Arsenic bioaccumulation and biotransformation in different tissues of Nile tilapia (Oreochromis niloticus): A comparative study between As(III) and As(V) exposure and evaluation of antagonistic effects of selenium.

The speciation of arsenic in fish has been widely investigated, but bioaccumulation and biotransformation of inorganic As in different tissues of Nile tilapia (Oreochromis niloticus) are not fully understood. The present study aimed to investigate the bioaccumulation of As in Nile tilapia, as well as to evaluate the distribution of the main arsenic species (As(III), As(V), MMA, DMA, and AsB) in liver, stomach, gill, and muscle, after controlled exposures to As(III) and As(V) at concentrations of 5.0 and 10.0 mg L-1 during periods of 1 and 7 days. Total As was determined by inductively coupled plasma mass spectroscopy (ICP-MS). For both exposures (As(III) and As(V)), the total As levels after 7-day exposure were highest in the liver and lowest in the muscle. Overall, the Nile tilapia exposed to As(III) showed higher tissue levels of As after the treatments, compared to As(V) exposure. Speciation of arsenic present in the tissues employed liquid chromatography coupled to ICP-MS (LC-ICP-MS), revealing that the biotransformation of As included As(V) reduction to As(III), methylation to monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA), and subsequent conversion to nontoxic arsenobetaine (AsB), which was the predominant arsenic form. Finally, the interactions and antagonistic effects of selenium in the bioaccumulation processes were tested by the combined exposure to As(III), the most toxic species of As, together with tetravalent selenium (Se(IV)). The results indicated a 4-6 times reduction of arsenic toxicity in the tilapia.

Use of deep eutectic solvents in environmentally-friendly dye-sensitized solar cells and their physicochemical properties: a brief review.

A novel way to mitigate the greenhouse effect is to use dye-sensitized solar cells (DSSCs) to convert carbon dioxide from the air into useful products, such as hydrocarbons, which can also store energy from the sun, a plentiful, clean, and safe resource. The conversion of CO2 can help reduce the impacts of greenhouse gas emissions that contribute to global warming. However, there is a major obstacle in using DSSCs, since many solar devices operate with organic electrolytes, producing pollutants including toxic substances. Therefore, a key research area is to find new eco-friendly electrolytes that can effectively dissolve carbon dioxide. One option is to use deep eutectic solvents (DESs), which are potential substitutes for ionic liquids (ILs) and have similar advantages, such as being customizable, economical, and environmentally friendly. DESs are composed of low-cost materials and have very low toxicity and high biodegradability, making them suitable for use as electrolytes in DSSCs, within the framework of green chemistry. The purpose of this brief review is to explore the existing knowledge about how CO2 dissolves in DESs and how these solvents can be used as electrolytes in solar devices, especially in DSSCs. The physical and chemical properties of the DESs are described, and areas are suggested where further research should be focused.

A novel dispersive liquid-liquid microextraction using a low density deep eutectic solvent-gas chromatography tandem mass spectrometry for the determination of polycyclic aromatic hydrocarbons in soft drinks.

Ready-to-drink teas can provide, if properly packaged, the taste and wellness character of traditional teas. Nevertheless, in tea processing, there may be several contaminations, among which polycyclic aromatic hydrocarbons (PAHs), anthropogenic contaminants that can present carcinogenic and mutagenic properties. In this work, a novel low-density deep eutectic solvent-based dispersive liquid-liquid microextraction (LDDES-DLLME) procedure followed by gas chromatography tandem mass spectrometry (GC-MS/MS) was optimized for analysis of 15 polycyclic aromatic hydrocarbons (PAHs) in ready-to-drink herbal-based beverages. The new deep eutectic solvent (DES) was synthesized with natural compounds (camphor and hexanoic acid). Several parameters of the extraction procedure such as type and volume of extraction solvent, type, volume of dispersive solvent, and time of extraction were evaluated to achieve the highest yield and to attain the lowest detection limits. The validated method showed very low limits of detection (0.01 µg L-1) and quantification (0.2 µg L-1), good inter- and intra-day precisions (RSD<16.87%), and recoveries higher than 69%. The method was applied to 16 type of samples and it was found total PAHs levels ranging from 0.20 to 1.82 µg L-1. The developed LDDES-DLLME showed a reliable and innovative alternative for the extraction of PAHs from beverages, cost-effective and environmentally friendly, and providing a satisfactory throughput.

Bacterial cellulose membrane associated with red propolis as phytomodulator: Improved healing effects in experimental models of diabetes mellitus.

Since early times, propolis has been used in folk medicine. The red propolis, collected in the northeast region of Brazil has been highlighted due to its popular use as an antimicrobial, with anti-inflammatory and healing properties, which are associated with its chemical composition. Here, we combine a bacterial membrane with red propolis to treat wounds of diabetic mice. This work aims to evaluate a biocurative from bacterial cellulose associated with red propolis in diabetic mice as wound healing model. Biocuratives from bacterial cellulose membrane and different extracts of red propolis were produced. The qualification and quantification of the presence of propolis chemical compounds in the membrane were investigated through high-resolution mass spectrometry (HRMS). Tests in vivo with biocuratives were performed on Swiss male diabetic mice induced by estroptozotocin. The animals were submitted to a surgical procedure and a single lesion was produced in the dorsal region, which was treated with the biocuratives. Macroscopic assessments were performed at 2, 7 and 14 postoperative days, and biopsies were collected on days 0, 7 and 14 for histological analysis, myeloperoxidase enzyme activity (MPO) and cytokines (TNF-α, IL-1ß, and TGF-ß). Altogether, ten compounds were identified in membranes and five were further quantified. The ethyl acetate extract showed more red propolis markers, and the most prevalent compound was Formononetin with 4423.00-2907.00 µg.g-1. Macroscopic analyses demonstrated that the two groups treated with red propolis (GMEBT and GMEAE) showed significantly greater healing capabilities compared to the control groups (GS and GMS). An increase in leukocyte recruitment was observed, confirmed by the activity of the enzyme myeloperoxidase (MPO) in GMEBT and GMEAE groups. The levels of TNF-α were significantly higher in wounds stimulated with red propolis, as well as in TGF-ß (GMEBT and GMEAE) on day 7. This was different from the IL-1ß levels that were higher in the control groups (GS and GMS). In summary, the biocuratives produced in this work were able to accelerate the wound healing process in a diabetic mouse model. In this way, the traditional knowledge of red propolis activity helped to create a biotechnological product, which can be used for diabetic wound healing purpose.

Fractionation of inorganic arsenic by adjusting hydrogen ion concentration.

The inorganic fraction of arsenic species, iAs=∑[As(III)+As(V)] present in fish samples can be quantified in the presence of other arsenic species also found in fishes, such as: monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and arsenobetaine (AsB). The toxic arsenic fraction was selected taking into account the dissociation constants of these arsenic species in different hydrogen ions concentration leading to the arsine formation from iAs compounds detected as As(III) by HG AAS. For thus, a microwave assisted extraction was carried out using HCl 1molL(-1) in order to maintain the integrity of the arsenic species in this mild extraction media. Recovery experiments were done for iAs fraction, in the presence of other arsenic species. The recovery values obtained for iAs fraction added were quantitative about 87-107% (for N=3, RSD⩽3%). The limit of detection (LOD), and the limit of quantification (LOQ), were 5µgkg(-1) and 16µgkg(-1) respectively.