scholarly journals Visible-Light Photoswitching of G-Quadruplex Ligand Binding Mode Allows Reversible Control of G-Tetrad Structure

2020 ◽  
Author(s):  
Michael O'Hagan ◽  
Javier Ramos Soriano ◽  
Susanta Haldar ◽  
Juan Carlos Morales ◽  
Adrian Mulholland ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Visible Light ◽  
Uv Light ◽  
Binding Mode ◽  
High Energy ◽  
Light Sources ◽  
Biologically Relevant ◽  
G Quadruplex ◽  
Potential Applications ◽  
Robust Regulation

<div><p>Photoresponsive ligands for G-quadruplex oligonucleotides (G4) offer exciting opportunities for the reversible regulation of these assemblies with potential applications in biological chemistry and responsive nanotechnology. However, achieving the robust regulation of G4 ligand activity with low-energy visible light sources that are easily accessible and compatible with biological systems remains a significant challenge to realizing these applications. Herein, we report the G4-binding properties of a photoresponsive dithienylethene (DTE). We demonstrate the first example of G4-specific acceleration of the photoswitching kinetics of a small molecule and the visible-light mediated switching of the G4 ligand binding mode in physiologically-relevant conditions, which in turn allows control over the G4 tetrad structure of telomeric G4 in potassium buffer. The process is fully reversible and avoids the need for high-energy UV light. This affords an efficient, practical and biologically-relevant means of control that may be applied in the generation of new responsive G4/ligand supramolecular systems.</p></div><br>

scholarly journals Visible-Light Photoswitching of G-Quadruplex Ligand Binding Mode Allows Reversible Control of G-Tetrad Structure

2020 ◽  
Author(s):  
Michael O'Hagan ◽  
Javier Ramos Soriano ◽  
Susanta Haldar ◽  
Juan Carlos Morales ◽  
Adrian Mulholland ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Visible Light ◽  
Uv Light ◽  
Binding Mode ◽  
High Energy ◽  
Light Sources ◽  
Biologically Relevant ◽  
G Quadruplex ◽  
Potential Applications ◽  
Robust Regulation

<div><p>Photoresponsive ligands for G-quadruplex oligonucleotides (G4) offer exciting opportunities for the reversible regulation of these assemblies with potential applications in biological chemistry and responsive nanotechnology. However, achieving the robust regulation of G4 ligand activity with low-energy visible light sources that are easily accessible and compatible with biological systems remains a significant challenge to realizing these applications. Herein, we report the G4-binding properties of a photoresponsive dithienylethene (DTE). We demonstrate the first example of G4-specific acceleration of the photoswitching kinetics of a small molecule and the visible-light mediated switching of the G4 ligand binding mode in physiologically-relevant conditions, which in turn allows control over the G4 tetrad structure of telomeric G4 in potassium buffer. The process is fully reversible and avoids the need for high-energy UV light. This affords an efficient, practical and biologically-relevant means of control that may be applied in the generation of new responsive G4/ligand supramolecular systems.</p></div><br>

scholarly journals Visible-Light Photoswitching of G-Quadruplex Ligand Binding Mode Allows Reversible Control of G-Tetrad Structure

2020 ◽  
Author(s):  
Michael O'Hagan ◽  
Javier Ramos Soriano ◽  
Susanta Haldar ◽  
Juan Carlos Morales ◽  
Adrian Mulholland ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Visible Light ◽  
Uv Light ◽  
Binding Mode ◽  
High Energy ◽  
Light Sources ◽  
Biologically Relevant ◽  
G Quadruplex ◽  
Potential Applications ◽  
Robust Regulation

<div><p>Photoresponsive ligands for G-quadruplex oligonucleotides (G4) offer exciting opportunities for the reversible regulation of these assemblies with potential applications in biological chemistry and responsive nanotechnology. However, achieving the robust regulation of G4 ligand activity with low-energy visible light sources that are easily accessible and compatible with biological systems remains a significant challenge to realizing these applications. Herein, we report the G4-binding properties of a photoresponsive dithienylethene (DTE). We demonstrate the first example of G4-specific acceleration of the photoswitching kinetics of a small molecule and the visible-light mediated switching of the G4 ligand binding mode in physiologically-relevant conditions, which in turn allows control over the G4 tetrad structure of telomeric G4 in potassium buffer. The process is fully reversible and avoids the need for high-energy UV light. This affords an efficient, practical and biologically-relevant means of control that may be applied in the generation of new responsive G4/ligand supramolecular systems.</p></div><br>

scholarly journals Visible-light photoswitching of ligand binding mode suggests G-quadruplex DNA as a target for photopharmacology

2020 ◽  
Vol 56 (38) ◽  
pp. 5186-5189 ◽  
Author(s):  
Michael P. O’Hagan ◽  
Javier Ramos-Soriano ◽  
Susanta Haldar ◽  
Sadiyah Sheikh ◽  
Juan C. Morales ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Visible Light ◽  
Binding Mode ◽  
Quadruplex Dna ◽  
G Quadruplex

A pyridinium-decorated photoresponsive dithienylethene selectively targets G-quadruplex DNA, allowing binding mode and toxicity to be controlled exclusively with visible light.

scholarly journals Visible Light-Enabled Paternò-Büchi Reaction via Triplet Energy Transfer for the Synthesis of Oxetanes

2020 ◽  
Author(s):  
Katie Rykaczewski ◽  
Corinna Schindler
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Uv Light ◽  
Cycloaddition Reaction ◽  
High Energy ◽  
Triplet Energy ◽  
Reaction Conditions ◽  
Triplet Energy Transfer

<div> <p>One of the most efficient ways to synthesize oxetanes is the light-enabled [2+2] cycloaddition reaction of carbonyls and alkenes, referred to as the Paternò-Büchi reaction. The reaction conditions for this transformation typically require the use of high energy UV light to excite the carbonyl, limiting the applications, safety, and scalability. We herein report the development of a visible light-mediated Paternò-Büchi reaction protocol that relies on triplet energy transfer from an iridium-based photocatalyst to the carbonyl substrates. This mode of activation is demonstrated for a variety of aryl glyoxylates and negates the need for both, visible light-absorbing carbonyl starting materials or UV light to enable access to a variety of functionalized oxetanes in up to 99% yield.</p> </div> <br>

scholarly journals Zn Doped α-Fe2O3: An Efficient Material for UV Driven Photocatalysis and Electrical Conductivity

Crystals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 273 ◽  
Author(s):  
Suman ◽  
Surjeet Chahal ◽  
Ashok Kumar ◽  
Parmod Kumar
Keyword(s):  
Band Gap ◽  
Room Temperature ◽  
Uv Light ◽  
Sol Gel ◽  
High Energy ◽  
Lattice Parameter ◽  
Dielectric Behavior ◽  
Energy Storage Devices ◽  
Vis Spectroscopy ◽  
Potential Applications

Zinc (Zn) doped hematite (α-Fe2O3) nanoparticles with varying concentrations (pure, 2%, 4% and 6%) were synthesized via sol-gel method. The influence of divalent Zn ions on structural, optical and dielectric behavior of hematite were studied. X-ray diffraction (XRD) pattern of synthesized samples were indexed to rhombohedral R3c space group of hematite with 14–21 nm crystallite size. The lattice parameter (a and c) values increase upto Zn 4% and decrease afterwards. The surface morphology of prepared nanoparticles were explored using transmission electron microscopy (TEM). The band gap measured from Tauc’s plot, using UV-Vis spectroscopy, showed reduction in its values upto Zn 4% and the reverse trend was obtained in higher concentrations. The dielectric properties of pure and Zn doped hematite were investigated at room temperature and followed the same trends as that of XRD parameters and band gap. Photocatalytic properties of nanoparticles were performed for hazardous Rose bengal dye and showed effective degradation in the presence of UV light. Hence, Zn2+ doped hematite can be considered as an efficient material for the potential applications in the domain of photocatalysis and also higher value of dielectric constant at room temperature makes them applicable in high energy storage devices.

scholarly journals Study on influencing factors of photocatalytic performance of CdS/TiO2 nanocomposite concrete

2020 ◽  
Vol 9 (1) ◽  
pp. 1160-1169
Author(s):  
Kang He ◽  
Yu Chen ◽  
Mengjun Mei
Keyword(s):  
High Temperature ◽  
Visible Light ◽  
Photocatalytic Performance ◽  
Catalytic Efficiency ◽  
High Energy ◽  
Temperature Treatment ◽  
High Temperature Treatment ◽  
Light Sources ◽  
Photocatalytic Efficiency ◽  
Photocatalytic Concrete

AbstractIn this study, a high-energy ball mill was used to composite nano-TiO2 and CdS, and three kinds of nanocomposite photocatalysts TiO2, CdS/TiO2-R400, and CdS/TiO2-R600 were prepared, which can respond to visible light. The photocatalytic concrete test block was prepared by mixing the nanocomposite photocatalyst and other masses with cement by incorporation method. To study the effect of the photocatalyst content on the photocatalytic performance of nanoconcrete, a total of four catalyst contents (0, 2%, 5%, and 8%) were set. The effects of high-temperature treatment (400°C) and different light sources (ultraviolet and visible light) on photocatalytic efficiency were also considered. The results show that the catalytic efficiency of CdS/TiO2-R400 under two light sources is higher than that of the other two photocatalysts. Compared to ultraviolet light sources, the photocatalytic efficiency of CdS/TiO2 nanocomposite concrete under visible light is lower, and the efficiency is below 9%. The optimal amounts of CdS/TiO2 nanocomposite photocatalyst under ultraviolet and visible light are 2% and 5%, respectively. The high-temperature treatment can improve the photocatalytic performance of CdS/TiO2 nanocomposite photocatalyst by 2% to 3%.

scholarly journals Probing Ligand and Cation Binding Sites in G-Quadruplex Nucleic Acids by Mass Spectrometry and Electron Photodetachment Dissociation Sequencing

2019 ◽  
Author(s):  
Dababrata Paul ◽  
Adrien Marchand ◽  
Daniela Verga ◽  
Marie-Paule Teulade-Fichou ◽  
Sophie Bombard ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Ligand Binding ◽  
Binding Sites ◽  
Binding Mode ◽  
Cation Binding ◽  
Potassium Cation ◽  
Telomeric Sequences ◽  
G Quadruplex ◽  
Electron Photodetachment ◽  
Noncovalent Bonds

ABSTRACTMass spectrometry provides exquisite detail on ligand and cation binding stoichiometries with a DNA target. The next important step is to develop reliable methods to determine the cation and ligand binding sites in each complex separated by the mass spectrometer. To circumvent the caveat of ligand derivatization for cross-linking, which may alter the ligand binding mode, we explored a tandem mass spectrometry (MS/MS) method that does not require ligand derivatization, and is therefore also applicable to localize metal cations. By obtaining more negative charge states for the complexes using supercharging agents, and by creating radical ions by electron photodetachment, oligonucleotide bonds become weaker than the DNA-cation or DNA-ligand noncovalent bonds upon collision-induced dissociation of the radicals. This electron photodetachment (EPD) method allows to locate the binding regions of cations and ligands by top-down sequencing of the oligonucleotide target. The very potent G-quadruplex ligands 360A and PhenDC3 were found to replace a potassium cation and bind close to the central loop of 4-repeat human telomeric sequences.

Experimental Characterization and Modeling of Photon Upconversion in Azobenzene Photomechanical Polymers

2015 ◽  
Author(s):  
Sadiyah Sabah Chowdhury ◽  
Catherine Kent ◽  
Sean P. Hill ◽  
Enric Baduell ◽  
Kenneth Hanson ◽  
...  
Keyword(s):  
Visible Light ◽  
Energy Conversion ◽  
Uv Light ◽  
Green Light ◽  
High Energy ◽  
Photochemical Reactions ◽  
Low Energy ◽  
Mechanical Work ◽  
Solar Irradiation ◽  
Azobenzene Polymer

Azobenzene polymers show promising photostrictive behavior for a broad range of applications in flow control, robotics, and energy harvesting applications. The conversion of solar energy directly into mechanical work provides unique capabilities in adaptive structures; however, the energy conversion of visible light into mechanical work presents several material chemistry challenges. Azobenzene strongly absorbs ultraviolet (UV) light and blue/green light which limits the efficiency of the photomechanical response under solar irradiation. Photon upconversion — combining two or more low energy photons (longer wavelength) to generate a higher energy excited state (shorter wavelength), provides an intriguing strategy to drive these high energy photochemical reactions with low energy light. We present an experimental study showing the feasibility to drive azobenzene photoisomerization using visible light via select up-conversion molecules in the fluidic state. Multi-physics modeling is then used to predict advances in photomechanical energy conversion when up-conversion molecules are introduced within an azobenzene polymer.

scholarly journals Degradation of Phenol By Photolysis Using N-doped TiO2 Catalyst

Molekul ◽  
2019 ◽  
Vol 14 (1) ◽  
pp. 6
Author(s):  
Safni Safni ◽  
Mechy Rezita Wahyuni ◽  
Khoiriah Khoiriah ◽  
Yulizar Yusuf
Keyword(s):  
Blood Pressure ◽  
Visible Light ◽  
Uv Light ◽  
Phenol Degradation ◽  
Light Sources ◽  
Lower Blood Pressure ◽  
Dose Irradiation ◽  
Lower Blood ◽  
Liver And Kidney ◽  
Liver And Kidney Damage

Phenol (C6H5OH) is a common contaminant in wastewater. In certain concentrations, phenol can inhibit the activity of microorganisms and give adverse effects tohumanhealth, such as liver and kidney damage, perfect heart rate, and lower blood pressure. In this study, phenol was degraded with andwithoutN-doped TiO2under photolysis UV-light (10 Watts, λ = 365 nm) and visible-light (13 watt Philips, lux= 1400, λ = 465-640 nm)irradiation. The reductionof phenol concentrationwas measured by a UV-Vis spectrophotometer at a wavelength 200-400 nm. Some parameters such as catalyst dose, irradiation timesand type of light sources were studied. The XRD and DRS UV-Vis characterization confirmthat the nitrogen modified of titania catalyst potentially actives in visible-light. The N-doped TiO2is able to catalyze and improve the efficiency of phenol degradation in photocatalysissystem. Phenol with initialconcentration 8 mg/L was degraded by 33.89% and 30.51% without catalyst and increased to be 90.8% and 67.80%by additionof 15 mg N-doped TiO2catalyst under UV-light and visible-lightfor 210 minutes photolysis, respectively. From the results,irradiation using UV-light achieveshigherefficiency than visible-lightonphenol degradation.

scholarly journals Co-harvesting Solar Energy with Ambient Heat and On-Demand Release of Thermal Energy Below 0 oC Through Visible-Light-Controlled Photochemical Phase Transitions of Azopyrazoles

2021 ◽  
Author(s):  
Zhichun Shangguan ◽  
Wenjin Sun ◽  
Zhao-yang Zhang ◽  
Dong Fang ◽  
Si Wu ◽  
...  
Keyword(s):  
Visible Light ◽  
Uv Light ◽  
Green Light ◽  
High Energy ◽  
Solar Thermal ◽  
High Energy Density ◽  
On Demand ◽  
Thermal Batteries ◽  
Liquid Transition ◽  
532 Nm

Photochemical crystal-to-liquid transition generally needs UV light as a stimulus and it is even more challenging to carry out below 0 oC. Here, we design a series of 4-alkylthioarylazopyrazoles as molecular solar thermal batteries, which show bidirectional visible-light-triggered photochemical trans-crystal ↔ cis-liquid transitions below ice point (-1 oC). Through co-harvesting visible-light energy and low-temperature ambient heat, high energy density (0.25 MJ kg-1) is achieved. Further, the rechargeable solar thermal batteries devices are fabricated, which can be charged by blue light (400 nm) at -1 oC. Then, the charged devices can release energy on demand in the form of high-temperature heat. Under green light (532 nm) irradiation, the temperature difference between the charged devices and the ice-cold surrounding is up to 13.5 oC. This study paves the way for the design of advanced molecular solar thermal batteries that store both natural sunlight and ambient heat over a wide temperature range.

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