Oil Irradiation Experiments Document Changes in Oil Properties, Molecular Composition, and Dispersant Effectiveness Associated with Oil Photo-Oxidation.

While chemical dispersants are a powerful tool for treating spilled oil, their effectiveness can be limited by oil weathering processes such as evaporation and emulsification. It has been suggested that oil photo-oxidation could exacerbate these challenges. To address the role of oil photo-oxidation in dispersant effectiveness, outdoor mesocosm experiments with crude oil on seawater were performed. Changes in bulk oil properties and molecular composition were quantified to characterize oil photo-oxidation over 11 days. To test relative dispersant effectiveness, oil residues were evaluated using the Baffled Flask Test. The results show that oil irradiation led to oxygen incorporation, formation of oxygenated hydrocarbons, and higher oil viscosities. Oil irradiation was associated with decreased dispersant efficacy, with effectiveness falling from 80 to <50% in the Baffled Flask Test after more than 3 days of irradiation. Increasing photo-oxidation-induced viscosity seems to drive the decreasing dispersant effectiveness. Comparing the Baffled Flask Test results with field data from the Deepwater Horizon oil spill showed that laboratory dispersant tests underestimate the dispersion of photo-oxidized oil in the field. Overall, the results suggest that prompt dispersant application (within 2-4 days), as recommended by current oil spill response guidelines, is necessary for effective dispersion of spilled oil.

Cosolvent and Crowding Effects on the Temperature- and Pressure-Dependent Dissociation Process of the α/ß-Tubulin Heterodimer.

Tubulin is one of the main components of the cytoskeleton of eukaryotic cells. The formation of microtubules depends strongly on environmental and solution conditions, and has been found to be among the most pressure sensitive processes in vivo. We explored the effects of different types of cosolvents, such as trimethylamine-N-oxide (TMAO), sucrose and urea, and crowding agents to mimic cell-like conditions, on the temperature and pressure stability of the building block of microtubules, i. e. the α/ß-tubulin heterodimer. To this end, fluorescence and FTIR spectroscopy, differential scanning and pressure perturbation calorimetry as well as fluorescence anisotropy and correlation spectroscopies were applied. The pressure and temperature of dissociation of α/ß-tubulin as well as the underlying thermodynamic parameters upon dissociation, such as volume and enthalpy changes, have been determined for the different solution conditions. The temperature and pressure of dissociation of the α/ß-tubulin heterodimer and hence its stability increases dramatically in the presence of TMAO and the nanocrowder sucrose. We show that by adjusting the levels of compatible cosolutes and crowders, cells are able to withstand deteriorating effects of pressure even up to the kbar-range.

Multi-Solvent Microdroplet Evaporation: Modeling and Measurement of Spray-Drying Kinetics with Inhalable Pharmaceutics.

PURPOSE: Evaporation and particle formation from multi-solvent microdroplets containing solid excipients pertaining to spray-drying of therapeutic agents intended for lung delivery were studied. Various water and ethanol co-solvent systems containing a variety of actives and excipients (beclomethasone, budesonide, leucine, and trehalose) were considered. METHODS: Numerical methods were used to predict the droplet evaporation rates and internal solute transfers, and their results verified and compared with results from two separate experimental setups. In particular, an electrodynamic balance was used to measure the evaporation rates of multicomponent droplets and a monodisperse droplet chain setup collected dried microparticles for further analytical investigations and ultramicroscopy. RESULTS: The numerical results are used to explain the different particle morphologies dried from solutions at different co-solvent compositions. The obtained numerical data clearly show that the two parameters controlling the general morphology of a dried particle, namely the Péclet number and the degree of saturation, can change with time in a multi-solvent droplet. This fact complicates product development for such systems. However, this additional complexity vanishes at what we define as the iso-compositional point, which occurs when the solvent ratios and other composition-dependent properties of the droplet remain constant during evaporation, similar to the azeotrope of such systems during distillation. CONCLUSIONS: Numerical and experimental analysis of multi-solvent systems indicate that spray-drying near the iso-compositional ratio simplifies the design and process development of such systems.

Modulation of the Polymerization Kinetics of α/ß-Tubulin by Osmolytes and Macromolecular Crowding.

Tubulin is one of the main components of the cytoskeleton and can be found in nearly all eukaryotic cells. In this study, we explored the effects of kosmotropic and chaotropic osmolytes, such as trimethylamine-N-oxide (TMAO) and the metabolic waste product urea, as well as the crowding agents Ficoll and sucrose on the polymerization reaction of α/ß-tubulin. Time-dependent turbidimetry and fluorescence anisotropy experiments were performed to explore the kinetics of the polymerization reaction. Under different solvent conditions, diverse changes in the lag time, the half-life of the polymerization reaction, and the critical concentration of the polymerization reaction were observed. The apparent growth rate of the formation of microtubules was dramatically decreased in the presence of urea but significantly increased in the presence of TMAO. Measurements using mixtures of these two cosolvents showed that TMAO was able to counteract the deteriorating effect of urea on the polymerization reaction of tubulin. To create a more cell-like environment, Ficoll was added as a macromolecular crowding agent. The presence of 10 wt % Ficoll increased the apparent growth rate by one order of magnitude. Our results clearly show that the polymerization of tubulin is very sensitive to the surrounding solvent.

Formulation approaches to improving the delivery of an antiviral drug with activity against seasonal flu.

The main objective of the present study was to develop formulations of noscapine hydrochloride hydrate with enhanced solubility and bioavailability using co-solvent- and cyclodextrin-based approaches. Different combinations of co-solvents, which were selected on the basis of high-throughput solubility screening, were subjected to in vitro intestinal drug permeability studies conducted with Ussing chambers. Vitamin E tocopherol polyethylene glycol succinate and propylene glycol based co-solvent formulations provided the maximum permeability coefficient for the drug. Inclusion complexes of the drug were prepared using hydroxypropyl-ß-cyclodextrin and sulphobutylether cyclodextrins. Pharmacokinetic studies were carried out in male Sprague-Dawley rats for the selected formulations. The relative bioavailabilities of the drug with the co-solvent- and cyclodextrin-based formulations were found to be similar.

Computational library design for increasing haloalkane dehalogenase stability.

We explored the use of a computational design framework for the stabilization of the haloalkane dehalogenase LinB. Energy calculations, disulfide bond design, molecular dynamics simulations, and rational inspection of mutant structures predicted many stabilizing mutations. Screening of these in small mutant libraries led to the discovery of seventeen point mutations and one disulfide bond that enhanced thermostability. Mutations located in or contacting flexible regions of the protein had a larger stabilizing effect than mutations outside such regions. The combined introduction of twelve stabilizing mutations resulted in a LinB mutant with a 23 °C increase in apparent melting temperature (Tm,app , 72.5 °C) and an over 200-fold longer half-life at 60 °C. The most stable LinB variants also displayed increased compatibility with co-solvents, thus allowing substrate conversion and kinetic resolution at much higher concentrations than with the wild-type enzyme.

Locally Concentrated Deep Eutectic Liquids Electrolytes for Low-Polarization Aluminum Metal Batteries.

Low-cost and nontoxic deep eutectic liquid electrolytes (DELEs), such as [AlCl3]1.3[Urea] (AU), are promising for rechargeable non-aqueous aluminum metal batteries (AMBs). However, their high viscosity and sluggish ion transport at room temperature lead to high cell polarization and low specific capacity, limiting their practical application. Herein, non-solvating 1,2-difluorobenzene (dFBn) is proposed as a co-solvent of DELEs using AU as model to construct a locally concentrated deep eutectic liquid electrolyte (LC-DELE). dFBn effectively improves the fluidity and ion transport without affecting the ionic dynamics in the electrolyte. Moreover, dFBn also modifies the solid electrolyte interphase growing on the aluminum metal anodes and reduces the interfacial resistance. As a result, the lifespan of Al/Al cells is improved from 210 to 2000 h, and the cell polarization is reduced from 0.36 to 0.14 V at 1.0 mA cm-2. The rate performance of Al-graphite cells is greatly improved with a polarization reduction of 0.15 and 0.74 V at 0.1 and 1 A g-1, respectively. The initial discharge capacity of Al-sulfur cells is improved from 94 to 1640 mAh g-1. This work provides a feasible solution to the high polarization of AMBs employing DELEs and a new path to high-performance low-cost AMBs.

Solvents and detergents compatible with enzyme kinetic studies of cholinesterases.

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) are enzymes that serve a wide range of physiological functions including the hydrolysis of the neurotransmitter acetylcholine and several other xenobiotics. The development of inhibitors for these enzymes has been the focus for the treatment of several conditions, such as Alzheimer's disease. Novel chemical entities are evaluated as potential inhibitors of AChE and BChE using enzyme kinetics. A common issue encountered in these studies is low aqueous solubility of the possible inhibitor. Additives such as cosolvents or detergents can be included in these studies improve the aqueous solubility. Typical cosolvents include acetonitrile or dimethyl sulfoxide while typical detergents include Polysorbate 20 (Tween 20) or 3-((3-cholamidopropyl) dimethylammonio)-1-propanesulfonate (CHAPS). When solubility is not improved, these molecules are often not evaluated further. To address this issue eleven cosolvents and six detergents that could facilitate aqueous solubility were evaluated to understand how they would affect cholinesterase enzymes using Ellman's assay. These studies show that propylene glycol, acetonitrile, methanol, Tween 20, Polysorbate 80 (Tween 80), polyoxyethylene 23 lauryl ether (Brij 35) and polyoxyethylene 10 oleoyl ether (Brij 96v) have the least inhibitory effects towards cholinesterase activity. It is concluded that these cosolvents and detergents should be considered as solubilizing agents for evaluation of potential cholinesterase inhibitors with low aqueous solubility.

Co-Solvent Electrolyte Design to Inhibit Phase Transition toward High Performance K+ /Zn2+ Hybrid Battery.

Manganese hexacyanoferrate (MnHCF) is one of the most promising cathode materials for aqueous battery because of its non-toxicity, high energy density, and low cost. But the phase transition from MnHCF to Zinc hexacyanoferrate (ZnHCF) and the larger Stokes radius of Zn2+ cause rapid capacity decay and poor rate performance in aqueous Zn battery. Hence, to overcome this challenge, a solvation structure of propylene carbonate (PC)-trifluoromethanesulfonate (Otf)-H2 O is designed and constructed. A K+ /Zn2+ hybrid battery is prepared using MnHCF as cathode, zinc metal as anode, KOTf/Zn(OTf)2 as the electrolyte, and PC as the co-solvent. It is revealed that the addition of PC inhabits the phase transition from MnHCF to ZnHCF, broaden the electrochemical stability window, and inhibits the dendrite growth of zinc metal. Hence, the MnHCF/Zn hybrid co-solvent battery exhibits a reversible capacity of 118 mAh g-1 and high cycling performance, with a capacity retention of 65.6% after 1000 cycles with condition of 1 A g-1 . This work highlights the significance of rationally designing the solvation structure of the electrolyte and promotes the development of high-energy-density of aqueous hybrid ion batteries.

Directional depolymerization of lignin into high added-value chemical with synergistic effect of binary solvents.

This work exploits a one-pot method for directional depolymerizing organosolv lignin into high added-value phenolic monomers with synergistic reaction system consisted of methanol-dimethoxymethane binary solvents and acid catalyst. The influence of solvent composition and reaction parameters such as different catalyst, binary solvents ratio, time, and temperature on the conversion of lignin and yield of products were investigated carefully, the optimum yield of liquid products and phenolic monomers were achieved at 67.39% and 27.67% at 200 °C kept for 60 min with low amount of acid catalyst. The plausible mechanism on the depolymerization of lignin was proposed in view of product distributions. Moreover, the combination of co-solvents and acidic catalyst was also suitable for converting different types of lignin into phenolic monomers, and the recyclability of joint reaction system was satisfactory. These results can provide promising prospects on developing an effective method for achieving high added-value phenolic compounds from lignin.

Membrane-water partitioning - Tackling the challenges of poorly soluble drugs using chaotropic co-solvents.

Many newly developed drugs suffer from poor water solubility and low bioavailability and hence, need special formulation vehicles like vesicular or micellar drug delivery systems. The knowledge of their membrane-water partition coefficient K becomes critical as is governs drug loading and release from the vehicle, as well as absorption into the body. The dilemma is that measuring K is particularly challenging for these very compounds. Here we establish a strategy to resolve this problem. We added DMSO to shift K and solubility into a convenient range and extrapolated these results back to zero-DMSO. Isothermal titration calorimetry revealed that logK of the kinase inhibitor Lapatinib decreased proportionally to DMSO content (2.5 - 20v%) with a slope of -1/20v% (m value = 28 kJ/mol). This implies a K of 84 mM-1 in DMSO-free buffer. This strategy should be transferable to other poorly soluble drugs and further detection methods.

Oil sludge washing with surfactants and co-solvents: oil recovery from different types of oil sludges.

Different physicochemical and biological treatments have been used to treat oil sludges, and oil recovery techniques are preferred such as oil sludge washing (OSW) with surfactants and co-solvents. Toluene is commonly used as co-solvent, but it is non-benign to the environment. This study tested alternative co-solvents (n-pentane, n-hexane, cyclohexane, and isooctane) at 1:1 and 2:1 C/OS (co-solvent to oil sludge ratio). Also, this study evaluated the effect on the oil recovery rate (ORR) of three main parameters in the washing: type, concentration, and application ratio (S/OS) of surfactants to oil sludges. To date, no study has assessed these parameters in the washing of oil sludges from different sources. Four types of oil sludges and five surfactants (Triton X-100 and X-114, Tween 80, sodium dodecyl sulphate (SDS), and rhamnolipid) were used. The results showed that cyclohexane had high ORR and could be used instead of toluene because it is more benign to the environment. The S/OS ratio had a high effect on the ORR and depended on the type of oil sludge. Rhamnolipid, Triton X-100, and Triton X-114 had the highest oil recovery rates (40 - 70%). In addition, it was found that the surfactant concentration had no effect on the ORR. Consequently, the addition of surfactant was not significantly different compared to the washing with no surfactants, except for one sludge. The use of the surfactant in the washing solution can help in the selective extraction of specific oil hydrocarbon fractions in the recovered oil to assess its potential reuse as fuel. Further recommendations were given to improve the OSW process.

Eco-scalable baicalin loaded vesicles developed by combining phospholipid with ethanol, glycerol, and propylene glycol to enhance skin permeation and protection.

A new class of biocompatible and scalable phospholipid vesicles was developed, aiming at improving the efficacy of baicalin on the skin. Phosphatidylcholine and baicalin (a natural polyphenol) were hydrated in two steps with a mixture of ethanol, glycerol, and propylene glycol at different ratios, and a low amount of water (4%). Hence, water was almost completely replaced by the co-solvents, which were never used before as predominant dispersing medium of phospholipid vesicles. The vesicles appeared three-dimensionally structured, forming a network that conferred a high viscosity to the dispersions. The vesicles were unilamellar, small in size (∼100 nm), and stable during 12 months of storage. They disclosed optimal performances in the transdermal delivery of baicalin, and high biocompatibility with skin cells (i.e., keratinocytes and fibroblasts). Furthermore, the vesicles promoted the efficacy of baicalin in protecting skin cells against oxidative stress in vitro and injured skin in vivo.

Evaluations of N-(Isobutoxymethyl) acrylamide gel dosimeter by NMR technique for radiotherapy and uncertainty in dose measurements.

N-(Isobutoxymethyl) acrylamide (NIBMA) monomer in gelatin, named NIBMAGAT gel dosimeter, was prepared and investigated by nuclear magnetic imaging (NMR) for radiotherapy in the dose range of 0-30 Gy. NIBMA monomer polymerizes upon irradiation, increasing spin-spin relaxation rate R2. The addition of glycerol as a co-solvent in the gel matrix improved its radiation sensitivity better than the co-solvents of acetone and methanol. The increase of glycerol content by 1% wt/wt enhanced the sensitivity by ˜ 3.1%. This gel has better radiation sensitivity as compared to the polyacrylamide gel (PAG) dosimeter; the sensitivities of NIBMAGAT gel and normoxic polyacrylamide gel (nPAG) are ≈0.13 and ≈0.1 s-1.Gy-1, respectively. By comparing NIBMAGAT gel dosimeter with PAG, nMAG and nPAG gel dosimeters, NIBMAGAT gel dosimeter is less influenced by scanning temperature than the last three dosimeters. The gel is water equivalent and has an energy-independent response from 80 keV to 20 MeV. The overall uncertainty of dose measurement using NIBMAGAT gel is 5.46% at 2σ. Our findings suggest the applicability of using NIBMAGAT gel dosimeter by NMR technique for dose verification/planning in the practice of clinical radiotherapy.

Optimization of Innovative Three-Dimensionally-Structured Hybrid Vesicles to Improve the Cutaneous Delivery of Clotrimazole for the Treatment of Topical Candidiasis.

New three-dimensionally-structured hybrid phospholipid vesicles, able to load clotrimazole in a high amount (10 mg/mL), were obtained for the first time in this work by significantly reducing the amount of water (≤10%), which was replaced with a mixture of glycerol and ethanol (≈90%). A pre-formulation study was carried out to evaluate the effect of both the composition of the hydrating medium and the concentration of the phospholipid on the physico-chemical properties of hybrid vesicles. Four different three-dimensionally-structured hybrid vesicles were selected as ideal systems for the topical application of clotrimazole. An extensive physico-chemical characterization performed using transmission electron microscopy (TEM), cryogenic transmission electron microscopy (cryo-TEM), 31P-NMR, and small-angle X-ray scattering (SAXS) displayed the formation of small, multi-, and unilamellar vesicles very close to each other, and was capable of forming a three-dimensional network, which stabilized the dispersion. Additionally, the dilution of the dispersion with water reduced the interactions between vesicles, leading to the formation of single unilamellar vesicles. The evaluation of the in vitro percutaneous delivery of clotrimazole showed an improved drug deposition in the skin strata provided by the three-dimensionally-structured vesicles with respect to the commercial cream (Canesten®) used as a reference. Hybrid vesicles were highly biocompatible and showed a significant antifungal activity in vitro, greater than the commercial cream Canesten®. The antimycotic efficacy of formulations was confirmed by the reduced proliferation of the yeast cells at the site of infection in vivo. In light of these results, clotrimazole-loaded, three-dimensionally-structured hybrid vesicles appear to be one of the most innovative and promising formulations for the treatment of candidiasis infections.

Protein-solvent interaction.

Protein folding and assembly can be manipulated in in vitro systems by co-solvents at high concentrations. A number of co-solvents that enhance protein stability and assembly have been shown to be excluded from the protein surface. Such co-solvent exclusion has been demonstrated by dialysis experiments and shown to be correlated with their effects on protein stability and assembly.

High-level expression and molecular characterization of a recombinant prolidase from Escherichia coli NovaBlue.

Long-term use of organophosphorus (OP) compounds has become an increasing global problem and a major threat to sustainability and human health. Prolidase is a proline-specific metallopeptidase that can offer an efficient option for the degradation of OP compounds. In this study, a full-length gene from Escherichia coli NovaBlue encoding a prolidase (EcPepQ) was amplified and cloned into the commercially-available vector pQE-30 to yield pQE-EcPepQ. The overexpressed enzyme was purified from the cell-free extract of isopropyl thio-ß-D-galactoside IPTG-induced E. coli M15 (pQE-EcPepQ) cells by nickel-chelate chromatography. The molecular mass of EcPepQ was determined to be about 57 kDa by 12% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the result of size-exclusion chromatography demonstrated that the enzyme was mainly present in 25 mM Tris-HCl buffer (pH 8.0) as a dimeric form. The optimal conditions for EcPepQ activity were 60 °C, pH 8.0, and 0.1 mM Mn2+ ion. Kinetic analysis with Ala-Pro as the substrate showed that the K m and k cat values of EcPepQ were 8.8 mM and 926.5 ± 2.0 s-1, respectively. The thermal unfolding of EcPepQ followed a two-state process with one well-defined unfolding transition of 64.2 °C. Analysis of guanidine hydrochloride (GdnHCl)-induced denaturation by tryptophan emission fluorescence spectroscopy revealed that the enzyme had a [GdnHCl]0.5,N-U value of 1.98 M. The purified enzyme also exhibited some degree of tolerance to various water/organic co-solvents. Isopropanol and tetrahydrofuran were very detrimental to the enzymatic activity of EcPepQ; however, other more hydrophilic co-solvents, such as formamide, methanol, and ethylene glycol, were better tolerated. Eventually, the non-negative influence of some co-solvents on both catalytic activity and structural stability of EcPepQ allows to adjust the reaction conditions more suitable for EcPepQ-catalyzed bioprocess.

Hotspot Identification on Protein Surfaces Using Probe-Based MD Simulations: Successes and Challenges.

Molecular Dynamics (MD) based computational co-solvent mapping methods involve the generation of an ensemble of MD-sampled target protein conformations and using selected small molecule fragments to identify and characterize binding sites on the surface of a target protein. This approach incorporates atomic-level solvation effects and protein mobility. It has shown great promise in the identification of conventional competitive and allosteric binding sites. It is also currently emerging as a useful tool in the early stages of drug discovery. This review summarizes efforts as well as discusses some methodological advances and challenges in binding site identification process through these co-solvent mapping methods.

Bio-oil extraction of Jatropha curcas with ionic liquid co-solvent: Fate of biomass protein.

The fate of oil-seed biomass protein has been tracked through all steps of a multi-phase extraction process using an ionic liquid based co-solvent system previously demonstrated to extract bio-oil and phorbol esters and to recover fermentable sugars from Jatropha oil seed. These analyses, however, did not address the fate of biomass protein. This work demonstrated that the majority of protein (∼86%) tracked with the biomass with the balance lost to co-solvent (∼12%) and methanol (∼2%) washes. A significant portion of the ionic liquid remained with the treated biomass and required aggressive methanol washes to recover. A system analysis showed a net-positive energy balance and thus the potential of this system to produce both bio-oil and protein-rich toxin-free biomass. While these results further support Jatropha as an oil seed crop, the additional costs of solvent recovery will need to be addressed if commercialization is to be realized.

Enhanced Enzymatic Synthesis of a Cephalosporin, Cefadroclor, in the Presence of Organic Co-solvents.

In this study, we investigated the enzymatic synthesis of a semi-synthetic cephalosporin, cefadroclor, from 7-aminodesacetoxymethyl-3-chlorocephalosporanic acid (7-ACCA) and p-OH-phenylglycine methyl ester (D-HPGM) using immobilized penicillin G acylase (IPA) in organic co-solvents. Ethylene glycol (EG) was employed as a component of the reaction mixture to improve the yield of cefadroclor. EG was found to increase the yield of cefadroclor by 15-45%. An investigation of altered reaction parameters including type and concentration of organic solvents, pH of reaction media, reaction temperature, molar ratio of substrates, enzyme loading, and IPA recycling was carried out in the buffer mixture. The best result was a 76.5% conversion of 7-ACCA, which was obtained from the reaction containing 20% EG (v/v), D-HPGM to 7-ACCA molar ratio of 4:1 and pH 6.2, catalyzed by 16 IU mL-1 IPA at 20 °C for 10 h. Under the optimum conditions, no significant loss of IPA activity was found after seven repeated reaction cycles. In addition, cefadroclor exhibited strong inhibitory activity against yeast, Bacillus subtilis NX-2, and Escherichia coli and weaker activity against Staphylococcus aureus and Pseudomonas aeruginosa. Cefadroclor is a potential antibiotic with activity against common pathogenic microorganisms.