Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0432222 (SEM)
 47,337 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In order to protect implanted glucose sensors from biofouling, novel hydrogels (146-217% water by mass) were developed based on a copolymer of hydroxyethyl methacrylate (HEMA) and 2,3-dihydroxypropyl methacrylate (DHPMA). The porosity and mechanical properties of the hydrogels were improved using N-vinyl-2-pyrrolidinone (VP) and ethyleneglycol dimethacrylate (EGDMA). The results of SEM and DSC FT-IT analyses showed that the hydrogel (VP30) produced from a monomeric mixture of 34.5% HEMA, 34.5% DHPMA, 30% VP and 1% EDGMA (mol%) had an excellent pore structure, high water content at swelling equilibrium (W eq=166% by mass) and acceptable mechanical properties. Two kinds of VP30-coated sensors, Pt/GOx/VP30 and Pt/GOx/epoxy-polyurethane (EPU)/VP30 sensors were examined in glucose solutions during a period of 4 weeks. The Pt/GOx/VP30 sensors produced large response currents but the response linearity was poor. Therefore, further studies were focused on the Pt/GOx/EPU/VP30 sensors. With a diffusion-limiting epoxy-polyurethane membrane, the linearity was improved (2-30 mM) and the response time was within 5 min. Eight Pt/GOx/EPU/VP30 sensors were subcutaneously implanted in rats and tested once per week over 4 weeks. All of the implanted sensors kept functioning for at least 21 days and 3 out of 8 sensors still functioned at day 28. Histology revealed that the fibrous capsules surrounding hydrogel-coated sensors were thinner than those surrounding Pt/GOx/EPU sensors after 28 days of implantation.
 ...
PMID:Use of hydrogel coating to improve the performance of implanted glucose sensors. 1818 83

A novel calix[4] open-chain crown ether (p-tert-butylcalix[4]arene-1,3-bis(allyloxyethy) ether)-modified, organic-inorganic hybrid silica-based monolithic column possessing vinyl ligands for CEC is described. The monolithic silica matrix containing a vinyl functionality was synthesized by in situ cocondensation of tetramethoxysilane (TMOS) and vinyltrimethoxysilane (VTMS) via sol-gel process and chemically modified with calix[4] open-chain crown ether by free radical polymerization procedure using alpha, alpha'-azobisisobutyronitrile (AIBN) as an initiator. Morphology of the monolithic column was examined by SEM and the successful incorporation of calix[4] open-chain crown ether to the vinyl-hybrid monolith was characterized by infrared (IR) spectra. Compared with an unmodified vinyl-hybrid monolithic column, slightly stronger EOF at pH >7.5 was observed for this monolithic column due to the ionization of phenolic hydroxyls on the lower rim of calix[4]arene. VTMS/TMOS ratios in the reaction mixture were varied and 1:4 was found to be optimum to obtain homogeneous monolith with good permeability. The performance of the column was evaluated by nucleotides, beta-blockers, neurotransmitters, and PAHs as test solutes and compared with that of unmodified vinyl-hybrid monolithic column. Greatly improved column performance was obtained due to the host-guest interaction and intermolecular hydrogen bonding provided by the calix[4] open-chain crown ether moiety. The column efficiencies for neurotransmitters and nucleotides are up to 120 000 and 110 000 plates/m, respectively. Migration time and theoretical plate number reproducibilities were reasonable with RSDs less than 1.0 and 1.8% each for within column runs and not more than 7.2 and 8.6% each for column-to-column measurements, using four nucleotides as test solutes.
 ...
PMID:Calix[4] open-chain crown ether-modified, vinyl-functionalized hybrid silica monolith for capillary electrochromatography. 1821 98

Photo-cross-linked poly(vinyl pyrrolidone) (PVP) and poly(ethylene oxide)(PEO)/PVP electrospun nanofibrous mats containing complex-bound iodine have been studied. FT-IR spectroscopy analyses have proved that coordination of molecular iodine with carbonyl group and nitrogen atom of pyrrolidone rings of the PVP chains has taken place. The distribution of iodine along the fibers is uniform as revealed by X-ray mapping. The microbiological tests have demonstrated that the iodine complex-containing electrospun mats are highly effective against the Gram-positive bacterium Staphylococcus aureus, the Gram-negative bacterium Escherichia coli and the fungus Candida albicans. Comparison with iodine complex-containing films has shown that the iodine complex-containing nanofibers exhibit a higher killing rate than the films against bacteria E. coli. SEM observations showed that PVP-iodine nanofibrous mats inhibit the adhesion of bacteria S. aureus. These characteristic features make the electrospun iodine-containing nanofibers good candidates for wound-dressing materials.
 ...
PMID:Antibacterial and antimycotic activity of a cross-linked electrospun poly(vinyl pyrrolidone)-iodine complex and a poly(ethylene oxide)/poly(vinyl pyrrolidone)-iodine complex. 1832 37

Nanocomposites with multi-walled carbon nanotubes (MWNT) and polystyrene (PS) were synthesized via an in-situ bulk sonochemical polymerization under the application of ultrasonication to open pi-bonds in the MWNT, thus enhancing the PS polymerization. Sonication of vinyl monomers such as styrene leads to radical initiation of polymerization. Various characteristics such as morphology, thermal property of the synthesized PS in the presence of the MWNT in the PS/MWNT composites were examined by SEM, TEM, thermogravimetric analysis, respectively. Their rheological properties were also investigated using a stress-controlled rotational rheometer under small amplitude oscillation and steady transient shear in their melt state.
 ...
PMID:Multi-walled carbon nanotube/polystyrene composites prepared by in-situ bulk sonochemical polymerization. 1833 Jan 47

The TiO(2) film was coated on poly vinyl chloride (PVC) surface by dip-coating process from TiO(2)-PVC-THF suspension. The morphology and crystal structure of the as-synthesized samples were characterized by SEM and XRD. The photocatalytic properties were measured by the photodegradation reaction of RhB and the anti-adhesion and anti-bacteria for Escherichia coli. The results show that the resultant TiO(2) film is well-conglutinated on PVC surface and has the same crystal structure as the original TiO(2) powder. The TiO(2)/PVC shows excellent photocatalytic activity for the degradation of aqueous RhB and the activity increases with increasing reaction time and tends toward stable after accumulative illumination for 11.5 h. The TiO(2) film shows good bacterial anti-adhesion activity following photo-activation and sterilization property under UV irradiation. The E. coli can be killed completely after UV irradiation for 1.5 h.
 ...
PMID:Photocatalytic and antibacterial properties of medical-grade PVC material coated with TiO2 film. 1850 14

Oral drug administration is convenient with pH dependent drug delivery system since the drug has to pass through different pH environments in gastro intestinal (GI) tract. The pH dependent swelling/shrinking behavior of hydrogel drug carrier controls the drug release without affecting the function of drug. pH dependent hydrogels of poly (vinyl alcohol) (PVA) were prepared by cross linking with maleic acid (MA). The hydrogels were characterized by attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, DSC, porosimetry, SEM, TEM, biocompatibility study and by measuring their swelling behavior in water, simulated gastric fluid (SGF) and intestinal fluid (SIF). Swelling of the hydrogels was found to be highest in SIF (pH: 7.5) and lowest in SGF (pH: 1.2) resembling that required in colon targeted drug delivery systems. Since the swelling behavior of the gel is pH dependent, these hydrogels were studied for colon targeted drug delivery in an in-vitro set-up resembling the condition of GI tract. The ratio of PVA and MA in the hydrogel was varied to study the effect on the drug diffusion rate. For drug delivery study, vitamin B12 and salicylic acid were used as model drugs. The hydrogel, loaded with model drugs vitamin B12 and salicylic acid also demonstrated colon specific drug release with a relatively higher drug release in SIF (pH: 7.5) than that in SGF (pH: 1.2).
 ...
PMID:Poly (vinyl alcohol) hydrogels for pH dependent colon targeted drug delivery. 1859 50

Silica-polymer hybrid materials (Sil-T1) have been successfully synthesized from a self-assembling polymerizable organogelator; N'-octadecyl-N(alpha)-(4-vinyl)-benzoyl-L-phenylalanineamide (C(18)-L-Phe-St or 1). Telomerization of compound 1 has been done with commonly used silane coupling agent; 3-mercaptopropyltrimethoxysilane (MPS), and the telomer (T1) was grafted onto porous silica surface to prepare a stationary phase (Sil-T1) for reversed-phase high-performance liquid chromatography. The composition of the new hybrid material (Sil-T1) was determined by elemental analysis, DRIFT-IR, TGA and by (13)C and (29)Si (CP/MAS) NMR spectroscopic measurements. The elemental analysis measurements revealed that the surface coverage by organic phase in Sil-T1 is significantly (about 135%) lower than commercial polymeric octadecylsilyalted silica (ODS-p). In addition, the results of (13)C CP/MAS NMR demonstrated that the N-alkyl moieties of the grafted polymers chain in Sil-T1 remained disordered, amorphous, and mobile represented by gauche conformational form. Furthermore, from the characterization data, the successful grafting process and unagglomerated state of the grafted particles (as observed by scanning electron microscopic, SEM measurements) prove the material to be suitable for HPLC application. The evaluation of chromatographic performance has been done from the retention studies of different size and shape PAHs and aromatic positional isomers. Significantly higher selectivity for PAHs was attributed by Sil-T1 than ODS-p regardless it has low surface coverage and lower order of alkyl chain. The enhancement of selectivity obtained by Sil-T1 can be explained by the contribution of multiple pi-pi interactions between the guest PAHs and the pi-electrons sources (carbonyls and aromatic moieties) of the organic phase of Sil-T1.
 ...
PMID:Preparation, telomerization, immobilization and application of N-alkyl L-phenylalanine-derived polymerizable organogelator for reversed-phase high-performance liquid chromatography. 1865 2

Bioactive glasses (BaG) can bind to human bone tissues and have been used in many biomedical applications for the last 30 years. However they usually are weak and brittle. On the other hand, composites that combine polymers and BaG are of particular interest, since they often show an excellent balance between stiffness and toughness. Bioactive glass-poly(vinyl alcohol) foams to be used in tissue engineering applications were previously developed by our group, using the sol-gel route. Since bioactive glass-polymer composite derived from the sol-gel process cannot be submitted to thermal treatments at high temperatures (above 400 degrees C), they usually have unreacted species that can cause cytotoxicity. This work reports a technique for stabilizing the sol-gel derived bioactive glass/poly(vinyl alcohol) hybrids by using glutaraldehyde (GA), NH(4)OH solutions and a blocking solution containing bovine serum albumin. PVA/BaG/GA hybrids were characterized by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM/EDX) analyses. Moreover, MTT (3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide) biocompatibility and cytotoxicity assays were also conducted. The hybrids exhibited pore size varying from 80 to 820 mum. After treatments, no major changes in the pore structure were observed and high levels of cell viability were obtained.
 ...
PMID:Synthesis, neutralization and blocking procedures of organic/inorganic hybrid scaffolds for bone tissue engineering applications. 1880 51

In the present work we report the synthesis, characterization, and preliminary biocompatibility of polymer blends based on Chitosan and poly(vinyl alcohol) (PVA) with low degree of hydrolysis and chemically crosslinked by glutaraldehyde for potential application on skin tissue repairing. The microstructure and morphology of the blended hydrogels were characterized through Fourier Transform Infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM/EDX) analysis. Hydrogels were investigated by swelling as preliminary in vitro test using simulated body fluid. In addition, biocompatibility, cytotoxicity, and cell viability were assessed via MTT assay with VERO cell culture and cell spreading-adhesion analysis. It was found that by increasing the chitosan to PVA ratio, simulated body fluid uptake of the material was significantly altered. All the tested hydrogels have clearly presented adequate cell viability, non-toxicity, and suitable properties which can be tailored for prospective use in skin tissue engineering.
 ...
PMID:Properties and biocompatibility of chitosan films modified by blending with PVA and chemically crosslinked. 1898 49

In this study it was aimed to produce nano fibers of poly vinyl alcohol PVA polymer via electrospinning ES method and to investigate the role of PVA concentration in the spinning dope on diameter, beads and HHS of produced fibers. Spinning dopes with different concentrations of PVA at rang of 5 to 20% (wt/wt on weight of solution) prepared. The requisite voltage for ES (30 kv) was supplied by a DC high voltage power supply and for collecting the fibers a grounded aluminum foil target placed 17 cm below the tip of capillary tube (spinning nozzle). The results showed that spinning dopes with PVA concentration between 8 to 12% (wt/wt) are capable of producing PVA fibers, but those below 8% (wt/wt) concentrations because of low viscosity formed droplets known as electrospray effect. Electrospinning suppressed at spinning dope concentrations above 12% (wt/wt) due to high viscosity of dope. According to the SEM photographs of electrospun PVA fibers it revealed that in higher concentrations produced nanofibers have larger diameter with less beads and HHS in compare with lower concentrations.
 ...
PMID:Effect of polyvinyl alcohol concentration in spinning dope on diameter, beads and HHS of produced nanofibers. 1907 34


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>