Preparation and characterization of alginate microspheres containing a model antigen

Lemoine, D.; Wauters, F; Bouchend'homme, S; Préat, Véronique

doi:10.1016/s0378-5173(98)00303-2

Cited by 155 publications

(101 citation statements)

References 33 publications

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“…Estes resultados são condizentes com o trabalho de outros autores. 17,23,34 Como a liberação do agente encapsulado pode ocorrer por mecanismos difusivo e pela degradação da rede polimérica da matriz de alginato e uma vez que a quantidade de agente antigênico liberado após a incubação foi muito pequena, pode-se supor que a liberação do agente ocorreu preferencialmente pelo mecanismo difusivo, já que as partículas mantiveram-se praticamente íntegras quando submetidas às condições gastrointestinais simuladas. Observou-se que as amostras não apresentaram mudança morfológica significativa ao longo da exposição às diferentes condições de pH.…”

Section: Estabilidade E Liberação In Vitrounclassified

“…16 Dentre as variáveis que afetam a formação de micropartículas produzidas por emulsão podem ser incluídas a concentração de alginato, a concentração do agente antigênico, a composição do agente gelificante, 12,[17][18][19][20][21] o tipo de equipamento usado na formação da emulsão, a taxa de agitação empregada, 19 a temperatura, o tipo e a concentração de emulsificante 22 e a proporção entre as fases aquosa e não-aquosa. O tamanho das micropartículas está diretamente associado com a concentração e a viscosidade da solução de alginato empregada, observando-se que baixas concentrações favorecem a redução do tamanho das partículas.…”

Section: Introductionunclassified

“…12,18,23 Entretanto, concentrações reduzidas diminuem também a resistência mecânica e a estabilidade das micropartículas em condições gastrointestinais. 17 O aumento na proporção de 10 para 50% da fase aquosa aumenta o diâmetro das micropartículas, sendo que partículas menores são obtidas quando esta proporção é fixada em 10%. 23 O uso de emulsificantes como o Span 80 também reduz o tamanho das micropartículas, pela diminuição da tensão superficial das gotas, prevenindo sua coalescência.…”

Section: Introductionunclassified

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Produção de micropartículas de alginato contendo Flavobacterium columnare inativada pelo método de emulsão para vacinação de peixes por via oral

Sacchetin¹,

Moraes²,

Leal³

et al. 2010

Quím. Nova

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Recebido em 6/1/09; aceito em 7/8/09; publicado na web em 21/1/10 PRODUCTION BY EMULSION METHOD OF ALGINATE MICROPARTICLES CONTAINING INACTIVATED Flavobacterium columnare FOR ORAL FISH VACCINATION. Alginate microparticles were prepared by an emulsion method aiming oral controlled release of antigens to fish. The effects of emulsification temperature and impeller type on particle morphology, average diameter, and size distribution were evaluated. Microparticles contaning formalin-killed Flavobacterium columnare cells (a model antigen) were prepared and characterized regarding bacterial release and particle stability when exposed to Nile tilapia (Oreochromis niloticus) typical gastrointestinal conditions. This methodology allowed the production of microparticles containing up to 14.3 g/L of bacterin, stable at a pH range from 2.0 to 9.0 for 12 h and smaller than 35 mm.Keywords: alginate microparticles; emulsion; fish vaccine. INTRODUÇÃODentre as atividades que têm demonstrado grande potencial quanto ao acesso e fornecimento de alimentos ricos em proteínas, destaca-se a piscicultura. Nesses sistemas, as altas densidades de estocagem, o manejo intenso dos animais e a baixa qualidade da água contribuem para a ocorrência de doenças infecciosas, um dos principais entraves para o sucesso desta atividade no país. Com a intensificação e ampliação da piscicultura, a ocorrência destas doenças tende a aumentar significativamente.Dentre as enfermidades diagnosticadas em peixes, as de etiologia bacteriana estão entre as mais impactantes, devido às altas taxas mortalidade e ao custo elevado para sua prevenção e controle. Destaca-se, neste sentido, a espécie Flavobacterium columnare, que é considerada um patógeno de ocorrência mundial capaz de causar doenças em praticamente todos os tipos de peixes de água doce.1,2 Atualmente, o tratamento da doença é realizado através de banhos com substâncias desinfetantes e antibioticoterapia oral.3 No entanto, o uso de antibióticos em sistemas de cultivo de peixes é bastante problemático, uma vez que o uso repetitivo destes pode levar ao desenvolvimento de microorganismos resistentes no ambiente e na microbiota dos animais. 4 Uma alternativa mais conveniente é a imunoprofilaxia, que consiste no estímulo da imunidade específica e não específica do peixe pelo contato com patógenos atenuados e/ou inativados. Sua administração na forma de vacinas leva a uma diminuição da dependência do uso de antibióticos.5 Dentre os métodos de imunização que se têm mostrado atraentes, destacam-se as formulações injetáveis e as administradas por imersão e via oral. A vacinação oral, na qual se mistura o agente vacinal à ração, é uma técnica pouco invasiva, de fácil administração, de custo moderado frente aos demais métodos e que provoca estresse mínimo nos peixes sendo, por estas razões, bastante vantajosa.Assim, pesquisas focadas na proteção dos antígenos contra os processos digestivos e de sua possível decomposição durante a passagem pelo trato gastrointestinal têm sido realizadas, 5 sendo uma estratégia comum...

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Section: Estabilidade E Liberação In Vitrounclassified

Section: Introductionunclassified

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Produção de micropartículas de alginato contendo Flavobacterium columnare inativada pelo método de emulsão para vacinação de peixes por via oral

Sacchetin¹,

Moraes²,

Leal³

et al. 2010

Quím. Nova

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“…The characteristics of the alginate particle are a result of its size, antigenic composition, the strategy in its production, the choice of alginate and the antigen concentration. For example, the production of microparticles from alginate is generally done by emulsifi cation/gelation, where the alginate emulsion in the presence of the molecule to be encapsulated reacts with calcium ions that promote the piling of G. In this technique, the specifications of the protocol, that is, the viscosity, molecular weight and the concentration of the alginate, stirring times, temperature, gelation agent, the arrangement of its monomers (MM, GG and MG form), type of surfactant, among others, markedly influence the physical-chemical characteristics obtained (Lemoine et al, 1998;Rodrigues et al, 2006). Similarly, molecules are mainly released by diff usion or erosion of the microparticle, which depends on the molecular size of the active agent and the concentration of the alginate, as well as the external environment (Tanaka et al, 1984).…”

Section: Alginatementioning

confidence: 99%

Nanoparticles and microparticles of polymers and polysaccharides to administer fish vaccines

2013

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Aquaculture has become an important economic sector worldwide, but is faced with an ongoing threat from infectious diseases. Vaccination plays a critical role in protecting commercially raised fi sh from bacterial, viral and parasitic diseases. However, the production of eff ective vaccines is limited by the scarcity of knowledge about the immune system of fi sh. Improving vaccines implies using antigens, adjuvants and employing methods of administration that are more eff ective and less harmful to the fi sh. In this context, in recent year there have studies of methods of encapsulating antigens in matrices of diff erent types to apply in fi sh vaccines. This work reviews the new methods to improve fi sh vaccines by encapsulating them in polymers and polysaccharides.

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“…The later relatively slow release rate could be attributed to release and diffusion of the drug from the interior of MS. The drug release was characterized by biphasic pattern matrix diffusion kinetics [45]. Primarily, diffusion of the aqueous dissolution medium into pores of MS results in dissolution of the drug.…”

Section: In Vitro Release Studymentioning

confidence: 99%

Preparation and Evaluation of 5-Fluorouracil Loaded Microsponges for Treatment of Colon Cancer

Othman¹,

Zayed²,

El‐Sokkary³

et al. 2017

J Cancer Sci Ther

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5-Fluorouracil (5-FU) has a wide anticancer activity versus several types of solid tumors. The activity of 5-FU can be improved and its toxicity can be diminished by enhancing the relative specific accumulation in the tumor regions. The aim of this work was to develop Eudragit RS100 based 5-FU microsponges (MS) for treatment of colon cancer. Oil in oil emulsion solvent diffusion method was used for the preparation of 5-FU sustained release Eudragit RS100 MS. MS were characterized for their encapsulation efficiency, production yield, drug polymer interaction and drug release profiles. Shape, surface morphology visualized by scanning electron microscope (SEM) and particle size of MS was investigated using laser light scattering technique and. Eventually, HCT 116 and CACO2 cell lines were used for determination of cell viability by MTT assay. The results showed that all prepared MS were spherical in shape with several pores on their surfaces. The production yield was in (62.76% ±1.06% and 93.80% ± 1.75%), encapsulation efficiency was in (71.80% ± 1.62% and 101.3% ± 2.60%) and particle size was in ( 53.11 µm ± 41.03 nm and 118.12 µm ± 48.21 nm). Fourier transform infrared revealed that there is no chemical interaction between 5-FU and Eudragit RS100. MS loaded 5-FU was more effective than 5-FU itself as shown by cell viability assay. The results demonstrated that 5-FU with Eudragit RS100 was successfully formulated as sustained release manner and could be a substitution delivery method of 5-FU for oral anticancer treatment.represent an important factor to oral as compared to administration intravenously as reported previously [9].Conversely, intravenous administration of 5-FU yields severe systemic toxic effects of gastrointestinal (GIT), blood complaints, and skin diseases, due to the 5-FU cytotoxicity on healthful human cells. Hence, the need to formulate targeted delivery of 5-FU through oral route would not only diminish the exposure of healthy cells to the drug but also provide an efficient and harmless curative effect for colon cancer with a lower dose and reduced duration of therapy [5]. It was reported that the therapeutic effect of 5-FU can be augmented and its harmful effects can be suppressed by the precise accumulation of the anticancer agent in the tumor regions with continued exposure of the cells to this drug [10]. To extend the exposure time of cancer cells to 5-FU, the drug delivery was formulated by incorporation into microsponge formulation.Microsponges (MS) are micro-sized particles with high porosity and unique ability for encapsulation of a wide multiplicity of pharmaceutical active ingredients. MS delivery system is used to target and modify the release of active ingredients from pharmaceutical formulations, enhance the stability and decrease the side effects [11]. MS have high load activity reach up to 90% entrapment efficiency [12], self-sterilizing Citation: Othman MH, Zayed GM, El-Sokkary GH, Ali UF, Abdellatif AAH (2017) Preparation and Evaluation of 5-Fluorouracil Loaded Microsp...

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Preparation and characterization of alginate microspheres containing a model antigen

Cited by 155 publications

References 33 publications

Produção de micropartículas de alginato contendo Flavobacterium columnare inativada pelo método de emulsão para vacinação de peixes por via oral

Produção de micropartículas de alginato contendo Flavobacterium columnare inativada pelo método de emulsão para vacinação de peixes por via oral

Nanoparticles and microparticles of polymers and polysaccharides to administer fish vaccines

Preparation and Evaluation of 5-Fluorouracil Loaded Microsponges for Treatment of Colon Cancer

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