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Query: UMLS:C0276640 (TEM)
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Four long-chain phenyl glucoside amphiphiles possessing a saturated or unsaturated long alkyl chain group as the self-assembling unit of a highly organized molecular architecture were synthesized. Their self-assembling properties were investigated by EF-TEM, SEM, CD, FT-IR, and XRD. Compound 2 possessing one double bond in the lipophilic portion showed twisted helical fibers, which formed a bilayered structure with a 3.59 nm period, while compound 3 showed the helical ribbons and left-handed nanotubular structures with 150-200 nm inner diameters and ca. 20 nm of wall. Very interestingly, compound 4 possessing three double bonds showed a nanotubular structure with ca. 70 nm of inner diameter through a helical ribbon, which formed a loose bilayered structure with 4.62 nm. These results indicate that self-assembling properties strongly depend on the number of cis double bonds.
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PMID:Self-assembling structures of long-chain phenyl glucoside influenced by the introduction of double bonds. 1220 20

We report a novel vesicle formed by an amphiphilic CB[6] derivative, the surface of which can be easily modified via host-guest interactions by taking advantage of molecular cavities, readily accessible at the vesicle surface, and their strong affinity toward polyamines. Amphiphilic CB[6] derivative 1 synthesized by reaction between (allyloxy)12CB[6] and 2-[2-(2-methoxyethoxy)ethoxy]ethanethiol affords a vesicle that has been characterized by TEM, light scattering, and fluorescent dye entrapment experiments. Treatment of vesicle 1 with FITC (fluorescein isothiocyanate)-spermine conjugate ligand 2, in which spermine serves as a binding motif to CB[6] and FITC as a fluorescent tag, produced a surface-modified vesicle, which can be easily visualized by a confocal microscope. This result provides us with a new noncovalent, modular approach to the modification of vesicle surfaces. By treating the vesicle derived from the amphiphilic CB[6] with a tag-attached polyamine, we can easily decorate the surface of the vesicle with the tag. Sugar-decorated vesicles were prepared by this noncovalent method, and their interactions with concanavalin A (ConA) were studied. The binding constant of the vesicle decorated with mannose-spermidine conjugate 3 to ConA was measured to be approximately 3 x 104 M-1, which is almost 3 orders of magnitude higher than that of free ligand 3 to ConA (K = approximately 50 M-1). On the other hand, the binding constant of the vesicle coated with galactose-spermidine conjugate 4 to ConA was too small to be measured. These results illustrate the specific and multivalent interactions between the mannose-decorated vesicle and ConA. The ability for facile surface modification suggests many practical applications, including its use in targeted drug delivery and immunization.
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PMID:Vesicle formed by amphiphilc cucurbit[6]uril: versatile, noncovalent modification of the vesicle surface, and multivalent binding of sugar-decorated vesicles to lectin. 1581 Aug 20

In the present study it was intended to deliver primaquine phosphate (PP), a liver schizonticide directly to liver cells using polypropyleneimine (PPI) dendrimers-coated peripherally with galactose. PPI dendrimers were synthesized by consecutive Michael double addition reaction (using ethyelenediamine as core), followed by hydrogenation reaction. Galactose conjugation was carried out by ring opening reactions, followed by Schiff's reaction and reduction to secondary amine in sodium acetate buffer (pH 4.0). IR, NMR, MASS spectroscopy were used for the confirmation of synthesis of uncoated and coated dendrimers. The formulations were made by equilibrium dialysis of dendrimers with the solution of PP. Then the formulations were characterized by TEM for size and shape. Release rate, hemolytic toxicity; bio-distribution and blood level studies were also performed on lyophilized formulations. The results obtained indicated that galactose coating of PPI systems increases the drug entrapment efficiency by 5-15 times depending upon generations. Galactose coating prolonged release up to 5-6 days as compared to 1-2 days for uncoated PPI systems. The hemolytic toxicity, blood level and hematological studies proved these systems to be safer and suitable for sustained drug delivery. Blood level studies proved the suitability of the systems for the prolonged circulations and delivery of PP to liver. The galactose coating of PPI dendrimers can therefore make the PPI systems more effective and suitable for targeted delivery of Primaquine phosphate to liver.
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PMID:Glycodendrimeric nanoparticulate carriers of primaquine phosphate for liver targeting. 1584 7

Nine phenyl glucoside or galactoside amphiphiles possessing a saturated or unsaturated long alkyl-chain group as the self-assembling unit of a highly organized molecular architecture were synthesized. Their self-assembly properties were investigated by using energy-filtering TEM (EF-TEM), SEM, CD, XRD, and FT-IR techniques. Compound 2, possessing one cis double bond in the lipophilic portion, exhibited twisted helical fibers, which formed a bilayered structure with a 3.59 nm period, while 3 exhibited helical ribbons and left-handed nanotubular structures with 150-200 nm inner diameters and a wall thickness of approximately 20 nm. Very interestingly, 4, possessing three cis double bonds, exhibited a nanotubular structure with an inner diameter of approximately 70 nm and a d spacing value of 4.62 nm. On the other hand, 7, possessing two trans double bonds in the lipophilic region, exhibited crystal- or plate-like structures, which formed a bilayer structure with a d spacing value of 3.93 nm. These results indicate that the self-assembly properties are strongly dependent on the type of double bond. Furthermore, 8 and 9, with the galactopyranose moiety, revealed helical ribbon and well-defined double helical fiber structures, respectively. These findings support the view that the orientation of the intermolecular hydrogen-bonding interaction between the sugar moieties plays a critical role in producing the nanotubular structures. According to CD and powder XRD experiments, the relatively strong intermolecular hydrogen-bonding interaction of the glucopyranoside moiety in 3 and 4 provided a highly ordered chiral packing structure. Even though these compounds formed a weak hydrophobic interaction between lipophilic groups, it led to the formation of the nanotubular structure.
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PMID:Self-assembling structures of long-chain sugar-based amphiphiles influenced by the introduction of double bonds. 1600 91

In Part 1 of our work (1), four nanoparticles were synthesized specifically for the purpose of identifying design constraints to guide next generation gene delivery to the liver. The four nanoparticles are Gal-50 and Gal-140 (galactosylated 50 and 140 nm nanoparticles) and MeO-50 and MeO-140 (methoxy-terminated 50 and 140 nm nanoparticles). All four particles have the same surface charge, and Gal-50 and Gal-140 have the same surface galactose density (ca. 25-30 pmol/cm2). Here, the hepatocyte uptake in vitro and hepatic distribution in vivo of these four nanoparticles is investigated. With freshly isolated hepatocytes, Gal-50 nanoparticles are taken up to a greater extent than are MeO-50, and both 50 nm beads are taken up to a much greater extent than either of the 140 nm nanoparticles. In mice, about 90% of the in vivo dose of Gal-140 nanoparticles is found within the liver 20 min after tail-vein injection. TEM and immunohistochemistry images confirm that Gal-140 nanoparticles are primarily internalized by Kupffer cells, though isolated examples of a few Gal-140 in hepatocytes are also observed. Gal-50 nanoparticles are overwhelmingly found in vesicles throughout the cytoplasm of hepatocytes, with only isolated examples of Kupffer cell uptake 20 min after tail vein injections in mice. Despite similar surface charge and ligand density, 50 nm nanoparticles are primarily found in hepatocytes while 140 nm nanoparticles are primarily observed in Kupffer cells. These results clearly show that slightly anionic, galactose-PEGylated nanoparticles with 25-30 pmol/cm2 galactose should be about 50 nm in diameter to preferentially target hepatocytes while they should be about 140 nm in diameter to selectively target Kupffer cells.
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PMID:A nanoparticle-based model delivery system to guide the rational design of gene delivery to the liver. 2. In vitro and in vivo uptake results. 1617 82

A novel biocompatible polyelectrolyte poly(vinyl raffinose-co-acrylic acid) (PRCA) containing a raffinose branch was prepared via redox polymerization using Fe(2+)/K(2)S(2)O(8)/H(2)O(2) starting from enzymatically-synthesized monomer: 1-O-vinyldecanedioyl raffinose. Copolymers with different monomer feed ratios were prepared and characterized with IR, NMR, and GPC. PRCA can be alternated with polycation to form microcapsules on a crystals template by electrostatic layer-by-layer technique. The multilayers of PRCA/poly(methacryloyloxyethyl dimethylbenzyl ammonium chloride) (PMBA) on quartz slides and PRCA/poly(dimethyldiallyl ammonium chloride) (PDDA) on acyclovir crystals template were fabricated and characterized with UV-Vis spectra, the microelectrophoretic measurement, and TEM. Hollow capsules can be formed after the removal of acyclovir crystals template in a buffer solution. The nano-capsule-carrying galactose residue is a potential targeting drug-controlled delivery systems.
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PMID:Chemo-enzymatic synthesis of raffinose-branched polyelectrolytes and self-assembly application in microcapsules. 1637 73

The color changes associated with the aggregation of metal nanoparticles has led to the development of colorimetric-based assays for a variety of target species. We have examined both silver- and gold-based nanoparticles in order to establish whether either metal exhibits optimal characteristics for bioassay development. These silver and gold nanoparticles have been stabilized with a self-assembled monolayer of a mannose derivative (2-mercaptoethyl alpha-d-mannopyranoside) with the aim of inducing aggregation by exploiting the well-known interaction between mannose and the lectin Concanavalin A (Con A). Both metal glyconanoparticles were determined to be ca. 16 nm in diameter (using TEM measurements). Aggregation was observed on addition of Con A to both silver and gold nanoparticles resulting in a shift in the surface plasmon absorption band and a consequent color change of the solution, which was monitored using UV-visible spectrophotometry. Mannose-stabilized silver nanoparticles at a concentration of 3 nM provide an assay for Con A with the largest linear range (between 0.08 and 0.26 microM). Additionally, the kinetic rate of aggregation of the silver-nanoparticle-based bioassay was significantly greater than that of the gold-nanoparticle system. However, in terms of sensitivity, the mannose-stabilized gold-nanoparticle-based assay was optimum with a limit of detection of 0.04 microM Con A, as compared with a value of 0.1 microM obtained for the mannose-stabilized silver nanoparticles. Additionally, a lactose derivative (11-mercapto-3,6,9-trioxaundecyl beta-D-lactoside) was used to stabilize gold nanoparticles to induce aggregation upon addition of the galactose specific lectin Ricinus communis agglutinin (RCA(120)). To examine the specificity of the bioassay, lactose-stabilized gold nanoparticles were mixed with a solution of mannose-stabilized silver nanoparticles to give an aggregation assay capable of detecting two different lectins. When either Con A or RCA(120) was added to the mixed glyconanoparticles, selective recognition of the respective natural ligand was shown by aggregation of a single metal nanoparticle. Centrifugation and removal of the aggregated species enabled further bioassay measurements using the second glyconanoparticle system.
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PMID:Silver and gold glyconanoparticles for colorimetric bioassays. 1683 Oct 17

In the study, a novel chitosan (CS) derivative conjugated with multiple galactose residues in an antennary fashion (Gal-m-CS) was synthesized. A galactosylated CS (Gal-CS) was also prepared by directly coupling lactobionic acid on CS. Using an iontropic gelation method, CS and the synthesized Gal-CS and Gal-m-CS were used to prepare nanoparticles (CS, Gal-CS, and Gal-m-CS NPs) for targeting hepatoma cells. TEM examinations showed that the morphology of all three types of NPs was spherical in shape. No aggregation or precipitation of NPs in an aqueous environment was observed during storage for all studied groups, as a result of the electrostatic repulsion between the positively charged NPs. Little fluorescence was observed in HepG2 cells after incubation with the FITC-labeled CS NPs. The intensity of fluorescence observed in HepG2 cells incubated with the Gal-m-CS NPs was stronger than that incubated with the Gal-CS NPs. These results indicated that the prepared Gal-m-CS NPs had the highest specific interaction with HepG2 cells among all studied groups, via the ligand-receptor-mediated recognition.
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PMID:Synthesis of a novel glycoconjugated chitosan and preparation of its derived nanoparticles for targeting HepG2 cells. 1731 43

We describe the construction of hepatic-targeting microcapsules by self-assembly of chemo-enzymatic synthesized poly(vinyl galactose ester-co-methacryloxyethyl trimethylammonium chloride) (PGEDMC) containing galactose branches, which can be specifically recognized by membrane bound galactose receptors (ASGPR), for acyclovir (ACV) controlled release system. Alternate deposition of PGEDMC and poly(sodium 4-styrenesulfonate) (PSS) was carried out on ACV microcrystals. It was revealed that the drug release rate decreases with the increase of coated layer number and a microcapsule-drying treatment would enhance the sustained release effect probably because of a multilayer shrink and tightness during the process. The complete release of ACV yielded a hollow PGEDMC/PSS multilayered network with favorable integrity and nano-thickness by TEM and SEM. The potential targetability of the system was proved in vitro by PNA lectin recognition. Lectin hardly adsorbed on the film where the outmost layer was a polyanion or a polycation without galactose component. Whilst the galactose-containing layer (PGEDMC) was the outmost layer, a significant lectin combination was observed. This technique could provide a promising way to encapsulate and deliver various target substances in biological and pharmaceutical applications.
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PMID:Hepatic-targeting microcapsules construction by self-assembly of bioactive galactose-branched polyelectrolyte for controlled drug release system. 1793 43

The facile synthesis of highly ordered mesoporous aluminas with high thermal stability and tunable pore sizes is systematically investigated. The general synthesis strategy is based on a sol-gel process associated with nonionic block copolymer as templates in ethanol solvent. Small-angle XRD, TEM, and nitrogen adsorption and desorption results show that these mesoporous aluminas possess a highly ordered 2D hexagonal mesostructure, which is resistant to high temperature up to 1000 degrees C. Ordered mesoporous structures with tunable pore sizes are obtained with various precursors, different acids as pH adjustors, and different block copolymers as templates. These mesoporous aluminas have large surface areas (ca. 400 m2/g), pore volumes (ca. 0.70 cm3/g), and narrow pore-size distributions. The influence of the complexation ability of anions and hydro-carboxylic acid, acid volatility, and other important synthesis conditions are discussed in detail. Utilizing this simple strategy, we also obtained partly ordered mesoporous alumina with hydrous aluminum nitrate as the precursor. FTIR pyridine adsorption measurements indicate that a large amount of Lewis acid sites exist in these mesoporous aluminas. These materials are expected to be good candidates in catalysis due to the uniform pore structures, large surface areas, tunable pore sizes, and large amounts of surface Lewis acid sites. Loaded with ruthenium, the representative mesoporous alumina exhibits reactant size selectivity in hydrogenation of acetone, D-glucose, and D-(+)-cellobiose as a test reaction, indicating the potential applications in shape-selective catalysis.
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PMID:Facile synthesis for ordered mesoporous gamma-aluminas with high thermal stability. 1828 38


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