4,046 research outputs found

    Design and testing of hydrophobic core/hydrophilic shell nano/micro particles for drug-eluting stent coating

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    In this study, we designed a novel drug-eluting coating for vascular implants consisting of a core coating of the anti-proliferative drug docetaxel (DTX) and a shell coating of the platelet glycoprotein IIb/IIIa receptor monoclonal antibody SZ-21. The core/shell structure was sprayed onto the surface of 316L stainless steel stents using a coaxial electrospray process with the aim of creating a coating that exhibited a differential release of the two drugs. The prepared stents displayed a uniform coating consisting of nano/micro particles. In vitro drug release experiments were performed, and we demonstrated that a biphasic mathematical model was capable of capturing the data, indicating that the release of the two drugs conformed to a diffusion-controlled release system. We demonstrated that our coating was capable of inhibiting the adhesion and activation of platelets, as well as the proliferation and migration of smooth muscle cells (SMCs), indicating its good biocompatibility and anti-proliferation qualities. In an in vivo porcine coronary artery model, the SZ-21/DTX drug-loaded hydrophobic core/hydrophilic shell particle coating stents were observed to promote re-endothelialization and inhibit neointimal hyperplasia. This core/shell particle-coated stent may serve as part of a new strategy for the differential release of different functional drugs to sequentially target thrombosis and in-stent restenosis during the vascular repair process and ensure rapid re-endothelialization in the field of cardiovascular disease

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    Department of Energy Engineering (Battery Science and Technology)The continuous throng in demand for high energy density rechargeable batteries innovatively drives technological development in cell design as well as electrochemically active materials. In that perspective metal-free batteries consisting of a flowing seawater as a cathode active material were introduced. However, the electrochemical performance of the seawater battery was restrained by NASICON (Na3Zr2Si2PO12) ceramic solid electrolyte. Here, we demonstrate a new class of fibrous nanomat hard-carbon (FNHC) anode/1D (one-dimensional) bucky paper (1DBP) cathode hybrid electrode architecture in seawater battery based on 1D building block-interweaved hetero-nanomat frameworks. Differently from conventional slurry-cast electrodes, exquisitely designed hybrid hetero-nanomat electrodes are fabricated through concurrent dual electrospraying and electrospinning for the anode, vacuum-assisted infiltration for the cathode. HC nanoparticles are closely embedded in the spatially reinforced polymeric nanofiber/CNT hetero-nanomat skeletons that play a crucial role in constructing 3D-bicontinuous ion/electron transport pathways and allow to eliminate heavy metallic aluminum foil current collectors. Eventually the FNHC/1DBP seawater full cell, driven by aforementioned physicochemical uniqueness, shows exceptional improvement in electrochemical performance (Energy density = 693 Wh kg-1), (Power density = 3341 W kg-1) removing strong stereotype of ceramic solid electrolyte, which beyond those achievable with innovative next generation battery technologies.ope

    Synthesis and precise deposition of gold nanoparticles using electrospray technique

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    The main dissertation subject is the study on new synthesis method of highly monodisperse gold nanoparticles in organic media and elaboration of nanoparticles deposition technique onto different substrates including memory devices.Praca naukowa zrealizowana w ramach międzynarodowego projektu badawczego: 7 Programu Ramowego UE: Hybrydowe organiczno-nieorganiczne elementy pamięci wykorzystujące zintegrowane układy elektroniczne i fotoniczne (HYMEC)

    Electrospinning predictions using artificial neural networks

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    Electrospinning is a relatively simple method of producing nanofibres. Currently there is no method to predict the characteristics of electrospun fibres produced from a wide range of polymer/solvent combinations and concentrations without first measuring a number of solution properties. This paper shows how artificial neural networks can be trained to make electrospinning predictions using only commonly available prior knowledge of the polymer and solvent. Firstly, a probabilistic neural network was trained to predict the classification of three possibilities: no fibres (electrospraying); beaded fibres; and smooth fibres with > 80% correct predictions. Secondly, a generalised neural network was trained to predict fibre diameter with an average absolute percentage error of 22.3% for the validation data. These predictive tools can be used to reduce the parameter space before scoping exercises

    Singularities on charged viscous droplets

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    We study the evolution of charged droplets of a conducting viscous liquid. The flow is driven by electrostatic repulsion and capillarity. These droplets are known to be linearly unstable when the electric charge is above the Rayleigh critical value. Here we investigate the nonlinear evolution that develops after the linear regime. Using a boundary elements method, we find that a perturbed sphere with critical charge evolves into a fusiform shape with conical tips at time t0t_0, and that the velocity at the tips blows up as (t0t)α(t_0-t)^\alpha, with α\alpha close to -1/2. In the neighborhood of the singularity, the shape of the surface is self-similar, and the asymptotic angle of the tips is smaller than the opening angle in Taylor cones.Comment: 9 pages, 6 figure

    Optimization of electrospraying conditions for the microencapsulation of probiotics and evaluation of their resistance during storage and in-vitro digestion

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    Electrospraying has recently emerged as a novel microencapsulation technique with potential for the protection of probiotics. However, research efforts are still needed to minimize the viability loss observed during the processing of sensitive strains, and to maximize productivity. The aim of the present work was the optimization of the electrospraying conditions for the microencapsulation of a model probiotic microorganism, Lactobacillus plantarum, within a whey protein concentrate matrix. In a pre-optimization step, the convenience of encapsulating fresh culture instead of freeze-dried bacteria was established. Additionally, a surface response methodology was used to study the effect of the applied voltage, surfactant concentration, and addition of a prebiotic to the formulation on cell viability and productivity. Viability losses lower than 1 log10 CFU were achieved and the bacterial counts of the final products exceeded 8.5 log10 CFU/g. The protection ability of the developed structures during storage and in-vitro digestion was also evaluated.Laura G. Gómez-Mascaraque is recipient of a predoctoral contract from the Spanish Ministry of Economy and Competitiveness (MINECO), Call 2013. Russell Cruz Morfin received a scholarship from the Mexican National Council for Science and Technology (CONACYT), Call 2014. Gloria Sánchez is supported by the “Ramón y Cajal” Young Investigator program of the MINECO. This work was financially supported by the Spanish MINECO project AGL2012-30647 and by the CSIC project 201470I002.Peer reviewe

    Development and Optimization of Novel Encapsulation Structures of Interest in Functional Foods Through Electrospraying

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    The aim of this work was to establish strategies for the development of electrosprayed encapsulation structures, of interest in food applications, based on aqueous hydrocolloid dispersions. Specifically, various polysaccharides and two different proteins were evaluated for capsule formation. To this aim, the hydrocolloid dispersion properties were analysed and compared with the solution properties of two polymers readily spinnable in water (polyvinyl alcohol (PVOH) and polyethylene oxide (PEO)). Increasing the hydrocolloid concentration to promote chain entanglements resulted in a valid strategy only for a few matrices (related to their greater Mw). As alternative strategies to improve the physical properties and, thus, the sprayability of the dispersions, addition of gums and surfactants to modify their viscosity and surface tension, respectively, was evaluated. Moreover, denaturation of proteins was also carried out in order to investigate the effect of this treatment on the electrospraying process and on capsule formation. Results showed that the incorporation of some of these molecules, as well as protein denaturation, significantly changed the physical properties, allowing the development of encapsulation structures from all the hydrocolloids assayed. The morphology of the structures obtained was characterized, and the molecular organization of some of the capsules was studied and related to the electrosprayability and capsules morphology.A. Lopez-Rubio is recipient of a Ramon y Cajal contract from the Spanish Ministry of Science and Innovation. The authors thank the Spanish MINECO projects AGL2012-30647, FUN-C-FOOD (CSD2007-00063), and the EU project of the FP7 FRISBEE for the financial support.Peer reviewe

    Production and characterization of carbamazepine nanocrystals by electrospraying for continuous pharmaceutical manufacturing

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    In this paper, an electrospray technique followed by annealing at high temperatures was developed to produce nanocrystals of carbamazepine (CBZ), a poorly water-soluble drug, for continuous pharmaceutical manufacturing process. Electrospraying solutions of CBZ in methanol obeys the expected scaling law of current, which is I ∼ Q[superscript 1/2] (I, electrical current; Q, flow rate), for liquids with sufficiently high conductivity and viscosity. Lower flow rates during electrospraying were preferred to produce smaller diameters of monodisperse, dense CBZ nanoparticles. CBZ nanoparticles were predominantly amorphous immediately after electrospraying. Crystallization of CBZ nanoparticles was accelerated by annealing at high temperatures. CBZ nanocrystals with the most stable polymorph, form III, were obtained by annealing at 90°C, which is above the transition temperature, 78°C, for the enantiotropic CBZ form III and form I. The solubility and dissolution rates of CBZ nanocrystals increased significantly as compared with those of CBZ bulk particles. Therefore, electrospray technology has the potential to produce pharmaceutical dosage forms with enhanced bioavailability and can readily be integrated in a continuous pharmaceutical manufacturing process.Novartis-MIT Center for Continuous Manufacturin

    Electrosprayed core-shell nanoparticles of PVP and shellac for furnishing biphasic controlled release of ferulic acid

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    Coaxial electrospraying was explored to organize polymer excipients in a core-shell manner for providing biphasic controlled release of active ingredient. With ferulic acid (FA) as a model drug, and shellac and polyvinylpyrrolidone (PVP) as the core and shell polymeric matrices, core-shell nanoparticles were successfully fabricated. A series of tests were carried out to characterize the prepared core-shell nanoparticles and also the nanoparticles prepared using a single fluid electrospraying of the shell or core fluids alone. The core-shell nanoparticles had an average diameter of 530 ± 80 nm with clear core-shell structure. The contained FA was converted to an amorphous state both in the core and the shell parts due to the favorable hydrogen bonding between the components. In vitro dissolution tests demonstrated that the core-shell nanoparticles were able to provide the desired biphasic drug-controlled release profiles. Coaxial electrospraying is a useful tool for the development of novel nanodrug delivery systems from polymers