-
Environmental Science and Pollution... Nov 2020It is important to study the fate and transport of antibiotics in aquatic environments to reveal their pollution status. The premise behind fate and transport studies is...
It is important to study the fate and transport of antibiotics in aquatic environments to reveal their pollution status. The premise behind fate and transport studies is to evaluate the reaction processes of the target antibiotics. However, available research on the environmental behaviors of antibiotics in certain natural waters, such as estuarine water, is scarce. In this study, single reactions such as sorption, biodegradation, and photolysis and multiple degradation reactions of sulfamethoxazole (SMX), trimethoprim (TMP), and ciprofloxacin (CIP) in the estuarine water were studied. The sorption rates of the target antibiotics in the estuarine water-sediment system were very fast, and the sorption amounts varied among sediments and antibiotics. Hydrolysis did not contribute to the degradation of the target antibiotics. Biodegradation had a low contribution to the degradation of the target antibiotics in the estuarine water. In comparison, photolysis was the dominant degradation process for SMX, TMP, and CIP. The rates of photolysis of the tested antibiotics in the estuarine water were greater than those in pure water; thereby, indicating photolysis of these antibiotics was more prone to occur in the estuarine water. In the multiple degradation experiments, it was found that there may be synergistic effects between the single degradation processes. Thus, the aqueous concentrations of antibiotics decreased rapidly by sorption after entering the estuarine water and then decreased relatively slowly by photolysis and biodegradation. This study provides information for evaluating the environmental behaviors of antibiotics in estuarine environments.
Topics: Anti-Bacterial Agents; Kinetics; Photolysis; Sulfamethoxazole; Trimethoprim; Water Pollutants, Chemical
PubMed: 32705565
DOI: 10.1007/s11356-020-10194-4 -
The Science of the Total Environment Dec 2021Oxygen vacancy as a typical point defect has incited substantial interest in photocatalysis due to its profound impact on optical absorption response and facile... (Review)
Review
Oxygen vacancy as a typical point defect has incited substantial interest in photocatalysis due to its profound impact on optical absorption response and facile isolation of photocarriers. The presence of oxygen vacancy can introduce the midgap defect states, which promote extended absorption in the visible region. The redistribution of electron density at the surface can stimulate the adsorption and activation kinetics of adsorbates, manifesting optimal photocatalytic performance. Despite such alluring outcomes, the ambiguity in understanding the precise location, appropriate concentration, and oxygen vacancy role is still a long-standing task. The present review article comprehensively outlines the identification of oxygen vacancy defects at bulk or on the surface and its ultimate effect on the photocatalytic degradation of phenolic compounds. Particular emphasis has been drawn to summarize the critical influence of oxygen vacancy on different factors such as crystal structure, bandgap energy, electronic structure, and charge carrier mobility by integrating experimental results and theoretical calculations. We have also explored the reaction pathways and the intermediate chemistry of phenol photodegradation by analyzing the molecular activation (O, HO, and sulphate activation) through oxygen vacancy defects. Finally, the review concludes with the various challenges and future perspectives, aiming to provide a firm base for further progressions towards photocatalysis.
Topics: Nanostructures; Oxygen; Phenols; Photolysis
PubMed: 34391150
DOI: 10.1016/j.scitotenv.2021.149410 -
Journal of Pharmaceutical and... Apr 2021Ruxolitinib is a Janus Kinase inhibitor currently approved for the treatment of myelofibrosis. It is also a promising drug for the treatment of skin and infectious...
Ruxolitinib is a Janus Kinase inhibitor currently approved for the treatment of myelofibrosis. It is also a promising drug for the treatment of skin and infectious diseases. In terms of pharmaceutical stability, although ruxolitinib has been established as being sensitive to light, no data on photodegradation processes are available to date, while these may be useful for quality risk management and any potential development of other pharmaceutical forms for other routes of administration. One way to partially fill this gap was to carry out a study that combines a consistent determination of the most sensitive sites of the molecule to photolysis through theoretical calculations based on functional density, with the identification of the main photodegradation products obtained after forced degradation. This integrated approach has shown converging results describing the mechanisms based on photo-oxidation that can lead to the opening of the pyrrole ring. Having access to the structure of the degradation products and intermediates then made it possible to carry out an in silico evaluation of their potential mutagenicity and it appears that some of them feature alert structures.
Topics: Nitriles; Pharmaceutical Preparations; Photolysis; Protein Kinase Inhibitors; Pyrazoles; Pyrimidines
PubMed: 33640689
DOI: 10.1016/j.jpba.2021.113983 -
Journal of Hazardous Materials Feb 2022Photodegradation of the insecticide pymetrozine (PYM) was studied on surface of wax films, and in aqueous and nonaqueous phase. The half-life of PYM on the wax surface...
Photodegradation of the insecticide pymetrozine (PYM) was studied on surface of wax films, and in aqueous and nonaqueous phase. The half-life of PYM on the wax surface was approximately 250 times longer than in water. Scavenging experiments, laser flash photolysis, and spectra analysis indicated the first singlet excited state of PYM (S1 *) to be the most important photoinduced species initiating the photodegradation. Quantum chemistry calculations identified significant molecular torsion and changes in the structure C-CN-N of S1 *, and the absolute charges of the CN atoms increased and the bond strength weakened. Free energy surface analysis, and O labeling experiments further confirmed that the mechanism was two-step photoinduced hydrolysis. The first step is the hydrolysis of S1 * at CN upon reaction with 2-3 water molecules (one HO molecule as the catalyst). The second step is an intramolecular hydrogen transfer coupled with the cleavage of C-N bond and formation of two cyclic products. During the interactions, water molecules experience catalytic activation by transferring protons, while there is a negligible solvent effect. Clarifying the detailed photodegradation mechanisms of PYM is beneficial for the development of green pesticides that are photostable and effective on leaf surfaces, and photolabile and detoxified in the aquatic environment.
Topics: Pesticides; Photolysis; Triazines; Water
PubMed: 34844343
DOI: 10.1016/j.jhazmat.2021.127197 -
Environmental Science & Technology Nov 2021The roles that chemical environment and viscosity play in the photochemical fate of molecules trapped in atmospheric particles are poorly understood. The goal of this...
The roles that chemical environment and viscosity play in the photochemical fate of molecules trapped in atmospheric particles are poorly understood. The goal of this work was to characterize the photolysis of 4-nitrocatechol (4NC) and 2,4-dinitrophenol (24DNP) in semisolid isomalt as a new type of surrogate for glassy organic aerosols and compare it to photolysis in liquid water, isopropanol, and octanol. UV/vis spectroscopy was used to monitor the absorbance decay to determine the rates of photochemical loss of 4NC and 24DNP. The quantum yield of 4NC photolysis was found to be smaller in an isomalt glass (2.6 × 10) than in liquid isopropanol (1.1 × 10). Both 4NC and 24NDP had much lower photolysis rates in water than in organic matrices, suggesting that they would photolyze more efficiently in organic aerosol particles than in cloud or fog droplets. Liquid chromatography in tandem with mass spectrometry was used to examine the photolysis products of 4NC. In isopropanol solution, most products appeared to result from the oxidation of 4NC, in stark contrast to photoreduction and dimerization products that were observed in solid isomalt. Therefore, the photochemical fate of 4NC, and presumably of other nitrophenols, should depend on whether they undergo photodegradation in a liquid or semisolid organic particle.
Topics: 2,4-Dinitrophenol; Aerosols; Catechols; Photolysis; Sugars
PubMed: 34669384
DOI: 10.1021/acs.est.1c04975 -
The Journal of Organic Chemistry Jan 2022Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we...
Two fluorophores bound with a short photoreactive bridge are fascinating structures and remained unexplored. To investigate the synthesis and photolysis of such dyes, we linked two rhodamine dyes via a diazoketone bridge (-COCN-) attached to position 5' or 6' of the pendant phenyl rings. For that, the mixture of 5'- or 6'-bromo derivatives of the parent dye was prepared, transformed into 1,2-diarylacetylenes, hydrated to 1,2-diarylethanones, and converted to diazoketones ArCOCNAr. The high performance liquid chromatography (HPLC) separation gave four individual regioisomers of ArCOCNAr. Photolysis of the model compound─CHCOCNCH─in aqueous acetonitrile at pH 7.3 and under irradiation with 365 nm light provided diphenylacetic acid amide (Wolff rearrangement). However, under the same conditions, ArCOCNAr gave mainly α-diketones ArCOCOAr. The migration ability of the very bulky dye residues was low, and the Wolff rearrangement did not occur. We observed only moderate fluorescence increase, which may be explained by the insufficient quenching ability of diazoketone bridge (-COCN-) and its transformation into another (weaker) quencher, 1,2-diarylethane-1,2-dione.
Topics: Fluorescent Dyes; Photolysis; Rhodamines; Spectrometry, Fluorescence; Water
PubMed: 34919387
DOI: 10.1021/acs.joc.1c01721 -
Chembiochem : a European Journal of... Nov 2015It has been postulated that sugar radicals and related species are involved in oxidative events involving RNA. To determine the contribution, if any, of these species to...
It has been postulated that sugar radicals and related species are involved in oxidative events involving RNA. To determine the contribution, if any, of these species to the deleterious effects of the endogenous exposome, it is important to unambiguously identify their degradation products. C5'-Pivaloyl uridine was successfully synthesized and subsequently photolytically converted to a C5'-uridinyl radical. Generation of the radical under anaerobic conditions in the presence of glutathione led to the formation of the expected reduction product, uridine. However, regardless of the presence or absence of reductant, the base elimination product, uracil, was also observed. Mass balances and product distributions were dependent upon the pH of the photolysis mixture. At low pH, trapping with glutathione successfully competed with base loss. These results indicate that this precursor should function efficiently in an investigation of the fate of the C5'-uridinyl radical in RNA oligomers.
Topics: Crystallography, X-Ray; Free Radicals; Glutathione; Hydrogen-Ion Concentration; Light; Molecular Conformation; Photolysis; RNA; Uridine
PubMed: 26338230
DOI: 10.1002/cbic.201500330 -
Chemical Record (New York, N.Y.) Jun 2017Photoactivatable substrates, which show changes in surface cell adhesiveness in response to photoirradiation, are promising platforms for cell manipulation with high... (Review)
Review
Photoactivatable substrates, which show changes in surface cell adhesiveness in response to photoirradiation, are promising platforms for cell manipulation with high spatiotemporal resolution. In addition to having applications in cell and tissue engineering, these materials are unique tools for basic biological sciences research, and they complement conventional genetic engineering technologies. One of the most useful applications is in the study of cell migration, which occurs in various physiological and pathological processes. In this personal account, I provide a brief overview of the development of photoactivatable substrates and their applications, highlighting in particular the contributions of our research group to collective cell migration studies. This material-based approach is useful for dissecting the molecular biological and mechanobiological aspects of the regulatory mechanisms in the cellular social activities.
Topics: Animals; Biocompatible Materials; Cell Line; Cell Movement; Epithelial-Mesenchymal Transition; Extracellular Matrix; Humans; Light; Oligopeptides; Photolysis; Polyethylene Glycols; Surface Properties
PubMed: 27996194
DOI: 10.1002/tcr.201600090 -
Environmental Science and Pollution... Apr 2017Sulfonamides are one of the most frequently used antibiotics worldwide. Therefore, processes that determine their fate in the environment are of great interest. In the...
Sulfonamides are one of the most frequently used antibiotics worldwide. Therefore, processes that determine their fate in the environment are of great interest. In the present work, biodegradation as biotic process and hydrolysis and photolysis as abiotic processes were investigated. In biodegradation experiments, it was found out that sulfonamides (sulfadiazine and sulfamethazine) and their N -acetylated metabolites were not readily biodegradable. The results showed that decrease of concentrations were in the range from 4% for sulfadiazine to 22% for N -acetylsulfamethazine. Hydrolytic experiments examined at pH values normally found in the environment also showed their resistance. However, photolysis proved to be significant process for decreasing concentrations of sulfonamides and their metabolites in three various aqueous matrices (Milli-Q water, river water, and synthetic wastewater). In addition, influence of ubiquitous water constituents (Cl, NO, SO, PO, and humic acids) was also investigated, showing their different impact on photolysis of investigated pharmaceuticals. The results showed that photolysis followed first-order kinetics in all cases. The obtained results are very important for assesing the environmental fate of sulfonamides and their metabolites in the aquatic environment.
Topics: Anti-Bacterial Agents; Photolysis; Sulfadiazine; Sulfamethazine; Water Pollutants, Chemical
PubMed: 28258427
DOI: 10.1007/s11356-017-8639-8 -
Journal of Environmental Management Apr 2020The environmentally extended presence of triclosan, TCS, component of many pharmaceutical and personal care products, and its known persistent character have awoke the... (Review)
Review
The environmentally extended presence of triclosan, TCS, component of many pharmaceutical and personal care products, and its known persistent character have awoke the scientific and social concern leading to the study of effective remediation techniques. Advanced oxidation techniques stand out for the effectiveness in degrading many persistent compounds, and as a result, they have been addressed by many researchers. However, the powerful oxidation media might lead to the formation of undesirable by-products, concern that has also been widely addressed. With regard to the presence of TCS, photolytic and photocatalytic processes provide a very effective degradation yield and rate, with a large number of reports addressing its removal from different environmental matrices. But currently, there is no clear understanding of the mechanisms involved and the routes responsible for the formation of degradation products. Thus, this work presents an exhaustive and critical analysis of the state of the art related to the photo-degradation of TCS, with special focus on the formation of oxidation by-products, on the phenomena responsible and on the influence of operation variables. This report aims at offering valuable information to researchers dealing with this environmentally relevant problem.
Topics: Oxidation-Reduction; Photolysis; Triclosan; Water Pollutants, Chemical
PubMed: 32090818
DOI: 10.1016/j.jenvman.2020.110101