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1.
Carbohydr Polym ; 242: 116417, 2020 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-32564826

RESUMO

Poly(lactide-co-glycolide) (PLGA) colloidal particles stabilized by complexes of two oppositely charged polysaccharides, chitosan (cationic, CS) and sodium carboxymethylcellulose (anionic, NaCMC), were fabricated. Dichloromethane containing dissolved PLGA was first emulsified in an aqueous phase containing mixtures of CS and NaCMC. Evaporation of dichloromethane from the resulting emulsion led to CS/NaCMC-covered-PLGA particles. CS and NaCMC contents affected the short-term stability of PLGA particles and also their intrinsic characteristics. The particles displayed pH-dependent characteristic. Zeta potential varied from +54 to -50 mV when pH was varied from 3 to 10. CS/NaCMC-covered-PLGA particles showed colloidal stability, over a wider pH range as compared to CS-covered-PLGA particles. Curcumin, a model hydrophobic drug, was encapsulated into the particles up to 10 wt% of PLGA. The CS/NaCMC-covered-PLGA particles loaded with curcumin showed delayed release in mildly acidic conditions and faster release in neutral and basic conditions. Cytotoxicity experiments were carried out with human colorectal carcinoma cells.

2.
Macromol Rapid Commun ; 41(9): e2000058, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32187400

RESUMO

Currently, the phase transition of aqueous binary systems containing thermoresponsive (co)polymers, and exhibiting upper critical solution temperature (UCST), is exclusively investigated in dilute solutions, which can limit the knowledge of their UCST-type phase transition. Herein, a photo-RAFT polymerization approach, using acrylamide (AAm) and acrylonitrile (AN) as monomer models, is used to prepare well-controlled poly(AAm-co-AN) copolymers "in situ" in highly concentrated dispersions (60 wt%). The impact of the copolymer concentration and the chemical composition (as a variation of AN fraction in the copolymers) on the cloud point temperature (TCP ) are investigated using turbidity measurements. Importantly, the results show that upon increasing the polymer concentration, a sharp increase of TCP up to a maximum point is observed, representing the UCST, before the decrease of TCP at higher polymer concentrations. Finally, a model equation is developed to fit the UCST values of poly(AAm-co-AN), which can be useful to design new poly(AAm-co-AN) copolymers with a desired UCST for a specific application.

3.
J Colloid Interface Sci ; 569: 57-67, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-32105903

RESUMO

Aiming to prepare oily core pH-sensitive nanocapsules (NCs) for anticancer drugs delivery, the use of a dextran-based transurf (DexN3-τCTAγ) as both stabilizer and macromolecular chain transfer agent in methyl methacrylate/2-(diethylamino)ethyl methacrylate (MMA/DEAEMA) miniemulsion copolymerization was investigated. NCs of about 195 nm with an oily-core of Miglyol 810 (M810) and a dextran coverage covalently linked to the poly(MMA-co-DEAEMA) intern shell have been obtained. Compared to the non-sensitive PMMA-based NCs (prepared in a similar way), these novel objects were shown to swell in acidic media and to trigger Coumarin 1 release in physiological relevant pH range. As a starting point of NCs biological effects, cytotoxicity and NCs-proteins interactions studies were performed with both PMMA and poly(MMA-co-DEAEMA)-based NCs. Finally, free azide functions from dextran-based coverage were successfully exploited to attach fluorescent model dyes to NCs surface. The overall results suggest that this novel NCs platform could be potentially used as drug nanocarriers for intravenous injection.

4.
Carbohydr Polym ; 224: 115153, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31472862

RESUMO

A multi-reactive polysaccharide-based transurf (acting both as macro-Chain Transfer Agent and stabilizer) was used to confine RAFT polymerization of methyl methacrylate (MMA) at the oil/water (o/w) miniemulsion interface. Dithiobenzoate groups and hydrophobic aliphatic side chains were introduced onto dextran, conferring it both transfer agent properties and ability to stabilize direct miniemulsion of MMA in the presence of a biocompatible oil, used as co-stabilizer. Because of their amphiphilic character, transurfs were initially adsorbed at the (o/w) interface and their reactive sites mediated RAFT polymerization via the R-group approach. PMMA-grafted dextran glycopolymers were consequently produced at the o/w interface, thus leading to dextran coverage/PMMA shell/oily core nanocapsules (NCs) as evidenced by Cryo-TEM analyses. The influence of dextran-based transurf chemistry and oil amount on MMA RAFT polymerization control was investigated. Positive preliminary results on NCs cytotoxicity suggest the potential of these objects for biomedical applications.

5.
Materials (Basel) ; 12(18)2019 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-31547298

RESUMO

From a set of around 100 phosphorus-containing polymers tested in pyrolysis-combustion flow calorimetry, the contributions to flammability of two phosphorus-containing pendant groups (called 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and PO3) were calculated using an advanced method previously proposed and validated. The flammability properties include total heat release (THR) and heat release capacity (HRC) measured in standard conditions, i.e., anaerobic pyrolysis and complete combustion. The calculated contributions are in good agreement with the main modes of action of both phosphorus groups, i.e., flame inhibition for DOPO and char promotion for PO3. Moreover, the results provide first conclusions about the cooperative interaction between phosphorus and nitrogen, as well as the influence of the architecture of tested co-polymers.

6.
Colloids Surf B Biointerfaces ; 176: 9-17, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30590347

RESUMO

The cytotoxicity of monomyristin (MM), a monoacylglycerol, was investigated against cervical cancer cells (HeLa) and two normal cells (Vero and endometrial epithelial cells). MM exhibited cytotoxicity specifically to HeLa cells and not against normal cells except at the highest investigated doses (> 500 µg/mL). MM was showed to increase apoptotic dead cells by intrinsic mitochondrial pathway. To overcome the poor water solubility of MM and increase its efficacy against HeLa cells, MM was encapsulated into dextran-covered polylactide (PLA) nanoparticles (NPs). NPs comprised a PLA core which encapsulated MM and a superficial layer of dextran loops which was used for conjugating a protein, transferrin (Tf), known to be overexpressed on cancer cells' surface. Encapsulation of MM into NPs increased its cytotoxicity against HeLa cells at lower doses of MM than free MM. Additionally, the presence of conjugated Tf further increased the cytotoxicity of MM against HeLa cells as compared to non-conjugated NPs. Remarkably, both conjugated and non-conjugated MM loaded NPs were safe to normal cells (Vero and endometrial).


Assuntos
Antineoplásicos/farmacologia , Monoglicerídeos/farmacologia , Nanopartículas/química , Polímeros/química , Neoplasias do Colo do Útero/tratamento farmacológico , Animais , Antineoplásicos/química , Apoptose/efeitos dos fármacos , Proliferação de Células/efeitos dos fármacos , Células Cultivadas , Chlorocebus aethiops , Portadores de Fármacos/química , Ensaios de Seleção de Medicamentos Antitumorais , Feminino , Células HeLa , Humanos , Monoglicerídeos/química , Propriedades de Superfície , Neoplasias do Colo do Útero/metabolismo , Neoplasias do Colo do Útero/patologia , Células Vero
7.
Colloids Surf B Biointerfaces ; 162: 351-361, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-29227921

RESUMO

PLA nanoparticles loaded with n-alkyl gallates (AGs) were prepared either by nanoprecipitation (NP) or by O/W emulsion/solvent evaporation (E/SE). A nonionic hydrophobically modified polysaccharide was used for surface coverage and for ensuring colloidal stability. Different parameters were systematically assessed to enhance the drug incorporation, with the aim of obtaining monomodal and narrow particle size distributions. The nanoparticles were characterized by 1H NMR, transmission electron microscopy (TEM) and laser light scattering granulometry. The colloidal stability of suspensions was evaluated after incubation in NaCl solutions and was maintained up to 1M NaCl. The mean particle diameter and the width of size distribution were found very similar for both processes (slightly lower diameters when using E/SE) with various drug loadings. The amount of encapsulated AG by E/SE was about twice that encapsulated by NP. The in-vitro release of AG was evaluated under sink conditions and no burst effect was observed. Release curves were successfully modeled using the Fick diffusion model with a constant diffusion coefficient and assuming non-swellable particles. Diffusion coefficients of AG loaded in nanoparticles prepared by NP were higher than those found in nanoparticles elaborated by E/SE.


Assuntos
Portadores de Fármacos , Composição de Medicamentos/métodos , Ácido Gálico/análogos & derivados , Nanopartículas/química , Poliésteres/química , Precipitação Química , Liberação Controlada de Fármacos , Estabilidade de Medicamentos , Emulsões , Ácido Gálico/química , Cinética , Tamanho da Partícula , Cloreto de Sódio/química
8.
Carbohydr Polym ; 177: 460-468, 2017 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-28962792

RESUMO

This work studied the adsorption at dodecane/water interface of amphiphilic polysaccharides derived from dextran (a nonionic bacterial polysaccharide) by random attachment of phenoxy groups along the chains (between 10 and 20 attached phenoxy groups per 100 glucose repeat units). The long-time kinetics of interfacial tension decrease was satisfactorily described assuming diffusion-limited adsorption of hydrophobic units (over 4h). Dilational rheology of dodecane/water interface was studied for the first time with that kind of amphiphilic polysaccharides and evidenced a significant elastic component. For all dextran derivatives, experimental results were conveniently described using Lucassen-van den Tempel model which assumed diffusion-limited of surface active species. The characteristic frequency increased with the number of attached phenoxy groups and its order of magnitude (10-3-10-2rad.s-1) was consistent with estimations based on the previous model. Experimental results were compared to those obtained with commercial stabilizers like Pluronics (L64, P105, F68 and F127) and Tween 80.


Assuntos
Dextranos/química , Óleos/química , Água/química , Adsorção , Reologia , Propriedades de Superfície , Tensoativos
9.
J Biotechnol ; 259: 182-190, 2017 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-28751275

RESUMO

Sucrose monocaprate was synthesized by carrying out a lipase-catalyzed transesterification in a non-aqueous biphasic medium. Vinyl caprate was mechanically dispersed into a solution of sucrose in DMSO. The use of DMSO allowed increasing sucrose concentration up to 0.7M (in DMSO). The denaturing effect of DMSO on lipase was avoided by pretreatment of lipase by pH adjustment in the presence of crown ether. This pretreatment maintained a significant catalytic activity which led to 0.2M sucrose monoester within 1h at 50°C, which represented higher productivity than already reported. Detailed structural characterization revealed that only monoester was recovered and the 2-O-acylated sucrose monocaprate was the major isomer in the final product.


Assuntos
Éteres de Coroa/química , Éteres de Coroa/metabolismo , Lipase/metabolismo , Sacarose/química , Sacarose/metabolismo , Reatores Biológicos , Candida/enzimologia , Esterificação , Proteínas Fúngicas/metabolismo
10.
Carbohydr Polym ; 130: 141-8, 2015 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-26076610

RESUMO

A multi-reactive polysaccharide-based inisurf (acting both as initiator and stabilizer) has been designed for the first time from dextran with the aim of preparing dextran-covered nanoparticles with covalent linkage between core and coverage. This inisurf was used for polymerizing butyl acrylate in miniemulsion by AGET-ATRP. Both hydrophobic phenoxy groups and initiator groups (bromoisobutyryl ester) were introduced within hydrophilic dextran chain, conferring it amphiphilic and macroinitiator characters. Amphiphilic properties of dextran inisurfs have been evidenced as well as their ability to stabilize the direct miniemulsion of n-butyl acrylate. After optimization of polymerization conditions with model studies, assays were successfully realized with dextran-based inisurfs. Because of their amphiphilic character, inisurfs migrated at oil/water interface and initiated polymerization from bromoisobutyryl ester groups. Therefore graft copolymers were produced at oil/water interface, due to the multifunctional character of these inisurfs and constituted the particle inner core with covalent links to the dextran coverage.


Assuntos
Dextranos/química , Emulsões/química , Polimerização , Interações Hidrofóbicas e Hidrofílicas , Cinética , Espectroscopia de Ressonância Magnética , Nanopartículas/química , Propriedades de Superfície , Tensoativos/química
11.
Colloids Surf B Biointerfaces ; 113: 254-60, 2014 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-24103504

RESUMO

The preparation of polyester particles using enzyme-catalyzed (lipase from Candida antarctica B, CALB) ring-opening polymerization of ε-caprolactone (ε-CL) in aqueous dispersion was demonstrated for the first time. Immobilization of CALB enabled a significant increase of the number-average degree of polymerization of ε-CL oligomers (up to 38) as compared to dissolved CALB (8 at the maximum). The nature and amount of lipase, as well as the nature of the support material were identified as key parameters controlling ring-opening polymerization of ε-CL in aqueous dispersion. In addition, the involvement of solubilized monomers in polymerization elementary reactions was demonstrated and the consequences on oligomers average length were detailed. An overall mechanism of lipase-catalyzed ε-CL polymerization in aqueous dispersion taking into account the colloidal nature of reaction medium was proposed on the basis of experimental results.


Assuntos
Enzimas Imobilizadas/metabolismo , Lipase/metabolismo , Poliésteres/química , Candida/enzimologia , Caproatos/química , Enzimas Imobilizadas/química , Cinética , Lactonas/química , Lipase/química , Espectroscopia de Ressonância Magnética
12.
Carbohydr Polym ; 95(1): 360-5, 2013 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-23618280

RESUMO

Hydrophobically modified dextrans were prepared by reacting native polysaccharide with 1,2-epoxydodecane in dimethylsulfoxide. Epoxide oligomerization was shown to occur as a secondary reaction when hydroxide ions were used as base catalysts. By adjusting the amount of epoxide in the feed, dextran derivatives with degrees of substitution (DS) between 0% and 164% were obtained. Polymers with DS above 100% were readily soluble in organic solvents like tetrahydrofuran, dioxane and water-saturated chloroform and dichloromethane. Their solution properties in organic solvent were characterized by capillary viscometry. Water-soluble derivatives were compared to other amphiphilic dextrans obtained using a heterogeneous modification in aqueous medium. The effect of modification conditions on substitution pattern was evidenced.


Assuntos
Dextranos/química , Compostos de Epóxi/química , Compostos de Amônio Quaternário/química , Catálise , Dimetil Sulfóxido/química , Solubilidade , Solventes/química , Viscosidade , Água/química
13.
Carbohydr Polym ; 93(2): 537-46, 2013 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-23499094

RESUMO

Dextran-covered PLA nanoparticles have been formulated by two strategies. On one hand, dextran-g-PLA copolymers have been synthesized by click-chemistry between azide-multifunctionalized dextran (DexN3) and alkyne end-functionalized PLA chains (α-alkyne PLA); then nanoprecipitated without any additional surfactants. On the other hand, DexN3 exhibiting surfactant properties have been emulsified with unfunctionalized or α-alkyne PLA, which are dissolved in organic phase with or without CuBr. Depending on the o/w emulsion/evaporation process experimental conditions, dextran-g-PLA copolymers have been produced in situ, by click chemistry at the liquid/liquid interface during the emulsification step. Whatever the process, biodegradable core/shell polymeric nanoparticles have been obtained, then characterized. Colloidal stability of these nanoparticles in the presence of NaCl or SDS has been studied. While the physically adsorbed polysaccharide based shell has been displaced by SDS, the covalently-linked polysaccharide based shell ensures a permanent stability, even in the presence of SDS.

14.
J Biosci Bioeng ; 112(2): 124-9, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21602099

RESUMO

Vinyl decanoate-modified dextran macromolecules (DexT40-VD) were synthesized in dimethyl sulfoxide at 50°C using lipase AY from Candida rugosa for catalyzing transesterification between polysaccharide and vinyl fatty esters. The extent of dextran modification (quantified by the molar ratio of attached alkyl tails to sugar repeat units) with native-, pH-adjusted-, 18-crown-6 ether pretreated pH-adjusted-, and stepwise addition of pretreated lipase AY yielded <3%, 49%, 64% and 96% modified dextran respectively. Lipase AY accelerated the transesterification of DexT40 from 2- to 63-fold higher than the non-catalyzed system. This procedure was extended to other acyl donors showing that modification pattern exhibited regioselectivity depending on acyl donor structure. Regioselectivity equaled between 2- and 3-OH with saturated fatty acyl donors. The 2-OH was favored for unsaturated fatty acyl donors, while sterically hindered acyl donors oriented modification toward 3-OH position. DexT40-VD at 96% modification was a water-insoluble polymer forming 150nm diameter nanoparticles in water which can be used as drug carrier systems.


Assuntos
Candida/enzimologia , Dextranos/biossíntese , Lipase/metabolismo , Biocatálise , Éteres de Coroa/química , Decanoatos/química , Dextranos/química , Dimetil Sulfóxido/química , Esterificação , Interações Hidrofóbicas e Hidrofílicas , Lipase/química , Compostos de Vinila/química
15.
Appl Microbiol Biotechnol ; 90(4): 1409-17, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21380515

RESUMO

Bacillus subtilis(B. subtilis) cells were placed in various environmental conditions to study the effects of aeration, water activity of the medium, temperature, pH, and calcium content on spore formation and the resulting properties. Modification of the sporulation conditions lengthened the growth period of B. subtilis and its sporulation. In some cases, it reduced the final spore concentration. The sporulation conditions significantly affected the spore properties, including germination capacity and resistance to heat treatment in water (30 min at 97°C) or to high pressure (60 min at 350 MPa and 40°C). The relationship between the modifications of these spore properties and the change in the spore structure induced by different sporulation conditions is also considered. According to this study, sporulation conditions must be carefully taken into account during settling sterilization processes applied in the food industry.


Assuntos
Bacillus subtilis/crescimento & desenvolvimento , Viabilidade Microbiana , Esporos Bacterianos/química , Esporos Bacterianos/crescimento & desenvolvimento , Bacillus subtilis/química , Temperatura Alta , Pressão
16.
Bioresour Technol ; 102(6): 4416-24, 2011 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21273061

RESUMO

Pretreatment of lignocellulosic residues like water hyacinth (WH) and wheat straw (WS) using crude glycerol (CG) and ionic liquids (IL) pretreatment was evaluated and compared with conventional dilute acid pretreatment (DAT) in terms of enzymatic hydrolysis yield and fermentation yield of pretreated samples. In the case of WS, 1-butyl-3-methylimidazolium acetate pretreatment was found to be the best method. The hydrolysis yields of glucose and total reducing sugars were 2.1 and 3.3 times respectively higher by IL pretreatment than DAT, while it was 1.4 and 1.9 times respectively higher with CG pretreatment. For WH sample, CG pretreatment was as effective as DAT and more effective than IL pretreatment regarding hydrolysis yield. The fermentation inhibition was not noticeable with both types of pretreatment methods and feedstocks. Besides, CG pretreatment was found as effective as pure glycerol pretreatment for both feedstocks. This opens up an attractive economic route for the utilization of CG.


Assuntos
Biocombustíveis/análise , Biotecnologia/métodos , Eichhornia/química , Etanol/análise , Triticum/química , Resíduos/análise , Celulase/metabolismo , Fermentação , Glucose/biossíntese , Hidrólise , Oxirredução , Saccharomyces cerevisiae/metabolismo , Fatores de Tempo
18.
J Microbiol Biotechnol ; 20(12): 1664-71, 2010 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21193821

RESUMO

A new biosurfactant producer was isolated from palm-oilcontaminated soil and later identified through morphology and DNA sequencing as the yeast-like fungus Exophiala dermatitidis. Biosurfactant production was catalyzed by vegetable oil, supplemented with a basal medium. The culture conditions that provided the biosurfactant with the highest surface activity were found to be 5% palm oil with 0.08% NH4NO3, at a pH of 5.3, with shaking at 200 rpm, and a temperature of 30 degrees C for a 14-day period of incubation. The biosurfactant was purified, in accordance with surfactant properties, by solvent fractionation using silica gel column chromatography. The chemical structure of the strongest surface-active compound was elucidated through the use of NMR and mass spectroscopy, and noted to be monoolein, which then went on to demonstrate antiproliferative activity against cervical cancer (HeLa) and leukemia (U937) cell lines in a dose-dependent manner. Interestingly, no cytotoxicity was observed with normal cells even when high concentrations were used. Cell and DNA morphological changes, in both cancer cell lines, were observed to be cell shrinkage, membrane blebbling, and DNA fragmentation.


Assuntos
Antibióticos Antineoplásicos/metabolismo , Antineoplásicos/metabolismo , Exophiala/metabolismo , Microbiologia do Solo , Tensoativos/metabolismo , Antibióticos Antineoplásicos/química , Antibióticos Antineoplásicos/isolamento & purificação , Antibióticos Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/isolamento & purificação , Antineoplásicos/farmacologia , Linhagem Celular Tumoral , Cromatografia Líquida , Meios de Cultura/química , Exophiala/classificação , Exophiala/genética , Exophiala/isolamento & purificação , Humanos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Óleos Vegetais/metabolismo , Sílica Gel , Tensoativos/química , Tensoativos/isolamento & purificação , Tensoativos/farmacologia
19.
Adv Colloid Interface Sci ; 150(2): 90-105, 2009 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-19660729

RESUMO

The use of polymeric surfactants as stabilizers in miniemulsion polymerization was reviewed. The structural characteristics of reported polymeric surfactants were detailed and compared. The concept of multi-functional polymeric surfactants was evidenced. The specificities brought by polymeric surfactants in the process of miniemulsion polymerization in comparison to molecular surfactants were analysed for the stability of the initial monomer emulsion, polymerization kinetics and characteristics of the obtained latexes. The contribution of polymeric surfactants to the control of the characteristics of the obtained nanoparticles was detailed with regard to the nature of the core material and to the surface coverage. Polymeric surfactants can be seen as powerful tools for the design of original nanoparticles. On the basis of the available data, possible research topics are suggested.

20.
Carbohydr Res ; 344(2): 223-8, 2009 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-19084823

RESUMO

New amphiphilic derivatives of sodium alginate were prepared by covalent attachment of dodecylamine onto the polysaccharide via amide linkages at different substitution ratios, using 2-chloro-1-methylpyridinium iodide (CMPI) as coupling reagent. The aim was to limit the progressive loss of associative behaviour which occurs in the case of previously described dodecyl ester alginate derivatives due to hydrolysis of ester bonds. A series of hydrogels was obtained which differed by the amount of attached dodecyl tails. The stability and viscoelastic properties were evaluated and compared to those of hydrogels obtained with alginate esters. The observed differences were discussed in relation to the synthesis procedures. The advantages of amide links are underlined, especially with regard to long-term stability of hydrogels.


Assuntos
Alginatos/química , Amidas/química , Hidrogéis/química , Hidrogéis/síntese química , Ácido Glucurônico/química , Ácidos Hexurônicos/química , Espectroscopia de Ressonância Magnética , Polissacarídeos/química
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