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Faraday Discussions Oct 2019We describe cyclic peptide progelators which cleave in response to UV light to generate linearized peptides which then self-assemble into gel networks. Cyclic peptide...
We describe cyclic peptide progelators which cleave in response to UV light to generate linearized peptides which then self-assemble into gel networks. Cyclic peptide progelators were synthesized, where the peptides were sterically constrained, but upon UV irradiation, predictable cleavage products were generated. Amino acid sequences and formulation conditions were altered to tune the mechanical properties of the resulting gels. Characterization of the resulting morphologies and chemistry was achieved through liquid phase and standard TEM methods, combined with matrix assisted laser desorption ionization imaging mass spectrometry (MALDI-IMS).
Topics: Biocompatible Materials; Bioprinting; Gels; Peptides, Cyclic; Photolysis; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Ultraviolet Rays
PubMed: 31549115
DOI: 10.1039/c9fd00026g -
Water Research Jul 2023Environment disinfection effectively curbs transmission of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). However, elevated concentration of free...
Environment disinfection effectively curbs transmission of the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2). However, elevated concentration of free available chlorine (FAC) in disinfectants can be discharged into surface water, generating toxic disinfection byproducts (DBPs). The impact of solar photolysis of FAC on natural organic matter (NOM) to form DBPs has not been well studied. In this work, solar photolysis of FAC was found to result in higher formation of DBPs, DBPs formation potential (DBPsFP), total organic chlorine (TOCl) and lower specific ultraviolet absorbance at 254 nm (SUVA), compared to dark chlorination. In solar photolysis of FAC, formation of total DBPs was promoted by pH=8, but hindered by the addition of HCO, radical scavenger or deoxygenation, while addition of NOand NHboth enhanced the formation of nitrogenous DBPs. Differences in the formation of DBPs in solar photolysis of FAC under various conditions were influenced by reactive species. The formation of trichloromethane (TCM) and haloacetic acids (HAAs) in solar photolysis of FAC positively correlated with the steady-state concentrations of ClO and O. The steady-state concentrations of NO and NH positively correlated with the formation of halonitromethanes (HNMs). HAAs and haloacetonitriles (HANs) mainly contributed to calculated cytotoxicity of DBPs. This study demonstrates that solar photolysis of FAC may significantly impact the formation of DBPs in surface water due to extensive use of disinfectants containing FAC during SARS-CoV-2 pandemic.
Topics: Humans; Disinfection; Chlorine; Photolysis; Water Purification; COVID-19; SARS-CoV-2; Disinfectants; Halogenation; Water; Water Pollutants, Chemical
PubMed: 37167852
DOI: 10.1016/j.watres.2023.120020 -
International Journal of Environmental... Dec 2022Phytoremediation is an environmentally friendly and economical method for removing organic contaminants from water. The purpose of the present study was to use for the...
Phytoremediation is an environmentally friendly and economical method for removing organic contaminants from water. The purpose of the present study was to use for the phytoremediation of water from sulfamethoxazole (SMX) and trimethoprim (TRI) residues. The experiment was conducted for 14 days, in which the loss of the pharmaceuticals in water and their concentration in plant tissues was monitored. Determination of SMX and TRI was conducted using liquid chromatography coupled with tandem mass spectrometry. The results revealed that various factors affected the removal of the contaminants from water, and their bioaccumulation coefficients were obtained. Additionally, the transformation products of SMX and TRI were identified. The observed decrease in SMX and TRI content after 14 days was 96.0% and 75.4% in water, respectively. SMX removal mainly involved photolysis and hydrolysis processes, whereas TRI was mostly absorbed by the plant. Bioaccumulation coefficients of the freeze-dried plant were in the range of 0.043-0.147 for SMX and 2.369-2.588 for TRI. Nine and six transformation products related to SMX and TRI, respectively, were identified in water and plant tissues. The detected transformation products stemmed from metabolic transformations and photolysis of the parent compounds.
Topics: Sulfamethoxazole; Trimethoprim; Hydrocharitaceae; Water; Water Pollutants, Chemical
PubMed: 36554877
DOI: 10.3390/ijerph192416994 -
Methods in Molecular Biology (Clifton,... 2022The successful isolation of mycolactone in a laboratory or from a clinical sample relies on proper handling and storage of the toxin. Mycolactone is a light-sensitive...
The successful isolation of mycolactone in a laboratory or from a clinical sample relies on proper handling and storage of the toxin. Mycolactone is a light-sensitive and an amphiphilic toxin produced by Mycobacterium ulcerans. The biochemistry of the toxin makes it unstable in aqueous matrices such as blood, which causes it to self-aggregate or present in complex with carrier molecules. This biochemistry also impacts the use of the toxin in vitro, in that it tends to aggregate and stick to substrates in an aqueous environment, which alters its physiological presentation and limits its availability in a sample. Glass materials (i.e., tubes, vials, syringes, plates) should be used when possible to avoid loss of mycolactone sticking to plastic surfaces. Dark containers such as amber vials or aluminum-foil wrapped tubes should be used to avoid photodegradation of the toxin upon exposure to light. Sample storage in organic solvents is ideal for mycolactone stability and recovery; however, this is not always amenable as multiple diagnostic assays might be performed on a single sample (such as PCR or ELISA). In these cases, samples can be stored in an aqueous solution containing a small amount of detergent to enhance recovery of the toxin, and in order to avoid aggregation. Therefore, the downstream manipulations should be carefully considered prior to sample collection and storage. Here we present considerations for the optimal handling and storage of mycolactone in order to obtain quality yield of the toxin for various research and diagnostic applications.
Topics: Buruli Ulcer; Enzyme-Linked Immunosorbent Assay; Humans; Macrolides; Mycobacterium ulcerans; Photolysis
PubMed: 34643907
DOI: 10.1007/978-1-0716-1779-3_12 -
Membranes Apr 2023According to the World Health Organization, antibiotic resistance is one of the main threats to global health. The excessive use of several antibiotics has led to the...
According to the World Health Organization, antibiotic resistance is one of the main threats to global health. The excessive use of several antibiotics has led to the widespread distribution of antibiotic-resistant bacteria and antibiotic resistance genes in various environment matrices, including surface water. In this study, total coliforms, and enterococci, as well as total coliforms and resistant to ciprofloxacin, levofloxacin, ampicillin, streptomycin, and imipenem, were monitored in several surface water sampling events. A hybrid reactor was used to test the efficiency of membrane filtration, direct photolysis (using UV-C light emitting diodes that emit light at 265 nm and UV-C low pressure mercury lamps that emit light at 254 nm), and the combination of both processes to ensure the retention and inactivation of total coliforms and as well as antibiotic-resistant bacteria (total coliforms and ) present in river water at occurrence levels. The membranes used (unmodified silicon carbide membranes and the same membrane modified with a photocatalytic layer) effectively retained the target bacteria. Direct photolysis using low-pressure mercury lamps and light-emitting diode panels (emitting at 265 nm) achieved extremely high levels of inactivation of the target bacteria. The combined treatment (unmodified and modified photocatalytic surfaces in combination with UV-C and UV-A light sources) successfully retained the bacteria and treated the feed after 1 h of treatment. The hybrid treatment proposed is a promising approach to use as point-of-use treatment by isolated populations or when conventional systems and electricity fail due to natural disasters or war. Furthermore, the effective treatment obtained when the combined system was used with UV-A light sources indicates that the process may be a promising approach to guarantee water disinfection using natural sunlight.
PubMed: 37103852
DOI: 10.3390/membranes13040425 -
Angewandte Chemie (International Ed. in... Aug 2021A dynamic nucleophilic aromatic substitution of tetrazines (S Tz) is presented herein. It combines all the advantages of dynamic covalent chemistry with the versatility...
A dynamic nucleophilic aromatic substitution of tetrazines (S Tz) is presented herein. It combines all the advantages of dynamic covalent chemistry with the versatility of the tetrazine moiety. Indeed, libraries of compounds or sophisticated molecular structures can be easily obtained, which are susceptible to post-functionalization by inverse electron demand Diels-Alder (IEDDA) reaction, which also locks the exchange. Additionally, the structures obtained can be disassembled upon the application of the right stimulus, either UV irradiation or a suitable chemical reagent. Moreover, S Tz is compatible with the imine chemistry of anilines. The high potential of this methodology has been proved by building two responsive supramolecular systems: A macrocycle that displays a light-induced release of acetylcholine; and a truncated [4+6] tetrahedral shape-persistent fluorescent cage, which is disassembled by thiols unless it is post-stabilized by IEDDA.
PubMed: 34085747
DOI: 10.1002/anie.202106230 -
British Journal of Pharmacology Feb 2021Coordinated endothelial control of cardiovascular function is proposed to occur by endothelial cell communication via gap junctions and connexins. To study intercellular...
BACKGROUND AND PURPOSE
Coordinated endothelial control of cardiovascular function is proposed to occur by endothelial cell communication via gap junctions and connexins. To study intercellular communication, the pharmacological agents carbenoxolone (CBX) and 18β-glycyrrhetinic acid (18βGA) are used widely as connexin inhibitors and gap junction blockers.
EXPERIMENTAL APPROACH
We investigated the effects of CBX and 18βGA on intercellular Ca waves, evoked by inositol 1,4,5-trisphosphate (IP ) in the endothelium of intact mesenteric resistance arteries.
KEY RESULTS
Acetycholine-evoked IP -mediated Ca release and propagated waves were inhibited by CBX (100 μM) and 18βGA (40 μM). Unexpectedly, the Ca signals were inhibited uniformly in all cells, suggesting that CBX and 18βGA reduced Ca release. Localised photolysis of caged IP (cIP ) was used to provide precise spatiotemporal control of site of cell activation. Local cIP photolysis generated reproducible Ca increases and Ca waves that propagated across cells distant to the photolysis site. CBX and 18βGA each blocked Ca waves in a time-dependent manner by inhibiting the initiating IP -evoked Ca release event rather than block of gap junctions. This effect was reversed on drug washout and was unaffected by small or intermediate K -channel blockers. Furthermore, CBX and 18βGA each rapidly and reversibly collapsed the mitochondrial membrane potential.
CONCLUSION AND IMPLICATIONS
CBX and 18βGA inhibit IP -mediated Ca release and depolarise the mitochondrial membrane potential. These results suggest that CBX and 18βGA may block cell-cell communication by acting at sites that are unrelated to gap junctions.
Topics: Calcium; Calcium Signaling; Carbenoxolone; Endothelial Cells; Gap Junctions; Glycyrrhetinic Acid; Inositol 1,4,5-Trisphosphate; Mitochondria
PubMed: 33269468
DOI: 10.1111/bph.15329 -
RSC Advances Jul 2020Tetracycline (TC), a frequently used drug for human and veterinary therapeutics, is among the most common antibiotic residues found in nature. Lack of advanced treatment... (Review)
Review
Tetracycline (TC), a frequently used drug for human and veterinary therapeutics, is among the most common antibiotic residues found in nature. Lack of advanced treatment techniques in the wastewater treatment plants (WWTPs) to remove residual TC from domestic and hospital wastewater poses a serious environmental risk. It is important to have an insight into the different advanced treatment techniques for efficient removal of TC from the surface water and in the WWTPs. The aim of this review is to discuss the nature and occurrence of TC in surface water and to present an overview of the various advanced treatment techniques for TC removal. The advanced treatment techniques include advanced oxidation processes (photolysis, ozonation, and catalytic/UV light-based degradation), membrane filtration, reverse osmosis, and adsorption techniques. Adsorption and integrated oxidation treatment techniques are the most widely studied methods, and they are widely accepted because of less cost, reusability, and toxic-free nature. Further, the uses of various types of catalysts for photodegradation and various sorbents for adsorption of TC are also presented. Finally, the importance of green nanocomposite for environmental sustainability in TC removal is emphasized.
PubMed: 35515769
DOI: 10.1039/d0ra04264a -
Toxics Feb 2024Florfenicol (FLO) is a widely used antibacterial drug, which is often detected in the environment. In this paper, the photolysis mechanism of FLO in water was...
Study on the Direct and Indirect Photolysis of Antibacterial Florfenicol in Water Using DFT/TDDFT Method and Comparison of Its Reactivity with Hydroxyl Radical under the Effect of Metal Ions.
Florfenicol (FLO) is a widely used antibacterial drug, which is often detected in the environment. In this paper, the photolysis mechanism of FLO in water was investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The focus of the study is to elucidate the direct photolysis mechanism of FLO in the water environment and the indirect photolysis of free radicals (·OH, ·NO, and ·SO) as active species. The effect of metal ions Ca/Mg/Zn on the indirect photolysis was also investigated. The results show that the direct photolysis of FLO involves C-C/C-N/C-S bond cleavage, the C5-S7 bond cleavage is most likely to occur, and the C17-C18 cleavage reaction is not easy to occur during the direct photodegradation of FLO. The indirect photolysis of FLO is more likely to occur in the environment than direct photolysis. The main indirect photolysis involves OH-addition, NO-addition, and SO-addition on benzene ring. The order of difficulty in the indirect photolysis with ·OH is C2 > C3 > C4 > C5 > C6 > C1, Ca can promote the indirect photolysis with ·OH, and Mg/Zn has a dual effect on the indirect photolysis with ·OH. In other words, Mg and Zn can inhibit or promote the indirect photolysis with ·OH. These studies provide important information for theoretical research on the environmental behavior and degradation mechanism of drug molecules.
PubMed: 38393222
DOI: 10.3390/toxics12020127 -
Nature Communications Jul 2022Uranium nitrides play important roles in dinitrogen activation and functionalization and in chemistry for nuclear fuels, but the synthesis and isolation of the highly...
Uranium nitrides play important roles in dinitrogen activation and functionalization and in chemistry for nuclear fuels, but the synthesis and isolation of the highly reactive uranium(VI) nitrides remains challenging. Here, we report an example of transition metal (TM) stabilized U(VI) nitride complexes, which are generated by the photolysis of azide-bridged U(IV)-TM (TM = Rh, Ir) precursors. The U(V) nitride intermediates with bridged azide ligands are isolated successfully by careful control of the irradiation time, suggesting that the photolysis of azide-bridged U(IV)-TM precursors is a stepwise process. The presence of two U(VI) nitrides stabilized by three TMs is clearly demonstrated by an X-ray crystallographic study. These TM stabilized U(V) nitride intermediates and U(VI) nitride products exhibit excellent stability both in the solid-state and in THF solution under ambient light. Density functional theory calculations show that the photolysis necessary to break the N-N bond of the azide ligands implies excitation from uranium f-orbital to the lowest unoccupied molecular orbital (LUMO), as suggested by the strong antibonding N-(N) character present in the latter.
PubMed: 35778419
DOI: 10.1038/s41467-022-31582-z