Water-miscible Solvents Research Articles

Solvo-Driven Dimeric Nanoplasmon Coupling Under DNA Direction

Strong coupling is a prerequisite for nanoassemblies to deliver functions and applications unrealizable by noninteracting building units. DNA-Directed metamaterials, albeit highly programmable, oft...

Extending the Library of Light‐Dependent Protochlorophyllide Oxidoreductases and their Solvent Tolerance, Stability in Light and Cofactor Flexibility

AbstractBiocatalysis is increasingly used in combination with light to develop new and more sustainable synthetic methods. Thereby, mostly a chemical photocatalyst harvesting the light energy is combined with an established enzymatic reaction, thus the biocatalyst itself does not require the light for its specific reaction. Here we expand the library of an enzyme which requires light for its natural reaction, namely the light‐dependent protochlorophyllide oxidoreductase (LPOR). This enzyme catalyzes the NADPH‐dependent reduction of a C=C in a N‐heterocycle. Out of five LPORs identified by sequence search, four were found to be well expressible in E. coli and active. Investigating the light intensity, which is an important parameter describing energy input and subsequently may enable fast reaction, it turned out that the four LPORs can stand the maximum light intensity reachable with the equipment used (1450 μmol photons m−2 s−1). However, the natural substrate and product were degraded at these conditions, allowing only 15 % of the maximum input (211 μmol photons m−2 s−1). Furthermore, the LPORs accepted seven different water miscible solvents with a solvent content of up to 20 % v/v and were active at a pH from 6 to 10. While all LPORs known to date are exclusively NADPH dependent, two LPORs identified here were active also with NADH. The cofactor selectivity could be pinned to three amino acid residues, which interestingly do not directly bind to the cofactor.

The pharmaceutical solvent N-methyl-2-pyrollidone (NMP) attenuates inflammation through Kr\xfcppel-like factor 2 activation to reduce atherogenesis

N-methyl-2-pyrrolidone (NMP) is a versatile water-miscible polar aprotic solvent. It is used as a drug solubilizer and penetration enhancer in human and animal, yet its bioactivity properties remain elusive. Here, we report that NMP is a bioactive anti-inflammatory compound well tolerated in vivo, that shows efficacy in reducing disease in a mouse model of atherosclerosis. Mechanistically, NMP increases the expression of the transcription factor Kruppel-like factor 2 (KLF2). Monocytes and endothelial cells treated with NMP express increased levels of KLF2, produce less pro-inflammatory cytokines and adhesion molecules. We found that NMP attenuates monocyte adhesion to endothelial cells inflamed with tumor necrosis factor alpha (TNF-α) by reducing expression of adhesion molecules. We further show using KLF2 shRNA that the inhibitory effect of NMP on endothelial inflammation and subsequent monocyte adhesion is KLF2 dependent. Enhancing KLF2 expression and activity improves endothelial function, controls multiple genes critical for inflammation, and prevents atherosclerosis. Our findings demonstrate a consistent effect of NMP upon KLF2 activation and inflammation, biological processes central to atherogenesis. Our data suggest that inclusion of bioactive solvent NMP in pharmaceutical compositions to treat inflammatory disorders might be beneficial and safe, in particular to treat diseases of the vascular system, such as atherosclerosis.

Hypoxanthine-Guanine Phosphoribosyltransferase/adenylate Kinase From Zobellia galactanivorans: A Bifunctional Catalyst for the Synthesis of Nucleoside-5′-Mono-, Di- and Triphosphates

In our search for novel biocatalysts for the synthesis of nucleic acid derivatives, we found a good candidate in a putative dual-domain hypoxanthine-guanine phosphoribosyltransferase (HGPRT)/adenylate kinase (AMPK) from Zobellia galactanivorans (ZgHGPRT/AMPK). In this respect, we report for the first time the recombinant expression, production, and characterization of a bifunctional HGPRT/AMPK. Biochemical characterization of the recombinant protein indicates that the enzyme is a homodimer, with high activity in the pH range 6-7 and in a temperature interval from 30 to 80°C. Thermal denaturation experiments revealed that ZgHGPRT/AMPK exhibits an apparent unfolding temperature (Tm) of 45°C and a retained activity of around 80% when incubated at 40°C for 240 min. This bifunctional enzyme shows a dependence on divalent cations, with a remarkable preference for Mg2+ and Co2+ as cofactors. More interestingly, substrate specificity studies revealed ZgHGPRT/AMPK as a bifunctional enzyme, which acts as phosphoribosyltransferase or adenylate kinase depending upon the nature of the substrate. Finally, to assess the potential of ZgHGPRT/AMPK as biocatalyst for the synthesis of nucleoside-5′-mono, di- and triphosphates, the kinetic analysis of both activities (phosphoribosyltransferase and adenylate kinase) and the effect of water-miscible solvents on enzyme activity were studied.

Synthesis and Crystallographic Characterization of X-Substituted 2,4-Dinitrophenyl-4′-phenylbenzenesulfonates

Treatment of 2,4-dinitrophenol with sulfonyl chlorides in the presence of pyridine results in the formation of undesired pyridinium salts. In non-aqueous environments, the formation of the insoluble pyridinium salt greatly affects the formation of the desired product. A facile method of producing the desired sulfonate involves the use of an aqueous base with a water-miscible solvent. Herein, we present the optimization of methods for the formation of sulfonates and its application in the production of desired x-substituted 2,4-dinitrophenyl-4′-phenylbenzenesulfonates. This strategy is environmentally benign and supports a wide range of starting materials. Additionally, the intermolecular interactions of these sulfonate compounds were investigated using single-crystal x-ray diffraction data.

Development of a stir bar sorptive extraction method coupled to solidification of floating droplets dispersive liquid-liquid microextraction based on deep eutectic solvents for the extraction of acidic pesticides from tomato samples.

A stir bar sorptive extraction method coupled with deep eutectic solvent based solidification of floating organic droplets-dispersive liquid-liquid microextraction has been used for the simultaneous derivatization and extraction of some acidic pesticides in tomato samples. In this method, initially the analytes are adsorbed on a coated stir bar from tomato juice filled in a narrow tube. After extraction, the stir bar is removed and a water-miscible deep eutectic solvent is used to elute the analytes. Afterward, a derivatization agent and a water-immiscible deep eutectic solvent (as an extraction solvent) with melting point near to room temperature are added to the obtained eluant at µL-levels and the obtained mixture is rapidly injected into deionized water. Under the optimum conditions, the introduced method indicated high enhancement (1543-3353) and enrichment (2530-2999) factors, low limits of detection (7-14ng/L) and quantification (23-47ng/L), good linearity (r2 ≥ 0.9982), and satisfactory repeatabilities (relative standard deviation ≤12% for intra- and inter-day precisions at a concentration of 100ng/L of each analyte). Finally, the proposed method was applied in analysis of the analytes in tomato samples.

In-situ forming implants for the treatment of periodontal diseases: Simultaneous controlled release of an antiseptic and an anti-inflammatory drug.

Different types of in-situ forming implants based on poly(lactic-co-glycolic acid) (PLGA) for the controlled dual release of an antiseptic drug (chlorhexidine) and an anti-inflammatory drug (ibuprofen) were prepared and thoroughly characterized in vitro. N-methyl-pyrrolidone (NMP) was used as water-miscible solvent, acetyltributyl citrate (ATBC) as plasticizer and hydroxypropyl methylcellulose (HPMC) was added to enhance the implants' stickiness/bioadhesion upon formation within the periodontal pocket. Different drug forms exhibiting substantially different solubilities were used: chlorhexidine dihydrochloride and digluconate as well as ibuprofen free acid and lysinate. The initial drug loadings were varied from 1.5 to 16.1%. In vitro drug release, dynamic changes in the pH of the surrounding bulk fluid and in the systems' wet mass as well as polymer degradation were monitored. Importantly, the release of both drugs, chlorhexidine and ibuprofen, could effectively be controlled simultaneously during several weeks. Interestingly, the tremendous differences in the drug forms' solubilities (e.g., factor >5000) did not translate into major differences in the resulting release kinetics. In the case of ibuprofen, this can likely (at least in part) be attributed to significant drug-polymer interactions (ibuprofen acts as a plasticizer for PLGA). In the case of chlorhexidine, the release of the much less soluble dihydrochloride was even faster compared to the more soluble digluconate (when combined with ibuprofen free acid). In the case of ibuprofen, at higher initial drug loadings also limited solubility effects within the implants seem to play a role, in contrast to chlorhexidine. In the latter case, instead, increased system porosity effects likely dominate at higher drug loadings.

Dual drug-loaded biodegradable Janus particles for simultaneous co-delivery of hydrophobic and hydrophilic compounds.

Bicompartmental Janus particles have many advantages in drug delivery, including co-delivery of two compounds with varying solubilities, differential release kinetics, and two surfaces available for targeting ligands. We present a novel strategy using the double emulsion method for the coencapsulation and staggered release of a hydrophobic and hydrophilic drug from anisotropic PLGA/PCL Janus particles, as well as a UV detection method to measure the release of two different compounds from Janus particles. Curcumin and quercetin were chosen as the model hydrophobic compounds for drug loading studies, while acetaminophen (APAP) and naproxen were chosen as the model hydrophilic–hydrophobic drug pair for encapsulation methods and drug loading. Also, a similar double emulsion method was also applied for PLGA/Preicrol® Janus particles containing Doxorubicin and Curcumin. Hydrophobic drugs were encapsulated by the single O/W emulsion technique. Hydrophilic compounds required special modifications due to their poor oil solubility and tendency to escape to the outer aqueous phase during the emulsification and solvent evaporation steps. In total, three different strategies for incorporating hydrophilic drugs were employed: (1) O/W emulsion with partially water miscible solvent, (2) O/W emulsion with co-solvent (i.e. acetone, methanol, ethanol), or (3) W/O/W double emulsion. The encapsulation efficiencies and drug loading percentages were measured using UV/Vis spectroscopy and compared for the different synthesis methods. It was found that the double emulsion method resulted in the highest encapsulation efficiency and drug loading of the hydrophilic drug.

Development and Characterization of the Solvent-Assisted Active Loading Technology (SALT) for Liposomal Loading of Poorly Water-Soluble Compounds.

A large proportion of pharmaceutical compounds exhibit poor water solubility, impacting their delivery. These compounds can be passively encapsulated in the lipid bilayer of liposomes to improve their water solubility, but the loading capacity and stability are poor, leading to burst drug leakage. The solvent-assisted active loading technology (SALT) was developed to promote active loading of poorly soluble drugs in the liposomal core to improve the encapsulation efficiency and formulation stability. By adding a small volume (~5 vol%) of a water miscible solvent to the liposomal loading mixture, we achieved complete, rapid loading of a range of poorly soluble compounds and attained a high drug-to-lipid ratio with stable drug retention. This led to improvements in the circulation half-life, tolerability, and efficacy profiles. In this mini-review, we summarize our results from three studies demonstrating that SALT is a robust and versatile platform to improve active loading of poorly water-soluble compounds. We have validated SALT as a tool for improving drug solubility, liposomal loading efficiency and retention, stability, palatability, and pharmacokinetics (PK), while retaining the ability of the compounds to exert pharmacological effects.

Reconfigurable solid-state electrolytes for high performance flexible supercapacitor

To realize high performance and a flexible supercapacitor, it is necessary to address the fundamental issues including low ionic conductivity of solid electrolytes and high interfacial resistance of electrode/electrolyte pairs. Here we present unique solid-state electrolytes by integrating highly engineered nano-porous polyvinyl alcohol (PVA) with super-flat vertically aligned single-walled carbon nanotubes (VA-SWNTs). Highly engineered PVA nano-porous films are fabricated by a generic freeze-thaw process followed by water-miscible solvent treatment in order to create highly controlled nano/microscale pores inside of PVA. Such highly porous PVA films act as both reconfigurable electrolyte template and separator where H3PO4 aqueous solution or ionic liquids can be selectively inserted for a variety of power requirements in flexible electronic applications. Our developed pore formation process is suitable for directly integrating high performance VA-SWNTs electrode as it allows the effective permeation of the polymer electrolyte into nanoscale inter-tube space enabling the easy access and faster transport of ions for higher power capability. This unique entity of reconfigurable electrolyte and nanostructured electrode demonstrates high power and energy densities and remarkable stability after 10,000 charge/discharge cycles.

(Invited) Prato Addition to C70: A New Adduct and Water-Soluble Derivatives

Due to the higher absorption of light at longer wavelengths and increased lifetime of the triplet state, C70has been recognized as a better photosensitizer than C60for applications in photodynamic therapy (PDT). Similar to C60, the main obstacle to bioapplication of C70is its hydrophobicity, resulting in insolubility in water or water-miscible solvents and rendering functionalization with water-soluble anchors necessary. Additional complications in the functionalization of C70is lower symmetry of the molecule in comparison to C60. Even mono-addition reactions can provide several distinct derivatives of C70, which may exhibit a different range of the functions of the obtained derivatives. In this study, we used a 1,3-dipolar cycloaddition reaction (Prato reaction) for the functionalization of C70. It is known that this reaction provides very stable pyrrolidine adducts of fullerenes in sufficient yields. We used a N-glycine derivative 1and formaldehyde in the Prato reaction; three obtained adducts (2A-C) were purified by HPLC (Figure) and their structures were elucidated by 1H and 13C NMR. While the addition sites of two major adducts 2Aand 2Bwere found to be ab-[6,6] and cc-[6,6] – similar to the previous reports – the structure of the third minor adduct 2Cwas determined as dd-[5,6]-2,in contrast to the previous studies. The deprotection of major adducts 2A-B under acidic conditions and subsequent conjugation with PEG-NH2derivatives successfully provided water-soluble C70-PEG conjugates. Figure 1

Development of microwave-assisted liquid-liquid extraction combined with lighter than water in syringe dispersive liquid-liquid microextraction using deep eutectic solvents: Application in extraction of some herbicides from wheat

A deep eutectic solvent-based microwave-assisted liquid-liquid microextraction method followed by gas chromatography-mass spectrometry has been reported for the extraction and preconcentration of seven herbicides from wheat samples. The analytes are extracted into a water-miscible deep eutectic solvent under microwave irradiations, and then the extractant is used as a dispersive solvent in the following dispersive liquid-liquid microextraction method. In this method, ChCl: phenol and ChCl: butyric acid deep eutectic solvents were used in the first and second steps mentioned above, respectively. After that, the mixture was dispersed into deionized water placed into a syringe with a retracted plunger. By this action, ChCl: butyric acid was dispersed in all parts of the solution. To break up the cloudy state, acetonitrile was added and the collected organic phase is used in determination system. Low limits of detection and quantification in the ranges of 1.6–12, and 5.5–42 ng kg−1, relative standard deviations ≥6.1% (at a concentration of 50 ng kg−1, each analyte) and extraction recoveries and enrichment factors in the ranges of 69–94% and 345–470, were obtained, respectively, under optimal conditions. Lastly, some wheat samples were analyzed, and diclofob-methyl was found in two samples.

Analysis of Endocrine-Disrupting Compounds from Cheese Samples Using Pressurized Liquid Extraction Combined with Dispersive Liquid–Liquid Microextraction Followed by High-Performance Liquid Chromatography

Simultaneous extraction and preconcentration of five endocrine disrupting compounds including di-butyl phthalate, di-iso-nonyl phthalates, di-ethylhexyl phthalate, di-ethylhexyl adipate, and bisphenol A from cheese have been developed using pressurized liquid extraction combined with dispersive liquid–liquid extraction followed by high-performance liquid chromatography-diode array detector. In this method, initially, the analytes are extracted into a water-miscible extraction solvent (acetone) at high pressure (1000 psi) and temperature (70 °C) in the presence of carbon tetrachloride as a modifier. After extraction, a volume of the organic phase is removed and dispersed into deionized water. The cloudy solution was centrifuged, and the sedimented phase is used in analysis. Efficient parameters were optimized using one-parameter-at-one-time strategy, and low limits of detection and quantification in the ranges of 0.82–3.1 and 2.8–10 ng g−1 were obtained, respectively. Relative standard deviations lower than 8% show an acceptable precision for the present method. The enrichment factors and extraction recoveries in the ranges of 259–319 and 78–96% were achieved, respectively. Lastly, some real samples were analyzed and di-butyl phthalate and di-ethylhexyl phthalate were found in them.

Development of Solid Lipid Nanoparticles by Cold Dilution of Microemulsions: Curcumin Loading, Preliminary In Vitro Studies, and Biodistribution.

Background: Solid lipid nanoparticles (SLNs) are attractive drug delivery systems for lipophilic molecules like curcumin (CURC) with low chemical stability. Methods: A simple, innovative, and cold-operating method, named “cold dilution of microemulsion” is developed by the authors to produce SLNs. An oil-in-water microemulsion (µE), whose disperse phase consisted of a solution of trilaurin in a partially water-miscible solvent, was prepared after mutually saturating solvent and water. Trilaurin SLNs precipitated following solvent removal upon water dilution of the µE. After SLN characterization (mean size, Zeta potential, CURC entrapment efficiency, and over time stability), they were tested for in vitro cytotoxicity studies on pancreatic adenocarcinoma cell lines and for in vivo preliminary biodistribution studies in Wistar healthy rats. Results: CURC loaded SLNs (SLN-CURC) had mean diameters around 200 nm, were negatively charged, stable over time, and able to entrap CURC up to almost 90%, consequently improving its stability. SLN-CURC inhibited in vitro pancreatic carcinoma cell growth in concentration-dependent manner. Their in vivo intravenous administration suggested a possible long circulation. Conclusions: These results, according to a concomitant study on chitosan-coated SLNs, confirm the possibility to apply the developed SLN-based delivery systems as a means to entrap CURC, to improve both its water dispersibility and chemical stability, facilitating its application in therapy.

Explorations of combined nonsolvent and thermally induced phase separation (N-TIPS) method for fabricating novel PVDF hollow fiber membranes using mixed diluents

The combination of nonsolvent and thermally induced phase separation (N-TIPS) method has shown promising ability in harvesting the features from the nonsolvent induced phase separation (NIPS) and thermally induced phase separation (TIPS) processes for developing membranes with a tailorable surface pore structure. However, previous approaches have been subjected to either the formation of macrovoids or dense layer due to the dominant NIPS effect, or required sophisticated instruments and operation skills. In this work, a facile attempt was carried out to fabricate novel polyvinylidene fluoride (PVDF) hollow fiber membranes with tunable surface pore structure while maintaining the narrow pore size distribution and mechanical strength. A modified N-TIPS method was developed by using mixed diluents: dimethyl phthalate (DMP) as a water-immiscible poor solvent for TIPS process, and triethyl phosphate (TEP) as a water-miscible neutral solvent to bridge the TIPS and NIPS processes. To further control the membrane formation especially near the membrane surface, an amphiphilic additive Pluronic F127 was also added as a potential pore-former and surface hydrophilicity modifier. PVDF hollow fiber membranes with a highly porous structure and a narrow pore size distribution were successfully synthesized by using TEP and Pluronic F127 in the N-TIPS process. The mechanism of N-TIPS process was thoroughly discussed. The water permeability of the membrane increased significantly from 389 ± 30–922 ± 36 L m–2 h–1 bar–1, with overall porosity improved from 50 ± 2.2–69 ± 2.9%, and a mean pore size of ~ 0.18 µm. The membranes produced by N-TIPS method also exhibited a good tensile strength ranging from 5.6 ± 0.1–6.5 ± 0.2 MPa, showing a great potential for a broad range of water applications after further modifications. Besides, the formation of piezoelectric β-phase crystals of the PVDF membrane was observed when the mixed diluent was used, which sheds light on the possible applications of resultant membranes in electrochemical separation process.

Waste residues from Opuntia ficus indica for peroxidase-mediated preparation of phenolic dimeric compounds

A methodology to detect peroxidase activity in Opuntia ficus indica cladodes waste extracts was performed and then used towards phenolic compounds. The extracts were able to dimerize three different molecules. Dimeric compounds were produced with yields ranging from 11% to 55%. The influence of H2O2 concentration was also tested, finding better yields when the peroxide-to-substrate ratio was 1:1. Some water-miscible solvents were used trying to increase overall yields, but no-significant positive results were found. In fact, one of them, THF, seemed to inhibit dimerization reaction. Hence, we have tested an alternative natural peroxidase source obtained from the wastes of a local highly-consumed vegetable and studied their enzymatic activity towards the preparation of biologically active, valuable compounds.

An automated homogeneous liquid-liquid microextraction based on deep eutectic solvent for the HPLC-UV determination of caffeine in beverages

This work presents an automated homogeneous liquid-liquid microextraction procedure for separation of caffeine from beverages. The microextraction procedure involved mixing sample and water-miscible deep eutectic solvent (DES, choline chloride with phenol at a 1:3 molar ratio) into a mixing chamber of a flow system resulting formation of homogeneous solution. Injection of aprotic solvent (tetrahydrofuran) into homogeneous sample solution promoted the fine DES droplets formation and caffeine extraction into DES phase separated. The automated homogeneous liquid-liquid microextraction procedure was coupled with a HPLC-UV system. The conditions of caffeine microextraction and its HPLC-UV determination in DES phase were studied and optimized. Under optimal experimental conditions the linear detection range and limit of detection, calculated from a blank test, based on 3σ were found to be 0.1–200 mg L−1 and 0.03 mg L−1, respectively. The application of the developed procedure was demonstrated in the determination of caffeine in commercial soft drinks samples.

Single step fabrication of polymer/silicate porous composite membranes via water-glass induced phase inversion

ABSTRACTWater-glass, a low-cost silica precursor solution, is used to produce mostly skinned, polymer–silicate composite membranes with a porous bulk. We explore primarily Nylon 6-10/formic acid dopes where the polymer solvent is an acid, and polysulfone/DMF dope as an example of a polymer dope based on a non-acidic water-miscible solvent. Elemental distribution of silicon in cross sections suggests compositional uniformity of the formed membranes with in some cases 20 wt. % of silicate load. Membranes formed can be used either as separation media or as precursors for compact polymers reinforced with silicate particles.

Emulsification liquid–liquid microextraction method based on a deep eutectic solvent for separation and preconcentration of lead from environmental water samples

Abstract In this paper, a novel emulsification liquid–liquid microextraction method based on deep eutectic solvents (DESs) for the preconcentration of lead from water samples and its determination by flame atomic absorption spectrometry is described. Purpurin was used as complexing ligand and the Pb(II)-purpurin complexes were extracted and preconcentrated from the aqueous phase using a choline chloride/2-chlorophenol (at a 1:2 molar ratio) based DES as a water-miscible extraction solvent and tetrahydrofuran as an emulsifier solvent. Some analytical parameters affecting the extraction yield were investigated and optimized. Using a 20 mL aqueous sample, the limit of detection and preconcentration factor of the method were 5.93 μg L−1 and 20, respectively. The accuracy of the method was assessed through the analysis of certified reference surface water (SPS-SW2 Batch 127) and spiked water samples. The certified and obtained values were statistically in good agreement at 95% confidence level. The recovery values of spiked water samples were between 102% and 105%.

Studies on the catalytic behavior of a membrane-bound lipolytic enzyme from the microalgae Nannochloropsis oceanica CCMP1779

The catalytic behavior of a membrane-bound lipolytic enzyme (MBL-Enzyme) from the microalgae Nannochloropsis oceanica CCMP1779 was investigated. The biocatalyst showed maximum activity at 50 °C and pH 7.0, and was stable at pH 7.0 and temperatures from 40 to 60 °C. Half-lives at 60 °C, 70 °C and 80 °C were found 866.38, 150.67 and 85.57 min respectively. Thermal deactivation energy was 68.87 kJ mol−1. The enzyme’s enthalpy (ΔΗ*), entropy (ΔS*) and Gibb’s free energy (ΔG*) were in the range of 65.86–66.27 kJ mol−1, 132.38–140.64 J mol−1 K−1 and 107.80–115.81 kJ mol−1, respectively. Among p-nitrophenyl esters of fatty acids tested, MBL-Enzyme exhibited the highest hydrolytic activity against p-nitrophenyl palmitate (pNPP). The Km and Vmax values were found 0.051 mM and of 0.054 mmole pNP mg protein−1 min−1, respectively with pNPP as substrate. The presence of Mn2+ increased lipolytic activity by 68.25%, while Fe3+ and Cu2+ ions had the strongest inhibitory effect. MBL-Enzyme was stable in the presence of water miscible (66% of the initial activity in ethanol) and water immiscible (71% of the initial activity in n-octane) solvents. Myristic acid was found to be the most efficient acyl donor in esterification reactions with ethanol. Methanol was the best acyl acceptor among the primary alcohols tested.