Polyhydroxyalkanoates (PHA) are biopolyesters regarded as an attractive alternative to petroleum-derived plastics. Nitrogen limitation and phosphate limitation in glucose cultivations were evaluated ...for poly(3-hydroxybutyrate) (P(3HB)) production by
1H9
, a moderate halophilic strain. Co-production of P(3HB) and gluconic acid was observed in fed-batch glucose cultivations under nitrogen limiting conditions. A maximum P(3HB) accumulation of 53.0% (
/
) and a maximum co-production of 133 g/L of gluconic acid were attained. Fed-batch glucose cultivation under phosphate limiting conditions resulted in a P(3HB) accumulation of only 33.3% (
/
) and no gluconic acid production. As gluconic acid is a valuable organic acid with extensive applications in several industries, this work presents an interesting approach for the future development of an industrial process aiming at the co-production of an intracellular biopolymer, P(3HB), and a value-added extracellular product, gluconic acid.
The unexpected incorporation of ionic Mn and Fe in the crystalline structure of titanate nanowires was accomplished when a contaminated a titanium source was used. The presence of Mn (8.1 mg L−1) and ...Fe (4.3 mg L−1) result in the production of a novel co-doped (Fe,Mn) titanate nanowires (TNW) material with improved optical and photocatalytic properties. After structural characterization, the results indicate that both Mn and Fe were incorporated in the TNW structure by replacement of Na+ in the interlayers, together with Ti4+ substitution in the TiO6 octahedra. The potential of this new material to be used for pollutants photocatalytic degradation was further investigated. The terephthalic acid was used as probe molecule to first evaluate the catalytic ability of the pristine and FeMnTNW modified powders for the photo-assisted hydroxyl radical formation. Afterwards, the degradation process of a model emergent pollutant, caffeine, was studied. The results showed that FeMnTNW was the best photocatalyst, with the complete caffeine removal (20 mg L−1) within 60 min of radiation (13 mg catalyst/L solution). The action of several oxidant species, including h+, OH• and O2•-, during caffeine removal was carefully analyzed using specific radical scavengers. A mechanism for the charge-transfer in irradiated FeMnTNW particles, including the possibility of a photo-Fenton and photodegradation combination process, is proposed and discussed.
•Novel FeMn-modified TNW were prepared using a Ti contaminated source.•Fe is present in two distinct structural positions in the FeMnTNW powder.•Both Mn/Fe contribute for TNW photocatalytic performance enhancement.•FeMnTNW was the best photocatalyst for caffeine degradation.•Photo-Fenton and photocatalysis were responsible for caffeine removal.
Titanate nanomaterials have been outstanding in the removal of emerging contaminants by the photocatalysis process. These photocatalysts, when modified through techniques such as doping with metals, ...they have advantages over TiO2, especially in the region of visible light. In this work, the photocatalytic performance of four recent reported catalysts, pristine titanate nanowires, cobalt-doped titanate nanowires, iron-doped titanate nanowires and ruthenium-doped titanate nanowires, for the removal of the antidepressant trazodone under visible light radiation was compared. The iron-doped titanate nanowires presented the best catalytic activity by the catalyst surface area. Additionally, thirteen transformation products (TPs) were identified by high-resolution mass spectrometry and, to the best of our knowledge, nine of them have never been described in the literature. It was shown that for each catalyst different TPs were formed with distinct time profiles. Finally, toxicity assessment by computational methods showed that TPs were not readily biodegradable and they presented toxicity to aquatic organisms with mutagenic potential. These findings reinforce the importance of taking into consideration the TPs formed during the removal of pollutants since many of them may be toxic and can be produced during photocatalysis.
Display omitted
•Photocatalytic performance of pristine and metal-doped nanoparticles was studied.•Iron-doped nanoparticles demonstrated the best degradation rate by surface area.•Thirteen transformation products were detected by high-resolution mass spectrometry.•Different photocatalysts generated distinct transformation products.•In silico prediction showed that transformation products were toxic and mutagenic.
A new analytical approach based on high-performance liquid chromatography with diode array detector (HPLC-DAD) and multivariate data analysis was applied and assessed for analyzing the red dye ...extracted from cochineal insects, used in precious historical textiles. The most widely used method of analysis involves quantification of specific minor compounds (markers), using HPLC-DAD. However, variation in the cochineal markers concentration, use of aggressive dye extraction methods and poor resolution of HPLC chromatograms can compromise the identification of the precise insect species used in the textiles. In this study, a soft extraction method combined with a new dye recovery treatment was developed, capable of yielding HPLC chromatograms with good resolution, for the first time, for historical cochineal-dyed textiles. After principal components analysis (PCA) and mass spectrometry (MS), it was possible to identify the cochineal species used in these textiles, in contrast to the accepted method of analysis. In order to compare both methodologies, 7 cochineal species and 63 historical cochineal insect specimens were analyzed using the two approaches, and then compared with the results for 15 historical textiles in order to assess their applicability to real complex samples. The methodology developed here was shown to provide more accurate and consistent information than the traditional method. Almost all of the historical textiles were dyed with
Porphyrophora
sp. insects. These results emphasize the importance of adopting the proposed methodology for future research on cochineal (and related red dyes). Mild extraction methods and HPLC-DAD/MS
n
analysis yield distinctive profiles, which, in combination with a PCA reference database, are a powerful tool for identifying red insect dyes.
Figure
In pursuit of a precious red dye! A new methodology has been developed for determining the precise cochineal dye used in historical textiles. Mild extraction methods and HPLC-DAD yield distinctive profiles that, in combination with a dye reference database based on PCA, creates a powerful tool for identifying the precise red dye used. Surprisingly, almost all of the historical textiles analysed were not dyed with American cochineal.
Dengue is the most prevalent arthropod-borne viral disease, caused by dengue virus, a member of the Flaviviridae family. Its worldwide incidence is now a major health problem, with 2.5 billion people ...living in risk areas. In this review, we integrate the structural rearrangements of each viral protein and their functions in all the steps of virus entry into the host cells. We describe in detail the putative receptors and attachment factors in mammalian and mosquito cells, and the recognition of viral immunocomplexes via Fcγ receptor in immune cells. We also discuss that virus internalization might occur through distinct entry pathways, including clathrin-mediated or non-classical clathrin-independent endocytosis, depending on the host cell and virus serotype or strain. The implications of viral maturation in virus entry are also explored. Finally, we discuss the mechanisms of viral genome access to the cytoplasm. This includes the role of low pH-induced conformational changes in the envelope protein that mediate membrane fusion, and original insights raised by our recent work that supports the hypothesis that capsid protein would also be an active player in this process, acting on viral genome translocation into the cytoplasm.
This review addresses the structural rearrangements of dengue virus proteins and their functions during virus entry into the host cells, exploring (a) the cellular elements involved in virus binding to mammalian and mosquito cells, (b) the internalization routes that ultimately lead to virus entry into the cell and (c) the mechanisms by which viral genome gain access to the cytoplasm, including original insights from our recent work that supports the hypothesis that the capsid protein has a role in this process.
The present work describes the facile synthesis, full characterization, and architectural diversity of three new bioactive silver-organic networks, namely 1D Ag2(μ-PTA)2(μ-suc) n ·2nH2O (1), 2D ...Ag2(μ-PTA)2(μ4 -adip) n ·2nH2O (2), and 3D Ag2(μ4-PTA)(μ4 -mal) n (3) coordination polymers, generated via a mixed-ligand strategy using PTA (1,3,5-triaza-7-phosphaadamantane) as a main building block and flexible aliphatic dicarboxylic acids (succinic (H2suc), adipic (H2adip), or malonic (H2mal) acids) as an ancillary ligand source. The compounds 1–3 were isolated as moderately air and light stable crystalline solids and were fully characterized by IR and 1H and 31P{1H} NMR spectroscopy, elemental analysis, ESI(±)-MS spectrometry, and single-crystal X-ray crystallography. The type of aliphatic dicarboxylate plays a key role in defining the dimensionality and structural and topological features of the resulting networks, which are also driven by the PTA blocks that adopt unconventional N,P- or N3,P-coordination modes. The topological analysis of simplified underlying nets revealed that 1 possesses uninodal 3-connected chains with the SP 1-periodic net (4,4)(0,2) topology, 2 features a uninodal 4-connected layer with the skl topology, and 3 reveals a uninodal 4-connected metal–organic framework with the dia topology. The presence of the crystallization water molecules in polymers 1 and 2 gives rise to the extension of their metal–organic structures into 3D (1) or 2D (2) H-bonded networks that disclose rather rare topologies. All of the obtained silver(I) coordination polymers feature solubility in water (S 25 °C ≈ 3–5 mg mL–1) and show significant antibacterial and antifungal activity against the selected strains of Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria and yeast (Candida albicans).
The encapsulation of the 3-deoxyanthocyanidins (3-DXA) red dye, extracted from sorghum (
L.) leaves, was explored for food application. The extracts showed antioxidant activity at concentrations ...ranging from 803 to 1210 μg mL
and did not reveal anti-inflammatory or cytotoxic properties, indicating their potential for food application. Encapsulation was performed with two carrier agents (maltodextrin and Arabic gum) in different proportions (1:1, 2:1 and 1.5:2.5 (
/
)). The microparticles produced by freeze-drying and spray-drying were studied according to the concentration of the dye, the encapsulation efficiency, the process yield, the solubility and the colour of the powders. The dye extracts are released from the microparticles at different pHs. The variation in ratio composition of the 3-DXA encapsulation was assessed by principal component analysis (PCA) using data from ten physicochemical parameters. The results indicated that the maltodextrin at the 2:1 ratio had a higher dye concentration and total phenolic content (TPC) at pH 6. This ratio was selected to produce the microparticles by freeze-drying and spray-drying, and the particles were used in the temperature stability tests at pH 6. The results suggest that the freeze-drying process offers better protection to 3-DXA, with a degradation percentage of 22% during the heating period (80 °C for 18 h), compared to the non-encapsulated dye (48%). However, there were no significant differences between the two polymeric agents. The non-encapsulated 3-DXA was evaluated as control and lost 48% of the total colour with the same treatment. Red dyes from sorghum leaf by-products may constitute promising ingredients for the food industry and increase the value of this crop.
An efficient and sustainable one‐step procedure for the synthesis of new asymmetric phenazines and phenoxazinones from commercially available ortho‐substituted diamines and ortho‐substituted ...hydroxyamines is reported. In this study we have expanded the substrate scope of CotA‐laccase‐catalyzed aerobic oxidations through the use of aromatic amines presenting variable functional groups, including N‐substitution, contributing to the rational synthesis of different heterocyclic scaffolds. The transformations proceed smoothly through a cascade of oxidative reactions to the benzoquinonediimine intermediates followed by nucleophilic addition, intramolecular cyclization and aromatization, all performed in mild conditions.
Naphthol reds are historical pigments widely found in cultural heritage, characterized by 1-arylhydrazone-2-naphthol basic skeleton. Little is known about their degradation mechanisms, and this ...knowledge is essential for their long-term preservation. In this research, for the first time, the photodegradation quantum yields (ΦR) were calculated for a series of pigment reds selected based on published literature, in order to evaluate the effects of the electron-withdrawing and donating groups present in C(4′), in particular the effect of sulfonate groups on the stability of these compounds. ΦR values in homogeneous media, ranging from 3 × 10−6 to 4 × 10−5, are difficult to obtain in these systems, but provide the quantification of the stability of naphthol reds. One of the main conclusions is that the sulfonate groups have a stabilizing effect and that the keto forms are generally more stable. Another important piece of information is that the solvent, and as such the medium predictably, has a major impact on stability. For Sudan I and Orange II irradiation was also carried with a xenon source (λirr ≥ 300 nm), allowing characterizing the main degradation products by HPLC-DAD-MS and UHPLC-HRMS. For the dyes characterized by higher ΦR, extensive degradation was observed with the formation of volatile compounds as phthalates.
•The stability of 20th C. red pigments found in works of art is studied.•Quantum yields of degradation identify unstable β-naphthol reds.•Molecular markers of β-naphthol red degradation identified by mass spectrometry.•Science & Art to safeguard the 20th century cultural heritage.
Contaminants of environmental concern, like pharmaceuticals, are being detected in increasing amounts in soils and irrigation waters and can thus be taken up by plants. In this work, the uptake of ...acetaminophen (ACT) by lettuce plants was evaluated through a hydroponic experiment at different concentrations (0, 0.1, 1 and 5 mg L−1 ACT). The pathways related to oxidative stress induced by ACT were studied in lettuce leaves and roots at 1, 8 and 15 days after exposure. Stress indicators such as hydrogen peroxide and malondialdehyde (MDA) contents were analyzed, revealing increases in plants contaminated with ACT in comparison to control, confirming the occurrence of oxidative stress, with the exception of MDA in leaves. The enzymatic activities of catalase, superoxide dismutase, guaiacol peroxidase, ascorbate peroxidase and glutathione peroxidase, directly involved in the antioxidative system, showed significant differences when compared to control plants, and, depending on the enzyme and the tissue, different trends were observed. Glutathione reductase revealed a decrease in contaminated leaves, which may imply a specific impact of ACT in the glutathione cycle. Significant increases were found in the anthocyanin content of leaves, both with exposure time and ACT concentration, indicating an antioxidative response induced by ACT contamination.
PDF
