Influence of ethanol and glycerol concentration over functional and structural properties of zein-oleic acid films

This study was performed in order to determine the effect of the addition of different concentrations of glycerol and ethanol over functional and structural properties of zein-oleic acid films. Films were prepared from zein and oleic acid formulations, containing: 0, 10, 20 and 30% (w/w) of glycerol as plasticizer and 75, 80, 85, 90 and 95% (v/v) of ethanol as zein solvent. Water vapor permeability (WVP) at 4 and 24 C, opacity, water solubility and structural behavior of the film were assessed. The film water barrier properties, WVP and water solubility, were increased when higher ethanol concentration and lower glycerol concentration were used. Furthermore, WVP at 4 C was lower than WVP at 24 C due to the crystalline solid state of oleic acid at lower temperatures. Likewise, opacity, homogeneity and structure of the composite film were improved as ethanol increased and glycerol lowered. © 2013 Elsevier B.V. All rights reserved.

Influence of the relative amounts of crystalline and amorphous phases on the mechanical properties of polyamide-6 nanocomposites

The relative amounts of amorphous and crystalline ?- and a-phases in polyamide-6 nanocomposites, estimated from the deconvolution of X-ray diffraction peaks using Gaussian functions, correlates with their mechanical, thermomechanical, and barrier properties. The incorporation of organoclay platelets (Cloisite 15A and 30B) induced the crystallization of the polymer in the ? form at expense of the amorphous phase, such that 12 wt % of Cloisite is enough to enhance the mechanical and the thermomechanical properties. However, higher nanofiller loads were necessary to achieve good barrier effects, because this property is mainly dependent on the tortuous path permeation mechanism of the gas molecules through the nanocomposite films. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Interactions of inhaled nanoparticles with the alveolar-capillary barrier of the human respiratory tract

In dieser Arbeit wurden zytotoxische Effekte sowie die inflammatorische Reaktionen des distalen respiratorischen Traktes nach Nanopartikelexposition untersucht. Besondere Aufmerksamkeit lag auch auf der Untersuchung unterschiedlicher zellulärer Aufnahmewege von Nanopartikeln wie z.B. Clathrin- oder Caveolae-vermittelte Endozytose oder auch Clathrin- und Caveolae-unabhängige Endozytose (mit möglicher Beteiligung von Flotillinen). Drei unterschiedliche Nanopartikel wurden hierbei gewählt: amorphes Silica (aSNP), Organosiloxan (AmorSil) und Poly(ethyleneimin) (PEI). Alle unterschiedlichen Materialien gewinnen zunehmend an Interesse für biomedizinische Forschungsrichtungen (drug and gene delivery). Insbesondere finden aSNPs auch in der Industrie vermehrt Anwendung, und stellen somit ein ernstzunehmendes Gesundheitsrisiko dar. Dieser wird dadurch zu einem begehrten Angriffsziel für pharmazeutische Verabreichungen von Medikamenten über Nanopartikel als Vehikel aber bietet zugleich auch eine Angriffsfläche für gesundheitsschädliche Nanomaterialien. Aus diesem Grund sollten die gesundheitsschädigenden Risiken, sowie das Schicksal von zellulär aufgenommenen NPs sorgfältig untersucht werden. In vivo Studien an der alveolaren-kapillaren Barriere sind recht umständlich. Aus diesem Grund wurde in dieser Arbeit ein Kokulturmodel benutzt, dass die Alveolar-Kapillare Barrier in vivo nachstellt. Das Model besteht aus dem humanen Lungenepithelzelltyp (z.B. NCI H441) und einem humanen microvasculären Endothelzelltyp (z.B. ISO-HAS-1), die auf entgegengesetzten Seiten eines Transwell-Filters ausgesät werden und eine dichte Barriere ausbilden. Die NP Interaktion mit Zellen in Kokultur wurde mit denen in konventioneller Monokultur verglichen, in der Zellen 24h vor dem Experiment ausgesät werden. Diese Studie zeigt, dass nicht nur die polarisierte Eigenschaft der Zellen in Kokultur sondern auch die unmittelbare Nähe von Epithel und Endothelzelle ausschlaggebend für durch aSNPs verursachte Effekte ist. Im Hinblick auf inflammatorische Marker (sICAM, IL-6, IL8-Ausschüttung), reagiert die Kokultur auf aSNPs empfindlicher als die konventionelle Monokultur, wohingegen die Epithelzellen in der Kokultur auf zytotoxikologischer Ebene (LDH-Ausschüttung) unempfindlicher auf aSNPs reagierten als die Zellen in Monokultur. Aufnahmestudien haben gezeigt, dass die Epithelzellen in Kokultur entschieden weniger NPs aufnehmen. Somit zeigen die H441 in der Kokultur ähnliche epitheliale Eigenschaften einer schützenden Barriere, wie sie auch in vivo zu finden sind. Obwohl eine ausreichende Aufnahme von NPs in H441 in Kokultur erreicht werden konnte, konnte ein Transport von NPs durch die epitheliale Schicht und eine Aufnahme in die endotheliale Schicht mit den gewählten Inkubationszeiten nicht gezeigt werden. Eine Clathrin- oder Caveolae-vermittelte Endozytose von NPs konnte mittels Immunfluoreszenz weder in der Mono- noch in der Kokultur nachgewiesen werden. Jedoch zeigte sich eine Akkumulation von NPs in Flotillin-1 und-2 enthaltende Vesikel in Epithelzellen aus beiden Kultursystemen. Ergebnisse mit Flotillin-inhibierten (siRNA) Epithelzellen, zeigten eine deutlich geringere Aufnahme von aSNPs. Zudem zeigte sich eine eine reduzierte Viabilität (MTS) von aSNP-behandelten Zellen. Dies deutet auf eine Beteiligung von Flotillinen an unbekannten (Clathrin oder Caveolae -unabhängig) Endozytosemechanismen und (oder) endosomaler Speicherung. Zusammenfassend waren die Aufnahmemechanismen für alle untesuchten NPs in konventioneller Monokultur und Kokultur vergleichbar, obwohl sich die Barriereeigenschaften deutlich unterscheiden. Diese Arbeit zeigt deutlich, dass sich die Zellen in Kokultur anders verhalten. Die Zellen erreichen hierbei einen höheren Differenzierungsgrad und eine Zellkommunikation mit anderen relevanten Zelltypen wird ermöglicht. Durch das Einbringen eines dritten relevanten Zelltyps in die Kokultur, des Alveolarmakrophagen (Zelllinie THP-1), welcher die erste Verteidigungsfront im Alveolus bildet, wird diese Aussage weiter bekräftigt. Erste Versuche haben gezeigt, dass die Triplekultur bezüglich ihrer Barriereeigenschaften und IL-8-Ausschüttung sensitiver auf z.B. TNF- oder LPS-Stimulation reagiert als die Kokultur. Verglichen mit konventionellen Monokulturen imitieren gut ausgebildete, multizelluräre Kokulturmodelle viel präziser das zelluläre Zusammenspiel im Körper. Darum liefern Nanopartikelinteraktionen mit dem in vitro-Triplekulturmodel aufschlussreichere Ergebnisse bezüglich umweltbedingter oder pharmazeutischer NP-Exposition in der distalen Lung als es uns bisher möglich war.

β1-integrin/matrix interactions support blood-brain barrier integrity

Brain microvascular endothelium forms an active permeability barrier, the blood-brain barrier (BBB). In neurologic disorders, barrier properties of the BBB are often lost indicating their dependance on molecular cues of the brain microenvironment. In this issue, Osada et al demonstrate that the endothelial extracellular matrix (ECM) provides one of these cues. Their study shows that β1-integrin-mediated adhesion of brain endothelial cells to the surrounding ECM is critical for stabilizing claudin-5 in BBB tight junctions (TJs) and BBB integrity. These observations point to a novel intracellular signaling pathway from β1-integrin/ECM endothelial adhesions to BBB TJs contributing to BBB integrity.

Interferon-beta stabilizes barrier characteristics of the blood-brain barrier in four different species in vitro

BACKGROUND: Blood-brain barrier (BBB) breakdown is an early event in the pathogenesis of multiple sclerosis (MS). In a previous study we have found a direct stabilization of barrier characteristics after treatment of bovine brain capillary endothelial cells (BCECs) with human recombinant interferon-beta-1a (IFN-beta-1a) in an in vitro BBB model. In the present study we examined the effect of human recombinant IFN-beta-1a on the barrier properties of BCECs derived from four different species including humans to predict treatment efficacy of IFN-beta-1a in MS patients. METHODS: We used primary bovine and porcine BCECs, as well as human and murine BCEC cell lines. We investigated the influence of human recombinant IFN-beta-1a on the paracellular permeability for 3H-inulin and 14C-sucrose across monolayers of bovine, human, and murine BCECs. In addition, the transendothelial electrical resistance (TEER) was determined in in vitro systems applying porcine and murine BCECS. RESULTS: We found a stabilizing effect on the barrier characteristics of BCECs after pretreatment with IFN-beta-1a in all applied in vitro models: addition of IFN-beta-1a resulted in a significant decrease of the paracellular permeability across monolayers of human, bovine, and murine BCECs. Furthermore, the TEER was significantly increased after pretreatment of porcine and murine BCECs with IFN-beta-1a. CONCLUSION: Our data suggest that BBB stabilization by IFN-beta-1a may contribute to its beneficial effects in the treatment of MS. A human in vitro BBB model might be useful as bioassay for testing the treatment efficacy of drugs in MS.

Cell surface levels of endothelial ICAM-1 influence the transcellular or paracellular T-cell diapedesis across the blood-brain barrier

The extravasation of CD4(+) effector/memory T cells (TEM cells) across the blood-brain barrier (BBB) is a crucial step in the pathogenesis of experimental autoimmune encephalomyelitis (EAE) or multiple sclerosis (MS). Endothelial ICAM-1 and ICAM-2 are essential for CD4(+) TEM cell crawling on the BBB prior to diapedesis. Here, we investigated the influence of cell surface levels of endothelial ICAM-1 in determining the cellular route of CD4(+) TEM -cell diapedesis across cytokine treated primary mouse BBB endothelial cells under physiological flow. Inflammatory conditions, inducing high levels of endothelial ICAM-1, promoted rapid initiation of transcellular diapedesis of CD4(+) T cells across the BBB, while intermediate levels of endothelial ICAM-1 favored paracellular CD4(+) T-cell diapedesis. Importantly, the route of T-cell diapedesis across the BBB was independent of loss of BBB barrier properties. Unexpectedly, a low number of CD4(+) TEM cells was found to cross the inflamed BBB in the absence of endothelial ICAM-1 and ICAM-2 via an obviously alternatively regulated transcellular pathway. In vivo, this translated to the development of ameliorated EAE in ICAM-1(null) //ICAM-2(-/-) C57BL/6J mice. Taken together, our study demonstrates that cell surface levels of endothelial ICAM-1 rather than the inflammatory stimulus or BBB integrity influence the pathway of T-cell diapedesis across the BBB.

Combined Effect of Poly(hydroxybutyrate) and Plasticizers on Polylactic acid Properties for Film Intended for Food Packaging

Poly(lactic acid) PLA, and poly(hydroxybutyrate) PHB, blends were processed as films and characterized for their use in food packaging. PLA was blended with PHB to enhance the crystallinity. Therefore, PHB addition strongly increased oxygen barrier while decreased the wettability. Two different environmentally-friendly plasticizers, poly(ethylene glycol) (PEG) and acetyl(tributyl citrate) (ATBC), were added to these blends to increase their processing performance, while improving their ductile properties. ATBC showed higher plasticizer efficiency than PEG directly related to the similarity solubility parameters between ATBC and both biopolymers. Moreover, ATBC was more efficiently retained to the polymer matrix during processing than PEG. PLA–PHB–ATBC blends were homogeneous and transparent blends that showed promising performance for the preparation of films by a ready industrial process technology for food packaging applications, showing slightly amber color, improved elongation at break, enhanced oxygen barrier and decreased wettability.

Cling film as a barrier against CJD in Goldmann-type applanation tonometry

Purpose: To determine the feasibility of taking intra-ocular pressure (IOP) readings with Goldmann-type applanation tonometer probe covered with cling film to avoid transmission of Creutzfeldt-Jakob disease (CJD). Methods: Data were collected on two occasions from the right eyes of 30 healthy subjects using a Perkins applanation tonometer. On each occasion, a single tonometry measurement was made with and without cling film covering. Results: Cling film covering brought about a statistically significant IOP bias (-0.8 mmHg on first occasion and -1.17 mmHg on second occasion). The 95% limits of agreement, between readings made with and without cling film covering, were ±3.4 mmHg on first occasion; ±2.5 mmHg on second occasion. A statistically significant reduction of inter-sessional repeatability was observed for readings taken with cling film (±5.2 mmHg) compared to those made without (±3.9 mmHg). Conclusions: Even if the above findings are found to be acceptable, given the known intra-subject variations of this type of tonometry (±4 mmHg), ethical and legal considerations relating to the barrier properties of cling film are likely to prevent its routine use by optometrists. © 2004 The College of Optometrists.

Characterization of rice starch- ι-carrageenan biodegradable edible film. Effect of stearic acid on the film properties

The main aim of this study was to develop rice starch (RS), ι-carrageenan (ι-car) based film. Different formulations of RS (1-4%, w/w), ι-car (0.5-2%, w/w) was blended with stearic acid (SA; 0.3-0.9%, w/w) and glycerol (1%, w/w) as a plasticizer. The effect of film ingredients on the thickness, water vapour permeability (WVP), film solubility (FS), moisture content (MC), colour, film opacity (FO), tensile strength (TS), elongation-at-break (EAB) of film was examined. Interactions and miscibility of partaking components was studied by using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD). Hydrocolloid suspension solution of mix polysaccharides imparted a significant impact (p<0.05) on the important attributes of resulting edible film. TS and EAB of film were improved significantly (p<0.05) when ι-car was increased in the film matrix. Formulation F1 comprising 2% ι-car, 2% 33 RS, 0.3% SA, Gly 30% w/w and 0.2% surfactant (tween®20) provided film with good 34 physical, mechanical and barrier properties. FT-IR and XRD results reveal that molecular interactions between RS-ι-car have a great impact on the film properties confining the compatibility and miscibility of mixed polysaccharide. Results of the study offers new biodegradable formulation for application on fruit and vegetables.

Amino group positions dependent morphology and coverage of electropolymerized metallophthalocyanine (M = Ni and Co) films on electrode surfaces

Electropolymerized films of teraaminometallophthalocyanines (MTAPc; M = Ni and Co) with amino groups at α- (4α-MTAPc) and β- (4β-MTAPc) positions were prepared on glassy carbon (GC) and indium tin oxide (ITO) electrodes. It was found that the electropolymerization growth rate of 4α-MTAPc was less than that of 4β-MTAPc prepared under identical conditions. Further, the surface coverage of the polymerized 4β-MTAPc film was greater than that of 4α-MTAPc polymerized film. Atomic force microscopy (AFM), X-ray diffraction (XRD) and UV–visible spectroscopic studies were carried out for the polymerized films of 4α-NiIITAPc (p-4α-NiIITAPc) and 4β-NiIITAPc (p-4β-NiIITAPc) alone because both Ni(II) and Co(II) polymerized films show similar trend in electropolymerization and surface coverage values. AFM images show that p-4α-NiIITAPc film contains islands and the thickness of this film was nearly three times less than that of p-4β-NiIITAPc. XRD patterns for the two polymerized films reveal that p-4β-NiIITAPc film was relatively more crystalline than p-4α-NiIITAPc film. Further, the compactness of these films was scrutinized from their barrier properties toward [Fe(CN)6]3−/4− redox couple. The differences in the polymerization growth rate of 4α-MTAPc and 4β-MTAPc, and the thicknesses of the resultant polymerized films suggest that unlike 4β-MTAPc one or two amino groups might have not involved in electropolymerization in the case of 4α-MTAPc. Further, the influence of surface coverage on the electrocatalytic properties of the polymerized films was studied by taking p-4β-CoIITAPc and p-4α-CoIITAPc films as examples. The electrocatalytic oxygen reduction current was almost same at both the electrodes suggesting that only the surface species were involved in the electrocatalytic reduction of oxygen.

Compatibility of RuO2 electrodes with PZT ceramics

Because of its high electrical conductivity and good diffusion barrier properties ruthenium dioxide (RuO2) is a good electrode material for use with ferroelectric lead zirconate-titanate (PZT) solid solutions. Under certain conditions, RuO2 can react with PZT to form lead ruthenate (Pb2Ru2O6.5) during processing at elevated temperatures resulting in lead depletion from PZT. The standard Gibbs energies of formation of RuO2 and Pb2Ru2O6.5 and activities of components of the PZT solid solution have been determined recently. Using this data along with older thermodynamic information on PbZrO3 and PbTiO3, the stability domain of Pb2Ru2O6.5 is computed as a function of PZT composition, temperature and oxygen partial pressure in the gas phase. The results show PbZrO3-rich compositions are more prone to react with RuO2 at all temperatures. Increasing temperature and decreasing oxygen partial pressure suppress the reaction. Graphically displayed are the reaction zones as a function of oxygen partial pressure and PZT composition at temperatures 973, 1173 and 1373 K.

Konjac- ja galaktoglukomannaanipohjaiset emulsiokalvot

Emulsiokalvolla tarkoitetaan kalvoa, joka on valmistettu haihduttamalla ylimääräinen vesi pois emulsiosta. Polysakkaridipohjainen emulsiokalvo koostuu kalvonmuodostuspolysakkaridista, rasvasta, emulgointiaineesta ja pehmittimestä. Kirjallisuusosassa selvitettiin, mitä raaka-aineita polysakkaridipohjaisissa emulsiokalvoissa käytetään ja mitkä tekijät vaikuttavat emulsiokalvojen vesihöyrynläpäisevyyteen ja mekaanisiin ominaisuuksiin. Tutkimuksen kokeellisen osan tavoitteena oli selvittää, miten konjac-glukomannaani (KGM) ja kuusen galaktoglukomannaani (GGM) soveltuvat emulsiokalvon raaka-aineiksi. Lisäksi selvitettiin, miten rasvan tyyppi ja rasvapitoisuus vaikuttavat GGM-KGM-pohjaisten emulsiokalvojen mekaanisiin ominaisuuksiin ja vesihöyrynläpäisevyyteen. Mehiläisvahasta, mäntyöljystä ja rypsiöljystä valmistettiin emulsiokalvot, joissa oli 30 %:n (paino-% GGM:sta) rasvapitoisuudet. Lisäksi mehiläisvahasta valmistettiin emulsiokalvot, joissa oli 10 ja 50 % mehiläisvahaa. Emulsiokalvoja verrattiin vertailukalvoon, jossa ei ollut rasvaa. Kalvoissa käytetty KGM:n ja GGM:n suhde oli 1:1. Kalvoista mitattiin vesihöyrynläpäisevyys ja -läpäisynopeus, vetolujuus, Youngin moduuli ja murtovenymä. Näiden lisäksi kalvojen poikkileikkaus kuvattiin pyyhkäisyelektronimikroskoopilla. GGM ja KGM soveltuvat emulsiokalvon raaka-aineiksi. Huoneenlämpötilassa kuivatuista kalvoista saatiin tasaisemman näköisiä kuin lämpökaapissa kuivatuista. Pyyhkäisyelektronimikroskooppikuvissa vahapisarat olivat öljypisaroita pienempiä, mikä mahdollisesti vaikutti siihen, että vahapisarat pysyivät paremmin kiinnittyneenä kalvomatriisissa. Öljypisaroiden koko oli kalvoissa noin 10 ?m ja vahapisaroiden 2–6 ?m. Vesihöyrynläpäisynopeus oli pienin 50 %:n mehiläisvahakalvolla (p < 0,05). Vesihöyrynläpäisevyys laski lineaarisesti mehiläisvahapitoisuuden suurentuessa. Öljykalvot ja 10 %:n mehiläisvahakalvo eivät eronneet tilastollisesti merkitsevästi vesihöyrynläpäisevyyden suhteen vertailukalvosta. Pienin vetolujuus ja Youngin moduuli oli 50 %:n mehiläisvahakalvolla. Vertailukalvo oli kestävin ja jäykin. Murtovenymän suhteen kalvot eivät eronneet toisistaan tilastollisesti merkitsevästi. Tutkimuksessa onnistuttiin valmistamaan GGM-KGM-pohjaisia emulsiokalvoja, jotka pidättivät vesihöyryä vertailukalvoa paremmin ja silti säilyttivät mekaaniset ominaisuutensa kohtuullisen hyvin.

Avaliação das propriedades de barreira a gases de membranas obtidas a partir de dispersões aquosas à base de poliuretanos e argila

Materiais nanoestruturados têm recebido destaque na comunidade científica, destacando-se, dentre eles, os nanocompósitos à base de polímeros e argila. Quando esses materiais são obtidos no estado líquido, ressalta-se também o uso de água em substituição a solventes orgânicos, devido a questões ambientais. Neste trabalho foram sintetizadas dispersões aquosas à base de poliuretanos (WPUs) e argila hidrofílica do tipo montimorilonita (MMT) de natureza sódica, com o objetivo de avaliar as propriedades de barreira a gases conferidas pela presença de argila e pela variação nas proporções entre os segmentos flexíveis poli(glicol propilênico) (PPG) e o copolímero em bloco à base de poli(glicol etilênico) e poli(glicol propilênico) (EG-b-PG). Os monômeros empregados na síntese foram: poli(glicol propilênico) (PPG); copolímero em bloco à base de poli(glicol etilênico) e poli(glicol propilênico) (EG-b-PG), com teor de 7% de EG; ácido dimetilolpropiônico (DMPA), diisocianato de isoforona (IPDI) e etilenodiamina (EDA), como extensor de cadeia. Foram sintetizadas dispersões aquosas com e sem a presença de argila, fixando-se a razão entre o número de equivalentes-grama de grupos diisocianato e hidroxila (razão NCO/OH) em 1,5. Nas formulações foi variado também o teor de argila em relação à massa de prepolímero em 0,5% e 1%. Foi adicionada uma etapa de agitação adicional com dispersor Turrax em algumas formulações. A argila foi previamente deslaminada em água deionizada e incorporada à formulação na etapa da dispersão do prepolímero. As dispersões foram avaliadas, quanto ao teor de sólidos totais, tamanho médio de partícula e viscosidade aparente. Os filmes vazados a partir das dispersões foram caracterizados por espectrometria na região do infravermelho (FTIR) e permeabilidade ao CO2. A resistência térmica dos filmes foi determinada por termogravimetria (TG). Foram observadas modificações nas propriedades dos filmes obtidos com a inserção da argila e com a variação no teor de segmentos à base de poli(glicol etilênico). A inserção da argila promoveu uma melhoria na resistência térmica das membranas bem como uma redução na permeabilidade das mesmas. Foi observado um aumento na permeabilidade das membranas obtidas a partir das formulações com maior percentual de copolímero (EG-b-PG), com e sem argila.

Growth of ultrahigh density single-walled carbon nanotube forests by improved catalyst design.

We have grown vertically aligned single-walled carbon nanotube forests with an area density of 1.5 × 10(13) cm(-2), the highest yet achieved, by reducing the average diameter of the nanotubes. We use a nanolaminate Fe-Al(2)O(3) catalyst design consisting of three layers of Al(2)O(3), Fe, and Al(2)O(3), in which the lower Al(2)O(3) layer is densified by an oxygen plasma treatment to increase its diffusion barrier properties, to allow a thinner catalyst layer to be used. This high nanotube density is desirable for using carbon nanotubes as interconnects in integrated circuits.

Preparation and characterization of poly(ethyl acrylate)/bentonite nanocomposites by in situ emulsion polymerization

Transparent poly(ethyl acrylate) (PEA)/bentonite nanocomposites containing intercalated-exfoliated combinatory structures of clay were synthesized by in situ emulsion polymerizations in aqueous dispersions containing bentonite. The samples for characterization were prepared through direct-forming films of the resulting emulsions without coagulation and separation. An examination with X-ray diffraction and transmission electron microscopy showed that intercalated and exfoliated structures of clay coexisted in the PEA/bentonite nanocomposites. The measurements of mechanical properties showed that PEA properties were greatly improved, with the tensile strength and modulus increasing from 0.65 and 0.24 to 11.16 and 88.41 MPa, respectively. Dynamic mechanical analysis revealed a very marked improvement of the storage modulus above the glass-transition temperature. In addition, because of the uniform dispersion of silicate layers in the PEA matrix, the barrier properties of the materials were dramatically improved. The permeability coefficient of water vapor decreased from 30.8 x 10(-6) to 8.3 x 10(-6) g cm/cm(2)s cmHg. (C) 2002 Wiley Periodicals, Inc.