Poly(ethylene-co-methyl acrylate)/poly(caprolactone) triol blends for drug delivery systems: characterization and drug release

Poly(ethylene-co-methyl acrylate) (EMA) and poly (caprolactone) triol (PCL-T) blends, a biodegradable aliphatic polyester with low molecular weight and moderate water solubility containing diltiazem hydrochloride (DZ) were studied in terms of the thermal and morphological properties, and drug release mechanism. An increase in the PCL-T content in the EMA/PCL-T/DZ films decreased the degree of DZ crystallinity. Drug release from these films is temperature-dependent, and it is possible to modify the drug release rate by adjusting the EMA/PCL-T composition of the blends. The mechanism of drug release is governed by PCL-T melting and PCL-T leaching from EMA matrix

Mechanical and moisture barrier properties of titanium dioxide nanoparticles and halloysite nanotubes reinforced polylactic acid (PLA)

Polylactic acid (PLA) has been larger used in biomedical field due to its low toxicity and biodegradability. The aim of this study was to produce PLLA nanocomposites, by melt extrusion, containing Halloysite nanotubes (HNT) and/or titanium dioxide (TiO2) nanoparticles. Immediately after drying, PLLA was mechanically homogenized with the nanofillers and then melt blended using a single screw extruder (L/D = 30) at a speed of 110 rpm, with three heating zones in which the following temperatures were maintained: 150, 150 and 160ºC (AX Plásticos model AX14 LD30). The film samples were obtained by compression molding in a press with a temperature profile of 235 ± 5ºC for 2.5 min, after pressing, films were cooled up to room temperature. The mechanical tests were performed according to ASTM D882-09 and the water vapor permeability (WVP) was measured according to ASTM E-96, in triplicate. The tensile properties indicated that the modulus was improved with increased TiO2 content up to 1g/100g PLLA. The Young's modulus (YM) of the PLA was increased from 3047 MPa to 3222 MPa with the addition of 1g TiO2/100g PLLA. The tensile strength (TS) of films increases with the TiO2 content. In both cases, the YM and TS are achieved at the 1% content of TiO2 and is due to the reinforcing effect of nanoparticles. Pristine PLA showed a strain at break (SB) of 3.56%, while the SB of nanocomposites were significant lower, for instance the SB of composite containing 7.5 g HNT/100g PLLA was around 1.90 %. The WVP of samples was increased by increasing the nano filler content. It should be expected that an increase of nanofiller content would decrease the mass transfer of water molecules throughout the samples due to the increase in the way water molecules will have to cross to permeate the material. However, this was not observed. Therefore, this result can be explained considering the molecular structure of both fillers, which contain several hydroxyl groups in the surface, making the end material more hydrophilicPostprint (published version

Atividade antibacteriana de fibras têxteis contendo nanopartículas de poli (óxido de etileno-b-ácido lático) com óleos essenciais incorporados

Neste estudo foi avaliada a atividade antibacteriana de fibras têxteis contendo nanopartículas de poli(óxido de etileno-b-ácido lático) com óleos essenciais incorporados. O sistema desenvolvido demonstrou atividade antibacteriana contra Staphylococcus aureus, sugerindo seu potencial uso como agente antibacteriano. Foram utilizados copolímeros dibloco baseados em um bloco fixo de PEO (5kDa) e dois segmentos de PLA diferentes (4,5 e 10kDa). A morfologia, a eficiência do encapsulamento, a interação da blenda de óleos essenciais (incluindo, lavanda, melaleuca, tomilho, cravo, cedro e capim limão) e polímero e a cinética de liberação do agente ativo nas nanopartículas foram avaliadas. O raio hidrodinâmico das nanopartículas determinado pela dispersão da luz foi afetado pelo tamanho do bloco de poli(ácido lático). A liberação in vitro sugere que a barreira polimérica é capaz de controlar a liberação de óleo. A atividade antibacteriana foi mais eficaz em tecidos com fibras arranjadas aleatoriamente. De acordo com estudos da literatura, nanopartículas obtidas de copolímeros com menor massa molar de PLA favoreceram a liberação da mistura de óleos essenciais. O processo de incorporação dos óleos essenciais nas fibras têxteis mostrou-se eficiente sugerindo viabilidade quanto ao uso desse sistema no controle antibacteriano. Os sistemas desenvolvidos oferecem uma nova estratégia para a liberação controlada com atividade antibacteriana e apresentam potenciais aplicações na indústria calçadista.Palavras-chave: nanopartículas, óleos essenciais, efeito antibacteriano.

Dynamic light scattering and viscosimetry of aqueous solutions of pectin, sodium alginate and their mixtures: effects of added salt, concentration, counterions, temperature and chelating agent

The effects of added salt, concentration, counterions, temperature and chelating agent on aqueous solutions of pectin, sodium alginate and their mixtures were analyzed by viscosimetry and dynamic light scattering (DLS) techniques. The intrinsic viscosity of the binary systems decreased with the addition of salt and with temperature, while it was found to be insensitive to the addition of NaEDTA. As expected the intrinsic viscosity of the ternary alginate/pectin/water system was equal to the average of the intrinsic viscosity for the binary systems. The DLS studies indicated a bimodal distribution (fast and slow relaxation modes) for both binary and ternary systems at 25 °C, reflecting aggregation. A significant increase in the hydrodynamic radius, in the case of the slow mode, was observed for the binary and ternary systems in the presence of NaCl and KCl at 25 °C. However, at 80 °C the hydrodynamic radius for the slow mode in KCl solutions was practically constant for all the studied systems, except for the alginate binary solutions in which were not observed

Effect of polyethylene glycols addition in microsphere formulations of cellullose acetate butyrate on efficacy carbamazepine and particles morphology encapsulation

O desenvolvimento de microesferas de carbamazepina (CBZ) de liberação prolongada tem sido realizado, empregando-se a técnica de emulsificação/evaporação do solvente e o acetobutirato de celulose (ABC70) para a obtenção da matriz polimérica. Buscando modular a velocidade de liberação do fármaco, a adição de polietilenoglicóis na fase interna da emulsão foi testada. Quando comparados com as microesferas preparadas unicamente com ABC70, o teor e a eficiência de encapsulação da CBZ, estimados após análise por CLAE, foram drasticamente reduzidos com a adição de PEG4000. Entretanto, a adição de PEG 1500 perfazendo 10% da massa total de polímero não pareceu alterar o teor de CBZ, demonstrando que o peso molecular do PEG influencia a encapsulação da CBZ. Partículas mais porosas foram visualizadas por MEV, quando o PEG1500 ou 4000 foram adicionados. Entretanto, a perda da forma esférica foi observada quando uma mistura de ABC70:PEG 4000 1:1 foi empregada. A adição de polietilenoglicóis não pareceu afetar o diâmetro médio das microesferas. A redução na encapsulação da CBZ foi associada à extração do PEG durante a etapa de evaporação do solvente e a sua capacidade de dissolvê-la na fase externa da emulsão. O controle do desenvolvimento da presença de poros, pelo ajuste da concentração e do peso molecular do PEG, pode ser útil na modulação do perfil de liberação do fármaco.With the aim of obtaining carbamazepine (CBZ) prolonged release dosage forms, cellulose acetate butyrate (CAB70) microspheres have been prepared by the emulsion/solvent evaporation method. In order to modulate the CBZ release, the addition of polyethylene glycols (PEG) in the internal phase of the emulsion was carried out. When compared with microspheres prepared only from CAB70, the encapsulation efficiency and the CBZ content were drastically reduced by the PEG 4000 addition. On the other hand, the incorporation of 10% (w/w) of PEG1500 did not affect the drug content in the microspheres. Most porous particles werw observed by SEM when PEG 1500 or 4000 was added to the formulations, however the lost of the spherical shape of the particles was verified when an ABC70:PEG 4000 1:1 mixture was used to prepare the microspheres. The addition of PEGs did not appear to affect the mean diameter of the particles. The decrease of the CBZ content was related to the PEG extraction during the solvent evaporation step and to its ability to dissolve the CBZ in the external phase of the emulsion. The porosity development control, by adjusting the amount or the molecular weight of PEG, can be useful in the drug release from microparticles

Synthesis and Characterization of Poly(Styrene)-b-Poly(y-Benzyl-L-Glutamate) Diblock Copolymers

Neste trabalho foi realizada a síntese e a caracterização de copolímeros dibloco formados pelo poli(estireno)-b-poli(γ-benzil-L-glutamato) (PS-b-PBLG). O bloco de PS foi sintetizado via polimerização aniônica, enquanto o bloco de PBLG foi sintetizado via polimerização por abertura de anel. Os homopolímeros e copolímeros foram caracterizados por meio de técnicas clássicas de ressonância magnética nuclear de próton e carbono (RMN 1H e 13C), cromatografia de permeação em gel (GPC) e análise térmica (calorimetria de varredura diferencial (DSC) e termogravimetria (TG)). A caracterização em solução foi realizada utilizando-se a técnica de espalhamento de luz estático (SLS). Na análise de SLS foram determinados parâmetros como a massa molar ponderal média (Mwm), o segundo coeficiente virial (A2) e a concentração crítica (C*) para os homopolímeros puros e para o copolímero PS100-b-PBLG330. http://dx.doi.org/10.18226/23185279.v2iss1p31 The synthesis and characterization of diblock copolymers formed by poly(styrene) and poly(γ-benzyl-L-glutamate) (PBLG) were studied. The PS and PBLG blocks were obtained by anionic and open ring polymerization, respectively. The homopolymers and copolymers were characterized by classical techniques such as nuclear magnetic resonance of proton and carbon (1H and 13C NMR), gel permeation chromatography (GPC) and thermal analysis (differential scanning calorimetry (DSC) and thermogravimetry (TGA)). The characterization in solution was performed using static light scattering (SLS). In the analysis by SLS, parameters such as average molar mass (Mwm), second virial coefficient (A2) and critical concentration (C*) for the pure homopolymers and the copolymer PS100-b-PBLG330 were determined. http://dx.doi.org/10.18226/23185279.v2iss1p3

Potential use of cellulose acetate butyrate and pluronic F68® blends in the modulation of the diclofenac sodium release from microspheres

Microspheres were prepared using the emulsion/solvent evaporation method with the aim of obtaining diclofenac sodium (DFS) prolonged release dosage forms. The effects of the drug:polymer ratio and addition of Pluronic F68® to the formulations on drug content, particle size and DFS release rate were evaluated using a 22 factorial design. The DFS encapsulation efficiency (%) and the drug content varied from 40 to 70 % and from 4.5 to 13 mg/100 mg, respectively. The mean particle diameter varied from 720 to 850 μm. The addition of Pluronic F68® to the formulations led to an increase in the roughness of the surface. The differential scanning calorimetry (DSC) and infrared spectroscopy (FTIR) studies indicated the presence of Pluronic F68® in the particles. The statistical analysis revealed that the drug content and the release rate of DFS were significantly increased when 1:4 drug:polymer ratio and Pluronic F68® was used to prepare the microspheres.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Adhesion of L929 mouse ribroblast cells on poly(styrene)/poly(methyl methacrylate) films

Films of pure poly(styrene) (PS), pure poly(methyl methacrylate) (PMMA), a 1:1 PS/PMMA blend and a PS-b-PMMA copolymer, were prepared and tested for cell adhesion using L929 mouse fibroblasts. All polymer films were found to be good substrates for cell adhesion and proliferation, and both processes were slightly favored on films of the 1:1 PS/PMMA blend. The same results were obtained in terms of cell number and morphology for cells cultured on films, glass coverslips or plastic plates. The chemical characteristics of polymer films make them suitable supports for cell attachment and proliferation, indicating that these films are good candidates for biomedical uses