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Experimental Eye Research Dec 2014The fact that light is necessary for life is generally accepted as an axiom. The extent to which light interacts and influences human biology, however, is often not... (Review)
Review
The fact that light is necessary for life is generally accepted as an axiom. The extent to which light interacts and influences human biology, however, is often not fully appreciated. Exposure to sunlight, for instance, can both promote and degrade human health. There is now general scientific consensus that, although the eye evolved to respond to light, it is also damaged by excessive exposure. Light-mediated ocular damage is involved in the pathophysiology of many common forms of blindness. The type of ocular tissue damage induced by light exposure depends on the extent of exposure and wavelength. The tissues of the lens, cornea, and retina contain specific chemical moieties that have been proven to exhibit light-mediated oxidative degradation. Proteins and lipids present in the cornea, lens, and retina, meet all of the physical requirements known to initiate the process of oxidative photodegradation upon exposure to solar radiation. As such, different mechanisms have evolved in the lens, cornea, and retina to ameliorate such light-mediated oxidative damage. It appears, however, that such mechanisms are ill-matched to handle modern conditions: namely, poor diet and longer life-spans (and the degenerative diseases that accompany them). Hence, steps must be taken to protect the eye from the damaging effects of light. Preventative measures include minimizing actinic light exposure, providing exogenous filtering (e.g., through the use of protective lenses), and enhancing antioxidant defenses (e.g., through increased dietary intake of antioxidants). These strategies may yield long-term benefits in terms of reducing oxidative photodegradation of the ocular tissues.
Topics: Antioxidants; Eye; Eye Protective Devices; Humans; Oxidation-Reduction; Photolysis; Sunlight
PubMed: 25236792
DOI: 10.1016/j.exer.2014.09.005 -
Molecules (Basel, Switzerland) Oct 2022The need for fresh and conveniently treated water has become a major concern in recent years. Molybdenum disulfide (MoS) nanomaterials are attracting attention in... (Review)
Review
The need for fresh and conveniently treated water has become a major concern in recent years. Molybdenum disulfide (MoS) nanomaterials are attracting attention in various fields, such as energy, hydrogen production, and water decontamination. This review provides an overview of the recent developments in MoS-based nanomaterials for water treatment via adsorption and photodegradation. Primary attention is given to the structure, properties, and major methods for the synthesis and modification of MoS, aiming for efficient water-contaminant removal. The combination of MoS with other components results in nanocomposites that can be separated easily or that present enhanced adsorptive and photocatalytic properties. The performance of these materials in the adsorption of heavy metal ions and organic contaminants, such as dyes and drugs, is reviewed. The review also summarizes current progress in the photocatalytic degradation of various water pollutants, using MoS-based nanomaterials under UV-VIS light irradiation. MoS-based materials showed good activity after several reuse cycles and in real water scenarios. Regarding the ecotoxicity of the MoS, the number of studies is still limited, and more work is needed to effectively evaluate the risks of using this nanomaterial in water treatment.
Topics: Photolysis; Adsorption; Molybdenum; Water Pollutants; Water Pollutants, Chemical; Nanocomposites; Metals, Heavy; Coloring Agents; Hydrogen
PubMed: 36296375
DOI: 10.3390/molecules27206782 -
Scientific Reports Oct 2018DNA microarrays are important analytical tools in genetics and have recently found multiple new biotechnological roles in applications requiring free 3' terminal...
DNA microarrays are important analytical tools in genetics and have recently found multiple new biotechnological roles in applications requiring free 3' terminal hydroxyl groups, particularly as a starting point for enzymatic extension via DNA or RNA polymerases. Here we demonstrate the highly efficient reverse synthesis of complex DNA arrays using a photolithographic approach. The method is analogous to conventional solid phase synthesis but makes use of phosphoramidites with the benzoyl-2-(2-nitrophenyl)-propoxycarbonyl (BzNPPOC) photolabile protecting group on the 3'-hydroxyl group. The use of BzNPPOC, with more than twice the photolytic efficiency of the 2-(2-nitrophenyl)-propoxycarbonyl (NPPOC) previously used for 5'→3' synthesis, combined with additional optimizations to the coupling and oxidation reactions results in an approximately 3-fold improvement in the reverse synthesis efficiency of complex arrays of DNA oligonucleotides. The coupling efficiencies of the reverse phosphoramidites are as good as those of regular phosphoramidites, resulting in comparable yields. Microarrays of DNA surface tethered on the 5' end and with free 3' hydroxyl termini can be synthesized quickly and with similarly high stepwise coupling efficiency as microarrays using conventional 3'→5' synthesis.
Topics: DNA; Fluorescence; Gene Expression Regulation; Oligonucleotide Array Sequence Analysis; Organophosphorus Compounds; Photolysis; Time Factors
PubMed: 30305718
DOI: 10.1038/s41598-018-33311-3 -
Molecules (Basel, Switzerland) Mar 2017Molecular Modeling methods play a very important role in TiO₂ photocatalysis. Recent advances in TiO₂ photocatalysis have produced a number of interesting surface... (Review)
Review
Molecular Modeling methods play a very important role in TiO₂ photocatalysis. Recent advances in TiO₂ photocatalysis have produced a number of interesting surface phenomena, reaction products, and various novel visible light active photocatalysts with improved properties. Quantum mechanical calculations appear promising as a means of describing the mechanisms and the product distributions of the photocatalytic degradation reactions of organic pollutants in both gas and aqueous phases. Since quantum mechanical methods utilize the principles of particle physics, their use may be extended to the design of new photocatalysts. This review introduces molecular modeling methods briefly and emphasizes the use of these methods in TiO₂ photocatalysis. The methods used for obtaining information about the degradabilities of the pollutant molecules, predicting reaction mechanisms, and evaluating the roles of the dopants and surface modifiers are explained.
Topics: Catalysis; Models, Molecular; Molecular Dynamics Simulation; Photolysis; Quantum Theory; Surface Properties; Titanium
PubMed: 28358308
DOI: 10.3390/molecules22040556 -
Ecotoxicology and Environmental Safety Sep 2023Glyphosate is the most widely used herbicide in global agricultural cultivation. However, little is known about the environmental risks associated with its migration and...
Glyphosate is the most widely used herbicide in global agricultural cultivation. However, little is known about the environmental risks associated with its migration and transformation. We conducted light irradiation experiments to study the dynamics and mechanism of photodegradation of glyphosate in ditches, ponds and lakes, and evaluated the effect of glyphosate photodegradation on algae growth through algae culture experiments. Our results showed that glyphosate in ditches, ponds and lakes could undergo photochemical degradation under sunlight irradiation with the production of phosphate, and the photodegradation rate of glyphosate in ditches could reach 86% after 96 h under sunlight irradiation. Hydroxyl radicals (•OH) was the main reactive oxygen species (ROS) for glyphosate photodegradation, and its steady-state concentrations in ditches, ponds and lakes were 6.22 × 10, 4.73 × 10, and 4.90 × 10 M. The fluorescence emission-excitation matrix (EEM) and other technologies further indicated that the humus components in dissolved organic matter (DOM) and nitrite were the main photosensitive substances producing •OH. In addition, the phosphate generated by glyphosate photodegradation could greatly promote the growth of Microcystis aeruginosa, thereby increasing the risk of eutrophication. Thus, glyphosate should be scientifically and reasonably applied to avoid environmental risks.
Topics: Photolysis; Water; Sunlight; Water Pollutants, Chemical; Phosphates; Glyphosate
PubMed: 37418942
DOI: 10.1016/j.ecoenv.2023.115211 -
ACS Chemical Neuroscience Oct 2017We have made a new caged cGMP that is photolyzed with blue light. Using our recently developed derivative of 7-diethylaminocourmarin (DEAC) called DEAC450, we...
We have made a new caged cGMP that is photolyzed with blue light. Using our recently developed derivative of 7-diethylaminocourmarin (DEAC) called DEAC450, we synthesized coumarin phosphoester derivatives of cGMP with two negative charges appended to the DEAC450 moiety. DEAC450-cGMP is freely soluble in physiological buffer without the need for any organic cosolvents. With a photolysis quantum yield of 0.18 and an extinction coefficient of 43 000 M cm at 453 nm, DEAC450-cGMP is the most photosensitive caged cGMP made to date. In patch-clamped neurons in acutely isolated brain slices, blue light effectively uncaged cGMP from DEAC450 and facilitated activation of hyperpolarization and cyclic nucleotide gated cation (HCN) channels in cholinergic interneurons. Thus, DEAC450-cGMP has a unique set of optical and chemical properties that make it a useful addition to the optical arsenal available to neurobiologists.
Topics: Animals; Coumarins; Cyclic AMP; Cyclic GMP; Cyclic Nucleotide-Gated Cation Channels; Extracellular Space; Light; Mice; Neurons; Photolysis
PubMed: 28762726
DOI: 10.1021/acschemneuro.7b00237 -
Biomolecules Aug 2020Free-radical-mediated processes, such as peroxidation, isomerization and hydrogenation affecting fatty acid integrity and biological functions, have a trans-disciplinary...
Free-radical-mediated processes, such as peroxidation, isomerization and hydrogenation affecting fatty acid integrity and biological functions, have a trans-disciplinary relevance. Cardiolipins (CL, (1,3-diphosphatidyl--glycerol)) and tetra-linoleoyl-CL are complex phospholipids, exclusively present in the Inner Mitochondrial Membrane (IMM) lipids, where they maintain membrane integrity and regulate enzyme functionalities. Peroxidation pathways and fatty acid remodeling are known causes of mitochondrial disfunctions and pathologies, including cancer. Free-radical-mediated isomerization with the change of the cis CL into geometrical trans isomers is an unknown process with possible consequences on the supramolecular membrane lipid organization. Here, the formation of mono-trans CL (MT-CL) and other trans CL isomers (T-CL) is reported using CL from bovine heart mitochondria and thiyl radicals generated by UV-photolysis from 2-mercaptoethanol. Analytical approaches for CL isomer separation and identification via H/C NMR are provided, together with the chemical study of CL derivatization to fatty acid methyl esters (FAME), useful for lipidomics and metabolomics research. Kinetics information of the radical chain isomerization process was obtained using γ-irradiation conditions. The CL isomerization affected the structural organization of membranes, as tested by the reduction in unilamellar liposome diameter, and accompanied the well-known process of oxidative consumption induced by Fenton reagents. These results highlight a potential new molecular modification pathway of mitochondrial lipids with wide applications to membrane functions and biological consequences.
Topics: Animals; Cardiolipins; Cattle; Chromatography, Gas; Isomerism; Kinetics; Lipid Peroxidation; Lipidomics; Mercaptoethanol; Mitochondria, Heart; Mitochondrial Membranes; Photolysis
PubMed: 32824246
DOI: 10.3390/biom10081189 -
Journal of the American Chemical Society Jul 2022Photolabile protecting groups (PPGs) enable the precise activation of molecular function with light in many research areas, such as photopharmacology, where remote...
Photolabile protecting groups (PPGs) enable the precise activation of molecular function with light in many research areas, such as photopharmacology, where remote spatiotemporal control over the release of a molecule is needed. The design and application of PPGs in recent years have particularly focused on the development of molecules with high molar absorptivity at long irradiation wavelengths. However, a crucial parameter, which is pivotal to the efficiency of uncaging and which has until now proven highly challenging to improve, is the photolysis quantum yield (QY). Here, we describe a novel and general approach to greatly increase the photolysis QY of heterolytic PPGs through stabilization of an intermediate chromophore cation. When applied to coumarin PPGs, our strategy resulted in systems possessing an up to a 35-fold increase in QY and a convenient fluorescent readout during their uncaging, all while requiring the same number of synthetic steps for their preparation as the usual coumarin systems. We demonstrate that the same QY engineering strategy applies to different photolysis payloads and even different classes of PPGs. Furthermore, analysis of the DFT-calculated energy barriers in the first singlet excited state reveals valuable insights into the important factors that determine photolysis efficiency. The strategy reported herein will enable the development of efficient PPGs tailored for many applications.
Topics: Cations; Coumarins; Photolysis
PubMed: 35775744
DOI: 10.1021/jacs.2c04262 -
Chemosphere May 2021Enrofloxacin (ENR) belongs to the fluoroquinolone (FQ) antibiotics family, which are contaminants of emerging concern frequently found in effluents. Although many works...
Enrofloxacin (ENR) belongs to the fluoroquinolone (FQ) antibiotics family, which are contaminants of emerging concern frequently found in effluents. Although many works studying photo-Fenton process for FQ degradation have been reported, there are no reports analysing in deep the effect of iron complexation, as well as other metals, towards FQs' photolysis, which, evidently, also contributes in the overall degradation of the pollutant. Therefore, in this work, we report a comparative study between the photochemical fate of ENR and its complex with Fe(III) under simulated sunlight irradiation. In addition, the effect of dissolved oxygen, self-sensitization process, and HO addition on the studied photochemical systems are also investigated. Results indicate that, for free and iron-complexed ENR, singlet oxygen (O) is generated from the interaction of its triplet state with ground state oxygen. Half-life time (t) of ENR under sun simulated conditions is estimated to be around 22 min, while complexation with iron enhances its photostability, leading to a t of 2.1 h. Such finding indicates that at least the presence of iron, might notably increase the residence time of these pollutants in the environment. Eventually, only with the addition of HO, the FQ-iron complex is efficiently degraded due to photo-Fenton process even at circumneutral pH values due to the high stability of the formed complex. Finally, after LC/FT-ICR MS analysis, 39 photoproducts are detected, of which the 14 most abundant ones are identified. Results indicate that photoproducts formation is pH and iron dependent.
Topics: Enrofloxacin; Hydrogen Peroxide; Iron; Photolysis; Water Pollutants, Chemical
PubMed: 33556815
DOI: 10.1016/j.chemosphere.2021.129791 -
Journal of the American Chemical Society Sep 2021Oxidative stress produces a variety of radicals in DNA, including pyrimidine nucleobase radicals. The nitrogen-centered DNA radical 2'-deoxycytidin-4-yl radical (dC·)...
Oxidative stress produces a variety of radicals in DNA, including pyrimidine nucleobase radicals. The nitrogen-centered DNA radical 2'-deoxycytidin-4-yl radical (dC·) plays a role in DNA damage mediated by one electron oxidants, such as HOCl and ionizing radiation. However, the reactivity of dC· is not well understood. To reduce this knowledge gap, we photochemically generated dC· from a nitrophenyl oxime nucleoside and within chemically synthesized oligonucleotides from the same precursor. dC· formation is confirmed by transient UV-absorption spectroscopy in laser flash photolysis (LFP) experiments. LFP and duplex DNA cleavage experiments indicate that dC· oxidizes dG. Transient formation of the dG radical cation (dG) is observed in LFP experiments. Oxidation of the opposing dG in DNA results in hole transfer when the opposing dG is part of a dGGG sequence. The sequence dependence is attributed to a competition between rapid proton transfer from dG to the opposing dC anion formed and hole transfer. Enhanced hole transfer when less acidic 6-methyl-2'-deoxyguanosine is opposite dC· supports this proposal. dC· produces tandem lesions in sequences containing thymidine at the 5'-position by abstracting a hydrogen atom from the thymine methyl group. The corresponding thymidine peroxyl radical completes tandem lesion formation by reacting with the 5'-adjacent nucleotide. As dC· is reduced to dC, its role in the process is traceless and is only detectable because of the ability to independently generate it from a stable precursor. These experiments reveal that dC· oxidizes neighboring nucleotides, resulting in deleterious tandem lesions and hole transfer in appropriate sequences.
Topics: DNA; DNA Damage; Deoxycytidine; Deoxyguanosine; Free Radicals; Oximes; Photolysis; Ultraviolet Rays
PubMed: 34467764
DOI: 10.1021/jacs.1c06425