RESUMEN
Este estudo visou sintetizar e caracterizar mantas não tecidas de nanofibras (NFs) do acrilonitrila butadieno estireno (ABS), poliamida 6 (PA6) e poliestireno (PS), e avaliar sua capacidade de ser utilizada como reforço no polimetilmetacrilato (PMMA). O ABS foi dissolvido em diclorometano e acetona, a PA6 pelo 1,1,1,3,3,3- Hexafluoro-2-propanol e o PS pela dimetilformamida, em uma concentração definida em estudo piloto. Após determinados os melhores parâmetros de eletrofiação (tensão contínua, razão de fluxo e distância agulha/anteparo) as amostras de cada grupo foram analisadas em microscopia eletrônica de varredura, análise de molhabilidade, análise de difratometria de raios X, espectroscopia de infravermelho por transformada de Fourier, diâmetro das fibras e resistência a tração. As NFs produzidas foram incluídas na área de tração dos corpos de prova em resina acrílica ativada termicamente (RAAT) conforme ISO1567, perfazendo 4 grupos (n=20), 1 controle (Grupo 1) e 3 experimentais (Grupo 2, RAAT+NF/ABS; Grupo 2, RAAT+NF/PA6; Grupo 4, RAAT+NF/PS), para ensaio de flexão três pontos para analisar suas propriedades mecânicas, como: módulos de elasticidade e resistência a flexão. De acordo com os testes de caracterização, as mantas se apresentaram hidrofóbicas, não houve mudança de sua estrutura polimérica, concluindo-se então que a técnica da eletrofiação foi promissora na síntese de mantas de NFs. A variação dos parâmetros afetou diretamente a morfologia, resultando em fibras uniformes, volumosas e sem defeitos (beads). Os Grupos 3 e 4 (RAAT+NF/PA6 e RAAT+NF F/PS) apresentaram um maior módulo elástico, conferindo maior rigidez ao material (AU)
This study aimed to synthesize and characterize non-woven blankets of acrylonitrile butadiene styrene (ABS), polyamide 6 (PA6) and polystyrene (PS) nanofibers (NFs), and to evaluate their ability to be used as reinforcement in polymethyl methacrylate (PMMA). ABS was dissolved in dichloromethane and acetone, PA6 by 1,1,1,3,3,3- hexafluoro-2-propanol and PS by dimethylformamide at a concentration defined in a pilot study. After determining the best electrospun parameters (continuous voltage, flow rate and needle/shield distance) the samples from each group were analyzed by scanning electron microscopy, wettability analysis, X-ray diffraction analysis, Fourier transform infrared spectroscopy, fiber diameter and tensile strength. The NFs produced were included in the tensile area of the thermally activated acrylic resin (RAAT) specimens according to ISO1567, making up 4 groups (n = 20), 1 control (Group 1) and 3 experimental (Group 2, RAAT+NF/ABS; Group 3, RAAT+NF/PA6 and Group 4 (RAAT+NF/PS), for three point bending test to analyze their mechanical properties, as: modules of elasticity and flexural strength. According to the characterization tests, the blankets were hydrophobic, there was no change in their polymeric structure, concluding that the electrospinning technique was promising in the synthesis of NFs blankets. The parameters variation affected directly in the morphology, resulting in uniform, bulky and without defects (beads) NFs blankets. The Groups 3 and 4 (NF/PA6+RAAT and NF/PS+RAAT) presented a superior elastic modulus, therefore a superior rigidity(AU)
Asunto(s)
Polimetil Metacrilato/síntesis química , Polímeros/efectos adversos , Polimetil Metacrilato/administración & dosificaciónAsunto(s)
Materiales Biocompatibles/química , Sustitutos de Huesos/química , Cerámica/química , Colágeno/química , Magnesio/química , Andamios del Tejido/química , Animales , Materiales Biocompatibles/metabolismo , Regeneración Ósea , Sustitutos de Huesos/metabolismo , Cerámica/metabolismo , Colágeno/metabolismo , Reactivos de Enlaces Cruzados/química , Magnesio/metabolismo , Masculino , Fenómenos Mecánicos , Modelos Animales , Osteogénesis , Polimetil Metacrilato/síntesis química , Polimetil Metacrilato/metabolismo , Prótesis e Implantes , Ratas Wistar , Factores de Tiempo , Ingeniería de TejidosRESUMEN
The purpose of this Article is to characterize polymeric particles of poly(methylmethacrylate) (PMMA) synthesized in the presence of one of two different quaternary ammonium surfactants (QACs): cetyltrimethylammonium bromide (CTAB) or dioctadecyldimethylammonium bromide (DODAB). The methods used are dynamic light scattering for sizing, polydispersity and zeta potential analysis, scanning electron microscopy (SEM) for morphology visualization, and plating plus colony-forming unities (CFU) counting for the determination of antimicrobial activity. The results point out the high QAC concentration required to obtain cationic and bioactive antimicrobial particles with good colloidal stability and a permanent load of the polymeric network with QACs. Over a range of micromolar QAC concentrations, there is remarkable antimicrobial activity of PMMA/CTAB or PMMA/DODAB particles, which is much higher than those determined for the QACs by themselves. Loading the biocompatible polyacrylate particles with QACs is a facile, fast, low-cost approach to obtaining highly efficient antimicrobial nanoparticles.
Asunto(s)
Antibacterianos/farmacología , Polimetil Metacrilato/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Compuestos de Amonio Cuaternario/química , Staphylococcus aureus/efectos de los fármacos , Tensoactivos/química , Antibacterianos/síntesis química , Antibacterianos/química , Supervivencia Celular/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Emulsiones/síntesis química , Emulsiones/química , Emulsiones/farmacología , Pruebas de Sensibilidad Microbiana , Tamaño de la Partícula , Polimerizacion , Polimetil Metacrilato/síntesis química , Polimetil Metacrilato/química , Pseudomonas aeruginosa/citología , Staphylococcus aureus/citología , Relación Estructura-Actividad , Propiedades de SuperficieRESUMEN
Core-shell nanoparticles consisting of polybutyl acrylate (PBA) rubbery core and a polymethyl methacrylate (PMMA) shell, with different core-shell ratios, were synthesized in order to enhance the fracture toughness of the acrylic bone cements prepared with them. It was observed by TEM and SEM that the core-shell nanoparticles exhibited a spherical morphology with ca. 120 nm in diameter and that both modulus and tensile strength decreased by increasing the PBA content; the desired structuring pattern in the synthesized particles was confirmed by DMA. Also, experimental bone cements were prepared with variable amounts (0, 5, 10 and 20 wt.%) of nanoparticles with a core-shell ratio of 30/70 in order to study the influence of these nanostructured particles on the physicochemical, mechanical and fracture properties of bone cements. It was found that the addition of nanostructured particles to bone cements caused a significant reduction in the peak temperature and setting time while the glass transition temperature (Tg) of cements increased with increasing particles content. On the other hand, modulus and strength of bone cements decreased when particles were incorporated but fracture toughness was increased.
Asunto(s)
Fenómenos Mecánicos , Nanopartículas/química , Polimetil Metacrilato/química , Polimetil Metacrilato/síntesis química , Fuerza Compresiva , Módulo de Elasticidad , Emulsiones/química , Látex/química , Ensayo de Materiales , Microscopía Electrónica de Rastreo , Peso Molecular , Nanopartículas/ultraestructura , Tamaño de la Partícula , Polimerizacion , Polvos , Espectroscopía Infrarroja por Transformada de Fourier , Estrés Mecánico , Resistencia a la TracciónRESUMEN
The emergence of multidrug-resistant bacteria associated with blood-contacting artificial materials is a growing health problem, which demands new approaches in the field of biomaterials research. In this study, a poly(sulfhydrylated polyester) (PSPE) was synthesized by the polyesterification reaction of mercaptosuccinic acid with 3-mercapto-1,2-propanediol and blended with poly(methyl methacrylate) (PMMA) from solution, leading to solid PSPE/PMMA films, with three different PSPE : PMMMA mass ratios. These films were subsequently S-nitrosated through the immersion in acidified nitrite solution, yielding poly(nitrosated)polyester/PMMA (PNPE/PMMA) films. A polyurethane intravascular catheter coated with PNPE/PMMA was shown to release nitric oxide (NO) in phosphate buffered saline solution (pH 7.4) at 37 degrees C at rates of 4.6 nmol/cm(2)/h in the first 6 h and 0.8 nmol/cm(2)/h in the next 12 h. When used to coat the bottom of culture plates, NO released from these films exerted a potent dose- and time-dependent antimicrobial activity against Staphylococcus aureus and a multidrug-resistant Pseudomonas aeruginosa strains. This antibacterial effect of PSPE/PMMA films opens a new perspective for the coating of blood-contacting artificial materials, for avoiding their colonization with highly resistant bacteria.
Asunto(s)
Antibacterianos/administración & dosificación , Antibacterianos/farmacología , Materiales Biocompatibles/química , Óxido Nítrico/administración & dosificación , Óxido Nítrico/farmacología , Poliésteres/química , Materiales Biocompatibles/síntesis química , Materiales Biocompatibles/farmacología , Catéteres de Permanencia , Poliésteres/síntesis química , Poliésteres/farmacología , Polimetil Metacrilato/síntesis química , Polimetil Metacrilato/química , Polimetil Metacrilato/farmacología , Pseudomonas aeruginosa/efectos de los fármacos , Staphylococcus aureus/efectos de los fármacos , Compuestos de Sulfhidrilo/síntesis química , Compuestos de Sulfhidrilo/química , Compuestos de Sulfhidrilo/farmacologíaRESUMEN
A nitric oxide (NO) donor polyester containing multiple S-nitrosothiol (S-NO) groups covalently attached to the polymer backbone was synthesized through the esterification of poly(ethylene glycol) with mercaptosuccinic acid, followed by the nitrosation of the -SH moieties. The polynitrosated polyester (PNPE) obtained was blended with poly(methyl methacrylate) (PMMA), yielding solid films capable of releasing NO. Scanning electron microscopy analysis showed that acrylic plates and stainless steel intracoronary stents can be coated with continuous and adherent PNPE/PMMA films. After an initial NO burst, these films release NO spontaneously in dry condition or immersed in aqueous solution at constant rates of 1.8 and 180 nmol/g/h, respectively, for more than 24 h at physiological temperature. PNPE/PMMA coated surfaces were shown to inhibit platelet adhesion when in contact with whole blood. These results show that PNPE/PMMA blend can be used for the coating of blood-contacting surfaces, with potential to inhibit thrombosis and restenosis after stenting.