Imidazolate framework material for crude oil removal in aqueus media: Mechanism insight.

Considerable amount of produced water discharged by the oil industry contributes to an environmental imbalance due to the presence of several components potentially harmful to the ecosystem. We investigated the factors influencing the adsorption capacity of Zinc Imidazolate Framework-8 (ZIF-8) in finite bath systems for crude oil removal from petroleum extraction in synthetic produced water. ZIF-8, experimentally obtained by solvothermal method, was characterized by XRD, FTIR, TGA, BET and its point of zero charge (pHpcz) was determined. Synthesized material showed high crystallinity, with surface area equal to 1558 m2 g-1 and thermal stability equivalent to 400 °C. Adsorption tests revealed, based on the Sips model, that the process takes place in a heterogeneous system. Additionally, intraparticle diffusion model exhibited multilinearity characteristics during adsorption process. Thermodynamic investigation demonstrated that adsorption process is spontaneous and exothermic, indicating a physisorption phenomenon. These properties enable the use of ZIF-8 in oil adsorption, which presented an adsorption capacity equal to 452.9 mg g-1. Adsorption mechanism was based on hydrophobic interactions, through apolar groups present on ZIF-8 structure and oil hydrocarbons, and electrostatic interactions, through the difference in charges between positive surface of adsorbent and negatively charged oil droplets.

α-Synuclein Drives Tau's Cytotoxic Aggregates Formation through Hydrophobic Interactions.

Tau and α-synuclein are proteins involved in pathologies known as tauopathies and synucleinopathies, respectively. Moreover, evidence shows that there is a crosstalk between them as is seen in the brains of individuals with sporadic neurodegenerative disorders. Based on that, we present data showing that the hydrophobic α-peptide 71 VTGVTAVAQKTV82 induces the aggregation of the full-length tau fragment in the absence of heparin assessed by ThT. Moreover, AFM images reveal the presence of straight filaments and amorphous aggregates of full-length tau in the presence of the α-peptide. Additionally, ITC experiments showed the interaction of the α-peptide with tau full-length (441 amino acids),4R (amino acids from 244 to 369), and both hexapeptides 275 VQIINK280 and 306 VQIVYK311 through hydrophobic interactions. The Raman spectroscopy spectra showed conformational changes in the Amide region in the aggregates formed with full-length tau and α-syn peptide. Furthermore, the incubation of extracellular aggregates with N2a cells showed morphological differences in the cellular body and the nucleus suggesting cell death. Moreover,, the incubation of different types of aggregates in cell culture provokes the release of Lactate dehydrogenase (LDH). Altogether, we found that α-synuclein peptide can drive the aggregation of full-length tau-provoking morphological and structural changes evoking cytotoxic effects.

Polyphosphate accumulation and cell-surface properties by autochthonous bacteria from Argentinian Patagonia.

Bacteria persisting in environments contaminated with polycyclic aromatic hydrocarbons (PAHs) have developed physiological mechanisms to counteract environmental stress. Inorganic polyphosphate accumulation represents one of these possible mechanisms. Likewise, properties such as cell-surface hydrophobicity, auto-aggregation, biofilm formation and bioemulsifying activity could facilitate interaction of microorganisms with hydrophobic organic compounds. In this work, these physiological properties were compared in indigenous bacteria from polluted sediments from Argentinian Patagonia, which were cultivated in two culture media (LBm and JPP) as a way to improve in the next future the PAHs removal. The highest hydrophobicity values were obtained in Rhodococcus strains, while Bacillus sp. B18 showed the highest auto-aggregation percentage and emulsion index. The highest numerical values of biofilm formation were determined in Rhodococcus sp. F27, Pseudomonas sp. P26, and Gordonia sp. H19 either on hydrophilic or on hydrophobic support. The qualitative and quantitative polyP determinations confirmed the presence of this biopolymer in the strains evaluated. The highest intracellular phosphate mean values were obtained in Bacillus sp. B18 in LBm and Rhodococcus erythropolis 20 in JPP. The bacteria evaluated belonging to different genera showed significant differences in their cell-surface characteristics, bioemulsifying activity and polyP accumulation. The low-cost JPP culture medium was selected for future contaminant removal studies.

Sorption of endocrine disrupting compounds onto polyamide microplastics under different environmental conditions: Behaviour and mechanism.

Microplastics of polyamide are commonly found in aquatic environments and might act as vectors of different contaminants such as endocrine disrupting compounds (EDC). Therefore, sorption of 17α-ethynylestradiol (EE2), 17ß-estradiol (E2), and estriol (E3) on polyamide microplastics was studied under different simulated environments. The results suggest that the sorption process was affected by the presence of dissolved organic matter (DOM) and salinity, where both positive and negative effects were observed. Kinetics revealed that the process occurs through multiple steps wherever the sorption rate depicting the transportation of EDC molecules from the liquid phase to the solid boundary of the sorbent, is higher than the intraparticle and pore diffusion process. In addition, the sorption rate of E2 decreased with the increase of water matrix complexity from ultrapure water (UPW) > artificial seawater (ASW) > fulvic acid water (FAW) > artificial seawater with fulvic acid (AS/FAW), while the sorption rate of EE2 decreased from UPW > ASW > FAW and increased in the matrix combining salinity and organic matter (AS/FAW). On the contrary, the E3 sorption rate increased with matrix complexity, from UPW < ASW < FAW and decreased with the influence of salinity and organic matter combination (AS/FAW). The sorption capacity of the EDC reached maximum values of 82% for E2, 90% for EE2 and 56% for E3. Isotherms demonstrated the occurrence of multilayer sorption. A positive relationship has been found between the hydrophobicity of polyamide microplastics and the Log Kow of EDC, showing an important role of hydrophobic interactions in the sorption process under all the studied conditions. Moreover, hydrogen bonding and binding of contaminants and DOM to microplastics through bridges were also suggested. The results show that salinity and DOM can greatly influence the sorption and transportation of EDC in the aquatic environment and pose a risk to aquatic ecosystems.

Adsorción de acetaminofén sobre carbones activados a diferente pH. Entalpía y entropía del proceso / Acetaminophen adsorption on activated carbons at different pH. Change of enthalpy and entropy of the process / Adsorção de acetaminofeno em carvões ativados a diferentes pH. Entalpia e entropia do processo

Resumen Se analizaron los cambios entálpicos y entrópicos derivados del proceso de adsorción de acetaminofén sobre carbones activados con química superficial modificada. Se realizó, además, una variación del pH para determinar los cambios en las propiedades termodinámicas cuando existen cargas en el adsorbato y en el adsorbente. Se encontró que la máxima capacidad de adsorción (1,172 mmoles g-1) corresponde al proceso llevado a cabo en el carbón activado denominado CAR en este estudio a pH 7; los valores de las funciones termodinámicas de entalpía de inmersión y entropía de adsorción fueron -36,02 J g-1 y 0,123 J g-1 K-1, respectivamente. Así, el cambio de entropía de adsorción para el acetaminofén en los carbones activados estudiados dependió del pH. Se encontró que esta función termodinámica varía en el siguiente orden pH 2 > pH 11 > pH 7. Este comportamiento se relaciona con el número de especies presentes en la solución capaces de interactuar con la superficie del carbón activado.

Abstract The enthalpic and entropic changes resulting from the process of acetaminophen adsorption on activated carbons with modified surface chemistry were studied. A pH variation was performed to determine the changes in the thermodynamic properties when there are charges in the adsorbate and adsorbent. It was found that the maximum adsorption capacity (1.172 mmoles g-1) corresponds to the process carried out in the activated charcoal labeled as CAR in this study at pH 7; the values of the thermodynamic functions immersion enthalpy and entropy of adsorption were -36.02 J g-1 and 0.123 J g-1 K-1, respectively. Thus, the adsorption entropy change for the acetaminophen on the activated carbons depended on the pH. It was found that this thermodynamic function varies in the following order pH 2 > pH 11 > pH 7. This behavior is related to the number of species present in the solution capable of interact with the activated carbon surface.

Resumo Foram analisadas as mudanças entrópicas e entalpicas resultantes do processo de adsorção de acetaminofeno sobre carvões activados com superfície química modificada. Além disso, foi realizada uma variação do pH para determinar as alterações nas propriedades termodinâmicas quando existem cargas no adsorbato e no adsorvente. Foi encontrado que a máxima capacidade de adsorção (1.172 mmol g-1) corresponde ao processo realizado no carvão ativado chamado CAR neste estudo em pH 7; os valores das funções termodinâmicas de entalpia de imersão e entropia de adsorção foram -36,02 J g-1 e 0,123 J g-1 K-1 respectivamente. As mudança da entropia de adsorção para o acetaminofeno nos carvões activados dependeu do pH. Foi encontrado que esta função termodinâmica varia na seguinte ordem pH 2 > pH 11 > pH 7. Este comportamento está relacionado ao número de espécies presentes na solução capaz de interagir com a superfície de carvão activado.

Biochemical characterization of the interactions between doxorubicin and lipidic GM1 micelles with or without paclitaxel loading.

Doxorubicin (Dox) is an anthracycline anticancer drug with high water solubility, whose use is limited primarily due to significant side effects. In this study it is shown that Dox interacts with monosialoglycosphingolipid (GM1) ganglioside micelles primarily through hydrophobic interactions independent of pH and ionic strength. In addition, Dox can be incorporated even into GM1 micelles already containing highly hydrophobic paclitaxel (Ptx). However, it was not possible to incorporate Ptx into Dox-containing GM1 micelles, suggesting that Dox could be occupying a more external position in the micelles. This result is in agreement with a higher hydrolysis of Dox than of Ptx when micelles were incubated at alkaline pH. The loading of Dox into GM1 micelles was observed over a broad range of temperature (4°C-55°C). Furthermore, Dox-loaded micelles were stable in aqueous solutions exhibiting no aggregation or precipitation for up to 2 months when kept at 4°C-25°C and even after freeze-thawing cycles. Upon exposure to blood components, Dox-containing micelles were observed to interact with human serum albumin. However, the amount of human serum albumin that ended up being associated to the micelles was inversely related to the amount of Dox, suggesting that both could share their binding sites. In vitro studies on Hep2 cells showed that the cellular uptake and cytotoxic activity of Dox and Ptx from the micellar complexes were similar to those of the free form of these drugs, even when the micelle was covered with albumin. These results support the idea of the existence of different nano-domains in a single micelle and the fact that this micellar model could be used as a platform for loading and delivering hydrophobic and hydrophilic active pharmaceutical ingredients.

Role of co-solute in biomolecular stability: glucose, urea and the water structure.

We have studied the action of urea and glucose on the stability of DNAand micelles. We measured the melting temperature of aqueous solutionsof DNA with urea or glucose as a co-solute; we have also measured thechanges in the critical micelle concentrations (cmc) of Sodium DodecylSulfate and Triton X-100 by addition of urea and glucose. Ourexperimental results show that glucose increases the melting temperature ofDNA and decreases the cmc, while urea acts in the contrary direction. The effects of urea and glucose on the stability of DNA and micelles canbe explained by the weakening and enhancement of hydrophobicinteractions, respectively. These effects on hydrophobic interactions arediscussed in this paper.