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[en] Highlights: •21-Methylpyrenyl-cholesterol specifically and stably associates to lipoproteins. •It is not esterified by LCAT, and thus reliably labels their peripheral hemi-membrane. •HDL vs. LDL are well distinguishable by various fluorescent labelling characteristics. •LDL peripheral hemi-membrane harbors cholesterol-rich ordered lipid (micro)domains. •Cultured cells can be stained by such labelled lipoproteins-mediated delivery. -- Abstract: Lipoproteins are important biological components. However, they have few convenient fluorescent labelling probes currently reported, and their physiological reliability can be questioned. We compared the association of two fluorescent cholesterol derivatives, 22-nitrobenzoxadiazole-cholesterol (NBD-Chol) and 21-methylpyrenyl-cholesterol (Pyr-met-Chol), to serum lipoproteins and to purified HDL and LDL. Both lipoproteins could be stably labelled by Pyr-met-Chol, but virtually not by NBD-Chol. At variance with NBD-Chol, LCAT did not esterify Pyr-met-Chol. The labelling characteristics of lipoproteins by Pyr-met-Chol were well distinguishable between HDL and LDL, regarding dializability, associated probe amount and labelling kinetics. We took benefit of the pyrene labelling to approach the structural organization of LDL peripheral hemi-membrane, since Pyr-met-Chol-labelled LDL, but not HDL, presented a fluorescence emission of pyrene excimers, indicating that the probe was present in an ordered lipid micro-environment. Since the peripheral membrane of LDL contains more sphingomyelin (SM) than HDL, this excimer formation was consistent with the existence of cholesterol- and SM-enriched lipid microdomains in LDL, as already suggested in model membranes of similar composition and reminiscent to the well-described “lipid rafts” in bilayer membranes. Finally, we showed that Pyr-met-Chol could stain cultured PC-3 cells via lipoprotein-mediated delivery, with a staining pattern well different to that observed with NBD-Chol non-specifically delivered to the cells
[en] The annealing behavior of X-irradiated stable free radicals found in Pyrene (C16H10) single crystals was studied by EPR. Two processes of thermal decay kinetics were found, both with the same activation energy (1.9±0.1) ev. (author)
[pt]O comportamento de anelamento de radicais livres irradiados com raios-X, em cristais unicos de pireno (C16H10), foi estudado por meio de EPR. Dois processos de cinetica de decaimento termico foram achados, ambos com a mesma energia de ativacao: (1.9±0.1) ev. (autor)
[en] The Copper ion recognition ability of a pyrene based sensor (1) was explored. A selective Cu2+ ion induced colorimetric naked eye changes and a turn on emission was observed in acetonitrile medium. The results were monitored through UV–vis spectrophotometry, steady state emission and fluorescence life time studies. The outcome revealed a selective and sensitive Cu2+ recognition with a detection limit of 2.5 × 10−6 M. The compound exhibited aggregation induced emission (AIE) in water-acetonitrile mixture where its critical aggregate concentration was measured by tensiometry at the solvent fraction of maximum AIE. Moreover the compound exhibited an antioxidant nature in DPPH (2,2-diphenyl-1-picrylhydrazyl) assay.
[en] A new chemosensor with pyreneamide derivative of bipyridine is synthesized. In the free ligand, pyreneamide derivative has nearly no fluorescence in acetonitrile solution. However, in the presence of fluoride ion, a 'turn-on' fluorescence was observed. Simultaneously, the colorless ligand solution became markedly orange when fluoride ion was added to pyreneamide derivative in acetonitrile. This phenomenon suggest that the PET (photoinduced electron transfer) between anion electron and pyrene unit was changed the π-π interaction between bipyridine and pyrene that was modified structure by deprotonation. On account of the important roles of anion in biological, clinical, environmental, catalysis, and chemical processes, the selective and efficient recognition of anion is an area of growing interest in supramolecular chemistry. In particular, the studies of chemosensors toward F- anion are quite intriguing because of its beneficial effects in human physiology. Also, fluoride is interest due to its established role in dental care and osteoporosis. However, an excess of fluoride ion can lead to fluorosis. Therefore, the development of reliable sensors for F- is needed for environment and human health care. Color changes that can be detected by the naked eye are widely used as signals for events owing to the inexpensive equipment required or no equipment at all
[en] Effect-directed analysis (EDA) was performed to identify the major aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area (Lake Shihwa, Korea). Great AhR-mediated potencies were found in fractions containing aromatic compounds with log Kow values of 5–8, and relatively great concentrations of styrene oligomers (SOs) and polycyclic aromatic hydrocarbons (PAHs) were detected in those fractions. Until now, there was little information on occurrences and toxic relative potencies (RePs) of SOs in coastal environments. In the present study; i) distributions and compositions, ii) AhR binding affinities, and iii) contributions of SOs to total AhR-mediated potencies were determined in coastal sediments. Elevated concentrations of 10 SOs were detected in sediments of inland creeks ranging from 61 to 740 ng g−1 dry mass (dm), while lesser concentrations were found in inner (mean = 33 ng g−1 dm) and outer regions (mean = 25 ng g−1 dm) of the lake. Concentrations of PAHs in sediments were comparable to those of SOs. 2,4-diphenyl-1-butene (SD3) was the predominant SO analogue in sediments. SOs and PAHs were accumulated in sediments near sources, and could not be transported to remote regions due to their hydrophobicity. RePs of 3 SOs could be derived, which were 1000- to 10,000-fold less than that of one representative potent AhR active PAH, benzo[a]pyrene. Although concentrations of SOs in sediments were comparable to those of PAHs, the collective contribution of SOs to total AhR-mediated potencies were rather small (<1%), primarily due to their smaller RePs. Overall, the present study provides information on distributions and AhR binding affinities for SOs as baseline data for degradation products of polystyrene plastic in the coastal environment. - Highlights: • This is a first report describing occurrences and AhR potencies of SOs in sediments. • Great concentrations of SOs were found in inland creeks sediments of industrial area. • Novel relative potency values of SOs for AhR activity were established. • Contributions of SOs to overall AhR potencies in sediments were not very great. - Although concentrations of styrene oligomers in sediments are comparable to PAHs, the collective contributions of AhR-active styrene oligomers were rather small.
[en] Biosurfactants are promising substitutes for chemical surfactants during polycyclic aromatic hydrocarbon (PAH) bioremediation. However, recent studies have revealed contrasting findings and critical knowledge gaps regarding the impacts of biosurfactants on the soil PAH biodegradation efficiency and microbial community. Here, a laboratory study was conducted to evaluate the impact of rhamnolipid on the PAH dissipation efficiency and microbial community structure during the time-course incubation. The data showed that the contribution ratio of biotic loss and abiotic loss depended on the ring number of PAH. In the microcosms supplemented with 20 μg g−1 rhamnolipid, the biodegradation efficiencies of phenanthrene, fluoranthene, and pyrene increased by 10.1%, 12.3%, and 22.0%, respectively, compared to those in the rhamnolipid-free treatment after incubation for 7 days. In contrast, rhamnolipid either had no impact on or inhibited PAH degradation in the later time points (21–35 days). The abundance of bacterial 16S rRNA and phnAc genes showed significant increase in soil amended of both PAH and rhamnolipid. MiSeq sequencing results revealed that potential PAHs-degrading Massilia, Bacillus, Lysobacter, Archrobacter, and Phenylobacterium became dominant genera in PAH treatment, irrespective of the rhamnolipid added. Nevertheless, PAH addition in the presence of rhamnolipid also significantly stimulated the growth of Delftia, Brevundimonas, Tumebacillus, and Geobacillus. In contrast, the rhamnolipid altered the microbial community composition through the selection of Gaiella, Solirubrobacter, Nocardioides, and Bacillus. The results reveal the intensive selectivity effect of PAH and rhamnolipid on the soil microbes that are involved in bioremediation, and highlight the positive effect on PAHs biodegradation.
[en] Full text: It has been researched the photochemical conversion mechanism of polyciclic aromatic carbohydrogens of oil luminophors on the NaX zeolite under the radiation influence. It has been determined the role of photostimulated centers solid contact surface in formation of radical and radical-cation forms of polyciclic aromatic carbohydrogens. The particular attention is given to the identification of intermidiate particles during luminophor photochemical conversions on zeolite NaX. It has been established that cation-radicals of pyrene and perylene are such particles
[en] Uptake of six organic compounds, dinitrobenzene (DNB), dinitrotoluene (DNT), lindan (LIN), 1,2,3-triclorobenzene (TCB), phenanthrene (PHN) and pyrene (PYR) by freshly excised rice roots and dead rice roots (heated for 40 min at 105 oC) were investigated. Results indicated that the uptake by the two types of roots did not increase proportionally with those in external solution. There appears to be some special chemical function of root cells other than simple absorption by the cells. The contribution of this special function can be roughly estimated by deducting the partition uptake into cells from the total uptake. Both time-dependent uptake data and concentration-dependent uptake curves demonstrate that, DNT and DNB transport is achieved presumably mainly via the symplastic pathway, while PHN and PYR transport mainly via the apoplastic pathway. For LIN and TCB, apoplastic transport pathway plays major roles in the first 2 h of uptake, then symplastic transport pathway dominates uptake. - Different organic compounds may be transported via different pathways in plant roots depending on log K ow