This study presents a method for one-step formation ofpoly(ethyleneoxide) nanofibers incorporating nanoparticles of a poorly water-solublecompound. Using the new method reported here, nanofiberânanoparticlecomposites are fabricated in one step by electrospinning of an oil-in-watermicroemulsion, in which a model material, propylparaben, has beendissolved within the volatile dispersed phase in the presence of ahigh-molecular-weight polymer. The approach is based on nanoscaleconfinement to the dispersed phase of an oil-in-water microemulsionwith a volatile oil phase, in which the poorly water-soluble materialsare dissolved. Thus, when the thermodynamically stable oil-in-watermicroemulsion is combined with the rapid evaporation of solvent inherentin the electrospinning process, the droplets are converted into organicnanoparticles embedded within a polymeric nanofiber. In addition topossessing process simplicity, this method exhibits a very high percentageof nanoparticle loading with desirable active material properties.Specifically, the diameter of the nanofibers is in the range of 60â185nm, and propylparaben exists within the nanofiber as nanocrystalsof 30â120 nm. These dimensions suggest that the nanofiberânanocrystalcomposites could serve as a delivery system for water-insoluble materials. [ABSTRACT FROM AUTHOR]Copyright of Langmuir is the property of American Chemical Society and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Microemulsions have already been recognized as convenient templates for nanoparticle synthesis. Spontaneous formation of the compartmentalized domains within the microemulsions leads to facile and low-cost preparation processes.
The efflux transporter P-glycoprotein (P-gp) affects the pharmacokinetics of many drugs. Currently used methods for characterization of P-gp's functional activity in vivo involve the use of radiolabeled substrates, are costly, and are technically demanding. Our objective was to evaluate whether the FDA-approved near-infrared compound indocyanine green (ICG) can be used as a probe substrate of P-gp. We also characterized the interaction of ICG with another efflux transporter, the breast cancer resistance protein (BCRP). We evaluated ICG accumulation and transport in MDCK cells overexpressing P-gp or BCRP (MDCK-MDRI and MDCK-BCRP, respectively) compared to control MDCK cells, in the presence or the absence of transporter inhibitors. In vivo imaging of ICG biodistribution in mice was conducted over 3.5 h using valspodar as the P-gp inhibitor. The EC50 values for ICG accumulation in control MDCK and MDCK-MDR1 cells were 9.0 x 10(-6) +/- 5.7 x 10(-7) M and 1.5 x 10(-5) +/- 1.1 x 10(-6) M, respectively. The efflux ratio for ICG in MDCK-MDR1 cells was 6.8-fold greater than in control cells. P-gp inhibition attenuated ICG efflux from MDR1-MDCK cells, and their effects in those cells were greater than in control MDCK cells. In contrast, BCRP level of expression or pharmacological inhibition did not significantly affect ICG cellular accumulation. In vivo imaging indicated enhanced cerebral ICG distribution with valspodar (brain - foot area under the concentration-time curves of 3.0 x 10(10), 5.6 x 10(10) and 3.7 x 10(19) h.[p/s/sr]/mu W in valspodar-treated mice vs 9.0 x 10(9) and 5.3 x 10(9) h.[p/s/sr]/mu W in controls). The findings from this pilot study suggest that near-infrared imaging using ICG as the probe substrate should be further characterized as a methodology for in vivo evaluation of P-gp activity.
Carbon nanotube (CNTs) inks may provide an effective route for producing flexible electronic devices by digital printing. In this paper we report on the formulation of highly concentrated aqueous CNT inks and demonstrate the fabrication of flexible electroluminescent (EL) devices by inkjet printing combined with wet coating. We also report, for the first time, on the formation of flexible EL devices in which all the electrodes are formed by inkjet printing of low-cost multi-walled carbon nanotubes (MWCNTs). Several flexible EL devices were fabricated by using different materials for the production of back and counter electrodes: ITO/MWCNT and MWCNT/MWCNT. Transparent electrodes were obtained either by coating a thin layer of the CNTs or by inkjet printing a grid which is composed of empty cells surrounded by MWCNTs. It was found that the conductivity and transparency of the electrodes are mainly controlled by the MWCNT film thickness, and that the dominant factor in the luminance intensity is the transparency of the electrode.
This study presents a method for one-step formation of poly(ethylene oxide) nanofibers incorporating, nanoparticles of a poorly water-soluble compound. Using the new method reported here, nanofiber-nanoparticle composites are fabricated in one step by electrospinning of an oil-in-water microemulsion, in which a model material, propylparaben, has been dissolved within the volatile dispersed phase in the presence of a high-molecular-weight polymer. The approach is based on nanoscale confinement to the dispersed phase of an oil-in-water microemulsion with a volatile oil phase, in which the poorly water-soluble materials are dissolved. Thus, when the thermodynamically stable oil-in-water microemulsion is combined with the rapid evaporation of solvent inherent in the electrospinning process, the droplets are converted into organic nanoparticles embedded within a polymeric nanofiber. In addition to possessing process simplicity, this method exhibits a very high percentage of nanopartide loading with desirable active material properties. Specifically, the diameter of the nanofibers is in the range of 60-185 nm, and propylparaben exists within the nanofiber as nanocrystals of 30-120 nm. These dimensions suggest that the nanofiber nanocrystal composites could serve as a delivery system for water-insoluble materials.
Systemic antipsoriatic therapies have potentially life-threatening, long-term side effects. The efficacy of topical drugs is poor, but may be improved by the use of delivery systems based on drug nanoparticles. To produce nanoparticles (NP) composed of cyclosporin A, a classical antipsoriatic drug, and to investigate their penetration and biological effects in human skin affected by psoriatic symptoms, poly-e-caprolactone (PCL) and cyclosporin A (CsA) NP were prepared by the solvent evaporation method. Skin penetration was followed using fluorescently labeled NP in human skin organ cultures (hSOC). Psoriatic symptoms were mimicked in hSOC by the treatment with epidermal growth factor (EGF) and bacterial lipopolysaccharide (LPS). Cell viability in hSOC was evaluated by the resazurin test, and cytokine secretion into the growth medium was measured by immunodetection. We showed that topically applied NP diffused throughout the epidermis within two hours and through the dermis within the following day. They significantly reduced the secretion of inflammatory cytokines IL1 beta, IL6, IL8, IL20 and IL23. At active doses, no cytotoxicity was detected. This type of NP display relevant properties for the use as topical anti-inflammatory agents and may help to resorb psoriatic lesions.
A review on applications of metal-based ink-jet inks for printed electronics with a particular focus on inks contg. metal nanoparticles, complexes and metallo-org. compds. The review describes the prepn. of such inks and obtaining conductive patterns by using various sintering methods: thermal, photonic, microwave, plasma, elec., and chem. triggered. Various applications of metal-based ink-jet inks (metalization of solar cell, RFID antennas, OLEDs, thin film transistors, electroluminescence devices) are reviewed. [on SciFinder(R)]
The invention provides compns. and methods for prevention, treatment, or management of pulmonary hypertension using piperidine, pyrrolidine, or azepane derivs. comprising one to four nitric oxide (NO) donor groups and a reactive oxygen species (ROS) degrdn. catalyst. The invention further provides a water dispersible powder comprising nanoparticles comprising said derivs., as well as pharmaceutical compns. thereof and methods of use. Rat exptl. models of pulmonary hypertension were treated for 10 days with 3-nitratomethyl-2,2,5,5-tetramethylpyrrolidinyloxy for effective treatment. Dispersible powders contg. nanoparticles of 3-nitratomethyl-2,2,5,5-tetramethylpyrrolidinyloxy were prepd. [on SciFinder(R)]
Methods for the manuf. of a conductive transparent film on a substrate are described which entail coating the substrate with a first material to form a wet film of the first material on at least a region of a surface of the substrate; treating the film with at least one second material capable of displacing the first material in the film at the point of contact to expose the substrate to provide an array of spaced apart ring-voids in the film; and optionally treating the film to render the first material conductive. Methods for the manuf. of a conductive transparent pattern on a substrate are also described which entail treating a substrate with a plurality of droplets of a conductive material and permitting the droplets to form an array of intersecting ring structures on the substrate, the conductive material being selected from a combination of one or more metals or metal precursors, a semiconductor material, a carbon-based material, and/or quantum dots to obtain a conductive transparent pattern on the substrate. The substrate may comprise a material selected from glass, paper, inorg. or org. semiconductor materials, polymeric materials, and ceramics. Substrates are also described which are provided with a conductive transparent film of a material having a plurality of spaced apart material-free voids. Devices (e.g., photoconductors, photodiodes, solar cells, light emitting diodes, org. light emitting diodes, lasers, light sensors, transistors, org. transistors, inorg. transistors, hybrid transistors, touch screens, display backplanes, large area display arrays, flexible displays, electromagnetic interference shielding layers, and e-paper) provided with ≥1 of the conductive films are also described. [on SciFinder(R)]
Transparent conductive coatings are essential for fabrication of a variety of printed electronic devices such as flexible displays and solar cells. We report on a simple method to obtain such coatings by using aqueous dispersions of silver nanoparticles in an evaporative lithography process which is performed directly onto plastic substrates. In essence, a droplet containing silver nanoparticles is placed on top of a metallic mesh, instantaneously spreading over the mesh and the plastic substrate, and after the flow of the dispersion towards the wires of the mesh and drying, a transparent grid composed of the nanoparticles is formed. The silver nanoparticles are tailored to self-sinter upon short exposure to HCl vapors, due to the presence of polyacrylic acid salt on the surface of the particles. Therefore, immediate sintering of the silver nanoparticles in the thin lines of the grid occurs even at room temperature, enabling formation of transparent, flexible conductive grid on heat-sensitive substrates. The process yielded a conductive array having a very low sheet resistance, 9 ± 0.8 Ω/, and a transparency above 75%. The application of the flexible conductive grid, which can replace conventional and expensive ITO, is demonstrated in an electroluminescent (EL) device. [ABSTRACT FROM AUTHOR]Copyright of Journal of Materials Chemistry is the property of Royal Society of Chemistry and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
A new liposome-based near-infrared probe that combines both imaging and targeting abilities was developed for application in medical imaging. The near-infrared fluorescent molecule indocyanine green (ICG), and the cetuximab monoclonal antibody for epidermal growth factor receptor (EGFR) were attached to liposomes by passive adsorption. It was found that ICG molecules adsorbed to the liposomes are more fluorescent than free ICG and have a larger quantum yield. Cetuximab-adsorbed fluorescent liposomes preserved EGFR recognition, as is evident from internalization and selective binding to A431 colon carcinoma cells overexpressing EGFR. The binding of cetuximab-targeted fluorescent liposomes to A431 compared with IEC-6 cells (normal enterocytes expressing physiological EGFR levels) was greater by a factor of 3.5, ensuring imaging abilities with available fluorescent equipment. Due to relatively high quantum yield and specific tumor cell-recognizing ability, this technology deserves further in vivo evaluation for imaging and diagnostic purposes.