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Antibacterial Activity and Its Potential Mechanisms of Gellan GumMarran, Aldossari 15 September 2022 (has links)
No description available.
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Low Acyl Gellan Gum Application in Bone Tissue EngineeringBaawad, Abdullah 15 September 2022 (has links)
No description available.
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Preparação e estudo de eletrólitos poliméricos nanocompósitos de goma gelana e montmorilonita / Preparation and study of polymeric electrolytes nanocomposites of gellan gum and montmorilloniteCaliman, Willian Robert 26 February 2019 (has links)
O presente trabalho apresenta a preparação e caracterização de eletrólitos poliméricos nanocompósitos (NPEs - Nanocomposite Polymer Electrolytes) obtidos a partir da argila montmorilonita e goma gelana para aplicação em janelas eletrocrômicas. Para verificar a influência de argila nas propriedades físicas e químicas de nanocompósitos, incialmente foram preparadas membranas a base de goma gelana dos tipos low acyl (CGLA) ou high acyl (CGHA) contendo etilenoglicol ou glicerol como plastificantes e quantidades diferentes de LiClO4 (perclorato de lítio) como doador de cátions Li+. A caracterização por espectroscopia de impedância eletroquímica revelou que o eletrólito de goma gelana tipo low acyl (CGLA), com glicerol como plastificante e 0,40 g de LiClO4 (GGLA-G40) apresentava a condutividade iônica mais elevada entre as amostras, cujos valores ficaram entre 2,14 x 10-6 S/cm a 30 °C e 3,10 x 10-4 S/cm a 80°C. Ela foi usada para a preparação de nanocompósitos através de adição de quantidades diferentes de argila montmorilonita liofilizada Na+SYN-1 (synthetic mica-montmorillonite). O eletrólito com a melhor condutividade de 1,86 x 10-5 S/cm a 30°C e 3,74 x 10-4 S/cm à temperatura de 80°C continha 0,10 g de argila Na+SYN-1 (GG-MMT10). Essa mesma membrana apresentou uma transmitância entre 23% e 42% na faixa do visível, além de refletância no UV de 22% e 13% no visível. O difratograma de raios-X mostrou que os nanocompósitos formaram uma estrutura predominantemente intercalada e intercalada-floculada. Os termogramas revelaram que a estabilidade térmica dos eletrólitos não sofreu praticamente quase nenhuma alteração com a incorporação de argila. A morfologia microscópica apontou uma superfície não homogênea. Por fim, os ECDs transmissivos de configuração vidro/ITO/PB/eletrólito de goma gelana-Na+SYN-1/CeO2-TiO2/ITO/vidro montados usando o nanocompósito GG-MMT10 exibiram uma variação de transmitância no visível de 4%, indicando que esse material não apresenta benefícios em aplicações envolvendo janelas eletrocrômicas. / This work presents the preparation and characterization of nanocomposite polymer electrolytes (NPEs) obtained from montmorillonite clay and gellan gum for application in electrochromic devices. Initially, we produced membranes by using low (CGLA) and high acyl (CGHA) gellan gum, ethylene glycol or glycerol as plasticizers and different amounts of LiClO4 as a Li+ donor. Electrochemical impedance spectroscopy indicated that the sample with low acyl gellan gum (CGLA), glycerol as plasticizer and 0.40 g of LiClO4 (GGLA-G40) showed the highest conductivity of 2.14 x 10-6 S/cm at 30 °C and 3.10 x 10-4 S/cm at 80°C. This sample was used to obtain a NPE by addition of different amounts of lyophilized montmorillonite clay Na+SYN-1 (synthetic mica-montmorillonite). The sample with 0.10 g of Na+SYN-1 clay (GG -MMT10) showed the best conductivity of 1.86 x 10-5 S/cm at 30°C and 3.74 x 10-4 S/cm at 80°C. This membrane transmitted between 23% and 42% in the visible range (wavelength 400 nm to 800 nm), and had reflectance of 22% and 13% in the UV and Vis, respectively. The X-ray diffraction indicated that the nanocomposites formed a predominantly intercalated or intercalated-flocculated structure. The thermograms revealed that the thermal stability of the electrolytes does not change with the incorporation of clay, and the microscopic morphology indicated a non-homogeneous surface. Finally, the transmissive ECDs with glass/ITO/PB/gelan gum-Na+SYN-1 electrolyte/CeO2-TiO2/ITO/glass configuration, assembled using the sample GG-MMT10 exhibited a visible transmittance variation of 4%, indicating that this NPE is not suitable for electrochromic devices application.
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Polymer Gels as Pharmaceutical Dosage Forms : Rheological Performance and Physicochemical Interactions at the Gel-Mucus Interface for Formulations Intended for Mucosal Drug DeliveryHägerström, Helene January 2003 (has links)
<p>Drug delivery to the nasal and ocular mucosa faces several obstacles. One of these is from the effective clearance mechanisms present in the nose and eye. Polymer gels with suitable rheological properties can facilitate the absorption of poorly absorbed drugs by increasing the contact time of the drug with the mucosa. This has been attributed to the rheological and mucoadhesive properties of the gel. The main objective of this thesis was to investigate the importance of these features for the anticipated in vivo contact time, here exemplified by the ocular and nasal routes of administration.</p><p>The in situ gelling polymer gellan gum was found to have a favourable rheological and in vivo performance. When administered in the nasal cavity of rats, a gel was formed that could remain at the site of administration for up to 4 hours. In addition, the epithelial uptake and transfer of a 3 kDa fluorescein dextran was higher than for a mannitol solution. Therefore, it was concluded that a gellan gum formulation should be a promising strategy for nasal drug delivery.</p><p>The potential mucoadhesive properties of a variety of polymer gels were investigated using a rheological method and by measuring the tensile force required to detach the gel from a mucosa. With both methods the rheological properties of the gel were a determining factor for the results obtained. The rheological method was found to have several limitations. One of these was that a positive response, interpreted as mucoadhesion, was only seen with weak gels. The tensile method could, in contrast, detect strengthening of the mucus only for strong gels. However, this method reflects the in vivo performance of the gel better than the rheological method.</p><p>Finally, dielectric spectroscopy was explored as a tool for investigating the likelihood of intimate surface contact between the gel and the mucus layer. This novel approach involved determining the ease with which a charged particle can pass the gel-mucus interface layer, and may enable the study of the events at the interface closer to the molecular level, than is possible with the rheological and tensile strength methods.</p>
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Polymer Gels as Pharmaceutical Dosage Forms : Rheological Performance and Physicochemical Interactions at the Gel-Mucus Interface for Formulations Intended for Mucosal Drug DeliveryHägerström, Helene January 2003 (has links)
Drug delivery to the nasal and ocular mucosa faces several obstacles. One of these is from the effective clearance mechanisms present in the nose and eye. Polymer gels with suitable rheological properties can facilitate the absorption of poorly absorbed drugs by increasing the contact time of the drug with the mucosa. This has been attributed to the rheological and mucoadhesive properties of the gel. The main objective of this thesis was to investigate the importance of these features for the anticipated in vivo contact time, here exemplified by the ocular and nasal routes of administration. The in situ gelling polymer gellan gum was found to have a favourable rheological and in vivo performance. When administered in the nasal cavity of rats, a gel was formed that could remain at the site of administration for up to 4 hours. In addition, the epithelial uptake and transfer of a 3 kDa fluorescein dextran was higher than for a mannitol solution. Therefore, it was concluded that a gellan gum formulation should be a promising strategy for nasal drug delivery. The potential mucoadhesive properties of a variety of polymer gels were investigated using a rheological method and by measuring the tensile force required to detach the gel from a mucosa. With both methods the rheological properties of the gel were a determining factor for the results obtained. The rheological method was found to have several limitations. One of these was that a positive response, interpreted as mucoadhesion, was only seen with weak gels. The tensile method could, in contrast, detect strengthening of the mucus only for strong gels. However, this method reflects the in vivo performance of the gel better than the rheological method. Finally, dielectric spectroscopy was explored as a tool for investigating the likelihood of intimate surface contact between the gel and the mucus layer. This novel approach involved determining the ease with which a charged particle can pass the gel-mucus interface layer, and may enable the study of the events at the interface closer to the molecular level, than is possible with the rheological and tensile strength methods.
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Rheological Properties and Decomposition Rates of Gellan GumDhameri, Sulaiman Ali A. 04 September 2019 (has links)
No description available.
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ENHANCING AIR-WATER INTERFACE STABILITY WITH HEAT-TREATED WHEY PROTEIN IOSLATE (WPI)/HIGH ACYL GELLAN GUM (HAGG) COMPLEX PARTICLESRui Zhu (16637310) 08 August 2023 (has links)
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<p> In this study, whey protein isolate (WPI) and high gellan gum (HAGG) were selected as natural ingredients to produce food-grade biopolymer particles for stabilizing the air-water interface. To achieve this, different mixing ratios of WPI and HAGG were employed, and heat treatment was implemented at different pH levels under the same concentration based on investigations of the pH-driven phase behavior of the WPI/HAGG complex system. The resulting WPI/HAGG complex particles were then evaluated for their ability to stabilize air-water interfaces by measuring their foaming properties.</p>
<p><br></p>
<p> Foams generated using 0.1% (wt/wt) WPI/HAGG complex particles, heated at pH 5 with the mixing ratio 2:1 has demonstrated enhanced stability over a period of 30 hours compared to the WPI alone. The unique properties of these complex particles, including their smaller size (around 500nm), greater negative charge (more negative than -30 mV), and compact spherical core-shell structure, along with the higher viscosity in the continuous phase as well as the presence of small protein particles and gellan chains at the interface, collectively contribute to their superior performance as foam stabilizers. This allows for the creation of aerated food products with desirable characteristics, including product handling, enhanced texture, and prolonged shelf life in food industry.</p>
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[en] GELLAN-BASED MICROCAPSULES: PRODUCTION AND APPLICATIONS / [pt] MICROCÁPSULAS DE GELANA: PRODUÇÃO E APLICAÇÕESBRUNA COSTA LEOPERCIO 11 June 2021 (has links)
[pt] Microcápsulas são utilizadas em diversos setores da indústria para isolar o
material interno do ambiente externo. Elas protegem o conteúdo interno e permitem
uma liberação controlada. Neste trabalho, apresenta-se um método de produção
de microcápsulas de goma gelana monodispersas a partir da formação de
modelos de emulsão dupla óleo-em-água-em-óleo por microfluídica. A extração
do óleo externo, após a gelificação ionotrópica, permite a dispersão das microcápsulas
em meios aquosos. Assim, o método proposto permite encapsular ativos hidrofóbicos
e dispersar as microcápsulas em uma fase aquosa, tendo diversas aplicações.
Foram definidas janelas de operação para produção de microcápsulas de
gelana monodispersas em função da vazão volumétrica de cada fluido que forma
as microcápsulas e das dimensões do dispositivo microfluídico. Produziu-se microcápsulas
com diâmetros variando de 95 a 260 um e um coeficiente de variação
máximo de 5 per cent. Os resultados mostram que é possível controlar o diâmetro das
cápsulas e a espessura da membrana através das vazões da fase externa e intermediária,
respectivamente. Além disso, estudamos o escoamento de cápsulas de
gelana com diferentes diâmetros e espessuras de membrana por um capilar com
constrição através de imagens microscópicas e medidas de diferença de pressão.
Mapeamos as condições nas quais a membrana é rompida devido à constrição e o
conteúdo interno é liberado durante o escoamento. A gastroresistência das cápsulas
de gelana é verificada através de testes in vitro que simulam as fases gástrica e
intestinal da digestão. Mostramos, através de imagens fluorescentes, que as cápsulas
são capazes de liberar o conteúdo interno apenas no intestino devido ao
seu pH. Finalmente, demonstramos ser possível, não só produzir microcápsulas
magnéticas, mas controlar a resposta magnética delas regulando a quantidade de
ferrofluido que é adicionada à fase interna ou à membrana polimérica. As microcápsulas
produzidas neste estudo têm grande potencial de aplicação em diversos
setores, como alimentício, biomédico, farmacêutico e de óleo e gás. / [en] Microcapsules are applied in several sectors of industry when a physical
barrier between the core material and the external environment is required. They
protect their cargo and ultimately release it in a controlled way. In the present
work, microcapsules with hydrogel-based shells are produced. Monodispersed
microcapsules are formed by ionotropic gelation of gellan gum from monodispersed
oil-in-water-in-oil (O/W/O) double emulsion templates obtained using glasscapillary
microfluidic devices. An oil extraction step was added after the shell
gelation process to enable the dispersion of the microcapsules in an aqueous medium.
We report the operability window for the production of monodispersed
microcapsules as a function of the flow rate of each fluid phase and the dimensions
of the device. Microcapsules with mean diameters ranging from 95 to 260
um and a maximum coefficient of variation of 5 per cent were formed. The results show
how to independently control the capsule diameter and shell thickness by varying
the outer and middle phase flow rates. After that, we experimentally investigate
the flow of monodispersed gellan gum microcapsules through a constricted capillary
tube by measuring the evolution of the pressure difference and flow visualization.
The maximum pressure difference and capsule deformation is obtained
for capsules with different diameter and shell thickness. We map the conditions
at which the capsule membrane ruptures during the flow, releasing its internal
phase. Then, the gastro-resistance of gellan microcapsules is verified through an
in vitro test that mimics the gastric and intestinal phases of digestion. Confocal
fluorescence microscopy is used to track microcapsules integrity and we show
that microcapsules cargo is released in the intestine mostly due to its pH. Finally,
we demonstrate that it is possible to produce magnetic microcapsules with well
controlled magnetic response by adding different amounts of ferrofluid to their
core or shell. The microcapsules produced have great potential for different applications
in food, biomedical, pharmaceutical and oil and gas industries.
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Термодинамика взаимодействия полисахаридов гуара, геллана и полиакриловой кислоты с водой и друг с другом : магистерская диссертация / Thermodynamics of Interaction of Polysaccharides Guar gum, Gellan Gum and Polyacrylic Acid with Water and Each OtherЕвстифеева, В. Н., Evstifeeva, V. N. January 2018 (has links)
The water sorption of the films of polyacrylic acid, guar gum, gellan gum and PAA-guar, PAA-gellan mixtures of different compositions, prepared at 25°C and 70°C, was studied. The chemical potentials of water Δμ1, polymer component Δμ2, the average Gibbs energy of interaction of polymers and mixtures with water Δgm, the average Gibbs mixing energy of PAA and guar, PAA and gellan Δgx have been determined. It is established that the increase in the preparation temperature significantly enhances the films’ sorption capacity in relation to water. It is determined that the Gibbs mixing energy of polyacrylic acid with guar and gellan are negative for all component ratios (Δgx <0). The second derivative of Gibbs energy for PAA-guar mixtures has different signs, and in a wide range of concentrations of the mixture it is negative. This indicates the absence of compatibility and the formation of two-phase colloidal systems in mixtures of guar with PAA. In contrast to this for PAA-guar mixtures the second derivative of Gibbs energy is positive for all component ratios. This indicates the polymer compatibilityю The increase in the preparation temperature of mixtures leads to an increase in the interaction of the components in the two-phase system, which may be related to the reduction in size of the associates of macromolecules of guar in aqueous solutions. / Изучена равновесная сорбция паров воды пленками полиакриловой кислоты ПАК, гуара геллана и смесями ПАК-гуар разного состава, приготовленными при 25 °C и 70 °C. Рассчитаны разности химических потенциалов воды Δμ1, полимерных компонентов Δμ2, средние удельные энергии Гиббса взаимодействия полимеров и смесей с водой Δgm и друг сдругом Δgx. Установлено, что повышение температуры приготовления пленок значительно увеличивает их сорбционную способность по отношению к воде. Обнаружено, что энергии Гиббса смешения гуара и геллана с полиакриловой кислотой отрицательны при всех соотношениях компонентов (Δgx < 0). Вторая производная энергии Гиббса по составу имеет разные знаки, и для системы гуар – ПАК в широкой области концентраций смеси она отрицательна. Это свидетельствует об отсутствии совместимости и образовании двухфазных коллоидных систем в смесях гуара с ПАК. В противоположность этому для системы ПАК-геллан величина положительна во всей области составов. Это свидетельствует о совместимости полимеров. При этом повышение температуры приготовления смесей приводит к усилению взаимодействия компонентов в двухфазной системе, что может быть связано с уменьшением размеров ассоциатов макромолекул гуара в водных растворах при повышении температуры.
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