Hemocompatible properties of polymeric derivative of paracetamol

Microwave assisted synthesis and characterization of sodium alginate-graft-poly(N,N'-dimethylacrylamide)

Modification of sodium alginate (NaAlg) was carried out using N,N'-dimethylacrylamide (DMAAm) as a monomer and azobisizobutyronitrile (AIBN) as an initiator under microwave irradiation. The effect of reaction conditions such as concentrations of DMAAm, AIBN, NaAlg as well as microwave power and temperature on grafting and grafting efficiency has been explored. Maximum grafting and grafting efficiency has been observed at 1h of grafting time, 0.291 M of DMAAm concentration, 500 W microwave irradiation power, 0.134 M of AIBN concentration, 75°C of reaction temperature and 0.5 g/dL of NaAlg concentration. The grafted copolymer has been characterized by FTIR, DSC, TGA, (13)C NMR, XRD, SEM, and GPC analysis. Cytotoxicity as standard MTT assay, apoptotic and necrotic effects of graft copolymer were investigated on L929 fibroblast cell. It has been found that the grafted copolymer is biocompatible and thermally more stable than the ungrafted alginate.

Studies on graft copolymerization of gellan gum with N,N-dimethylacrylamide by the redox system

The present paper reports the graft copolymerization of N,N-dimethylacrylamide onto gellan gumby free radical polymerization using potassium peroxymonosulphate/sarbose redox system in an inert atmosphere. The reaction conditions for maximum grafting have been optimized by varying the reaction variables, including the concentration of N,N-dimethylacrylamide(4.0×10(-2)-20×10(-2) mol dm(-3)), potassium peroxymonosulphate (0.6×10(-2)-1.4×10(-2)mol dm(-3)), sarbose (0.4×10(-3)-3.6×10(-3) mol dm(-3)), sulphuric acid (2.0×10(-3)-10×10(-3) mol dm(-3)), gellan gum (0.6-1.4 g dm(-3)) along with time duration (60-180 min) and temperature (25-45°C).Water-swelling capacity, metal ion sorption and flocculation studies of synthesized graft copolymer have been performed with respect to the parent polymer. The graft copolymer has been characterized by FTIR spectroscopy and thermogravimetric analysis.

Polymeric drugs with prolonged sustained delivery of specific anti-aggregant agents for platelets: kinetic analysis of the release mechanism

The in vitro aqueous behaviour of a metacryloyloxyethyl [2-(acetyloxy)-4-(trifluoromethyl)]benzoate (THEMA)/N,N'-dimethylacrylamide (DMA) copolymer with a THEMA molar content of 39% (labeled THDMA39) has been investigated. This composition has been selected to achieve a system able to keep both the non-water solubility during the release and the resorbability (and the water solubility) after the completion of the drug release. This copolymer exhibited, at pH 7.4, a constant release during several months, very interesting for a long term treatments required for the application of some cardiovascular devices. A kinetic model has been developed to explain the pseudo-zero-order kinetics of the release process. This model, which considers (from the aqueous studies) a linear increase with time of the amount of water present in the polymeric matrix, has been able to fit adequately the experimental data.

Novas tendências dos polímeros epoxídicos: propriedades biológicas in vitro de formulações para aplicações médicas

Este trabalho descreve as propriedades biológicas in vitro de três formulações epoxídicas usando o monômero do tipo éter diglicidílico do bisphenol-A (DGEBA) com três co-monômeros do tipo poliamina alifática de maneira independente; trietilenotetramina (TETA), 1-(2-aminoetil)piperazina (AEP) e isoforonodiamina (IPD). As interações biológicas entre os polímeros obtidos e o sangue foram estudadas in vitro utilizando quatro métodos biológicos diferentes. Estudos de adsorção protéica, adesão plaquetária, formação de trombos e citotoxicidade são apresentados e discutidos. Os ensaios de adsorção protéica mostraram que a superfície dos polímeros adsorve mais albumina humana do que fibrinogênio humano. Os resultados de adesão plaquetária e formação de trombos indicaram que os sistemas DGEBA-IPD e DGEBA-AEP exibem boa hemocompatibilidade. Os três polímeros epoxídicos não revelaram toxicidade com células de ovário de hamster chinês. Os resultados obtidos indicam que os polímeros epoxídicos baseados no IPD obedecem aos critérios de hemocompatibilidade e citotoxicidade exigidos de um biomaterial. Os polímeros epoxídicos baseados nas aminas AEP e TETA exibem apenas um comportamento não citotóxico.

Synthesis and performance of amphiphilic copolymers for blood cell separation

Three types of amphiphilic copolymers using n-butylmethacrylate (BMA) as a hydrophobic monomer, and each of N,N'-dimethylacrylamide (DMA), N-acryloylmorpholine (AMO), and N-vinylpyrrolidone (VP) as hydrophilic comonomers were synthesized for coating filters used to remove leukocytes. The influence of the amphiphilic property of the resulting filters, which were composed of nonwoven fabrics coated with the above copolymers, on leukocyte removal and platelet permeation through the filters from whole blood was investigated. The platelet permeation ratio through hydrophobic noncoated filters was only 0.2%, because platelets in whole blood adhered easily to the hydrophobic filter material. However, filters coated with poly(AMO-co-BMA) of high AMO content showed a much higher platelet permeation ratio (nearly 90%). Further, the filters coated with poly(DMA-co-BMA) also showed high permeation ratios of platelets (more than 78%) over a broad range of DMA content in the copolymer. On the other hand, the coated filters showed slightly a higher permeation ratio of leukocytes than did the noncoated filters, resulting from the increase in hydrophilicity of the surface of the filters. Moreover, the coating of the amphiphilic copolymers on the surface of the nonwoven fabrics may have affected the pore size of the filters, affecting the permeation ratio of leukocytes more strongly than that of platelets. The coated filters effectively improved platelet permeation through the filters, with a slight increase in the permeation ratio of leukocytes.

Antithrombogenic properties of bioconjugate streptokinase-polyglycerol dendrimers

Dendrimers are monodisperse, spherical and hyperbranched synthetic macromolecules with a large number of surface groups that have the potential to act as carriers for drug immobilization by covalent binding or charge transfer complexation. In this work, a bioconjugate of streptokinase and a polyglycerol dendrimer (PGLD) generation 5 was used to obtain fibrinolytic surfaces. The PGLD dendrimer was synthesized by the ring opening polymerization of deprotonated glycidol using polyglycerol as core functionality in a step-growth processes denominated divergent synthesis. The PGLD dendritic structure was confirmed by gel permeation chromatography (GPC), nuclear magnetic resonance (1H-NMR, 13C-NMR) and matrix assisted laser desorption/ionization (MALDI-TOF) techniques. The synthesized dendrimer presented low dispersion in molecular weights (Mw/Mn = 1.05) and a degree of branching of 0.82 which characterize the polymer dendritic structure. The blood compatibility of the bioconjugate PGLD-Sk was evaluated by in vitro assays such as platelet adhesion and thrombus formation. Uncoated polystyrene -microtitre plates (ELISA) was used as reference. The epifluorescence microscopy results indicate that PGLD-Sk coating showed an improved antithrombogenic character relative to the uncoated ELISA plates.

Development of new hydroactive dressings based on chitosan membranes: characterization and in vivo behavior

Different poly(vinyl alcohol) (PVA)/chitosan lactate (ChL)-blended hydrogels containing nitrofurazone as a local anti-infective drug were prepared by the phase-inversion technique. The swelling degree, surface free energy, mechanical properties, and nitrofurazone release of these membranes were determined. Blood compatibility of these systems was evaluated by the open-static platelet adhesion test with whole human blood. The results showed that water absorption into the PVA/ChL membranes slowed down, governed by the rate at which the dressing interacted with the physiological fluid. Swelling degree values up to 200% were observed. The rate of release of nitrofurazone seemed to depend on the ChL percentage on the blend as well as the pH of the solution. The surface free energy values were in the range of 20-30 dynes/cm, which was appropriate for a favorable interaction with blood. From the Young's module curve, it could be seen that elastic hydrogels were obtained with increment of ChL in the PVA/ChL blends. Values of platelet adhesion and whole blood clotting times for the PVA/ChL blends as well as the increase of ChL, which appears to reduce the fibrinogen adsorption on the PVA/ChL membranes, demonstrated that the blood compatibility of PVP/ChL blends is superior to that separated polymers. The results of in vivo experiments in rats were in very good agreement with these observations, suggesting that PVA/ChL may serve as a new type of potential wound-dressing material.

Hydrophilic hybrid IPNs of segmented polyurethanes and copolymers of vinylpyrrolidone for applications in medicine

The preparation and biocompatibility properties of thermoplastic apparent interpenetrating polymer networks (T-IPNs) of a segmented polyurethaneurea, Biospan (BS), and vinylpyrrolidone-dimethylacrylamide (VP-DMAm) copolymers, are described. The biological interaction between the obtained materials and blood was studied by in vitro methods. The addition of the VP-DMAm copolymers to form T-IPNs with BS substantially increased the equilibrium water uptake and water diffusion coefficients. Investigation of the proteins adsorption, platelet adhesion, thrombus formation and factor XII activation is presented. Investigations of the proteins adsorption of the BS/VP-DMAm T-IPNs surfaces show that the segmented polyurethane (BS) containing VP-DMAm copolymers with higher VP content adsorb more albumin than fibrinogen and gamma-globulin. The platelets adhesion, thrombus formation and factor XII activation are effectively suppressed with respect to the segmented polyurethane when VP-DMAm copolymers with high VP contents are incorporated into BS as T-IPNs.

Vinylpyrrolidone-N,N'-dimethylacrylamide water-soluble copolymers: synthesis, physical-chemical properties and proteic interactions

The radical copolymerization of N-vinyl-2-pyrrolidone (NVP) with N,N'-dimethylacrylamide (DMAm) has been studied. The copolymer compositions were determined from 1H-NMR. The radical reactivity ratios for DMAm (M1) and VP (M2) were found to be r1 = 2.232 and r2 = 0.186. An analysis of the water vapor absorption isotherms as a function of the lactam content in the copolymer is reported. It was observed that the water vapor absorption decreases with increasing VP content in the copolymer and show anomalous diffusion behavior with increasing temperature due to the coupling of diffusion and polymer relaxation mechanisms. From the water vapor sorption data the Arrhenius activation parameter (ED) and enthalpy of sorption (deltaH S) were determined. The activation parameters are found to follow the conventional trend. The poly(DMAm-co-VP) copolymers exhibited a decreased critical solution temperature (LCST) in proportion to their lactam content. Contact angle data were evaluated for the determination of surface free energy components (gamma d SV, gamma P SV and gamma SV) of the synthesized polymers. The dispersion force component (gamma d SV) of copolymers increased only slightly with the VP content whereas the polar force component (gamma P SV) decreased with the lactam content. No dependence was observed between the surface free energy (gamma SV) and copolymer compositions. The complex formation between bovine serum albumin (BSA) and the VP-DMAm copolymers in water was studied by fluorescence spectroscopy. It was found that the copolymers bind to BSA non-specifically on the surface. Phase separation was not observed after addition of copolymers to BSA solutions at pH higher or lower than isoelectric point of BSA.