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Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A kind of novel biodegradable supramolecular hydrogel was synthesized via copolymerization of gelatin methacrylamide with photocurable and biodegradable polypseudorotaxanes under UV irradiation. These polypseudorotaxanes were prepared by supramolecular self-assemblies of alpha-cyclodextrins threaded onto amphiphilic LA-PEG-LA copolymers end-capped with methacryloyl groups. The hydrogels are injectable, and their structure was characterized in detail with FTIR, (1)H NMR, XRD, TG and DSC techniques. Their swelling behaviour and morphologies were also examined. The analytical results demonstrated that the channel-type crystalline structure of the polypseudorotaxanes remains in the as-obtained hydrogels. Moreover, the SEM pictures showed that the hydrogels having gelatin methacrylamide are more suitable for cell seeding and proliferation than those without gelatin added.
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PMID:A kind of novel biodegradable hydrogel made from copolymerization of gelatin with polypseudorotaxanes based on alpha-CDs. 1845 60

Fluid flow induces proliferation and differentiation of osteoblasts, and fibrous structure like a primary cilium on a cell surface contributes to flow sensing and flow-driven gene regulation. We address a question: Does attachment of synthetic polymers on a cell surface enhance mechanosensitivity of osteoblasts? Using MC3T3 osteoblast cells (C4 clone) and a PEG polymer, one of whose termini was covalently linked to a succinimidyl succinate group (functionalized PEG-PEGSS), we examined attachment of PEGSS to osteoblasts and evaluated its effects on the mRNA expression of stress-responsive genes. AFM images exhibited globular PEGSS conformation of approximately 100 nm in size, and SEM images confirmed the attachment of a cluster of pancake-like PEGSS molecules on the osteoblast surface. Compared to control cells incubated with unfunctionalized PEG, real-time PCR revealed that RNA upregulation of c-fos, egr1, ATF3 and Cox2 genes was magnified in the cells incubated with PEGSS. These results support a PEG-induced increase in mechanosensitivity of osteoblasts and indicate that the described approach would be useful to accelerate growth and development of osteoblasts for bone repair and tissue engineering.
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PMID:PEG attachment to osteoblasts enhances mechanosensitivity. 1852 42

In this contribution, PCL (poly-epsilon caprolactone) scaffolds were prepared by solvent-casting/particle-leaching technique in the presence of two pore formers, PEG(4000) or sucrose molecules in different quantities (0, 10, 20, 30, 40, 50, 55 w/w% PEG(4000)/PCL; 10, 20 w/w% Sucrose/PCL). The surface and bulk properties of the resulting scaffolds were studied by SEM, DSC and FTIR. SEM photographs showed that, macroporosity was obtained in the PCL structures prepared with sucrose crystals while microporous structure was obtained in the presence of PEG(4000) molecules. Average pore diameters calculated from SEM photographs were 40.1 and 191.2 mum for 40% PEG(4000)/PCL and 10% Sucrose/PCL scaffolds, respectively. The DSC and FTIR results confirmed that there is no any interaction between pore formers and PCL during structural formation, and both pore formers, PEG(4000) and sucrose, remained independently in the scaffolds. L929 mouse fibroblast cells were seeded onto PCL structures and maintained during 7 days to evaluate cell proliferation. Cell culture results showed that, 10% Sucrose/PCL scaffold was the most promising substrate for L929 cell growth due to 3-D architecture and macroporous structure of the scaffold.
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PMID:Comparison of cellular proliferation on dense and porous PCL scaffolds. 1872 92

Three-dimensional (3D) architectures of YBO(3)/Eu(3+) with different morphologies such as nest-like, rose-like, cruller-like, and flower-like, were hydrothermally synthesized by simply adjusting the ratios of surfactant polyethylene glycol-6000 (PEG-6000) to octadecylamine (ODA). These 3D architectures were all self-assembled by nanoflakes. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL) spectra were used to characterize the morphology and structures of the samples. PEG-6000, ODA, and the ODA/PEG ratio played important roles in the formation process of various architectures. Rose-like architecture was chosen as a candidate, and the formation mechanism of the architecture was proposed on the basis of XRD analysis and SEM observation of the products at different reaction periods of time. As-synthesized samples displayed strong emission located at 591, 610, and 615 nm. Water contact angle measurements indicated that the films fabricated by the samples obtained under the different ratios of PEG-6000/ODA could exhibit tunable wettability ranging from superhydrophilicity to superhydrophobicity. This kind of one-pot bisurfactant-controlled hydrothermal synthesis method reported here provides a new strategy to realize the surfaces of functional materials with tunable wettability.
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PMID:Bisurfactant-controlled synthesis of three-dimensional YBO3/Eu3+ architectures with tunable wettability. 1935 93

Poly(ether-ester urethane)s (PUs) multiblock co-polymers were synthesized from telechelic hydroxylated poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) and poly(ethylene glycol) (PEG) via a melting polymerization (MP) process using 1,6-hexamethylene diisocyanate (HDI) as a non-toxic coupling agent for the first time. The PHBHHx segments and PEG segments in the multiblock co-polymers behaved as a hard, hydrophobic and a soft, hydrophilic part, respectively. Their chemical structures and molecular characteristics were studied by gel-permeation chromatography (GPC), (1)H-NMR and Fourier transform infrared spectroscopy (FT-IR). The PU produced via the MP method showed a higher molecular weight than those resulting from the solvent polymerization (SP) reported previously. Thermal properties showed enhanced thermal stability with semi-crystalline morphology via incorporation of PEG. The segments compositions evaluated from thermogravimetric analysis (TGA) two-step thermal decomposition profiles suggested that MP enhanced the reactivity of PEG compared with the SP process. It was in good agreement with those calculated from (1)H-NMR, as well as the precursor feed ratio, respectively. Water contact angle measurements revealed that surface hydrophilicity of the PUs was enhanced by incorporating the PEG segment into PHBHHx polymer backbone. The mechanical properties assessment of the PUs recorded an improved and adjustable ductility and toughness than pure PHBHHx while preserving the tensile strength. Samples synthesized via MP were resistant to hydrolytic and lipase degradation, yet the multiblock co-polymers incorporating the highest amount of PEG degraded at the highest rate. SEM studies revealed that the surface of the PU films became increasingly porous as the degradation proceeded. Implantation of PU in mouse abdominal cavity indicated that tissue regeneration and tissue compatibility of PU film was better than that of PHBHHx-only film.
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PMID:Synthesis, characterization and biocompatibility of biodegradable elastomeric poly(ether-ester urethane)s Based on Poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) and Poly(ethylene glycol) via melting polymerization. 1952 7

The effect of complexation of irbesartan (IRB), a practically water-insoluble drug, with cyclodextrins in presence of different concentrations of water-soluble polymers (PEG 4000 and PVP K-90) on the dissolution rate of the drug has been investigated. Phase solubility studies were carried out to evaluate the solubilizing power of betaCD in association with water-soluble polymers towards IRB and to determine the apparent stability constant (K (S)) of the complexes. Improvement in K(S) value for ternary complexes (IRB-betaCD-polymers) clearly proved the benefit on the addition of water-soluble polymer to increase complexation efficiency. The dissolution rate of the drug from ternary systems containing PEG 4000 and PVP K-90 was higher as compared to the binary system. An optimum increase in the dissolution rate of the drug was observed at a polymer concentration of 5% w/w for PVP K-90 and 10% w/w for PEG 4000. DSC, FTIR, SEM, and XRD studies were carried out to characterize the complexes.
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PMID:Studies on the effect of water-soluble polymers on drug-cyclodextrin complex solubility. 1956 89

Electrospun tubular conduit (4 mm inner diameter) based on blends of polydioxanone (PDS II(R)) and proteins such as gelatin and elastin having a spatially designed trilayer structure was prepared for arterial scaffolds. SEM analysis of scaffolds showed random nanofibrous morphology and well-interconnected pore network. Due to protein blending, the fiber diameter was reduced from 800-950 nm range to 300-500 nm range. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) results confirmed the blended composition and crystallinity of fibers. Pure PDS scaffold under hydrated state exhibited a tensile strength of 5.61 +/- 0.42 MPa and a modulus of 17.11 +/- 1.13 MPa with a failure strain of 216.7 +/- 13%. The blending of PDS with elastin and gelatin has decreased the tensile properties. A trilayer tubular scaffold was fabricated by sequential electrospinning of blends of elastin/gelatin, PDS/elastin/gelatin, and PDS/gelatin (EG/PEG/PG) to mimic the complex matrix structure of native arteries. Under hydrated state, the trilayer conduit exhibited tensile properties (tensile strength of 1.77 +/- 0.2 MPa and elastic modulus of 5.74 +/- 3 MPa with a failure strain of 75.08 +/- 10%) comparable to those of native arteries. In vitro degradation studies for up to 30 days showed about 40% mass loss and increase in crystallinity due to the removal of proteins and "cleavage-induced crystallization" of PDS.
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PMID:A biomimetic tubular scaffold with spatially designed nanofibers of protein/PDS bio-blends. 1957 42

A poly(N-isopropylacrylamide-co-ethylene dimethacrylate) (poly(NIPAAm-co-EDMA)) monolith was in situ prepared in the capillary and was investigated for in-tube solid-phase microextraction (SPME). NIPAAm, an acrylamide monomer with isopropyl group, was crosslinked with EDMA. PEG of 400-20,000 Da molecular weight and methanol were selected as the binary porogens. The porous structures of the resulting monoliths have been assessed by SEM, nitrogen adsorption-desorption, and pressure drop measurements. To investigate the extraction mechanism, several groups of model analytes (including neutral, acidic, and basic) were examined. The result showed that this monolithic material exhibited high extraction efficiencies for compounds under highly acidic and basic conditions, which was due to the hydrophobic interactions and excellent pH stability of the monolith. The equilibrium extraction time profiles were also monitored for model compounds to evaluate the extraction capacity of monolithic capillary. Finally, the developed monolith in-tube SPME-HPLC method was applied to the determination of three tricyclic antidepressants from urine samples.
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PMID:Preparation of a poly(N-isopropylacrylamide-co-ethylene dimethacrylate) monolithic capillary and its application for in-tube solid-phase microextraction coupled to high-performance liquid chromatography. 1960 42

Prednisone is considered the glucocorticoid of choice for anti-inflammatory and immunosuppressant effects. However, its very low aqueous solubility can compromise oral bioavailability. Changes in the dissolution of a prednisone-PEG 6000 solid dispersion into capsule were investigated by addition of pregelatinized starch. Physical state of prednisone:PEG 6000 was analyzed by X-ray diffractometry, and scanning electron microscopy. Capsule formulations containing prednisone-PEG 6000 and pregelatinized starch showed superior dissolution properties (> 95% in 60 min) when compared with reference capsules without disintegrant (< 45% in 60 min). Water uptake and disintegration time were directly correlated with pregelatinized starch amount. The morphology of prednisone-PEG 6000 particles with disintegrant was analyzed by SEM, showing a novel surface structure. Thus, solid dispersions of a poorly water soluble drug combined with a disintegrant were confirmed as a valid approach to the improvement of drug dissolution.
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PMID:Influence of water uptake, gel network, and disintegration time on prednisone release from encapsulated solid dispersions. 1962 84

The principal aim of this study was to develop an intravenous formulation of itraconazole (ITZ) using lipid nanoparticles based on binary mixture of liquid and solid lipids. Lipid nanoparticles were developed to provide the controlled release of ITZ as well as to improve the solubility of ITZ. Lipid nanoparticles were prepared with tristearin as a solid lipid, triolein as a liquid lipid, and a surfactant mixture of eggPC, Tween 80 and DSPE-PEG(2000). ITZ was incorporated at the concentration of 20mg/g. Lipid nanoparticles were manufactured by high-pressure homogenization method. The particle size and polydispersity index (PI) of lipid nanoparticles were below 280 nm and 0.2, respectively. Zeta potentials and incorporation efficiencies of lipid nanoparticles were around -30 mV and above 80%, respectively. Lipid nanoparticles containing 1% of liquid lipid showed the smallest particles size and the highest incorporation efficiency. Results from SEM, DSC and PXRD revealed that ITZ in lipid nanoparticles exists in an amorphous state. Release rates were increased as the amount of liquid lipid in lipid core increased, demonstrating that the release of ITZ from lipid nanoparticles could be controlled by modulation of the amount of liquid lipid in lipid core. Pharmacokinetic studies were performed after intravenous administration of lipid nanoparticles in rats at the dose of 5mg/kg. The plasma concentration of ITZ was prolonged after intravenous administration of lipid nanoparticles. It is concluded that binary lipid nanoparticles could control the release and pharmacokinetic parameters of ITZ.
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PMID:Development of a binary lipid nanoparticles formulation of itraconazole for parenteral administration and controlled release. 1974 66


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