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1.
J Sci Food Agric ; 104(4): 2458-2466, 2024 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-37975168

RESUMO

BACKGROUND: Calcium alginate gels are widely used to encapsulate active compounds. Some characteristic parameters of these gels are necessary to describe the release of active compounds through mechanistic mathematical models. In this work, transport and kinetics properties of calcium alginate gels were determined through simple experimental techniques. RESULTS: The weight-average molecular weight ( M ¯ w = 192 × 103 Da) and the fraction of residues of α-l-guluronic acid ( F G = 0.356) of sodium alginate were determined by capillary viscometry and 1 H-nuclear magnetic resonance at 25 °C, respectively. Considering the half egg-box model, both values were used to estimate the molecular weight of calcium alginate as M g = 2.02 × 105 Da. An effective diffusion coefficient of water ( D eff , w = 2.256 × 10-9 m2 s-1 ) in calcium alginate was determined using a diffusion cell at 37 °C. Finally, a kinetics constant of depolymerization ( k m = 9.72 × 10-9 m3 mol-1 s-1 ) of calcium alginate was obtained considering dissolution of calcium to a medium under intestinal conditions. CONCLUSION: The experimental techniques used are simple and easily reproducible. The obtained values may be useful in the design, production, and optimization of the alginate-based delivery systems that require specific release kinetics of the encapsulated active compounds. © 2023 Society of Chemical Industry.


Assuntos
Alginatos , Imageamento por Ressonância Magnética , Alginatos/química , Géis/química , Espectroscopia de Ressonância Magnética , Modelos Teóricos , Cálcio/química , Ácidos Hexurônicos/química , Ácido Glucurônico/química
2.
Water Res ; 141: 163-171, 2018 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-29783169

RESUMO

The preliminary assessment of the properties of alginate immobilized aquatic weed Myriophyllum spicatum beads-MsAlg in a multi-element system of nine Serbian lakes water samples was done. Herein, the results obtained in the biosorption experiment with MsAlg contents of twenty-two elements analysed by inductively coupled plasma-optical emission spectrometry, biosorption capacity, element removal efficiency, total hardness (TH) and quality index of water (WQI) are presented. Scanning electron microscopy with energy dispersive X-ray spectroscopy was used for the characterization of M. spicatum and its beads. The study showed that aluminium, magnesium and strontium were adsorbed by MsAlg in the water samples from all examined lakes; barium and iron in the water samples from six lakes. The overall average efficiency of MsAlg in biosorption of elements was in the following order: Al > Ba > Sr > Fe > Mg (58.6, 51.7, 48.2, 23.9 and 17.7%, respectively). The increase of TH and WQI values after the biosorption was noticed in all studied lake water samples. The most significant correlations for pH were regarding the contents of B, Mg and Ca, whereas WQI was highly correlated to the contents of B and Mg, and pH. The complexity of the obtained data was explained by Cluster Analysis and Principal Component Analysis, which showed good discrimination capabilities between the water samples taken from different locations. Considering that the invasive M. spicatum is natural, widespread and that its immobilization is cheap and eco-friendly, presented findings could be helpful in further assessment of MsAlg beads for its potential use as biofilter.


Assuntos
Alginatos/química , Espécies Introduzidas , Metais/química , Traqueófitas/química , Poluentes Químicos da Água/química , Adsorção , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Lagos
3.
Int J Biol Macromol ; 115: 257-265, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29655888

RESUMO

This study explored the potential of composites organo-bentonite/alginate beads as adsorbents for the removal of 2,4-dichlorophenol (2,4DCP) from aqueous solution. Bentonite was firstly modified with cationic surfactants octadecyltrimethylammonium, hexadecyl trimethylammonium and phenyltrimethylammonium, then encapsulated with calcium alginate to form adsorbent composite beads. X-ray diffraction was used to study the change in the structural properties of the samples. The intercalated cationic surfactants were characterized by Fourier transform infrared spectroscopy (FTIR). The adsorption was studied using various operating parameters such as contact time, temperature, pH and initial 2,4DCP concentration. The results showed that the amount of 2,4DCP increased with increasing initial concentration, contact time and temperature indicating that the adsorption process of 2,4DCP onto composites is endothermic. Adsorption of 2,4DCP followed pseudo-second-order kinetics. The Langmuir isotherm model fitted well the isotherm data, indicating a monolayer homogeneous adsorption. The prepared adsorbents exhibited relatively high adsorption capacity of 142 to 391 mg/g founded by this model.


Assuntos
Alginatos/química , Bentonita/química , Clorofenóis/química , Clorofenóis/isolamento & purificação , Custos e Análise de Custo , Microesferas , Água/química , Adsorção , Cápsulas , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Cinética , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
4.
Ecotoxicol Environ Saf ; 147: 80-85, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28837873

RESUMO

Batch sorption and leaching of arsenic (1-30mgL-1) on Fe-sericite composite powder and beads were investigated in this study. Fe-sericite composite powder was made from natural sericite modified with iron, and alginate was used to transform the powder into beads. The maximum sorption capacities of the Fe-sericite composite powder (15.04 and 13.21mgg-1 for As(III) and As(V), respectively) were higher than those of the corresponding beads (9.02 and 7.11mgg-1 for As(III) and As(V), respectively) owing to the higher specific surface area of the powder. In addition, the leaching amounts of As(III) from Fe-sericite composite beads (≤ 15.03%) were higher than those of the corresponding powder (≤ 5.71%). However, acute toxicity of As(III)-sorbed Fe-sericite composite beads toward Daphnia magna was not significantly different from that of the corresponding powder (p > 0.05). Considering higher uptake of the powder particles by the daphnids, Fe-sericite composite beads seem to be a more appropriate and safer sorbent for arsenic removal in practical application. Based on Fe content, Fe-sericite composite beads had similar or higher maximum sorption capacities (71.19 and 56.11mgg-1 Fe for As(III) and As(V), respectively) than those of previously reported sorbents.


Assuntos
Arseniatos/análise , Arsenitos/análise , Ferro/química , Dióxido de Silício/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Alginatos/química , Animais , Arseniatos/toxicidade , Arsenitos/toxicidade , Daphnia/efeitos dos fármacos , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Modelos Teóricos , Tamanho da Partícula , Pós , Propriedades de Superfície , Testes de Toxicidade Aguda , Poluentes Químicos da Água/toxicidade
5.
Bioprocess Biosyst Eng ; 41(2): 185-194, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29052765

RESUMO

Equimolar amounts of lactobionic acid and sorbitol may be obtained in a reaction catalyzed by the enzymes glucose-fructose oxidoreductase and glucono-δ-lactonase, which are found in the periplasm of Zymomonas mobilis. These reactions are generally conducted using immobilized bacterial cells, and the cell treatment and immobilization steps are costly and time-consuming. This study evaluated alternatives to simplify the preparation of calcium alginate-immobilized biocatalyst and its application in different operation modes and types of reactors. It was possible to eliminate cell permeabilization with cetyltrimethylammonium bromide, and the reticulation of Z. mobilis cells with glutaraldehyde sufficed to inhibit the fermentative metabolism of carbohydrates by the bacterium, with accumulation of bioconversion products. When the process was carried out in a mechanically stirred reactor in batch mode, 530 mmol L- 1 of products were obtained in 24 h. The process was also tested in fed-batch mode so as to use of a larger amount of lactose, since it could not be used in the batch because of its low solubility in water. Under this condition, final products concentration reached 745 mmol L- 1 within 42 h. Similar results were obtained for reactions conducted in a pneumatically stirred reactor in batch and fed-batch modes, proving the potential use of this process in several industrial settings.


Assuntos
Alginatos/química , Células Imobilizadas/metabolismo , Sorbitol/metabolismo , Zymomonas/metabolismo , Ácido Glucurônico/química , Ácidos Hexurônicos/química
6.
Vaccine ; 35(48 Pt B): 6657-6663, 2017 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-29061347

RESUMO

An attenuated nanovaccine (Nps - V∗) has been developed to protect humans from fatal scorpion envenomation in at-risk regions. This study was conducted to evaluate the toxicity and the local reactogenicity of the Nps - V∗ nanovaccine developed against Androctonus australis hector (Aah) venom. Assessment of the systemic inflammatory response and serum cytokine levels were evaluated in vaccinated mice with 100µg of irradiated Aah venom (V∗) encapsulated or not into polymeric calcium-alginate nanoparticles (Nps) and injected by subcutaneous (s.c) route. The local reactogenicity was evaluated by dermal Draize observations and skin tissue analysis at the injection site of vaccinated rabbits with 250 or 500µg of V∗-loaded into Nps. All animals gained weight and had normal food consumption during the study. Additionally, results showed that the nanoformulation Nps - V∗ did not cause clinical evidence of systemic toxicity in mice or rabbits, a transient edema/erythema at the injection site was only recorded as treatment-related reactogenicity. These results indicated a favorable safety profile for Nps - V∗ and supported its use in superior animal tests, then in a Phase 1 clinical trial.


Assuntos
Alginatos/administração & dosagem , Nanopartículas/química , Venenos de Escorpião/administração & dosagem , Venenos de Escorpião/efeitos adversos , Venenos de Escorpião/efeitos da radiação , Alginatos/efeitos adversos , Alginatos/química , Animais , Citocinas/biossíntese , Citocinas/imunologia , Avaliação Pré-Clínica de Medicamentos , Edema , Eritema , Ácido Glucurônico/administração & dosagem , Ácido Glucurônico/efeitos adversos , Ácido Glucurônico/química , Ácidos Hexurônicos/administração & dosagem , Ácidos Hexurônicos/efeitos adversos , Ácidos Hexurônicos/química , Humanos , Camundongos , Nanopartículas/administração & dosagem , Nanopartículas/efeitos adversos , Nanopartículas/uso terapêutico , Nanotecnologia/métodos , Venenos de Escorpião/uso terapêutico , Vacinação/métodos
7.
Braz. j. microbiol ; 48(3): 515-521, July-Sept. 2017. graf
Artigo em Inglês | LILACS | ID: biblio-889145

RESUMO

Abstract Ammonia-oxidizing bacteria were immobilized by polyvinyl alcohol (PVA) and sodium alginate. The immobilization conditions and ammonia oxidation ability of the immobilized bacteria were investigated. The following immobilization conditions were observed to be optimal: PVA, 12%; sodium alginate, 1.1%; calcium chloride, 1.0%; inoculum concentration, 1.3 immobilized balls/mL of immobilized medium; pH, 10; and temperature, 30 °C. The immobilized ammonia-oxidizing bacteria exhibited strong ammonia oxidation ability even after being recycled four times. The ammonia nitrogen removal rate of the immobilized ammonia-oxidizing bacteria reached 90.30% under the optimal immobilization conditions. When compared with ammonia-oxidizing bacteria immobilized by sodium alginate alone, the bacteria immobilized by PVA and sodium alginate were superior with respect to pH resistance, the number of reuses, material cost, heat resistance, and ammonia oxidation ability.


Assuntos
Bactérias/química , Técnicas Microbiológicas/métodos , Amônia/metabolismo , Oxirredução , Álcool de Polivinil/química , Temperatura , Bactérias/metabolismo , Técnicas Microbiológicas/economia , Técnicas Microbiológicas/instrumentação , Células Imobilizadas/metabolismo , Células Imobilizadas/química , Ácido Glucurônico/química , Alginatos/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio
8.
Braz J Microbiol ; 48(3): 515-521, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28245966

RESUMO

Ammonia-oxidizing bacteria were immobilized by polyvinyl alcohol (PVA) and sodium alginate. The immobilization conditions and ammonia oxidation ability of the immobilized bacteria were investigated. The following immobilization conditions were observed to be optimal: PVA, 12%; sodium alginate, 1.1%; calcium chloride, 1.0%; inoculum concentration, 1.3 immobilized balls/mL of immobilized medium; pH, 10; and temperature, 30°C. The immobilized ammonia-oxidizing bacteria exhibited strong ammonia oxidation ability even after being recycled four times. The ammonia nitrogen removal rate of the immobilized ammonia-oxidizing bacteria reached 90.30% under the optimal immobilization conditions. When compared with ammonia-oxidizing bacteria immobilized by sodium alginate alone, the bacteria immobilized by PVA and sodium alginate were superior with respect to pH resistance, the number of reuses, material cost, heat resistance, and ammonia oxidation ability.


Assuntos
Amônia/metabolismo , Bactérias/química , Técnicas Microbiológicas/métodos , Alginatos/química , Bactérias/metabolismo , Células Imobilizadas/química , Células Imobilizadas/metabolismo , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Concentração de Íons de Hidrogênio , Técnicas Microbiológicas/economia , Técnicas Microbiológicas/instrumentação , Oxirredução , Álcool de Polivinil/química , Temperatura
9.
Int J Biol Macromol ; 97: 131-140, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28064048

RESUMO

Natural polymer-based hydrogel films have great potential for biomedical applications and are good candidates for wound dressings. In this study, we aimed to develop simvastatin-loaded crosslinked alginate-pectin hydrogel films by ionic crosslinking to improve the mechanical characteristics, wound fluid uptake and drug release behavior. Alginate-pectin hydrocolloid films were chemically crosslinked by immersing in different concentrations of CaCl2 (0.5-3% w/v) for 2-20min. The degree of crosslinking was influenced by both contact time and CaCl2 concentration. The optimized conditions for crosslinking were 0.5% and 1% (CaCl2) for 2min. The optimized hydrogel films were then characterized for their physical, mechanical, morphological, thermal, in vitro drug release, and cytocompatibility profiles. Crosslinking improved the mechanical profile and wound fluid uptake capacity of dressings. The hydrogel films were able to maintain their physical integrity during use, and the best results were obtained with the film in which the extent of crosslinking was low (0.5%). Thermal analysis confirmed that the crosslinking process enhanced the thermal stability of hydrogel films. Sustained, slow release of simvastatin was obtained from the crosslinked films and in vitro cytotoxicity assay demonstrated that the hydrogel films were non-toxic.


Assuntos
Alginatos/química , Bandagens , Portadores de Fármacos/química , Hidrogéis/química , Pectinas/química , Cicatrização , Cloreto de Cálcio/química , Portadores de Fármacos/farmacologia , Liberação Controlada de Fármacos , Fibroblastos/citologia , Fibroblastos/efeitos dos fármacos , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Humanos , Cinética , Teste de Materiais , Fenômenos Mecânicos , Sinvastatina/química , Sinvastatina/farmacologia , Pele/citologia , Vapor , Temperatura , Cicatrização/efeitos dos fármacos
10.
Carbohydr Polym ; 157: 981-990, 2017 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-27988017

RESUMO

In this study, pectin based films including different amounts of sodium alginate were prepared by casting method. All the films, with and without polyglycerol as plasticizer, were crosslinked with zinc ions in order to extend their potential functionality. The development of junction points, occurring during the crosslinking process with zinc ions, induced the increasing of free volume with following changing in chemico-physical properties of films. The inclusion of alginate in pectin based formulations improved the strength of zinc ions crosslinking network, whereas the addition of polyglycerol significantly improved mechanical performance. Finally, zinc-crosslinked films evidenced antimicrobial activity against the most common exploited pathogens: Staphylococcus Aureus, Escherichia Coli and Candida Albicans. These results suggest that zinc-crosslinked based films can be exploitable as novel bio-active biomaterials for protection and disinfection of medical devices.


Assuntos
Alginatos/química , Anti-Infecciosos/química , Pectinas/química , Candida albicans , Escherichia coli , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Staphylococcus aureus
11.
Methods Mol Biol ; 1506: 273-281, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-27830560

RESUMO

Alginate encapsulation of cells is an attractive technique in which alginate becomes polymerized entrapping the cells. The structure of formed microbeads/microcapsules is semipermeable as it allows oxygen and nutrients to go in, and waste products and other materials produced by the cells to go out. Here, we describe basic protocols for alginate encapsulation of human hepatocytes and methods for assessing the microbeads produced.


Assuntos
Alginatos/química , Transplante de Células/métodos , Composição de Medicamentos/métodos , Hepatócitos/transplante , Cápsulas/química , Técnicas de Cultura de Células , Separação Celular/métodos , Sobrevivência Celular , Transplante de Células/instrumentação , Colorimetria/métodos , Composição de Medicamentos/instrumentação , Ensaio de Imunoadsorção Enzimática/métodos , Ácido Glucurônico/química , Hepatócitos/fisiologia , Ácidos Hexurônicos/química , Humanos , Fígado/citologia , Fígado/cirurgia , Microscopia , Microesferas
12.
Drug Dev Ind Pharm ; 43(1): 120-131, 2017 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-27589817

RESUMO

INTRODUCTION: Periodontal disease broadly defines group of conditions in which the supportive structure of the tooth (periodontium) is destroyed. Recent studies suggested that the anti-diabetic drug metformin hydrochloride (MF) has an osteogenic effect and is beneficial for the management of periodontitis. OBJECTIVE: Development of strong mucoadhesive multiple layer film loading small dose of MF for intra-pocket application. METHODOLOGY: Multiple layer film was developed by double casting followed by compression method. Either 6% carboxy methyl cellulose sodium (CMC) or sodium alginate (ALG) constituted the inner drug (0.6%) loaded layer. Thiolated sodium alginate (TSA; 2 or 4%) constituted the outer drug free layers to enhance mucoadhesion and achieve controlled drug release. Optimized formulation was assessed clinically on 20 subjects. RESULTS: Films were uniform, thin and hard enough for easy insertion into periodontal pockets. Based on water uptake and in vitro drug release, CMC based film with 4% TSA as an outer layer was the optimized formulation with enhanced mucoadhesion and controlled drug release (83.73% over 12 h). SEM showed the effective fabrication of the triple layer film in which connective lines between the layers could be observed. FTIR examination suggests possibility of hydrogen bonding between the -NH groups of metformin and -OH groups of CMC. DSC revealed the presence of MF mainly in the amorphous form. Clinical results indicated improvement of all clinical parameters six months post treatment. CONCLUSION: The results suggested that local application of the mucoadhesive multiple layer films loaded with metformin hydrochloride was able to manage moderate chronic periodontitis.


Assuntos
Alginatos/administração & dosagem , Cimentos Dentários , Sistemas de Liberação de Medicamentos/métodos , Metformina/administração & dosagem , Bolsa Periodontal/tratamento farmacológico , Compostos de Sulfidrila/administração & dosagem , Adulto , Alginatos/química , Animais , Preparações de Ação Retardada/química , Cimentos Dentários/química , Feminino , Ácido Glucurônico/administração & dosagem , Ácido Glucurônico/química , Ácidos Hexurônicos/administração & dosagem , Ácidos Hexurônicos/química , Humanos , Masculino , Metformina/química , Pessoa de Meia-Idade , Bolsa Periodontal/diagnóstico , Periodontite/diagnóstico , Periodontite/tratamento farmacológico , Compostos de Sulfidrila/química , Suínos , Tionucleotídeos/administração & dosagem , Tionucleotídeos/química
13.
Lab Chip ; 16(16): 3130-8, 2016 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-27452345

RESUMO

Antimicrobial resistance (AMR) is a rapidly increasing threat to the effective treatment of infectious diseases worldwide. The two major remedies include: (1) using narrow-spectrum antibiotics based on rapid diagnosis; and (2) developing new antibiotics. A key part of both remedies is the antimicrobial susceptibility test (AST). However, the current standard ASTs that monitor colony formation are costly and time-consuming and the new strategies proposed are not yet practical to be implemented. Herein, we report a strategy to fabricate whole-hydrogel microfluidic chips using alginate-doped agar. This agar-based microfabrication makes it possible to prepare inexpensive hydrogel devices, and allows a seamless link between microfluidics and conventional agar-based cell culture. Different from common microfluidic systems, in our system the cells are cultured on top of the device, similar to normal agar plate culture; on the other hand, the microfluidic channels inside the hydrogel allow precise generation of linear gradient of drugs, thus giving a better performance than the conventional disk diffusion method. Cells in this system are not exposed to any shear flow, which allows the reliable tracking of individual cells and AST results to be obtained within 2-3 hours. Furthermore, our system could test the synergistic effect of drugs through two-dimensional gradient generation. Finally, the platform could be directly implemented to new drug discovery and other applications wherein a fast, cost-efficient method for studying the response of microorganisms upon drug administration is desirable.


Assuntos
Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Hidrogéis/química , Dispositivos Lab-On-A-Chip , Testes de Sensibilidade Microbiana/instrumentação , Ágar/química , Alginatos/química , Ampicilina/farmacologia , Cefradina/farmacologia , Difusão , Desenho de Equipamento , Escherichia coli/crescimento & desenvolvimento , Escherichia coli/metabolismo , Gentamicinas/farmacologia , Ácido Glucurônico/química , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Ácidos Hexurônicos/química , Temperatura Alta , Microscopia de Fluorescência , Organismos Geneticamente Modificados
14.
Methods Appl Fluoresc ; 4(4): 044002, 2016 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-28192295

RESUMO

The main goal of this study is to investigate a combination of viscosity-sensitive and viscosity-insensitive fluorescent dyes to distinguish different rheological states of hydrogel based biostructural materials and carriers in biological tissues and to assess their corresponding location areas. The research is done in the example of alginate hydrogel stained with viscosity-sensitive dyes Seta-470 and Seta-560 as well as the viscosity-insensitive dye Seta-650. These dyes absorb/emit at 469/518, 565/591 and 651/670 nm, respectively. The rheological state of the alginate, the area of the fluorescence signal and the mass of the dense alginate versus the calcium gluconate concentration utilized for alginate gelation were studied in vitro. The most pronounced change in the fluorescence signal area was found at the same concentrations of calcium gluconate (below ~1%) as the change in the alginate plaque mass. The stained alginate was also implanted in situ in rat hip and myocardium and monitored using fluorescence imaging. In summary, our data indicate that the viscosity sensitive dye in combination with the viscosity-insensitive dye allow tracking the biodegradation of the alginate hydrogel and determining the rheological state of hydrogel in biological tissue, which both should have relevance for research and clinical applications. Using this method we estimated the half-life of the dense alginate hydrogel in a rat hip to be in the order of 4 d and about 6-8 d in rat myocardium. The half-life of the dense hydrogel in the myocardium was found to be long enough to prevent aneurysm rupture of the left ventricle wall, one of the more severe complications of the early post-infarction period.


Assuntos
Alginatos/química , Animais , Corantes Fluorescentes , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Hidrogéis , Ratos , Viscosidade
15.
J Environ Manage ; 165: 263-270, 2016 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-26454070

RESUMO

In this paper, we investigated alginate microspheres as a low-cost adsorbent for strontium (Sr(II)) removal and recovery from seawater. Alginate microspheres have demonstrated a superior adsorption capacity for Sr(II) ions (≈110 mg/g). A Freundlich isotherm model fits well with the Sr(II) adsorption of an alginate microsphere. The mechanism of Sr(II) adsorption is inferred as an ion exchange reaction with Ca(II) ions. The effects of the solution pH and co-existing ions in seawater are also investigated. Except for a pH of 1-2, Sr(II) adsorption capacity is not affected by pH. However, increasing the seawater concentration of metal cations seriously decreases Sr(II) uptake. In particular, highly concentrated (15,000 mg/L) Na(I) ions significantly interfere with Sr(II) adsorption. Sr(II) desorption was performed using 0.1 M HCl and CaCl2. Both regenerants show an excellent desorption efficiency, but the FTIR spectrum reveals that the chemical structure of the microsphere is destroyed after repeated use of HCl. Conversely, CaCl2 successfully desorbed Sr(II) without damage, and the Sr(II) adsorption capacity does not decrease after three repeated uses. The alginate microsphere was also applied to the adsorption of Sr(II) in a real seawater medium. Because of inhibition by co-existing ions, the Sr(II) adsorption capacity was decreased and the adsorption rate was retarded compared with D.I. water. Although the Sr(II) adsorption capacity was decreased, the alginate microsphere still exhibited 17.8 mg/g of Sr(II) uptake in the seawater medium. Considering its excellent Sr(II) uptake in seawater and its reusability, an alginate microsphere is an appropriate cost-effective adsorbent for the removal and recovery of Sr(II) from seawater.


Assuntos
Alginatos/química , Microesferas , Água do Mar/química , Estrôncio/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Modelos Teóricos , Estrôncio/química , Poluentes Químicos da Água/química
16.
Curr Drug Deliv ; 13(1): 121-30, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-26212139

RESUMO

Enterotoxigenic Escherichia coli (ETEC) infection is one of the major causes contributing to the development of diarrhoea and mortality in new born, suckling and newly weaned piglets. To date, no preventive/treatment strategy showed promising results, which could be due to the lack of potent vaccines, and/or due to the development of resistance of ETEC to antibiotics. Therefore, in the present investigation, a novel porous sodium alginate (SA) tablet formulation loaded with F4 fimbriae antigen was developed and tested for efficacy against ETEC infections in piglet models. Precompression parameters of the powder mixes and post compression parameters of tablets have been evaluated and results were found to be satisfactory. Loading of F4 fimbrial antigens into the tablets was achieved by inducing pores in the tablets via the sublimation of camphor followed by incubation with purified F4 fimbriae. The loaded tablets have been coated with Eudragit L100 to protect the F4 fimbriae from (a) highly acidic gastric environment; (b) proteolytic cleavage by pepsin; and (c) to promote subsequent release in the intestine. Evaluation of developed F4 fimbrial tablets in a Pig model demonstrated induction of mucosal immunity, and a significant reduction of F4+ E. coli in faeces. Therefore, F4 fimbriae loaded porous tablets could be a novel oral vaccination candidate to induce mucosal and systemic immunity against ETEC infections.


Assuntos
Antígenos de Bactérias/imunologia , Escherichia coli Enterotoxigênica/imunologia , Infecções por Escherichia coli/imunologia , Proteínas de Escherichia coli/imunologia , Proteínas de Fímbrias/imunologia , Comprimidos/administração & dosagem , Comprimidos/química , Alginatos/química , Animais , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Imunidade nas Mucosas/imunologia , Mucosa Intestinal/imunologia , Mucosa Intestinal/microbiologia , Ácidos Polimetacrílicos/química , Pós/química , Suínos , Vacinação/métodos
17.
PLoS One ; 10(12): e0145080, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26675008

RESUMO

The current study has investigated the use of decellularised, demineralised bone extracellular matrix (ECM) hydrogel constructs for in vivo tissue mineralisation and bone formation. Stro-1-enriched human bone marrow stromal cells were incorporated together with select growth factors including VEGF, TGF-ß3, BMP-2, PTHrP and VitD3, to augment bone formation, and mixed with alginate for structural support. Growth factors were delivered through fast (non-osteogenic factors) and slow (osteogenic factors) release PLGA microparticles. Constructs of 5 mm length were implanted in vivo for 28 days within mice. Dense tissue assessed by micro-CT correlated with histologically assessed mineralised bone formation in all constructs. Exogenous growth factor addition did not enhance bone formation further compared to alginate/bone ECM (ALG/ECM) hydrogels alone. UV irradiation reduced bone formation through degradation of intrinsic growth factors within the bone ECM component and possibly also ECM cross-linking. BMP-2 and VitD3 rescued osteogenic induction. ALG/ECM hydrogels appeared highly osteoinductive and delivery of angiogenic or chondrogenic growth factors led to altered bone formation. All constructs demonstrated extensive host tissue invasion and vascularisation aiding integration and implant longevity. The proposed hydrogel system functioned without the need for growth factor incorporation or an exogenous inducible cell source. Optimal growth factor concentrations and spatiotemporal release profiles require further assessment, as the bone ECM component may suffer batch variability between donor materials. In summary, ALG/ECM hydrogels provide a versatile biomaterial scaffold for utilisation within regenerative medicine which may be tailored, ultimately, to form the tissue of choice through incorporation of select growth factors.


Assuntos
Regeneração Óssea , Matriz Extracelular , Hidrogéis/química , Peptídeos e Proteínas de Sinalização Intercelular/farmacologia , Osteoblastos/citologia , Alginatos/efeitos adversos , Alginatos/química , Animais , Condrogênese , Ácido Glucurônico/efeitos adversos , Ácido Glucurônico/química , Ácidos Hexurônicos/efeitos adversos , Ácidos Hexurônicos/química , Humanos , Hidrogéis/efeitos adversos , Ácido Láctico/efeitos adversos , Ácido Láctico/química , Camundongos , Pessoa de Meia-Idade , Osteoblastos/efeitos dos fármacos , Osteoblastos/metabolismo , Osteoblastos/transplante , Osteogênese , Ácido Poliglicólico/efeitos adversos , Ácido Poliglicólico/química , Copolímero de Ácido Poliláctico e Ácido Poliglicólico , Alicerces Teciduais/efeitos adversos , Alicerces Teciduais/química
18.
Mol Pharm ; 12(11): 3953-62, 2015 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-26448513

RESUMO

The combination of mesenchymal stem cells (MSCs) and biomimetic matrices for cell-based therapies has led to enormous advances, including the field of cell microencapsulation technology. In the present work, we have evaluated the potential of genetically modified MSCs from mice bone marrow, D1-MSCs, immobilized in alginate microcapsules with different RGD (Arg-Gly-Asp) densities. Results demonstrated that the microcapsules represent a suitable platform for D1-MSC encapsulation since cell immobilization into alginate matrices does not affect their main characteristics. The in vitro study showed a higher activity of D1-MSCs when they are immobilized in RGD-modified alginate microcapsules, obtaining the highest therapeutic factor secretion with low and intermediate densities of the bioactive molecule. In addition, the inclusion of RGD increased the differentiation potential of immobilized cells upon specific induction. However, subcutaneous implantation did not induce differentiation of D1-MSCs toward any lineage remaining at an undifferentiated state in vivo.


Assuntos
Alginatos/química , Biomimética , Diferenciação Celular/efeitos dos fármacos , Células Imobilizadas/citologia , Células-Tronco Mesenquimais/citologia , Oligopeptídeos/farmacologia , Animais , Antineoplásicos/farmacologia , Apoptose/efeitos dos fármacos , Cápsulas , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Células Imobilizadas/efeitos dos fármacos , Feminino , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Células-Tronco Mesenquimais/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos C57BL , Fenótipo
19.
Int J Pharm ; 495(2): 798-806, 2015 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-26434999

RESUMO

Topical chemotherapy is the application of cancer drugs directly onto the skin, which has become a standard treatment for basal cell carcinoma. Due to the promising results in the treatment of skin cancer, topical chemotherapy has recently been applied to breast cancer patients because some breast cancer tissues are only superficial. Hydroxytyrosol, a phenolic compound from olives that is present in high amounts in Hidrox(®) olive extract, has been shown to have a protective effect on normal cells and selective antitumor activities on cancerous cells. The aims of the present study were to develop an alginate bilayer film containing Hidrox(®) and to investigate its potential use as a topical chemotherapeutic agent. Alginate films were characterized for swelling and for physical, thermal, rheological, and mechanical properties. Drug content uniformity and in vitro drug release tests were also investigated. The alginate bilayer films containing Hidrox(®), HB2, showed controlled release of hydroxytyrosol at a flux of 0.094±0.009 mg/cm(2)/h. The results of the cytotoxic assay showed that the HB2 films were dose-dependent and could significantly reduce the growth of breast cancer cells (MCF-7) at 150 µg/mL for a cell viability of 29.34±4.64%. In conclusion, an alginate bilayer film containing Hidrox(®) can be a potential alternative for topical chemotherapeutic agent for skin and breast cancer treatment.


Assuntos
Alginatos/química , Antineoplásicos Fitogênicos/administração & dosagem , Olea/química , Álcool Feniletílico/análogos & derivados , Administração Cutânea , Antineoplásicos Fitogênicos/farmacocinética , Antineoplásicos Fitogênicos/farmacologia , Neoplasias da Mama/tratamento farmacológico , Sobrevivência Celular/efeitos dos fármacos , Preparações de Ação Retardada , Relação Dose-Resposta a Droga , Liberação Controlada de Fármacos , Feminino , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Humanos , Células MCF-7 , Álcool Feniletílico/administração & dosagem , Álcool Feniletílico/farmacocinética , Álcool Feniletílico/farmacologia , Reologia , Neoplasias Cutâneas/tratamento farmacológico
20.
J Colloid Interface Sci ; 448: 79-87, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25721859

RESUMO

An efficient one-step process to synthesize highly porous (Ca-alginate-SiO2-polycation) shell: (Na-alginate-SiO2) core hybrid beads for cell encapsulation, yielding a reusable long-life photosynthetically active material for a sustainable manufacture of high-value metabolites is presented. Bead formation is based on crosslinking of an alginate biopolymer and mineralisation of silicic acid in combination with a coacervation process between a polycation and the silica sol, forming a semi-permeable external membrane. The excellent mechanical strength and durability of the monodispersed beads and the control of their porosity and textural properties is achieved by tailoring the silica and alginate loading, polycation concentration and incubation time during coacervation. This process has led to the formation of a remarkably robust hybrid material that confers exceptional protection to live cells against sheer stresses and contamination in a diverse range of applications. Dunaliella tertiolecta encapsulated within this hybrid core-shell system display high photosynthetic activity over a long duration (>1 year). This sustainable biotechnology could find use in high value chemical harvests and biofuel cells to photosynthetic solar cells (energy transformation, electricity production, water splitting technologies). Furthermore the material can be engineered into various forms from spheres to variable thickness films, broadening its potential applications.


Assuntos
Alginatos/química , Clorófitas/fisiologia , Fotossíntese , Poliaminas/química , Dióxido de Silício/química , Alginatos/síntese química , Células Imobilizadas/fisiologia , Ácido Glucurônico/síntese química , Ácido Glucurônico/química , Ácidos Hexurônicos/síntese química , Ácidos Hexurônicos/química , Fotobiorreatores , Poliaminas/síntese química , Polieletrólitos , Porosidade , Dióxido de Silício/síntese química
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