Molecular Gel Research Articles

Isolation of lysozyme and an antifungal peptide from sea lamprey ( Petromyzon marinus) plasma

The sea lamprey ( Petromyzon marinus) belongs to the most primitive class of fish and has only innate immunity. The innate immune factors, lysozyme and an antifungal peptide, were isolated from sea lamprey plasma. Sea lamprey plasma (40.1 mg protein/ml) was assayed for lysozyme activity by gel diffusion assay. Using hen egg white lysozyme standards, plasma concentration of lamprey lysozyme was 5 μg lysozyme/mg total protein. The presence of lysozyme in such high concentration in lamprey plasma could be important in their innate immunity and resistance to infection. Lysozyme and the antifungal peptide were isolated by low molecular weight gel filtration chromatography from sea lamprey plasma. Gel filtration chromatography yielded two peak tubes containing lysozyme (1 μg/211 μg total protein) and antifungal peptide (1 μg/66 μg total protein). Lysozyme and antifungal activity of each fraction were determined by well diffusion assay using Gram-negative bacteria, Gram-positive bacteria and two fungal species. The molecular weight of lamprey lysozyme was 14.3 kDa. The sea lamprey lysozyme was effective against Gram-positive bacteria but not against Gram-negative bacteria or fungi. Molecular weight of the antifungal peptide was approximately 3000 Da. Antifungal plasma activity was seen against Penicillium notatum and Aspergillus flavus. No plasma antibacterial peptide was found.

A gel-forming poly-l-guluronic acid produced from no guluronate-rich marine algae using new hydrolysis method: test for endovascular embolization

To prepare a gel-forming poly-L-guluronic acid (Poly-G) from no guluronate-rich Laminaria japonica, a new hydrolysis method was employed with a lower HCl concentration (0.025-0.15 M) and a shorter treatment time (5 min). The Poly-Gs were set to measure purity, presence of poly-L-guluronic block, molecular weight distribution, polymer yield, viscosity, and compressive gel strength. Finally, the Poly-G was tested to embolize the renal vascular system by using a rabbit model and angiography. Optimized Poly-G could be selected with respect to wt% concentration, polymer yield, gel-forming stability, viscosity, and gel strength as an endovascular embolizing agent. Overall, 0.4-0.6% of 0.03 M-Poly-G obtained from acid treatment with 0.03 M of HCl had molecular weights greater than 80 kDa, and the best gelling capacity with an injectable viscosity (30-120 cP). It was successfully delivered into the vascular bed of a rabbit kidney and was shown angiographically to embolize the renal vascular system.

A Novel Chip-based Electroelution System for Rapid and Efficient Recovery of Intact Proteins from Polyacylamide Gels

A Novel Chip-based Electroelution System for Rapid and Efficient Recovery of Intact Proteins from Polyacylamide Gels

Functional Characterization of Muscle Fibres from Patients with Chronic Fatigue Syndrome: Case-Control Study

Chronic fatigue syndrome (CFS) is a disabling condition characterized by unexplained chronic fatigue that impairs normal activities. Although immunological and psychological aspects are present, symptoms related to skeletal muscles, such as muscle soreness, fatigability and increased lactate accumulation, are prominent in CFS patients. In this case-control study, the phenotype of the same biopsy samples was analyzed by determining i) fibre-type proportion using myosin isoforms as fibre type molecular marker and gel electrophoresis as a tool to separate and quantify myosin isoforms, and ii) contractile properties of manually dissected, chemically made permeable and calcium-activated single muscle fibres. The results showed that fibre-type proportion was significantly altered in CSF samples, which showed a shift from the slow- to the fast-twitch phenotype. Cross sectional area, force, maximum shortening velocity and calcium sensitivity were not significantly changed in single muscle fibres from CSF samples. Thus, the contractile properties of muscle fibres were preserved but their proportion was changed, with an increase in the more fatigue-prone, energetically expensive fast fibre type. Taken together, these results support the view that muscle tissue is directly involved in the pathogenesis of CSF and it might contribute to the early onset of fatigue typical of the skeletal muscles of CFS patients.

Self-assembling fullerene derivatives for energy transfer in molecular gel system

An L-glutamide-derived compound with a fullerene moiety was newly synthesized by the coupling of (6,6)-phenyl-C61 butyric acid with N,N'-didodecyl L-glutamide containing an amino alkyl group. In this paper, we describe that the solubility to an organic solvent was sufficiently improved by functionalization with L-glutamide and these fullerene derivatives could form ordered aggregates in organic solvents. It is also reported that the fullerene-containing derivatives were evaluated as a donor-acceptor model with the corresponding porphyrine derivative.

Effectiveness of Desiccant Coated Regenerative Wheels from Transient Response Characteristics and Flow Channel Properties—Part II: Predicting and Comparing the Latent Effectiveness of Dehumidifier and Energy Wheels Using Transient Data and Properties

In this paper, a new transient response theory is developed to predict the moisture or water transfer time constant and the fully developed flow moisture effectiveness of dehumidifier wheels and latent energy effectiveness of energy wheels. A new method to experimentally determine the latent energy or water transfer time constant is presented. This analytical model, which uses the new empirical time constant and its theoretical model, is then corrected for entrance length, carryover, sorption temperature changes, and manufacturing variations. The model permits the designer of these wheels and the HVAC applications engineer the opportunity to explore how each flow channel property and wheel operating condition changes the effectiveness. The theoretical latent and sensible effectiveness of energy wheels with molecular sieve and silica gel coatings are determined for two energy wheels, and these results are compared with the effectiveness calculated using experimental data at steady state ARI testing conditions. The comparisons are in agreement within the uncertainty bounds. The analytical model is also used to predict the latent effectiveness for two similar energy wheels where it is assumed that the desiccant coatings are interchanged. This comparison shows that the new hypothetical silica gel coating on the energy wheel would be more effective than the new molecular sieve coating on an energy wheel for the transfer of water vapor. The moisture transfer effectiveness is predicted for two dehumidifier wheels with the same design and desiccants as the tested energy wheels (i.e., the molecular sieve wheel and silica gel wheel). These wheels, which are used for supply air drying, are operated with the same ARI supply air condition and 5 rpm. Considering the comparisons for energy wheels, the molecular sieve and silica gel coatings are predicted to result in similar performance factors but with much lower effectiveness. This reduction in moisture effectiveness for the dehumidifier wheels is caused mostly by the reduction in wheel speed. Further research is required to investigate the performance of dehumidifier wheels at lower wheel speeds.

English

The present study was performed to evaluate the anti-ulcerogenic activity of hyaluronic acid against ethanol induced gastric mucosal injury in rats. Four groups of adultSprague Dawley rats were orally pre-treated respectively with distilled water (ulcer control groups), omeprazole (reference group), high molecular weight hyaluronic acid and 0.8% hyaluronic acid gel (experimental groups) one hour before oral administration of absolute ethanol to generate gastric mucosal. After an additional hour, the rats were sacrificed and the ulcer areas of the gastric walls were determined. Grossly, the ulcer control group exhibited severe mucosal injury, whereas pre-treatment with omeprazol, and both types of hyaluronic acid gel, exhibited significant protection of gastric mucosal injury. Histological studies of the gastric wall revealed that ulcer control group exhibited severe damage of gastric mucosa; along with edema and leucocytes infiltration of submucosal layer compared to rats pre-treated with hyaluronic acid gels which showed comparatively gastric mucosal protection, reduction or absence of edema and leucocytes infiltration of submucosal layer. The present finding suggests that high molecular weight hyaluronic acid gel promotes higher ulcer protection. Key words: Hyaluronic acid gel, cytoprotection, gastric ulcer, histology.

Gelation induced reversible syneresis via structural evolution

This paper reports a large volume change in a cholesterol based molecular gel in the presence of multi-amine as the gelling solvents dissociated from the gel in a dynamic manner. The release capability can be controlled by the ratio of multi-amine. The shrinkage capability can be restored and recycled by a gel–sol transformation. The mechanism of the shrinkage was followed by SEM, confocal laser scanning microscopy and X-ray diffraction studies. A structural evolution from lamellar vesicles to a more compact hexagonal structure driven by competitive intermolecular hydrogen bonds was proved to dominate the process of the solvent release. Moreover, the process can be stopped by addition of organic acid such as trifluoroacetic acid, which favors the application of this kind of material for molecular delivery systems.

The spatial effect of near-infrared spectroscopy and its application to the study of supramolecular chemistry

An unlooked-for experimental observation that in near-infrared spectroscopy (NIR) the absorption peak of the second overtone of aniline adsorbed by 13X molecular sieve nearly disappeared led us investigate a fundamental question: the behavior of NIR when the outside space surrounding a molecule is too small to allow the molecule to vibrate freely. Through NIR of various organic compounds adsorbed by different porous inorganic materials like 13X molecular sieve, silica gel and active aluminium oxide, and NIR of supramolecular cyanuric acid-melamine, we can reasonably confirm a theoretical inference that in the micro-environment above, all intensities of NIR absorbance decrease, and the second overtone decreases more than the first overtone does. Furthermore, one distinct feature of NIR, higher sensitivity to the size of micro-environmental space as compared with mid-infrared (MIR), and its potential application to the study of supramolecular structure are outlined by our experiments.

Near-Infrared Electrochromic and Chiroptical Switching Materials: Design, Synthesis, and Characterization of Chiral Organogels Containing Stacked Naphthalene Diimide Chromophores

Chiroptical switching materials in the visible and near-infrared spectral regions have been realized using a low molecular weight gel as a chiral scaffold and electrochromic chromophores as a stimulus-responsive trigger and operate as a result of the change in the electronic states of the chromophores within the chiral gel. N,N′-Bis(4-phenyl-2,3,4,6-tetra-O-acetyl-β-d-glucopyranoside)-1,4,5,8-naphthalenetetracarboxylic diimide, synthesized by imidization of 1,4,5,8-naphthalenetetracarboxylic dianhydride with a sugar-bearing amine, can form stable chiral gels at room temperature. The redox-active gels exhibited reversible and drastic changes in circular dichroism in the visible and near-infrared spectral region between the three redox states (neutral, radical anion, dianion) of the naphthalene diimide chromophore. A large circular dichroism at 1310−1550 nm was induced when the stacked naphthalene diimide chromophores in the chiral gels were reduced to the radical anion state.

Monte Carlo Simulation of Emulsion Polymerization Kinetics and the Evolution of Latex Particle Morphology and Polymer Chain Architecture

AbstractMonte Carlo methods were applied to the reaction kinetics and polymer diffusion at play during the dynamics of creating structured latex particles. Reaction kinetic events in both the water phase and the particles are combined with diffusion of polymer radicals in the particles to allow the prediction of the overall polymerization kinetics, including the Trommsdorf gel effect, chain transfer reactions to monomer, chain transfer agents (e.g., thiols) and polymer chains, and chain length dependent termination reactions. This allowed the calculation of latex particle morphology, as well as the polymer molecular weight, gel content and graft level, when applicable. A number of examples are used to provide experimental data with which to compare the Monte Carlo predictions.magnified image

In situ Preparation of Gold Nanoparticles of Varying Shape in Molecular Hydrogel of Peptide Amphiphiles

We have synthesized the gold nanoparticles (GNPs) of different shaped by in situ reduction within the structure-directing low molecular weight gel template of tryptophan-containing peptide amphiphiles in water without using any external reducing or capping agents. Gold nanocrystals with sheet, wire, octahedral, and decahedral shapes were modulated with the help of the different morphology of the supramolecular gel network. The gel morphology at minimum gelation concentration is the prime requirement to prepare such different nanocrystals of gold. We also elucidated that the seeding growth approach did not have any stimulating affect to control the shape of GNPs. The supramolecular template itself has the structure-directing capability. The formation of gold species in the aqueous solution was monitored by UV−vis spectroscopy, transmission electron microscopy, and X-ray diffraction studies. The tryptophan-based peptide hydrogelators are elegant hosts as structure-directing templates for in situ shape-contr...

(Mini)emulsion Polymerization: Effect of the Segregation Degree on Polymer Architecture

A continuous loop reactor was used for the production of 2-ethylhexyl acrylate (2-EHA), methyl methacrylate (MMA) and acrylic acid (AA) pressure sensitive adhesive by both emulsion and miniemulsion polymerization. Similar high monomer conversions were achieved in both processes, but striking differences in polymer architecture were found. A mathematical model was used to analyze these differences concluding that because the costabilizer suppressed monomer diffusion from miniemulsion droplets, the average polymer concentration in the polymerization loci was lower in the miniemulsion process. This resulted in less chain transfer to polymer, and hence in lower sol molecular weight and gel content.

Rheological properties of channel catfish ( Ictalurus punctaus) gelatine from fish skins preserved by different methods

Gelatins were extracted from channel catfish skins preserved by different methods using 50 mmol/l acetic acid. Molecular weight distribution, gel strength and viscoelastic properties of gelatin samples were studied. Compared to gelatins from fresh and frozen skins, gelatin from dried channel catfish skin exhibited higher gel strength. This can be explained by the large α-chains content of gelatin from the dried skins. The gelling point and melting point of dried channel catfish skin gelatin solution were similar to those of fresh skin gelatin solution, but distinctly different from those of frozen skin gelatin. After maturation at low temperature, melting points of gelatins increased. But the melting point of frozen skin gelatin was still the highest among the three gelatin samples studied.

Microbial Communities in Long-Term Heavy Metal Contaminated Ombrotrophic Peats

High concentrations of heavy metals are known to be toxic to many soil organisms. The effects of long-term exposure to lower levels of metals on the soil microbial community are, however, less well understood. The southern Pennines of the U.K. are characterised by expanses of ombrotrophic peat soils that have experienced deposition of high levels of heavy metals since the mid to late 1800s. Concentrations of metals in the peat remain high but the effect of the contamination on the in-situ microbial communities is unknown. Geochemical and molecular polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) and sequencing techniques were used to derive new information on the metal chemistry and microbial populations in peat soils from six locations in the southern Pennines. All sites were highly acidic (pH 3.00–3.14) with high concentrations of potentially toxic heavy metals, particularly porewater Zn and particulate-associated Pb. The results also reveal a split in site characteristics between the most polluted sites with the highest levels of bioavailable metals (Bleaklow, FeatherBed Moss and White Hill) and those with much lower bioavailable metals (Cowms Moor, Holme Moss and Round Hill). There was no difference in the number of dominant bacterial species between the sites but there were significant differences in the species composition. At the three sites with the highest levels of bioavailable metals, bacterial species with a high similarity to acidophilic sulphur- and iron-oxidizing bacteria and those from high metal environments were detected. The transformations carried out by these metal mobilising and acid producing bacteria may make heavy metals more bioavailable and therefore more toxic to higher organisms. Bacteria with similarity to those typically found in forest and grassland soils were documented at the three sites with the lowest levels of bioavailable metals. The data highlight the need for further studies to elucidate the species diversity and functionality of bacteria in heavy metal contaminated peats in order to assess implications for moorland restoration.

Concentration of chlorophenols in water to dialkyated catinonic surfactant–silica gel admicelles

Chlorophenols including monochlorophenol, dichlorophenol, trichlorophenol, tetrachlorophenol, and pentachlorophenol in water were extracted into dialkylated cationic surfactant–silica gel admicelles. The dialkylated cationic surfactants such as didecyldimethylammonium bromide (DC10) and didodedyldimethylammonium bromide (DC12) sorbed on silica gel surfaces to form admicelles at pH 9. Approximately 200 mg of DC10 was quantitatively sorbed on 1 g of silica gel. The sorption further increased by further addition of DC10. This is in contrast to the fact that the maximum sorption of mono-alkylated cetyltrimethyammonium chloride (CTAC) was only ca. 100 mg. Based on the fluorescent spectra of a molecular probe, N-phenyl-1-naphthylamine, DC10- and DC12-silica gel admicelles were more hydrophobic than CTAC-silica gel admicelles. The extents of the extraction of chlorophenols into DC10-silica gel admicelles were greater than those into CTAC-silica gel admicelles. However, the extractions to DC12-silica gel admicelles were insufficient due to leakage of DC12 vesicles. Consequently, DC10-silica gel admicelles were the most adequate for concentrating chlorophenols in water. An admicelle column was prepared by passing aqueous buffer solution of DC10 through a Bond Elut Jr. ® silica gel solid-phase extraction cartridge. It was successfully applied to the 500-fold concentration of chlorophenols including hydrophilic mono-substituted chlorophenol in water samples prior to their HPLC analysis.

Reverse Thermal Gelling PEG−PTMC Diblock Copolymer Aqueous Solution

In the search for a new thermogelling biomaterial, we are reporting poly(ethylene glycol)−poly(trimethylene carbonate) (PEG−PTMC) diblock copolymers. The PEG−PTMC (550−2750) diblock copolymer aqueous solutions (>25 wt %) underwent sol-to-gel-to-syneresis (macroscopic phase separation between the polymer and water) transition as the temperature increased. The sol-to-gel transition temperature could be controlled in a range of 20−75 °C by varying polymer concentration in water, molecular weight, and composition of the polymer. 13C NMR spectra, a transmission electron microscopic image, and dynamic light scattering suggest that the micellar aggregation through the dehydration of PEG is involved in the sol-to-gel transition. The in-situ gel formation was confirmed by subcutaneous injection of the polymer aqueous solution (30 wt %, 0.5 mL) into rats. Because of the diffusion of the polymer with a low molecular weight out of the gel, mass loss of 15 wt % was observed over 20 days in in-vivo study. On the other hand, the polymer is so stable in phosphate buffer saline that any changes in molecular weight, pH, and gel mass were not observed over the same period of time in in-vitro study.

Crystal Structure of the Heme-IsdC Complex, the Central Conduit of the Isd Iron/Heme Uptake System in Staphylococcus aureus

Pathogens such as Staphylococcus aureus require iron to survive and have evolved specialized proteins to steal heme from their host. IsdC is the central conduit of the Isd (iron-regulated surface determinant) multicomponent heme uptake machinery; staphylococcal cell-surface proteins such as IsdA, IsdB, and IsdH are thought to funnel their molecular cargo to IsdC, which then mediates the transfer of the iron-containing nutrient to the membrane translocation system IsdDEF. The structure of the heme-IsdC complex reveals a novel heme site within an immunoglobulin-like domain and sheds light on its binding mechanism. The folding topology is reminiscent of the architecture of cytochrome f, cellobiose dehydrogenase, and ethylbenzene dehydrogenase; in these three proteins, the heme is bound in an equivalent position, but interestingly, IsdC features a distinct binding pocket with the ligand located next to the hydrophobic core of the beta-sandwich. The iron is coordinated with a tyrosine surrounded by several non-polar side chains that cluster into a tightly packed proximal side. On the other hand, the distal side is relatively exposed with a short helical peptide segment that acts as a lip clasping onto almost half of the porphyrin plane. This structural feature is argued to play a role in the mechanism of binding and release by switching to an open conformation and thus loosening the interactions holding the heme. The structure of the heme-IsdC complex provides a template for the understanding of other proteins, such as IsdA, IsdB, and IsdH, that contain the same heme-binding module as IsdC, known as the NEAT (near transporter) domain.

Adsorbed Gels versus Brushes: Viscoelastic Differences

It is of fundamental importance to be able to easily distinguish between the viscoelastic properties of a molecular gel (noncovalent cross-linked three-dimensional polymer structure) and a brush (polymer structure that emanates from a surface in three dimensions without cross-linking). This has relevance in biology and in designing surfaces with desired chemical and viscoelastic properties for nano and genomic technology applications. Agarose and thiol-tagged poly(ethylene glycol) were chosen as model systems, as they are known, on adsorption, to behave like a molecular gel and brush, respectively. Here, we focus on their viscoelastic differences using a quartz crystal microbalance with dissipation monitoring (QCM-D). Changes in resonance frequency and dissipation for three overtones using QCM-D were fitted with the Voigt viscoelastic model to calculate the shear viscosity and shear modulus for the adsorbed agarose gel and the PEG brush. At a surface coverage of 500 ng/cm2, the shear viscosities and shear moduli were 0.0025 +/- 0.0002 Pa-s and 2.0 +/- 0.17 x 105 Pa and 0.0010 +/- 0.0001 Pa-s and 5.0 +/- 0.3 x 104 Pa for the gel and brush, respectively. Thus, the adsorbed agarose gel layer was far more rigid than that of the covalently bound PEG brush due to its cross-linked network. Also, the diffusivity of agarose and PEG in solution was compared during adsorption onto a bare gold surface. The estimated value for the effective diffusivity of the PEG (without a thiol tag) and of the agarose gel was on the order of 10(-11) and 10(-15) m2/s, respectively. This low diffusivity for agarose supports the contention that it exists as a molecular gel with a H-bonded cross-linked network in aqueous solution. With the methods used here, it is relatively easy to distinguish the differences in viscoelastic properties between an adsorbed gel and brush.

Fractal Study of Mesoporous Structure in Water Molecular Condensed System

Bis-(4-stearoylaminophenyl) ether (BSADE) can aggregate and self-assemble in water. Transmission electron microscopy (TEM) indicated that the morphology of BSADE aggregates in water was entanglement and thin fiber-like, and that a three dimensional network structure was formed. Water molecules were entrapped in this three dimensional network structure and formed a new type of condensed system (so-called water molecular gel). Water molecular gel is a typical mesoporous material which can be characterized by the fractal dimension D. Using gas adsorption method along with measurement of porosity and specific surface area, the fractal dimension D of the complicated pores was 2.1-2.2 for this water molecular gel. Using viscosity method and the Cayley fractal tree, the fractal dimension D of the fiber-like three dimensional network was determined to be 1.98. The formation process of water molecular gel can be described as nucleation followed by a repeated growing and branching cycle.