Hydrophilic Media Research Articles

Encapsulation of Either Hydrophilic or Hydrophobic Substances in Spongy Cellulose Particles.

We have reported cellulose particles with a spongy structure that we prepared by the solvent releasing method (SRM) from cellulose droplets composed of cellulose, 1-butyl-3-methylimidazoliumchrolide ([Bmim]Cl), and N,N-dimethylformamide (DMF). The spongy structure collapsed as the medium evaporated, resulting in dense cellulose particles. In this study, we encapsulated the hydrophilic and hydrophobic fluorescent substances in these particles to investigate the use of such particles in potential applications that require encapsulating of substances (e.g., drug delivery). Wet cellulose particles retained their spongy structure in both hydrophobic and hydrophilic media. When the spongy cellulose particles were dispersed in a solution containing nonvolatile solutes, these solutes were driven into the cellulose particles as media evaporated. Subsequently, the cellulose particles collapsed and encapsulated the nonvolatile solutes. Regardless of whether the solute was hydrophilic or hydrophobic, the encapsulation efficiency exceeds 80%. The maximum loading reflected the saturated solubility of solute in solution that filled the cellulose beads. Moreover, the encapsulated solute was released by dispersing the cellulose beads in the solvent, and the rate of release of the encapsulated solute could be controlled by coating the cellulose beads with a conventional polymer.

Analysis of antioxidant capacity and bioactive compounds in marine macroalgal and lichenic extracts using different solvents and evaluation methods

Natural extracts of macroalgae are widely recognized for their antioxidant properties. In this work, the antioxidant capacity of various aqueous and hydroalcoholic extracts obtained from red and green marine algae and from one marine lichen collected from different sites in southern Spain (intertidal and estuarine waters) was evaluated by different methods: ABTS free radical scavenging assay, DPPH assay, and beta-carotene bleaching method (BBM). Contents of total lipids, total carbohydrates, and UV photoprotectors with antioxidant capacity, such as mycosporine-like amino acids and phenolic compounds, were determined. Among the extraction solvents, the highest extraction yield was observed in H2O and 20% MeOH (v/v). The highest antioxidant activity was found in the extracts of the red macroalgae Hydropuntia cornea, Gracilariopsis longissima, Halopithys incurva, and Porphyra umbilicalis, whereas the lowest activity was detected in the green macroalga Ulva rotundata. In general, the antioxidant activity was higher using DPPH than BBM and ABTS. Even so, the ABTS assay is an easy and quick test that provides a comprehensive view of the entire extract in both the lipophilic medium and hydrophilic medium. The antioxidant activity was related to the composition of bioactive compounds and synergistic action is not discarded. The biotechnological use of macroalgal extracts with high antioxidant capacity is discussed.

Synthesis and Antioxidant Activity of Hydroxytyrosol Alkyl-Carbonate Derivatives.

Three procedures have been investigated for the isolation of tyrosol (1) and hydroxytyrosol (2) from a phenolic extract obtained from the solid residue of olive milling. These three methods, which facilitated the recovery of these phenols, were chemical or enzymatic acetylation, benzylation, and carbomethoxylation, and subsequent carbonylation or acetonation reactions. Several new lipophilic alkyl-carbonate derivatives of hydroxytyrosol have been synthesized, coupling the primary hydroxy group of this phenol, through a carbonate linker, using alcohols with different chain lengths. The antioxidant properties of these lipophilic derivatives have been evaluated by different methods and compared with free hydroxytyrosol (2) and also with the well-known antioxidants BHT and α-tocopherol. Three methods were used for the determination of this antioxidant activity: FRAP and ABTS assays, to test the antioxidant power in hydrophilic media, and the Rancimat test, to evaluate the antioxidant capacity in a lipophilic matrix. These new alkyl-carbonate derivatives of hydroxytyrosol enhanced the antioxidant activity of this natural phenol, with their antioxidant properties also being higher than those of the commercial antioxidants BHT and α-tocopherol. There was no clear influence of the side-chain length on the antioxidant properties of the alkyl-carbonate derivatives of 2, although the best results were achieved mainly by the compounds with a longer chain on the primary hydroxy group of this natural phenolic substance.

Nanoparticle suspensions enclosed in methylcellulose: a new approach for quantifying nanoparticles in transmission electron microscopy.

Nanoparticles are of increasing importance in biomedicine but quantification is problematic because current methods depend on indirect measurements at low resolution. Here we describe a new high-resolution method for measuring and quantifying nanoparticles in suspension. It involves premixing nanoparticles in a hydrophilic support medium (methylcellulose) before introducing heavy metal stains for visualization in small air-dried droplets by transmission electron microscopy (TEM). The use of methylcellulose avoids artifacts of conventional negative stain-TEM by (1) restricting interactions between the nanoparticles, (2) inhibiting binding to the specimen support films and (3) reducing compression after drying. Methylcellulose embedment provides effective electron imaging of liposomes, nanodiscs and viruses as well as comprehensive visualization of nanoparticle populations in droplets of known size. These qualities facilitate unbiased sampling, rapid size measurement and estimation of nanoparticle numbers by means of ratio counting using a colloidal gold calibrant. Specimen preparation and quantification take minutes and require a few microliters of sample using only basic laboratory equipment and a standard TEM.

ARTICLE RETRACTED: THE ALCOHOL CHOLESTEROL, ITS BIOLOGICAL ROLE DURING PHYLOGENESIS, MECHANISMS OF STEROL PRODUCTION BY STATINS, PHARMACOGENOMIC FACTORS AND DIAGNOSTIC VALIDIDTY OF LOW DENSITY LIPOPROTEIN CHOLESTEROL

Article retracted 11.11.2019 г.Hypolipidemic activity of statins is realized by inhibition of the alcohol cholesterol (CL) local pool production in hepatocyte endoplasmic reticulum. Before secretion of very low density lipoproteins (VLDL) into hydrophilic medium of the blood, CL covers the total hydrophobic mass of triglycerides (TG). The smaller the CL content in the monolayer between the enzyme (lipase) and substrate (TG), the higher the parameters of hydrolysis of palmitic and oleic VLDL. Statins act as follows: а) block hepatocyte production and decrease plasma content of nonesterified CL; b) activate TG hydrolysis in palmitic and oleic VLDL, formation of ligand VLDL and their uptake by insulin-dependent cells via apoE/B-100 endocytosis; c) activate TG hydrolysis in linolic and linolenic low density VLDL, formation of ligand low density lipoproteins (LDL) and their uptake by apoB-100 endocytosis; d) reduce blood content of equimolary esterified by the alcohol CL polyenic fatty acids, CL esters and CL-VLDL. Nonphysiological effect of impaired function of trophology (nutrition) on fatty acid (FA) metabolism in a population cannot be abolished by prescribing medicines. For lowering cardiovascular morbidity it is necessary to modify environmental factors, i.e., reduce dietary content of saturated FA (primarily of palmitic), trans-FA and palmitoleic FA to physiological levels and increase dietary content of unsaturated FA. Saturated FA block cellular uptake of unsaturated FA. Deficiency of unsaturated FA and excess of palmitic FA lead to the development of atherosclerosis.

Self-Assembling Nanoparticles of Amphiphilic Polymers for In Vitro and In Vivo FRET Imaging.

Self-assembling nanoparticles of amphiphilic polymers are viable delivery vehicles for transporting hydrophobic molecules across hydrophilic media. Noncovalent contacts between the hydrophobic domains of their macromolecular components are responsible for their formation and for providing a nonpolar environment for the encapsulated guests. However, such interactions are reversible and, as a result, these supramolecular hosts can dissociate into their constituents amphiphiles to release the encapsulated cargo. Operating principles to probe the integrity of the nanocarriers and the dynamic exchange of their components are, therefore, essential to monitor the fate of these supramolecular assemblies in biological media. The co-encapsulation of complementary chromophores within their nonpolar interior offers the opportunity to assess their stability on the basis of energy transfer and fluorescence measurements. Indeed, the exchange of excitation energy between the entrapped chromophores can only occur if the nanoparticles retain their integrity to maintain donors and acceptors in close proximity. In fact, energy-transfer schemes are becoming invaluable protocols to elucidate the transport properties of these fascinating supramolecular constructs in a diversity of biological preparations and can facilitate the identification of strategies to deliver contrast agents and/or drugs to target locations in living organisms for potential diagnostic and/or therapeutic applications.

Oxidative stress in the hydrophilic medium of algae and invertebrates

Fil: Malanga, Gabriela Fabiana. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Houssay. Instituto de Bioquimica y Medicina Molecular. Universidad de Buenos Aires. Facultad Medicina. Instituto de Bioquimica y Medicina Molecular; Argentina

Effects of surface treatment and storage conditions of silicon microchannel emulsification plates on their surface hydrophilicity and preparation of soybean oil-in-water emulsion droplets

A major problem of microchannel (MC) emulsification that enables producing monodisperse emulsions is difficulty in stably producing monodisperse emulsions using silicon MC array plates stored for a long period of time. The purpose of this study was to analyze the effects of storage conditions of silicon MC array plates on their surface properties and MC emulsification. To make the MC array plate surfaces hydrophilic, they were treated by oxygen plasma. Each silicon plate was then stored in air, nitric acid, or Milli-Q water at different temperature. The change in the hydrophilicity of the MC array plate surface was monitored with contact angle measurement. Hydrophilic property of the plasma treated MC array plate was better kept by storing in a hydrophilic medium with a low concentration of positively charged hydrogen ions which could be supported by the zeta-potential data of MC array plates and dynamic contact angle results. We also clarified that monodisperse food-grade O/W emulsions are produced using a MC array plate with a static contact angle below a critical value.

Interaction of α-Hexylcinnamaldehyde with a Biomembrane Model: A Possible MDR Reversal Mechanism.

The ability of the naturally derived compound α-hexylcinnamaldehyde (1) to interact with biomembranes and to modulate their permeability has been investigated as a strategy to reverse multidrug resistance (MDR) in cancer cells. Dimyristoylphosphatidylcholine (DMPC) multilamellar vesicles (MLVs) were used as biomembrane models, and differential scanning calorimetry was applied to measure the effect of 1 on the thermotropic behavior of DMPC MLVs. The effect of an aqueous medium or a lipid carrier on the uptake of 1 by the biomembrane was also characterized. Furthermore, taking into account that MDR is strictly regulated by redox signaling, the pro-oxidant and/or antioxidant effects of 1 were evaluated by the crocin-bleaching assay, in both hydrophilic and lipophilic environments. Compound 1 was uniformly distributed in the phospholipid bilayers and deeply interacted with DMPC MLVs, intercalating among the phospholipid acyl chains and thus decreasing their cooperativity. The lipophilic medium allowed the absorption of 1 into the phospholipid membrane. In the crocin-bleaching assay, the substance produced no pro-oxidant effects in both hydrophilic and lipophilic environments; conversely, a significant inhibition of AAPH-induced oxidation was exerted in hydrophilic medium. These results suggest a possible role of 1 as a chemopreventive and chemosensitizing agent for fighting cancer.

Calorimetric evidence of interaction of brominated flame retardants with membrane model

The presence of polybrominated flame retardants in the environment seems to be increasing in the past decade. Considering the toxic effects of these pollutants, it is important evaluating the potential interaction with biological membranes for a risk assessment. In this study low and high brominated biphenyls and biphenyl ethers were used to investigate their interaction with biological membrane models constituted by liposomes, using differential scanning calorimetry (DSC) technique. The medium influence on membrane absorption was also assessed. The findings indicate that membrane interaction is controlled by compound structural characteristics. The membrane absorption is allowed by lipophilic medium; instead hydrophilic medium prevents membrane permeation.

Photoactivatable BODIPYs Designed To Monitor the Dynamics of Supramolecular Nanocarriers

Self-assembling nanoparticles of amphiphilic polymers can transport hydrophobic molecules across hydrophilic media and, as a result, can be valuable delivery vehicles for a diversity of biomedical applications. Strategies to monitor their dynamics noninvasively and in real time are, therefore, essential to investigate their translocation within soft matrices and, possibly, rationalize the mechanisms responsible for their diffusion in biological media. In this context, we designed molecular guests with photoactivatable fluorescence for these supramolecular hosts and demonstrated that the activation of the fluorescent cargo, under optical control, permits the tracking of the nanocarrier translocation across hydrogel matrices with the sequential acquisition of fluorescence images. In addition, the mild illumination conditions sufficient to implement these operating principles permit fluorescence activation within developing Drosophila melanogaster embryos and enable the monitoring of the loaded nanocarriers for long periods of time with no cytotoxic effects and no noticeable influence on embryogenesis. These photoresponsive compounds combine a borondipyrromethene (BODIPY) chromophore and a photocleavable oxazine within their covalent skeleton. Under illumination at an appropriate activation wavelength, the oxazine ring cleaves irreversibly to bring the adjacent BODIPY fragment in conjugation with an indole heterocycle. This structural transformation shifts bathochromically the BODIPY absorption and permits the selective excitation of the photochemical product with concomitant fluorescence. In fact, these operating principles allow the photoactivation of BODIPY fluorescence with large brightness and infinite contrast. Thus, our innovative structural design translates into activatable fluorophores with excellent photochemical and photophysical properties as well as provides access to a general mechanism for the real-time tracking of supramolecular nanocarriers in hydrophilic matrices.

Role of mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate) in the obtaining of stabilized magnetite nanoparticles for biomedical application

Magnetite nanoparticles (NPs) are studied as agents for magnetic resonance imaging, hyperthermia of malignant tumors, targeted drug delivery as well as anti-anemic action. One of the main problems of such NPs is their aggregation that requires creation of methods for magnetite NPs stabilization during preparation of liquid medicinal forms on their basis. The present work is devoted to the possibility of mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate) use for solubilization of magnetite NPs in hydrophilic medium. For this purpose, the condensate produced by electron-beam evaporation and condensation, with magnetite particles of size 5-8 nm deposited into the crystals of sodium chloride were used in conjunction with substance of mexidol (2-ethyl-6-methyl-3-hydroxypyridine succinate), and low molecular weight polyvinylpyrrolidone (PVP). The NP condensate was dispersed in distilled water or PVP or mexidol solutions. NPs size distribution in the liquid phase of the systems was determined by photon correlation spectroscopy, iron (Fe) concentration was evaluated by atomic emission spectrometry. It is shown that in the dispersion prepared in distilled water, the major amount of NPs was of 13-120 nm in size, in mexidol solution - 270-1700 nm, in PVP solution - 30-900 nm. In the fluid containing magnetite NPs together with mexidol and PVP, the main fraction (99.9%) was characterized by the NPs size of 14-75 nm with maximum of 25 nm. This system had the highest iron concentration: it was similar to that in the sample with mexidol solution and 6.6-7.3 times higher than the concentration in the samples with distilled water or PVP. Thus, in the preparation of aqueous dispersions based on magnetite NPs condensate, mexidol provides a transition of Fe to the liquid phase in amount necessary to achieve its biological activity, and PVP stabilizes such modified NPs.

Durability and surface chemistry of horizontally aligned CNT films as electrodes upon electrolysis of acidic aqueous solution

We devised a simple and effective method of electrochemical functionalization of horizontally aligned CNT films in diluted HCl and H2SO4 solutions upon their electrolysis under a constant current mode. We were able to cause notable generation of carbon–oxygen and carbon–chlorine functional groups on the CNT film anodes as proven by EDX, XPS, and Raman spectroscopy. As a consequence, we observed significant changes of the morphology of the material under electron microscopy, what translated into improved compatibility of CNTs with hydrophilic media. In turn, application of CNT films as cathodes was found as a powerful tool for a thorough cleaning of the nanotubes. Finally, we demonstrated that by the selection of appropriate conditions, CNT films can act as easy-to-make and flexible electrodes with a high stability and performance superior to graphite for generation of non-oxidizing gases such as hydrogen from solution. CNT film electrodes are two orders of magnitude lighter and require much lower overpotential for faradaic splitting of water.

Efficiency of the Polyethylene-Glycol (PEG) Embedding Medium for Plant Histochemistry.

Histochemical analyses in plants are commonly performed on hand-made sections of fresh materials. The disadvantages of embedding in historesin, paraffin or paraplast® are the alterations to cellular contents, the high costs and few evident results, depending on the test. Polyethylene-glycol (PEG), as a low cost, hydrophilic medium that maintains most of the cellular features similar to fresh conditions, may be useful for obtaining good histochemical results in thinner and homogeneous sections. The current study aimed to compare the efficiency of PEG as an embedding medium for histochemical analyses of primary and secondary metabolites accumulation. Using hand-made sections of fresh samples (T1) as a comparison, we tested the influence of the use of Karnovsky's solution as a fixative (T2) versus embedding in PEG (T3). The samples herein analyzed comprise leaves, stems, seeds and insect galls of different plant species. Neither the Karnovsky's fixative nor the embedding in PEG altered the histochemical results for starch, lipids, terpenoids, proteins and reducing sugars in T1, T2, and T3. However, PEG binds to phenols, such as tannins, flavonoids and lignins, thereby presenting false negatives in T3.

A “green pathway” different from simple diffusion in soft matter: Fast molecular transport within micro/nanoscale multiphase porous systems

Soft matter has attracted extensive attention due to its special physical/chemical properties and holds great promise in many applications. However, obtaining a detailed understanding of both complex fluid and mass transport in soft matter, especially in hierarchical porous media of biological tissues, still remains a huge challenge. Herein, inspired by fast tracer transport in loose connective tissues of living systems, we observed an interesting phenomenon of fast molecular transport in situ in an artificial hierarchical multiphase porous medium (a micrometer scale hydrophobic fiber network filled with nanometer scale hydrophilic porous medium), which was simply fabricated through electrospinning technology and polymerization. The transportation speed of molecules in the micrometer fiber network is larger than simple diffusion in nanometer media, which is better described by Fick’s law. We further proved that the phenomenon is based on the nanoconfined air/water/solid interface around the micrometer hydrophobic fibers. We focus on the key factors, referring to S A, (the confined multiphase area around the microfibers) and N G (the connectivity node degree of the skeletal portion in the nanometer hydrogel medium). Next, a quantitative parameter, V TCM (transport chance mean-value), was introduced to describe the molecular transport capability of the fiber network within hierarchical multiphase porous systems. These fundamental advances can be applied de novo to understand the process of so-called simple diffusion in biological systems, and even to re-describe many molecular events in biologically nanoconfined spaces.

Mass Spectrometry of Supramolecular Complexes of Glycyrrhizic Acid and Benzimidazole Derivatives

Low-dose drug substances based on glycyrrhizic acid (1) and known active ingredients are currently being actively investigated [1, 2]. The effective doses of drugs can be decreased by 100–200 times [3, 4]. The glycyrrhizic acid in such substances acts as a polydentate ligand that forms supramolecular complexes of various stoichiometries with the active ingredient. The formation mechanisms of such host–guest complexes, where a saponin host molecule can form an endolipophilic cavity for the guest molecule in a hydrophilic medium, must be studied in order to establish the fundamental structure–property relationships [5, 6]. Researchers have previously used quantum-chemical calculations and mass spectrometry to show [7] that 1 forms stable self-associated clusters of general form Xn (n = 6). Hence, self-associates of 1 that are formed from two and more molecules have a cavity between them that is capable of incorporating commensurate guest molecules. Therefore, the goal of the present work was to study the structure of supramolecular complexes of 1 and benzimidazole derivatives (2) (e.g., 9-diethylaminoethyl-2,3-dihydroimidazo[1,2-a]benzimidazole dihydrochloride) using mass spectrometry with electrospray ionization.

Efficient glucosylation of flavonoids by organic solvent-tolerant Staphylococcus saprophyticus CQ16 in aqueous hydrophilic media

• A DMSO-tolerant bacterium S. saprophyticus CQ16 capable of glucosylating daidzein was isolated. • The glucosyltransferase from strain CQ16 showed broad substrate specificity to various kinds of flavonoids, and regio-selective glucosylation high activity in aqueous hydrophilic medium. • The polar solvent DMSO significantly improved the glucosylation of daidzein and other substrates. Glucosylation of flavonoids improves their bioavaibility and pharmacological properties. An organic solvent-tolerant bacterium Staphylococcus saprophyticus CQ16 was newly isolated and was found to glucosylate daidzein. Strikingly, the polar solvent 15% DMSO significantly improved the glucosylation of daidzein with 3.5 times yield, and glucosylation was further improved with the supplemental co-solvents. The most effective glucosylation of daidzein to daidzein-7- O -glucoside catalyzed by whole cells of strain CQ16 was achieved with a molar yield of 90% in a system with addition of 15% DMSO and 0.5% butyl acetate. The conversion process produced very few by-products, and therefore simplified purification of the glycoside product. The glucosyltransferase from strain CQ16 showed broad substrate specificity to the various flavonoids as well as flavonoid analogs, nonetheless an exquisite regioselectivity of the C-7 hydroxyl group of flavonoids. It would be substantive benefits for exploiting the new candidates with higher bioavailability for pharmaceuticals.

Turn-on Fluorescent InP Nanoprobe for Detection of Cadmium Ions with High Selectivity and Sensitivity

We reported a "turn-on" fluorescent InP nanoprobe for detection of cadmium ions in hydrophobic and hydrophilic media. The method based on the turn-on fluorescence detection of cadmium ions has shown its high selectivity and sensitivity, which are independent of the pH of the tested samples. Also, this approach exhibits an immediate response to cadmium ions, and visualized detection of cadmium ions has further been demonstrated under a UV lamp.

Polylactide nanofibers loaded with vitamin B6 and polyphenols as bioactive platform for tissue engineering

Electrospun polylactide nanofibers loaded with different antioxidants (i.e. vitamin B6 in pyridoxine and pyridoxal form, p-coumaric acid and caffeic acid) are prepared from N,N-dimethylformamide/dimethylsulfoxide solutions. Morphology, structure and crystallinity of the nanofibers are evaluated by transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction and differential scanning calorimetry (DSC) techniques. Fibers are highly amorphous but able to crystallize easily due to the high molecular orientation induced by the electrospinning process. The drug molecules are incorporated into the polymeric matrix or formed isolated crystals. A fast release of loaded drug occurs within the first 8 h in hydrophobic medium; but, a slow and sustained release during several days occurs in a hydrophilic medium. Cell attachment on the loaded scaffolds was unaffected by the incorporation of the antioxidants. In contrast, cell proliferation increases with high antioxidative activity against free radicals responsible for cell damage. These new electrospun scaffolds provide high protection of cells against oxidative stress and resulting in innovative 3D fibrous platforms for tissue growth and proliferation. Open image in new window

Synthesis of Ag Nanocubes 18–32 nm in Edge Length: The Effects of Polyol on Reduction Kinetics, Size Control, and Reproducibility

This article describes a robust method for the facile synthesis of small Ag nanocubes with edge lengths controlled in the range of 18-32 nm. The success of this new method relies on the substitution of ethylene glycol (EG)--the solvent most commonly used in a polyol synthesis--with diethylene glycol (DEG). Owing to the increase in hydrocarbon chain length, DEG possesses a higher viscosity and a lower reducing power relative to EG. As a result, we were able to achieve a nucleation burst in the early stage to generate a large number of seeds and a relatively slow growth rate thereafter; both factors were critical to the formation of Ag nanocubes with small sizes and in high purity (>95%). The edge length of the Ag nanocubes could be easily tailored in the range of 18-32 nm by quenching the reaction at different time points. For the first time, we were able to produce uniform sub-20 nm Ag nanocubes in a hydrophilic medium and on a scale of ∼20 mg per batch. It is also worth pointing out that the present protocol was remarkably robust, showing good reproducibility between different batches and even for DEGs obtained from different vendors. Our results suggest that the high sensitivity of synthesis outcomes to the trace amounts of impurities in a polyol, a major issue for reproducibility and scale up synthesis, did not exist in the present system.