fixed on the surface of a 3D-network of nanoscale pores of porous glass through ion-exchange reaction. The absorption and phosphorescence spectra indicated that PtCP can be loaded while maintaining monomeric dispersion at concentrations well beyond solubility limits of PtCP in solution. The phosphorescence quantum yield of PtCP fixed on the surface was also found to have double the enhancement of solution. The extended lifetime of phosphorescence of PtCP bonded on the surface compared to that in solution clearly indicated that suppression of nonradiative deactivation plays a key role in high quantum yield and long triplet lifetime...
April 26, 2018: Photochemical & Photobiological Sciences
Nisamanee Charoenchon, Lesley E Rhodes, Suzanne M Pilkington, Mark D Farrar, Rachel E B Watson
Long-term exposure of human skin to ultraviolet radiation (UVR) in sunlight negatively impacts its appearance and function with photoaged skin having a characteristic leathery, rough appearance, with deep wrinkles. These clinical features of photodamage are thought to result from UVR-induced remodelling of the dermal extracellular matrix, particularly the elastic fibre system. There are few in vivo human data on the impact of acute UVR exposure on this fibre system and particularly solar-simulated radiation (SSR)-mediated effects...
April 26, 2018: Photochemical & Photobiological Sciences
Tatjana Repenko, Anne Rix, Bastian Haehnle, Wiltrud Lederle, Laura De Laporte, Alexander J C Kuehne
Photoacoustic imaging presents an innocuous imaging modality with good penetration depth and resolution. To use this modality for detection and imaging of pathological sites, new imaging probes need to be developed to enhance the contrast over endogenous sonophores. These contrast agents should specifically bind to the site of interest, be non-toxic and be cleared renally if applied intravenously. Small organic dyes with absorption in the near infrared spectrum often exhibit good photoacoustic response. However, such dyes are often not water soluble or they are cytotoxic...
April 24, 2018: Photochemical & Photobiological Sciences
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"