Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 12 de 12
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Membranes (Basel) ; 9(8)2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31374830

RESUMO

In recent years, block copolymer micellar assemblies with the formation of structured nanoparticles have been considered as an emerging technology in membrane science. In this work, the poly(methyl methacrylate)-block-poly(sulfobetaine methacrylate) copolymer was directly synthesized using Reversible Addition-Fragmentation chain Transfer (RAFT) polymerization and self-assembled in a selective medium (2,2,2-trifluroethanol/water). Then, poly(methyl methacrylate)-block-poly(sulfobetaine methacrylate) copolymers were casted onto a commercial PVDF membrane to form a thin porous selective layer. The prepared nanoparticles and the resulting membranes were fully characterized using microscopy methods (SEM and AFM), whereas the membrane performance was evaluated in terms of permeability and the molecular weight cut off. The results from this study demonstrate the preparation of an ultrafiltration membrane made from the assembly of poly(methyl methacrylate)-block-poly(sulfobetaine methacrylate) copolymer micelles on the top of a PVDF membrane in the form of thin film. The copolymer chain orientation leads to a membrane surface enriched in hydrophilic PSBMA, which confers a suitable behavior for aqueous solution filtration on the membrane, while preserving the high chemical and mechanical resistance of the PVDF.

2.
Macromol Rapid Commun ; 40(2): e1800333, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30027594

RESUMO

This article presents the synthesis of poly(methacrylic acid)-b-poly(methyl methacrylate) diblock copolymer via polymerization-induced self-assembly in the presence of iron-oxide nanoparticles. Detailed phase diagrams with and without inorganic nanoparticles were constructed. Scanning transmission electron microscopy and energy dispersive X-ray photometry studies confirme the decoration of the polymeric nanoparticles with the iron-oxide nanoparticles. These hybrid nanoparticles were used to prepare porous thin film membranes by spin coating. Finally, the magneto-responsive properties of the membranes were assessed using water filtration tests in the presence and absence of a magnetic field.


Assuntos
Técnicas de Química Sintética/métodos , Nanopartículas de Magnetita/química , Nanopartículas/química , Polímeros/química , Ácidos Polimetacrílicos/química , Polimetil Metacrilato/química , Materiais Revestidos Biocompatíveis/química , Campos Magnéticos , Nanopartículas de Magnetita/ultraestrutura , Membranas Artificiais , Microscopia Eletrônica de Transmissão e Varredura , Nanopartículas/ultraestrutura , Polimerização , Polímeros/síntese química , Porosidade
3.
Polymers (Basel) ; 10(7)2018 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-30960658

RESUMO

The preparation of well-arranged nano-porous thin films from an ABA triblock copolymer of polystyrene-block-poly(sodium 4-styrenesulfonate)-block-polystyrene (PS-PNaSS-PS) is reported. This copolymer was self-assembled in a N,N-dimethylformamide (DMF)/water mixture and the resulting micellar solution was used to prepare thin films via the compact packing of the flower-like micelles using spin coating method. The films were characterized by several microscopy techniques such as TEM, AFM, and SEM. Permeation test was performed to highlight the interconnected porous nature of the polymeric network obtained. Under applied water pressure, the micellar morphology was altered and a partial fusion of the micelles was observed that resulted in a change in the water permeability. Such hydrophilic nanoporous thin films with negatively charged interface could find applications in membrane filtration.

4.
Soft Matter ; 13(38): 6689-6693, 2017 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-28948266

RESUMO

Herein, a membrane prepared from the self-assembly of poly(styrene-co-acrylonitrile)-b-poly(ethylene oxide)-b-poly(styrene-co-acrylonitrile) micelles is found to exhibit translocation of nano-objects dispersed in aqueous solution. With the water flow as a driving force, temporary pores are created in between the micelles to facilitate the passage of nano-objects. These temporary pores close afterwards through a self-healing mechanism. As main results, polystyrene and silica nanoparticles exhibited a selective translocation directly influenced by their size and applied pressure.

5.
Langmuir ; 33(8): 1914-1926, 2017 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-28147481

RESUMO

Cationic vectors are ideal candidates for gene delivery thanks to their capability to carry large gene inserts and their scalable production. However, their cationic density gives rise to high cytotoxicity. We present the proper designed core-shell polyplexes made of either poly(ethylene imine) (PEI) or poly(2-dimethylamino ethyl methacrylate) (PDMAEMA) as the core and zwitterionic poly(acrylic acid)-block-poly(sulfobetaine methacrylate) (PAA-b-PSBMA) diblock copolymer as the shell. Gel retardation and ethidium bromide displacement assays were used to determine the PEI/DNA or PDMAEMA/DNA complexation. At neutral pH, the copolymer serves as a protective shell of the complex. As PSBMA is a nonfouling block, the shell reduced the cytotoxicity and enhanced the hemocompatibility (lower hemolysis activity, longer plasma clotting time) of the gene carriers. PAA segments in the copolymer impart pH sensitivity by allowing deshielding of the core in acidic solution. Therefore, the transfection efficiency of polyplexes at pH 6.5 was better than at pH 7.0, from ß-galactosidase assay, and for all PAA-b-PSBMA tested. These results were supported by more favorable physicochemical properties in acidic solution (zeta potential, particle size, and interactions between the polymer and DNA). Thus, the results of this study offer a potential route to the development of efficient and nontoxic pH-sensitive gene carriers.


Assuntos
Polímeros/química , DNA , Técnicas de Transferência de Genes , Concentração de Íons de Hidrogênio , Iminas/química , Metacrilatos/química , Nylons/química , Polietilenos/química
6.
Macromol Biosci ; 16(1): 57-62, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26222768

RESUMO

Amphiphilic diblock copolymer containing randomly distributed positive and negative charged monomers are synthesized using RAFT polymerization technique to be used as anti-bioadhesion coatings for hydrophobic surfaces. Quaternized 2-(dimethylamino) ethyl methacrylate and potassium 3-sulfopropyl methacrylate (P[qDMAEMA-co-KSPMA]) are randomly polymerized to yield an anti-bioadhesion block which is, in one pot, copolymerized with styrene as an anchoring block. This copolymer has demonstrated high anti-bioadhesion properties to avoid the blood clotting in medical devices through a simple and facile approach to preparation of pseudozwitterionic copolymers.


Assuntos
Sangue , Polímeros/química , Adsorção , Materiais Revestidos Biocompatíveis , Humanos , Metacrilatos/química , Polimerização , Estireno/química
7.
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
8.
Langmuir ; 30(22): 6489-96, 2014 Jun 10.
Artigo em Inglês | MEDLINE | ID: mdl-24832682

RESUMO

In this work, the hemocompatibility of polyampholyte copolymers from the mixed-charge copolymerization of negatively charged 3-sulfopropyl methacrylate (SA) and positively charged [2-(methacryloyloxy)ethyl] trimethylammonium (TMA) was studied. Charge-bias variation of the prepared poly(SA-co-TMA) copolymers can be controlled using the regulated SA and TMA monomer ratio via homogeneous free radical copolymerization. A systematic study of how charge-bias variations in poly(SA-co-TMA) copolymers affect the hemocompatibility in human blood plasma was reported. The hydrodynamic size of prepared polymers and copolymers is determined to illustrate the correlations between intermolecular cationic/anionic associations and the blood compatibility of polySA, poly(SA-co-TMA), and polyTMA suspensions in human blood plasma. It was found that the protein resistance and hydration capability of prepared copolymers can be effectively controlled by regulating the charge balance of the SA/TMA compositions in poly(SA-co-TMA). The results suggest that polyampholyte copolymers of poly(SA-co-TMA) with overall charge neutrality have a high hydration capability and the best antifouling, anticoagulant, and antihemolytic activities as well as zwitterionic sulfobetaine-based homopolymers when in contact with blood plasma at human body temperature.


Assuntos
Materiais Biocompatíveis/química , Polímeros/química , Materiais Biocompatíveis/efeitos adversos , Humanos , Metacrilatos/química , Polímeros/efeitos adversos
9.
Adv Mater ; 25(27): 3739-44, 2013 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-23754442

RESUMO

A zipper-assembly of micelles into 2D/3D coatings is reported. Block copolymer micelles that incorporate a poly(n-octadecyl methacrylate) block are zipped and unzipped on demand onto a PMMA surface. The mechanism implies an interdigitation of molecular brushes enabling 15 nm micelles to be assembled into monolayers or multilayers.


Assuntos
Polímeros/química , Micelas , Tamanho da Partícula , Propriedades de Superfície
10.
Biomacromolecules ; 13(9): 2849-58, 2012 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-22838402

RESUMO

"Schizophrenic" diblock copolymers containing nonionic and zwitterionic blocks were prepared with well-controlled molecular weights via atom-transfer radical polymerization (ATRP). In this work, we report a systematic study of how morphological changes of poly(N-isopropylacrylamide)-block-poly(sulfobetaine methacrylate) (PNIPAAm-b-PSBMA) copolymers affect hemocompatibility in human blood solution. The "schizophrenic" behavior of PNIPAAm-b-PSBMA was observed by (1)H NMR, dynamic light scattering (DLS), and turbidity measurement with double morphological transition, exhibiting both lower critical solution temperature (LCST) and upper critical solution temperature (UCST) in aqueous solution. Below the UCST of PSBMA block, micelles were obtained with a core of insoluble PSBMA association and a shell of soluble PNIPAAm, whereas the opposite micelle structure was observed above the LCST of PNIPAAm block. In between the UCST and LCST, unimers with both soluble blocks were detected. Hydrodynamic size of prepared polymers and copolymers is determined to illustrate the correlations between intermolecular nonionic/zwitterionic associations and blood compatibility of PNIPAAm, PNIPAAm-b-PSBMA, and PSBMA suspension in human blood. Human fibrinogen adsorption onto the PNIPAAm-b-PSBMA copolymers from single-protein solutions was measured by DLS to determine the nonfouling stability of copolymer suspension. The new nonfouling nature of PNIPAAm-b-PSBMA copolymers was demonstrated to show extremely high anticoagulant activity and antihemolytic activity in human blood over a wide range of explored temperatures from 4 to 40 °C. The temperature-independent blood compatibility of nonionic/zwitterionic block copolymer along with their schizophrenic phase behavior in aqueous solution suggests their potential in blood-contacting applications.


Assuntos
Acrilamidas/química , Acrilamidas/síntese química , Materiais Biocompatíveis/síntese química , Eritrócitos/efeitos dos fármacos , Metacrilatos/síntese química , Polímeros/química , Acrilamidas/farmacologia , Resinas Acrílicas , Adsorção , Materiais Biocompatíveis/farmacologia , Eritrócitos/citologia , Fibrinogênio/química , Hemólise/efeitos dos fármacos , Humanos , Luz , Espectroscopia de Ressonância Magnética , Metacrilatos/farmacologia , Micelas , Peso Molecular , Nefelometria e Turbidimetria , Polimerização , Espalhamento a Baixo Ângulo , Soluções , Temperatura , Água
11.
Angew Chem Int Ed Engl ; 51(29): 7166-70, 2012 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-22696305

RESUMO

When pressure is applied to dynamic interactive membranes consisting of micelles composed of a triblock copolymer, their morphologies can be fine-tuned. Membranes with a range of porosities are accessible which can regulate and thereby control filtration performance and also display effective autonomous healing.

12.
Chem Commun (Camb) ; (48): 5051-3, 2006 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-17146524

RESUMO

The combination of reversible chain transfer chemistry with highly orthogonal [2 + 3] cycloadditions ('click chemistry') allows for the synthesis of well-defined block copolymers of monomers with extremely disparate reactivities.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA