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Query: UMLS:C1275122 (TEM)
 21,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Poly-L-lactic acid (PLLA)/hydroxyapatite (HA) hybrid membranes were fabricated via electrospinning of the PLLA/HA dispersion for use in bone tissue regeneration. The structural properties and morphologies of PLLA and PLLA/HA hybrid membrane were investigated by measuring the Brunauer-Emmett-Teller specific surface area, observations of SEM, and TEM. The dispersion and integrating of HA nanoparticles in the hybrid membrane were studied by energy dispersion X-ray analysis and FTIR. The mechanical properties of PLLA/HA membrane were also measured by tensile tests. For exploring biological behaviors of the hybrid membrane, in vitro degradation tests were carried out. The osteoblast cell (MG-63) was cultured in PLLA/HA hybrid membrane extract containing medium; the cell adhesion and growth capability were investigated by SEM observation and MTT assay. HA nanoparticles were not only dispersed in the PLLA but also reacted with the functional group of PLLA, resulting in strong surface bonding and high tensile strength of hybrid membrane. The cell adhesion and growth on the PLLA/HA hybrid membrane were far better than those on the pure PLLA membrane, which proves that the PLLA/HA hybrid membrane can be one of the promising biomaterials for bone tissue regeneration.
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PMID:Poly-L-lactic acid/hydroxyapatite hybrid membrane for bone tissue regeneration. 1729 52

(Poly)acrylonitrile/chitosan (PANCHI) composite membranes were prepared. The chitosan layer was deposited on the surface as well as on the pore walls of the base membrane. This resulted in the reduction of the pore size of the membrane and in an increase of their hydrophilicity. The pore structure of PAN and PANCHI membranes were determined by TEM and SEM analyses. It was found that the average size of the pore under a selective layer base PAN membrane is 7 microm, while the membrane coated with 0.25% chitosan shows a reduced pore size--small or equal to 5 microm and with 0.35% chitosan--about 4 microm. The amounts of the functional groups, the degree of hydrophilicity and transport characteristics of PAN/Chitosan composite membranes were determined. Urease was covalently immobilized onto all kinds of PAN/chitosan composite membranes using glutaraldehyde. Both the amount of bound protein and relative activity of immobilized urease were measured. The highest activity (94%) was measured for urease bound to PANCHI2 membranes (0.25% chitosan). The basic characteristics (pH(opt), pH(stability), T(opt), T(stability), heat inactivation and storage stability) of immobilized urease were determined. The obtained results show that the poly(acrylonitrile)chitosan composite membranes are suitable for enzyme immobilization.
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PMID:Poly(acrylonitrile)chitosan composite membranes for urease immobilization. 1732 Feb 33

Micelle formation induced by disproportionation was attained for a diblock copolymer containing 2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO). Poly(4-vinylbenzyloxy-TEMPO)-block-polystyrene (PVTEMPO-b-PSt) showed no self-assembly in 1,4-dioxane, a nonselective solvent. Light scattering studies demonstrated that the copolymer self-assembled into micelles in this solvent with the addition of hydrochloric acid (HCl). The hydrodynamic diameter of the copolymer was estimated to be ca. 55 nm based on the cumulant analysis of the complete micellization. A UV analysis confirmed that the micellizarion proceeded through the disproportionation of the TEMPO into the oxoaminium chloride and the hydroxylamine by the reaction with HCl, because the absorption based on the oxoaminium chloride increased with an increase in the amount of HCl. ESR verified that the radical concentration of the TEMPO decreased with an increase in the HCl. Before the addition of HCl, the PVTEMPO-b-PSt copolymer showed broad signals based on the random orientation. As the amount of HCl increased, the broad signals changed to the typical triplet of TEMPO, accompanied by a decrease in the signal intensity. The g values had a negligible change throughout the micellization. Finally, 40% of the TEMPO remained unreacted when the micellization was completed. The micellization prevented the dispropotionation of the TEMPO, because the PVTEMPO blocks formed the micellar cores which were covered with the micellar coronas of the PSt blocks. TEM observations demonstrated that PVTEMPO-b-PSt formed spherical micelles through the dispropotionation-induced micellization.
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PMID:Micelle formation induced by disproportionation of stable nitroxyl radicals supported on a diblock copolymer. 1789 95

Poly(3-butylthiophene) (P3BT) nanowires, prepared by solution-phase self-assembly, have been used to construct highly efficient P3BT/fullerene nanocomposite solar cells. The fullerene/P3BT nanocomposite films showed an electrically bicontinuous nanoscale morphology with average field-effect hole mobilities as high as 8.0 x 10(-3) cm2/Vs due to the interconnected P3BT nanowire network revealed by TEM and AFM imaging. The power conversion efficiency of fullerene/P3BT nanowire devices was 3.0% (at 100 mW/cm2, AM1.5) in air and found to be identical with our similarly tested fullerene/poly(3-hexylthiophene) photovoltaic cells. This discovery expands the scope of promising materials and architectures for efficient bulk heterojunction solar cells.
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PMID:Highly efficient solar cells based on poly(3-butylthiophene) nanowires. 1837 31

Nanocapsules containing hinokitiol (HKL) were prepared by an emulsion-diffusion method. In an emulsification step in preparing nanocapsules, cetyltrimethylamonium chloride (CTAC) was employed as a cationic emulsifier, Poly(epsilon-caprolactone) (PCL) was use as a wall material and HKL dissolved in octylsalicylate (OS) was used as a core material. The submicron-sized nanoparticle was observed on a TEM. The size ranged 55-234 nm and the mean diameters were 223 nm, which were determined by a dynamic light scattering method. According to the results of pH-dependent microelectrophoresis, the absolute value of the surface potential of the nanocapsules was greater than 20 mV. The nanocapsules were colloidally stable over the pH range of 3-11. The nanocapsules were included in two kinds of preparations, namely shampoo and hair tonic, and the preparations were applied every day for 3 weeks on the clipped backs of 6 week-old mouse (C57BL/6) to investigate the hair growth-promoting effect. The degree of hair growth was evaluated by image-analysing the photographs of the backs and, in parallel, by the histological observation of the formation and the growth of hair or hair bulbs. The results were compared with those of commercially available Minoxidil solution (3%). Phosphate buffered saline was used as a control. The in vivo hair growth-promoting effects of the two preparations were comparable to those of Minoxidil solution. These results are in a good agreement with the histological and structural changes of follicles of the model animals, of which skins were treated with either the testing samples or the control in the same way the experiments of in vivo hair growth promotion were performed.
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PMID:In vivo hair growth promotion effects of cosmetic preparations containing hinokitiol-loaded poly(epsilon-caprolacton) nanocapsules. 1846 97

Poly(amidoamine) (PAA) networks that are obtained by the use of cystamine as a cross-linking agent in the reaction with 2,2'-dithiodipyridine turn into linear PAAs with dithiopyridyl side groups that easily undergo an exchange reaction with thiocholesterol. The resultant products represent the first examples of amphiphilic PAA-cholesterol conjugates in which lipophilic cholesterol moieties are linked to the hydrophilic PAA chain by S-S bonds that are stable in blood but cleavable inside cells. In aqueous media, these conjugates self-assemble into nanoaggregates whose inner cores consist of lipophilic cholesterol domains. A series of PAA-cholesterol conjugates that are derived from two different bis-acrylamides, namely 2,2-bis(acrylamido)acetic acid and 1,4-bis(acryloyl)piperazine, and that have different cholesterol contents were obtained. All products were characterized by (1)H and (13)C NMR spectroscopy, and the average molecular weights of the soluble polymers were determined by size exclusion chromatography. In all instances, the segregation of cholesterol residues from the aqueous medium was revealed by the comparison of their NMR spectra in CDCl3 and D2O, respectively. The TEM analysis of the PAA-cholesterol aggregates in aqueous buffers revealed homogeneous round nanospheres whose dimensions and dimension distributions were determined by DLS. Preliminary cytocompatibility tests demonstrated that all prepared PAA-cholesterol samples are cytocompatible and thus show potential for biotechnological applications.
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PMID:Poly(amidoamine) conjugates with disulfide-linked cholesterol pendants self-assembling into redox-sensitive nanoparticles. 1878 98

In the present study, we have aimed to produce nanoparticles (NPs) possessing the capability of carrying both of the hydrophobic and hydrophilic drugs and reveal significant release for both drug types. Poly(epsilon-caprolactone) (PCL) grafted poly(vinyl alcohol) (PVA) copolymer (PCL-g-PVA) has been prepared and shaped in nano-particulate form to be adequate for carrying the drugs. Stannous octoate (Sn(II)Oct(2)) was used to catalyze PVA and epsilon-caprolactone monomer to chemically bond. Moreover, this catalyst enhanced side chain polymerization reaction for the utilized epsilon-caprolactone monomer to form poly(epsilon-caprolactone) (PCL). The formed PCL was attached as branches with PVA backbone. (1)H NMR has confirmed formation of PCL and grafting of PVA by this new polymer. Moreover, the vibration modes in the functional groups of PCL-g-PVA have been detected by FT-IR. The thermal alteration in the grafted polymer was checked by TGA analysis. The successfully synthesized grafted copolymer was able to self-aggregate into NPs by direct dialysis method. The size, morphology and charges associated with the obtained NPs were analyzed by DLS, TEM and ELS, respectively. PCL-g-PVA NPs were investigated as drug carrier models for hydrophobic and hydrophilic anti cancer drugs; paclitaxel and doxorubicin. In vitro drug release experiments were conducted; the loaded NPs reveal continuous and sustained release form for both drugs, up to 20 and 15 days for paclitaxel and doxorubicin, respectively. However, in a case of using pure drugs only, both drugs completely released within 1-2 h. The overall obtained results strongly recommend the use these novel NPs in future drug delivery systems.
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PMID:Novel self-assembled amphiphilic poly(epsilon-caprolactone)-grafted-poly(vinyl alcohol) nanoparticles: hydrophobic and hydrophilic drugs carrier nanoparticles. 1902 Sep 53

Poly[(D,L-lactide)-co-glycolide] nanoparticles coated with polyethyleneimine on their surface were prepared by an emulsification-solvent evaporation method and subsequently surface modified by LBL assembly. The assembly of poly(acrylic acid) and polyethyleneimine on a planar substrate and on the PLGA nanoparticles was monitored by QCM-D, zeta-potential, flow cytometry and TEM. Carboxylic and amino groups in the multilayers were crosslinked by carbodiimide condensation, which was also later used to graft poly(ethylene glycol) (PEG). Rhodamine 6G, 5(6)-carboxyfluorescein and fluorescein were incorporated into the nanoparticles and their release profiles were recorded at 60 degrees C and at 37 degrees C for rhodamine 6G, for nanoparticles with a multilayer coating, and those that were crosslinked and grafted with PEG.
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PMID:Polyelectrolyte coated PLGA nanoparticles: templation and release behavior. 1908 71

Linoleic acid attached chitosan beads [poly(LA-Ch)] (1.25 microm in diameter) are obtained by the formation of amide linkages between linoleic acid and chitosan. Poly(LA-Ch) beads are characterized by FTIR, TEM, and swelling studies. Poly(LA-Ch) beads are used for the purification of immunoglobulin-G (IgG) from human plasma in a batch system. The maximum IgG adsorption is observed at pH 7.0 for HEPES buffer. IgG adsorption onto the plain chitosan beads is found to be negligible. Adsorption values up to 136.7 mg/g from aqueous solutions are obtained by poly(LA-Ch) beads. IgG adsorption saw an increase as a result of increasing temperature. Higher amounts of IgG are adsorbed from human plasma (up to 390 mg/g) with a purity of 92%. The adsorption phenomena appeared to follow a typical Langmuir isotherm. It is observed that IgG could be repeatedly adsorbed and desorbed without significant loss when we take into account the adsorption amount. It is concluded that the poly(LA-Ch) beads allowed one-step purification of IgG from human plasma.
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PMID:A novel support for antibody purification: fatty acid attached chitosan beads. 1919 98

Poly(3-hexylthiophene) (P3HT) was synthesized via chemical oxidative polymerization with anhydrous FeCl(3) as oxidant, 3-hexylthiophene as monomer, chloroform as solvent. TiO(2) nanoparticles modified by a small amount of P3HT (TiO(2)/P3HT) were prepared by blending TiO(2) nanoparticles and P3HT in chloroform solution. The resulting photocatalysts were characterized by the methods of TEM, XRD, FT-IR, XPS and UV-vis diffuse reflectance spectroscope. The photocatalytic activity of TiO(2)/P3HT was investigated by degrading methyl orange under visible light. The degradation rate of methyl orange was 88.5 and 13.5% when it was degradated by TiO(2)/P3HT and neat TiO(2)(P-25) for 10h, respectively. In addition, TiO(2)/P3HT nanocomposites showed excellent photocatalytic stability after 10 cycles under visible light irradiation. A possible mechanism for the photocatalytic oxidative degradation was also discussed.
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PMID:Characterization and photocatalytic activity of poly(3-hexylthiophene)-modified TiO2 for degradation of methyl orange under visible light. 1941 Mar 63


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