Página 1 dos resultados de 2184 itens digitais encontrados em 0.007 segundos

Insulin encapsulation in reinforced alginate microspheres prepared by internal gelation

Silva, Catarina M.; Ribeiro, António J.; Ferreira, Domingos; Veiga, Francisco
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
37.24%
Insulin-loaded alginate microspheres prepared by emulsification/internal gelation were reinforced by blending with polyanionic additive polymers and/or chitosan-coating in order to increase the protection of insulin at simulated gastric pH and obtain a sustained release at simulated intestinal pH. Polyanionic additive polymers blended with alginate were cellulose acetate phtalate (CAP), Eudragit® L100 (EL100), sodium carboxymethylcellulose (CMC), polyphosphate (PP), dextran sulfate (DS) and cellulose sulfate (CS). Chitosan-coating was applied by using a one-stage procedure. The influence of additive polymers and chitosan-coating on the size distribution of microspheres, encapsulation efficiency and release profile of insulin in simulated gastrointestinal pH conditions was studied. The mean diameter of blended microspheres ranged from 65 to 106 [mu]m and encapsulation efficiency of insulin varied from 14 to 100%, reaching a maximum value when CS and DS were incorporated in the alginate matrix. Insulin release, at pH 1.2, was almost prevented by the incorporation of PP, DS and CS. When uncoated microspheres were transferred to pH 6.8, a fast dissolution occurred, independently of the additive polymer blended with alginate, and insulin was completely released. Increasing the additive polymer concentration in the alginate matrix and/or chitosan-coating the blended alginate microspheres did not promote a sustained release of insulin from microspheres at pH 6.8.; http://www.sciencedirect.com/science/article/B6T25-4K96S9W-1/1/bb451711b57f87e0d07aa047f0788cd5

Alginate microspheres prepared by internal gelation: Development and effect on insulin stability

Silva, Catarina M.; Ribeiro, António J.; Figueiredo, Isabel Vitória; Gonçalves, Alexandra Rocha; Veiga, Francisco
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
37.2%
Recombinant human insulin was encapsulated within alginate microspheres by the emulsification/internal gelation technique with the objective of preserving protein stability during encapsulation procedure. The influence of process and formulation parameters was evaluated on the morphology and encapsulation efficiency of insulin. The in vitro release of insulin from microspheres was studied under simulated gastrointestinal conditions and the in vivo activity of protein after processing was assessed by subcutaneous administration of extracted insulin from microspheres to streptozotocin-induced diabetic rats. Microspheres mean diameter, ranging from 21 to 287 [mu]m, decreased with the internal phase ratio, emulsifier concentration, mixer rotational speed and increased with alginate concentration. Insulin encapsulation efficiency, near 75%, was not affected by emulsifier concentration, mixer rotational speed and zinc/insulin hexamer molar ratio but decreased either by increasing internal phase ratio and calcium/alginate mass ratio or by decreasing acid/calcium molar ratio and alginate concentration. A high insulin release, above 75%, was obtained at pH 1.2 and under simulated intestinal pH a complete dissolution of microspheres occurred. Extracted insulin from microspheres decreased hyperglycemia of diabetic rats proving to be bioactive and showing that encapsulation in alginate microspheres using the emulsification/internal gelation is an appropriate method for protein encapsulation.; http://www.sciencedirect.com/science/article/B6T7W-4J4B994-3/1/737714c13ec0b481ae55c4c1c319f3e1

An effective device for generating alginate microcapsules

Bressel, Tatiana Azevedo Bastian; Paz, Ana Helena da Rosa; Baldo, Guilherme; Cirne Lima, Elizabeth Obino; Matte, Ursula da Silveira; Pereira, Maria Luiza Saraiva
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
ENG
Relevância na Pesquisa
37.15%
An alternative approach to somatic gene therapy is to deliver the therapeutic protein by implanting genetically modified cells that could overexpress the gene of interest. Microencapsulation devices were designed to protect cells from host rejection and prevent the foreign cells from spreading while allowing protein secretion. Alginate microcapsules form a semi-permeable structure that is suitable for in vivo injection. In this study, we report an effective laboratory protocol for producing calcium alginate microcapsules, following optimization of uniformly shaped and sized particles containing viable cells. Encapsulation of baby hamster kidney (BHK) cells in alginate microcapsules was performed using a simple device consisting of a cylinder of compressed air and a peristaltic pump. A cell suspension flow of 100 mL h-1 and an air jet flow of 10 L min-1 produced the best uniformity of microcapsule size and shape. Cells maintained viability in culture for 4 weeks without any signs of necrosis, and protein diffusion was observed during this period. Our results clearly demonstrated that microisolation of BHK cells in alginate using a simple assembly device could provide an environment that is capable of preserving live cells. In addition...

Polymeric alginate nanoparticles containing the local anesthetic bupivacaine

Grillo, Renato; de Melo, Nathalie F. S.; de Araujo, Daniele Ribeiro; de Paula, Eneida; Rosa, Andre Henrique; Fraceto, Leonardo Fernandes
Fonte: Informa Healthcare Publicador: Informa Healthcare
Tipo: Artigo de Revista Científica Formato: 688-699
ENG
Relevância na Pesquisa
37.3%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); Processo FAPESP: 06/00121-9; Bupivacaine (BVC; S75-R25, NovaBupi

Determination of calcium by atomic absorption spectrophotometry applied to the preparation of alginate:chitosan complexes

Lucinda-Silva, R. M.; Carvalho, L. Q.; Lepera, J. S.; Evangelista, R. C.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 11-16
ENG
Relevância na Pesquisa
37.2%
Polysaccharicles, as alginate and chitosan, have been used to obtain modified release dosage forms. Alginate, due to its property of building gels during the complex formation with calcium ions, allows the building of capsules containing a core constituted by calcium alginate. This work had for objective to determine the appropriate calcium concentration for the preparation of alginate-chitosan capsules, by means of calcium quantification using atomic absorption spectrophotometry. The methodology of calcium quantification was validated through analysis of the limit of detection, precision, accuracy and recovery of the method. The capsules, containing or not the drug, were prepared by the complex coacervation/ionotropic gelification method. Calcium was quantified after samples mineralization and dilution in lantanium solution. The results showed that the amount of calcium incorporated into the capsules depends on the amount of calcium added to the medium, and this ratio increases until the concentration of 1.5% of initial calcium chloride and above this concentration there is a decrease in the proportion of calcium bonded. It was observed that the proportion of calcium that links to the polymer is inversely proportional to the amount of calcium added. The calcium amount incorporated depends on the concentration of the polymeric dispersions used as well as on the ratio between the two polymers.

Chitosan and alginate biopolymer membranes for remediation of contaminated water with herbicides

Moraes, Mariana Agostini de; Cocenza, Daniela Sgarbi; Vasconcellos, Fernando da Cruz; Fraceto, Leonardo Fernandes; Beppu, Marisa Masumi
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 222-227
ENG
Relevância na Pesquisa
37.36%
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); This study investigated the adsorption behavior of the herbicides diquat, difenzoquat and clomazone on biopolymer membranes prepared with alginate and chitosan (pristine and multi-layer model) for contaminated water remediation applications. Herbicides, at concentrations ranging from 5 mu M to 200 mu M, were adsorbed in either pure alginate, pure chitosan or a bilayer membrane composed of chitosan/alginate. No adsorption of clomazone was observed on any of the membranes, probably due to lack of electrostatic interactions between the herbicide and the membranes. Diquat and difenzoquat were only adsorbed on the alginate and chitosan/alginate membranes, indicating that this adsorption takes place in the alginate layer. At a concentration of 50 mu M, diquat adsorption reaches ca. 95% after 120 min on both the alginate and chitosan/alginate membranes. The adsorption of difenzoquat, at the same concentration, reaches ca. 62% after 120 min on pure alginate membranes and ca. 12% on chitosan/ alginate bilayer membranes. The adsorption isotherms for diquat and difenzoquat were further evaluated using the isotherm models proposed by Langmuir and by Freundlich...

Preparação e caracterização de membranas de quitosana e alginato para aplicação na terapia de lesões; Preparation and characterization of chitosan and alginate membranes designed for the therapy of lesions

Ana Paula Rodrigues
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 02/07/2008 PT
Relevância na Pesquisa
37.28%
As membranas poliméricas destinadas ao tratamento de lesões cutâneas ou internas podem ser constituídas por vários tipos de polímeros, sendo a quitosana e o alginato compostos freqüentemente empregados para tal finalidade. Enquanto a quitosana é um aminopolissacarídeo derivado da quitina, o alginato é um polissacarídeo extraído de algas. Ambos são atóxicos, biocompatíveis e facilitam a cicatrização de feridas. Frente a isto, a obtenção de membranas de quitosana-alginato para serem utilizadas na terapia de lesões, como curativos, mostra-se de grande relevância. Neste contexto, este trabalho visou o desenvolvimento de metodologia escalonável de preparação e a caracterização de membranas de quitosana e alginato (contendo ou não bacitracina), empregando distintas condições controladas de vazão e agitação durante a mistura dos polissacarídeos. Em adição, o efeito da utilização do plastificante glicerol na preparação das membranas de quitosana-alginato, bem como a comparação das propriedades das mesmas às daquelas constituídas somente por quitosana, foi realizado. As membranas foram caracterizadas quanto à espessura, à capacidade máxima de absorção de diferentes soluções aquosas, à capacidade de drenagem de água...

Elaboração e caracterização de filmes a base de alginato de sódio, reticulados com íons bário (Ba²+), estrôncio (Sr²+) ou alumínio (Al³+); Elaboration and characterization of films based on sodium alginate crosslinked with barium ion (Ba2+), strontium ion (Sr2+) or aluminum ion (Al3+)

Lady Maria Salas Valero
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 04/04/2011 PT
Relevância na Pesquisa
37.15%
Alginatos são polissacarídeos extraídos de algas pardas que apresentam uma grande gama de aplicações tecnológicas devido a sua conhecida habilidade em formar géis fortes, biodegradáveis e insolúveis em água ao ser reticulado com Ca2+. Biofilmes baseados nesse mecanismo podem ser confeccionados, formando estruturas transparentes e de alta resistência mecânica, mas que exigem considerável quantidade de plastificante para adequar sua flexibilidade. O objetivo deste trabalho foi desenvolver e caracterizar filmes de alginato reticulados com cátions Ba2+, Sr2+ ou Al3+ e seus atributos funcionais foram comparados aos de filmes de alginato de cálcio. Filmes de diferentes espessuras foram elaborados por casting em processo em duas etapas: um protótipo de filme foi inicialmente formado, vertendo alíquotas de uma solução aquosa contendo alginato de sódio, glicerol como agente plastificante e uma pequena quantidade de íons cálcio para promover uma pré-reticulação, em placas quadradas de acrílico e submetidas a secagem a 40°C. A reticulação destes pré-filmes foi complementada por imersão em soluções de cloreto de bário, de estrôncio ou de alumínio. Filmes com diferentes graus de reticulação, e diferentes concentrações de glicerol foram caracterizados em relação a suas propriedades...

Production of a carotenoid-rich product by alginate entrapment and fluid-bed drying of Dunaliella salina

Leach, Gareth; Oliveira, Gisela; Morais, Rui
Fonte: Wiley Publicador: Wiley
Tipo: Artigo de Revista Científica
Publicado em //1998 ENG
Relevância na Pesquisa
37.24%
A new carotenoid-rich product was formed by entrapment of Dunaliella salina in calcium alginate beads of di†erent alginate concentrations, followed by drying in a Ñuid-bed dryer. The drying process yielded b-carotene recoveries of between 79 and 89% and produced a change in the 9-cis/all-trans ratio of b-carotene isomers. The carotenoid stability of the product was dependant on both the storage conditions and alginate content (range 3É3È7É3 g litre~1) of the beads. In the presence of light and oxygen total carotenoid degraded following a Ðrst order kinetic model with degradation constants between 0É016 and 0É039 days~1, with the lowest degradation occurring with the lowest alginate concentration. Product stored in the dark and Ñushed with nitrogen produced Ðrst-order degradation constants of 0É012 and 0É020 days~1 for the two higher alginate concentrations ; that with the lowest alginate content showed no noticeable degradation after 58 days storage. During storage, the 9-cis isomer was signiÐcantly more unstable showing a relative loss under all conditions, degrading almost completely when stored in the presence of light and oxygen and reaching an equilibrium ratio with the all-trans isomer when stored in the dark and Ñushed with nitrogen.

Application of Response Surface Methodology to study the effect of different calcium sources in fish muscle-alginate restructured products

Moreno,Helena María; Carballo,José; Borderías,Javier
Fonte: Sociedade Brasileira de Ciência e Tecnologia de Alimentos Publicador: Sociedade Brasileira de Ciência e Tecnologia de Alimentos
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/03/2011 EN
Relevância na Pesquisa
37.28%
Sodium alginate needs the presence of calcium ions to gelify. For this reason, the contribution of the calcium source in a fish muscle mince added by sodium alginate, makes gelification possible, resulting a restructured fish product. The three different calcium sources considered were: Calcium Chloride (CC); Calcium Caseinate (CCa); and Calcium lactate (CLa). Several physical properties were analyzed, including mechanical properties, colour and cooking loss. Response Surface Methodology (RSM) was used to determine the contribution of different calcium sources to a restructured fish muscle. The calcium source that modifies the system the most is CC. A combination of CC and sodium alginate weakened mechanical properties as reflected in the negative linear contribution of sodium alginate. Moreover, CC by itself increased lightness and cooking loss. The mechanical properties of restructured fish muscle elaborated were enhanced by using CCa and sodium alginate, as reflected in the negative linear contribution of sodium alginate. Also, CCa increased cooking loss. The role of CLa combined with sodium alginate was not so pronounced in the system discussed here.

Development and evaluation of calcium alginate beads prepared by sequential and simultaneous methods

Mandal,Sanchita; Kumar,S. Senthil; Krishnamoorthy,Balakrishnam; Basu,Sanat Kumar
Fonte: Universidade de São Paulo, Faculdade de Ciências Farmacêuticas Publicador: Universidade de São Paulo, Faculdade de Ciências Farmacêuticas
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2010 EN
Relevância na Pesquisa
37.2%
The objective of this study was to develop a sustained release dosage form of Trimetazidine dihydrochloride (TMZ) using a natural polymeric carrier prepared in a completely aqueous environment. TMZ was entrapped in calcium alginate beads prepared with sodium alginate by the ionotropic gelation method using calcium chloride as a crosslinking agent. The drug was incorporated either into preformed calcium alginate gel beads (sequential method) or incorporated simultaneously during the gelation stage (simultaneous method). The beads were evaluated for particle size and surface morphology using optical microscopy and SEM, respectively. Beads produced by the sequential method had higher drug entrapment. Drug entrapment in the sequential method was higher with increased CaCl2 and polymer concentration but lower with increased drug concentration. In the simultaneous method, drug entrapment was higher when polymer and drug concentration were increased and also rose to a certain extent with increase in CaCl2 concentration, where further increase resulted in lower drug loading. FTIR studies revealed that there is no interaction between drug and CaCl2. XRD studies showed that the crystalline drug changed to an amorphous state after formulation. Release characteristics of the TMZ loaded calcium alginate beads were studied in enzyme-free simulated gastric and intestinal fluid.

Versatile click alginate hydrogels crosslinked via tetrazine–norbornene chemistry

Desai, Rajiv; Koshy, Sandeep Tharian; Hilderbrand, Scott A.; Mooney, David J.; Joshi, Neel S.
Fonte: Elsevier BV Publicador: Elsevier BV
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
37.33%
Alginate hydrogels are well-characterized, biologically inert materials that are used in many biomedical applications for the delivery of drugs, proteins, and cells. Unfortunately, canonical covalently crosslinked alginate hydrogels are formed using chemical strategies that can be biologically harmful due to their lack of chemoselectivity. In this work we introduce tetrazine and norbornene groups to alginate polymer chains and subsequently form covalently crosslinked click alginate hydrogels capable of encapsulating cells without damaging them. The rapid, bioorthogonal, and specific click reaction is irreversible and allows for easy incorporation of cells with high post-encapsulation viability. The swelling and mechanical properties of the click alginate hydrogel can be tuned via the total polymer concentration and the stoichiometric ratio of the complementary click functional groups. The click alginate hydrogel can be modified after gelation to display cell adhesion peptides for 2D cell culture using thiol-ene chemistry. Furthermore, click alginate hydrogels are minimally inflammatory, maintain structural integrity over several months, and reject cell infiltration when injected subcutaneously in mice. Click alginate hydrogels combine the numerous benefits of alginate hydrogels with powerful bioorthogonal click chemistry for use in tissue engineering applications involving the stable encapsulation or delivery of cells or bioactive molecules.; Engineering and Applied Sciences

A prospective comparison of alginate-hydrogel with standard medical therapy to determine impact on functional capacity and clinical outcomes in patients with advanced heart failure (AUGMENT-HF trial)

Anker, Stefan D.; Coats, Andrew J.S.; Cristian, Gabriel; Dragomir, Dinu; Pusineri, Enrico; Piredda, Massimo; Bettari, Luca; Dowling, Robert; Volterrani, Maurizio; Kirwan, Bridget-Anne; Filippatos, Gerasimos; Mas, Jean-Louis; Danchin, Nicolas; Solomon, Sco
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica
EN_US
Relevância na Pesquisa
37.28%
Aims AUGMENT-HF was an international, multi-centre, prospective, randomized, controlled trial to evaluate the benefits and safety of a novel method of left ventricular (LV) modification with alginate-hydrogel. Methods: Alginate-hydrogel is an inert permanent implant that is directly injected into LV heart muscle and serves as a prosthetic scaffold to modify the shape and size of the dilated LV. Patients with advanced chronic heart failure (HF) were randomized (1 : 1) to alginate-hydrogel (n = 40) in combination with standard medical therapy or standard medical therapy alone (Control, n = 38). The primary endpoint of AUGMENT-HF was the change in peak VO2 from baseline to 6 months. Secondary endpoints included changes in 6-min walk test (6MWT) distance and New York Heart Association (NYHA) functional class, as well as assessments of procedural safety. Results: Enrolled patients were 63 ± 10 years old, 74% in NYHA functional class III, had a LV ejection fraction of 26 ± 5% and a mean peak VO2 of 12.2 ± 1.8 mL/kg/min. Thirty-five patients were successfully treated with alginate-hydrogel injections through a limited left thoracotomy approach without device-related complications; the 30-day surgical mortality was 8.6% (3 deaths). Alginate-hydrogel treatment was associated with improved peak VO2 at 6 months—treatment effect vs. Control: +1.24 mL/kg/min (95% confidence interval 0.26–2.23...

Einfluss subinhibitorischer Ciprofloxacinkonzentrationen auf die Virulenzfaktoren Alginat und Elastase von Pseudomonas aeruginosa; Influence of subinhibitory concentrations of Ciprofloxacin on the virulence factors alginate and elastase of Pseudomonas aeruginosa

Allgaier, Stefan Oliver
Fonte: Universidade de Tubinga Publicador: Universidade de Tubinga
Tipo: Dissertação
DE_DE
Relevância na Pesquisa
37.34%
Pseudomonas aeruginosa besitzt ein Quorum Sensing System, welches neben dem bakteriellen Wachstum auch die Produktion von Virulenzfaktoren wie Alginat undd Elastase reguliert. Das Pseudmonas Quinolone Signal (PQS) induziert ebenfalls die Expression von Elastase. Da PQS der Antibìotikaklasse der Chinolone chemisch nahe vewandt ist, können diese Antibiotika in subinhìbitorischen Konzentrationen wie sie bei der Therapie von chronischen Infektionen zu finden sind, möglicherweise analog dem PQS die Expression von Virulenzfaktoren modifzieren. In der vorliegenden Arbeit wurde deshalb untersucht, ob die Expression von Alginat und Elastase von P. aeruginosa gegenläufig oder gleichsinnig reguliert, ob subinhibitorische Konzentrationen des Chinolons Ciprofloxacin deren Expression induzieren und ob das Autoinducersystem dabei eine Rolle spielt. Labor- wnd Patientenisolate von P. aeruginosa wurden mit und ohne Ciprofloxacin in subinhibitorischer Konzentration inkubiert. Zusätzlich wurden Mutanten mit defektem Autoinducersystem eingesetzt. Die Bestimmung der Alginatkonzentration erfolgte biochemisch mit Hìlfe des Carbazol-Assays sowie immunologisch mit einem Alginat-Antikörper. Die Elastasekonzentrationen wurden radioimmunologisch ermittelt. Die Alginatproduktion aller untersuchten Stämme wurde unter subinhibitorischem Ciprofloxacin induziert. Der Defekt im Autoinducersystem änderte sich lediglich in einer leicht reduzierten Alginatsynthese. Der Einfluss von subinhibitorischem Ciprofloxacin auf die Elastasekonzentrationen war uneinheitlich: bei vier Stämmen wurde die Elastase hoch-...

MICRO/NANOENCAPSULATION OF PROTEINS WITHIN ALGINATE/CHITOSAN MATRIX BY SPRAY DRYING

Erdinc, Burak I.
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 4860440 bytes; application/pdf
EN; EN
Relevância na Pesquisa
37.2%
Currently, therapeutic proteins and peptides are delivered subcutaneously, as they are readily denatured in the acidic, protease rich environment of the stomach or gastrointestinal track and low bioavailability results from poor intestinal absorption through the paracellular route. Encapsulation of therapeutic peptides and proteins into polymeric micro- and nano- particle systems has been proposed as a possible strategy to overcome limitations to oral protein administration. Furthermore, it was shown that nanoparticles having diameters less than 5µm are able to be taken up by the M cells of Peyer’s patches found in intestinal mucosa . However, the current methodologies to produce particles within desired range involves organic solvents and several steps. In this study, spray drying was investigated as a microencapsulation alternative, as it offers the potential for single step operation, producing dry particles, with the potential for extending the microparticle size into the nano-range. The particles were produced by spray drying of alginate/protein solutions. The effect of spray drying operational parameters on particle properties such as recovery, residual activity and particle size was studied. Particle recovery depended on the inlet temperature of the drying air...

Alginate Microparticles Produced by Spray Drying for Oral Insulin Delivery

Bowey, KRISTEN
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 3836832 bytes; application/pdf
EN; EN
Relevância na Pesquisa
37.24%
The aim of this study was to prepare biologically active insulin-loaded alginate microparticles by spray drying. Particles were produced from three alginate feed concentrations of 1, 1.5 and 2% w/v, with respective insulin loadings of 11.8, 7.8 and 5.8 mg/g of alginate and investigated in terms of mass yield, moisture content, particle size, morphology and encapsulation efficiency. The mass yield of the system was determined to be between 15 and 30%, with approximately 3% of the initial dry mass ending up in the exhaust filter. The moisture content of the particles was found to be between 4.9 and 11.1% and the mean size ranged between 1.2 and 1.6 μm. Particulate morphologies were observed to be mostly spherical with some ‘divots’ present on the surface. Lastly, the encapsulation efficiency determined by absorbance assay was approximately 40%. Particles produced from a 2% alginate feed were further assayed by determining the release of insulin in simulated gastrointestinal conditions and looking at the insulin and alginate distribution within spray dried particles. A steep release profile was observed in the first 120 min of the simulation in a gastric pH of 1.2 and a longer, more sustained release is observed in intestinal conditions...

An alginate lyase functional coating catalysis-independent to prevent P. aeruginosa adhesion

Alves, D.; Sileika, T.; Messersmith, P.; Pereira, Maria Olívia
Fonte: Universidade do Minho Publicador: Universidade do Minho
Tipo: Conferência ou Objeto de Conferência
Publicado em /10/2014 ENG
Relevância na Pesquisa
37.4%
Bacterial colonisation of indwelling devices remains a serious threat in clinical field as it is commonly associated to persistent infections, called biomaterial-associated infections (BAI). Pseudomonas aeruginosa is the most common gram-negative bacillus associated with BAI and its emergence as a nosocomial pathogen is a growing concern. This opportunistic pathogen can produce a capsule-like polysaccharide called alginate that contributes to mucoid biofilm structure and persistent nature of infections. Given alginate's contribution to bacterial virulence, it has long been considered as a promising target for interventional therapies. Alginate lyase, an enzyme able to degrade alginate, has been shown to detach mucoid biofilms from abiotic surfaces and increase their antibiotic susceptibility. In this work, a new approach for alginate lyase was explored. Instead of using this enzyme for the treatment of pre-established mucoid biofilms, the ability of alginate lyase to prevent P. aeruginosa adhesion to a surface was investigated. For that purpose, a polydopamine (pDA) dip-coating strategy was applied for functionalization of biomaterials with alginate lyase. Polycarbonate (PC) substrates were immersed in an alkaline solution of dopamine to form a thin layer of pDA and then transferred into a solution of alginate lyase. Surface characterization was performed with XPS...

Modification of Alginate and Development of Polymeric Nanocarriers by Living Radical Polymerization for Controlled/Targeted Drug Delivery

Kapishon, Vitaliy
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
37.3%
Alginate-based amphiphilic graft copolymers were synthesized by single electron transfer living radical polymerization (SET-LRP), forming stable micelles during polymerization induced self-assembly (PISA). First, alginate macroinitiator was prepared by partial depolymerization of native alginate, solubility modification and attachment of initiator. Then, methyl methacrylate was polymerized from the alginate macroinitiator in mixtures of water and methanol forming poly(methyl methacrylate) grafts, prior to self-assembly. PISA of the amphiphilic graft-copolymer resulted in the formation of micelles with diameters of 50-300 nm. As the first reported case of LRP from alginate, this work introduces a synthetic route to of alginate-based hybrid polymers with a precise macromolecular architecture and desired functionalities. LRP from alginate can be applied to improve alginate-based hydrogel systems such as nano- and micro-hydrogel particles, islet encapsulation materials, hydrogel implants and topical applications. Such modified alginates can also improve the function and application of native alginates in food and agricultural technologies. Targeted drug delivery using polymeric nanostructures has been at the forefront of cancer research engineered for safer...

Novel non-cytotoxic alginate–lignin hybrid aerogels as scaffolds for tissue engineering

Quraishi, Sakeena; Martins, Marta; Barros, Alexandre A.; Gurikov, Pavel; Raman, S. P.; Smirnova, Irina; Duarte, Ana Rita C.; Reis, R. L.
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em /10/2015 ENG
Relevância na Pesquisa
37.2%
uncorrected proof; This paper presents a novel approach towards the production of hybrid alginate-lignin aerogels. The key idea of the approach is to employ pressurized carbon dioxide for gelation. Exposure of alginate and lignin solution containing calcium carbonate to CO2 at 4.5 MPa resulted in a hydrogel formation. Various lignin and CaCO3 concentrations were studied. Stable hydrogels can be formed up to 2:1 (w/w) alginate-to-lignin ratio. Upon substitution of water with ethanol, gels were dried in supercritical CO2 to produce aerogels. Aerogels were characterized in terms of bulk density, specific surface area and pore volume. To introduce macroporosity, the CO2 induced gelation was supplemented with rapid depressurization (foaming process). Porosity, mean pore size and interconnectivity in the macroporous range were assessed by micro-CT. Youngâ s modulus of alginate-lignin aerogels was measured in both dry and wet state. Cell studies revealed that alginate-lignin aerogels are non-cytotoxic and demonstrate good cell adhesion properties making them attractive candidates for a wide range of applications including tissue engineering and regenerative medicine.; Fundação da Ciência e Tecnologia (FCT) through the project ENIGMA – PTDC/EQU-EPR/121491/2010...

Development and evaluation of calcium alginate beads prepared by sequential and simultaneous methods

Mandal, Sanchita; Kumar, S. Senthil; Krishnamoorthy, Balakrishnam; Basu, Sanat Kumar
Fonte: Universidade de São Paulo. Faculdade de Ciências Farmacêuticas Publicador: Universidade de São Paulo. Faculdade de Ciências Farmacêuticas
Tipo: info:eu-repo/semantics/article; info:eu-repo/semantics/publishedVersion; ; ; ; ; ; Formato: application/pdf
Publicado em 01/12/2010 ENG
Relevância na Pesquisa
37.2%
O objetivo deste estudo foi desenvolver forma de liberação controlada de dicloridrato de trimetazidina (TMZ) utilizando transportador plomérico natural em ambiente completamente aquoso. A TMZ foi presa em pérolas de alginato de cálcio preparadas com alginato de sódio pelo método de gelatinização ionotrópica, usando cloreto de cálcio como agente de formação de ligações cruzadas. O fármaco foi incorporado nas pérolas de gel de alginato de cálcio (método sequencial) ou incorporado, simultaneamente, durante o estágio de gelificação (método simultâneo). As pérolas foram avaliadas quanto ao tamanho das partículas e morfologia da superfície utilizando microscopia óptica de SEM, respectivamente. As pérolas produzidas pelo método sequencial apresentaram maior capacidade de inclusão. No método sequencial, a inclusão de fármaco foi maior com o aumento de CaCl2 e da concentração do plímero, mas menor com o aumento da concentração de fármaco. No método simultâneo, a inclusão de fármaco foi mais alta quando as concentrações de fármaco e plímero foram aumentadas e, também, atingiram certa extensão com aumento na concentração de CaCl2, cujo aumento posterior resultou em carga menor de fármaco. Estudos de FTIR revelaram que não há interação entre fármaco e CaCl2. Estudos de XRD mostraram que o fármaco mudou do estado cristalino para o amorfo após a formulação. As características de liberação de TMZ das pérolas carregadas com alginato de cálcio foram estudadas em fluidos simulados...