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There are two commonly used drilling fluids, namely water-based muds (WBMs) and oil-based muds (OBMs); however, the latter type is more desirable for drilling unconventional oilfield reserves. To account for the potential encounter of hydrogen sulfide (H₂S) while drilling, the utilized OBMs should contain scavenger(s) with an effective H₂S mitigation capability in order to in-situ capture this very lethal and corrosive gas. To the best of our knowledge, studies on incorporating H₂S scavengers in OBMs and their testing are still greatly lacking in open literature. Thus, this study contributes into the filling of this gap by preparing a mineral oil-based drilling mud (MOBM) containing potassium permanganate as a promising, widely available, safe, and cheap H₂S scavenger. The MOBM also comprised other ingredients including rhamnolipid biosurfactant as an emulsifier and octadecanethiol-modified (i.e., hydrophobized) zinc nanoparticles (serving as weighting agent). These materials have not been widely utilized so far in open literature for the preparation of MOBM. The results obtained from this study demonstrated that this mud could fully scavenge H₂S for up to 22.7 h (i.e., breakthrough time), and it took about 63 h for the MOBM to become fully saturated with H₂S. The scavenged amounts of H₂S at these times reached 324.4 and 485.8 g/barrel MOBM, respectively. The formulated MOBM also displayed an appropriate non-Newtonian shear thinning behavior, where the apparent viscosity dropped sharply from about 1.96 to 0.71 Pa.s upon increasing the shear rate to from 1 to 10 s⁻¹, followed by a gradual decrease down to 0.31 Pa.s at a shear rate of 1000 s⁻¹. Additionally, the formulated mud is able to dissipate a significant amount of thermal energy as inferred from its estimated high activation energy of 34.93 kJ/mol, suggesting a good thermal stability of the MOBM. The present study reveals the possibility of formulating mineral OBMs with effective H₂S for safely drilling sour oil and gas reservoirs.

The large-scale culture of human induced pluripotent stem cells (hiPSCs) is essential for developing new pharmaceuticals and regenerative therapy methods. While for the development of cultured meat products, mass production of animal myoblasts is necessary. Both hiPSCs and animal myoblasts consume d-glucose as their energy source and produce l-lactate, which accumulates in cell culture media and inhibits cell proliferation. To make large-scale cell culture economically feasible, l-lactate removal and subsequent reuse of media are of high importance. The adsorption technique is attractive for l-lactate removal due to its low cost, ease of operation, and scalability. The current study is dedicated to 4-(2-hydroxyethyl)-1-piperazineethanesulfonate (HEPES) intercalated Mg–Al layered double hydroxide (LDH), which acts as a biocompatible anion-exchanger in media. HEPES‧Mg–Al LDH was able to remove l-lactate from hiPS cells and myoblast-relevant media selectively while mostly retaining d-glucose. Adsorbent exhibited dose-dependent cytotoxicity to hiPSCs and C2C12 cells, mainly related to elevated osmolarity, HEPES, and Mg levels and adsorption of media micro components. By employing alternatively prepared sol-gel derived HEPES‧Mg–Al LDH, the required adsorbent dose for efficient l-lactate removal was reduced to a safe level. The current study thoroughly evaluates Mg–Al layered double hydroxides as suitable adsorbents for cell culture media regeneration and discusses the limitations of Mg–Al LDHs in systems relevant to hiPS cells and C2C12 cells. This work promotes the cost-effective large-scale production of cells and gives insight into the limitations of Mg–Al LDHs applied to systems of biological origin.

The spread of bacterial infections aggravated by the development of microbial resistance to antibiotics requires the creation of protective antibacterial materials. Nanomaterials with biocides can provide antibacterial and antibiofilm properties against Gram-positive and Gram-negative bacteria. In this work, we synthesized nanocomposites with silver nanoparticles and different polyoxometalates of Keggin-structure (phosphomolybdic, phosphotungstic, and tungstosilicic acids) on eco-friendly nanoclay called halloysite. We found that the nanocomposite containing silver nanoparticles and phosphomolybdic acid deposited on the halloysite possesses the best antibacterial performance of all the obtained composites, having a minimal inhibitory concentration of 0.5 g/L against S. aureus, 0.25 g/L against P. aeruginosa and A. baumannii. This composite reduces the viability of formed biofilms at a concentration of 2.5 g/L.

A catalyst-free, green and efficient protocol for the one-pot, multi-component, synthesis of Methyleneisoxazole-5(4H)-ones (4a-l) from the reaction of Ethyl acetoacetate, aromatic aldehyde, and hydroxylamine hydrochloride in ethanol as green solvent under ultrasound irradiation at ambient temperature is described. This protocol offers several positive benefits, including simple handling, rapid reaction time period (≤10 mints), easy workup process, waste-free, gentler reaction conditions, ecologically friendly, cleaner reaction, absence of any a laborious purification and excellent yields.

The formation of an antibody (Ab) protein corona surrounding gold nanoparticles (AuNPs) is a crucial step in the design of immunological assays. The Ab corona stabilizes AuNPs, preventing their aggregation even at high ionic strength, and can be achieved by simply mixing Abs and AuNPs. In this paper, we report the unusual interactions between AuNPs and the antibody against L1 Cell Adhesion Molecule (L1CAM) purified from rabbits.

We have observed that at low ionic strength, the addition of a wide range of concentrations of rabbit monoclonal Abs against L1CAM protein immediately causes the coagulation of citrate-capped gold nanoparticles. This finding is surprising since the addition of proteins to colloidal gold usually forms a stable protein corona. The combination of extinction spectra, dynamic light scattering (DLS), and transmission electron microscopy (TEM) measurements reveals the presence of small clusters of AuNPs coated by the antibodies, as well as micron-sized antibody aggregates. Furthermore, static light scattering measurements demonstrate that Ab self-interactions are attractive (with a negative second virial coefficient, B2) and induce very slow Ab self-aggregation over several months. Overall, these results indicate that, at low ionic strength, the presence of AuNPs enhances Ab-Ab interactions, leading to their rapid aggregation. Simultaneously, the self-aggregation of the antibodies coating the AuNPs results in the formation of nanoparticle clusters.

The addition of NaCl to increase the ionic strength fully reverses the coagulation of AuNPs (the Ab-coated AuNPs repel each other) and dissolves the Ab aggregates (the Ab interactions become repulsive, with a positive B2). The AuNPs-induced enhancement of the aggregation process can be explained by considering that the highly favorable binding of Abs on the gold surface compensates for the entropic penalty associated with Ab-Ab aggregation.

The phenomenon we observed is specific to anti-L1CAM purified from rabbits and aligns with very old reports on AuNP coagulation induced specifically by the immunoglobulins present in the cerebrospinal fluid of patients suffering from neurosyphilis or multiple sclerosis (C. Lange Zeitschr. Chemotherap., 1912, 1, 44). It is reasonable to hypothesize that other antibodies exhibit this unusual behavior, so this work may aid in the interpretation of “anomalous” results that might otherwise be attributed to errors in fine-tuning AuNPs-Abs conjugation protocols.

Stability of dispersed materials remains an important question in a wide variety of fields such as cosmetics, catalysis, food or energy and the environment. As stability is directly linked to the size of the dispersed colloids it is essential to assess the size distribution of colloidal suspensions. Nowadays, microfluidic-based approaches generate increasing interest as they represent flexible and fast measurements allowing high throughput experimentations. However, characterization of colloidal dispersions is usually performed by dynamic light scattering (DLS), that requires static measurements as well as significant volumes, that are not compatible with on-line analysis and microfluidics. Moreover, due to flow-induced decorrelation terms, DLS measurements in microfluidic channels are only accurate at very low shear rates.

This work aimed at developing an on-line microfluidic device for dispersed materials characterization using DLS. The main challenges of this project were i) to adapt the microfabrication of the PDMS device in order to combine microchannels of hundreds of microns with a milli-fluidic cavity to perform the DLS measurements, and ii) to downsize the DLS set up. A PDMS microchip, consisting in a millimeter cavity for DLS measurements in parallel with a microchannel, was designed to perform the measurement on the sample without stopping the suspension flow during the microfluidic experiment. The cavity geometry was then optimized thanks to numerical simulation to ensure a good sweep efficiency and to downscale as much as possible without impairing the DLS signal.

By adapting the microfabrication process, a PDMS microfluidic chip was designed allowing the size measurements of successive suspensions containing 100 and 12 ​nm diameter particles. This work is a first step towards the implementation of a new technological building block for online microfluidic characterization.

© 2017 Elsevier Inc. All rights reserved.

Drug delivery approaches can be used to enhance the bioavailability of current antiretroviral drugs used to treat HIV. Lipid nanocarriers are attractive drug delivery vehicles and these systems can be classified based on their lipid composition into solid lipid nanoparticles (SLNs), nanostructured lipid carriers (NLCs) and nanoemulsions (NEs). In order to develop high drug loading nanoformulations for the treatment of HIV, we investigate the factors that influence the comparative production of SLNs, NLCs and NEs with Imwitor 900k and soybean oil as the solid and liquid lipids respectively. These nanoformulations contained a therapeutically relevant drug mixture of darunavir (DRV) and ritonavir (RTV). We used a simple nanoprecipitation method that does not require any heating of the lipid phase and screened three key formulation factors (lipid concentration, surfactant selection and drug loading) in order to determine their effect on the particle properties and stability of the formulations. Two different surfactants were used, (Brij 78 and Tween 80) which had a significant effect on the ability to form a viable nanodispersion; using Brij 78 as the surfactant resulted in more viable formulations for our lipids. A concentration of the lipid in the organic phase of 4 mg/mL was determined to achieve a good balance between viable formulations and lipid loading resulting in nanoparticles with mean diameters ∼200–300 ​nm. Drug loadings of 10% w/w DRV/total lipid was achieved for SLNs, with loadings of 20% w/w was possible for NLCs and NEs, these values are amongst the highest reported for lipid nanoformulations. All formulations had encapsulation efficiencies of ≥92.5%. Overall, this study shows the versatility of the nanoprecipitation method for producing SLNs, NLCs and NEs. The ability to produce all three formulations with identical compositions (other than the lipids) may allow direct comparison of the biological properties in the future.

Soil derived dissolved organic matter (DOM) is an important component of the carbon cycle and influences numerous biogeochemical processes, including the formation of mineral-organic associations. DOM ranges in size from small organic molecules to macromolecules and colloidal aggregates. In this study we have used small angle neutron (SANS) and X-ray (SAXS) scattering to characterize the colloidal DOM fraction from the organic layer of a boreal forest soil, and its interactions with hematite (α-Fe₂O₃) mineral nanoparticles. Comparison between SAXS and contrast variation SANS patterns revealed that the scattering form factor of the colloidal DOM aggregates was essentially independent of the scattering contrast, implying that the colloidal aggregates have an essentially homogeneous chemical composition, down to the nanometre length scale. Variation of the D₂O/H₂O ratio of the solvent yielded a SANS intensity minimum at ca. 40 ​vol % D₂O, which was consistent with colloids composed of mainly polysaccharides. At pH 5.5 the pure hematite nanoparticles were colloidally stable in water and characterized by a ζ-potential of +25 ​mV and a hydrodynamic radius of ca. 70 ​nm. In the presence of DOM, the hematite nanoparticles lost the colloidal stability and aggregated into larger clusters, displaying a negative ζ-potential of ca. −25 ​mV. The charge reversal suggested that negatively charged polyanions of DOM adsorbed onto the hematite particles, possibly leading to bridging flocculation. Our results suggested that mainly low molecular weight components induced hematite aggregation because no or very limited interactions between DOM colloids and hematite were detected.

Hypothesis

Supramolecular self-assembly derived from amphiphilic molecules is one of the prime interests with the motivation to develop new building blocks to create different task-specific self-assemblies. Considering the emergent applicability of these self-aggregates across the globe, it would be necessary to develop an alternate technique for the manufacture of self-aggregates employing novel building blocks.

Experiment

With this aim, we synthesized a palmitoyl moiety functionalized carbon quantum dot (FCQD). Interestingly, the synthesized FCQD was found to form a stable amphiphilic inclusion complex (βCD-FCQD) with the ‘host’ β-cyclodextrin (βCD). This amphiphilic βCD-FCQD complex was utilized as a building block to form a hierarchical vesicular self-aggregate (βCD-FCQD vesicle).

Findings

This βCD-FCQD vesicle was successfully employed to detect cholesterol. Moreover, cholesterol lowering hydrophilic drug rosuvastatin loaded βCD-FCQD vesicle was found to be potential in regulation of cholesterol. This work is anticipated to encourage the construction of drug loaded self-assembly based formulation to achieve a way out towards graded combined treatment for cholesterol related disorder like hypercholesterolemia.

Cellulose nanocrystals (CNC) have received much attention as a drug delivery vehicle, but their hydrophilic nature hinders hydrophobic drug loading. Ionotropic gelation using CNC and chitosan (CS) can enhance the loading/encapsulation capacity of hydrophobic compounds, improve colloidal stability, and strengthen mucoadhesion due to the cationic surface of CS. The colloidal behavior of CNC/CS nanocomposites loaded with emamectin benzoate (EMB) were elucidated by measuring the particle size, zeta potential, contact angle, and morphological structure using transmission electron microscopy. The mucoadhesive properties of the nanocomposites were evaluated by viscometric and titration method, followed by testing with zebrafish mucus. A facile and reproducible protocol to synthesize mucoadhesive CNC/CS nanocomposites that can encapsulate hydrophobic drugs is demonstrated. The optimal mass ratio for the synthesis was 1:10 (CS:CNC w/w), yielding the smallest average particle size (∼200 nm), highest zeta potentials (+40 mV), and highest drug encapsulation capacity (68.8 ± 8.7%). The steric stabilization effect of polyvinylpyrrolidone (PVP) and amphiphilic CNC stabilized the colloidal system. Importantly, the CS-coating technique enhanced the colloidal stability due to electrostatic intramolecular repulsion of the positive CS. CNC/CS nanocomposites exhibited enhanced mucoadhesive interaction with porcine mucin protein and live zebrafish mucus.