Assessment of electromechanically stimulated bone marrow stem cells seeded acellular cardiac patch in a rat myocardial infarct model

In this study, we evaluated cardiomyogenic differentiation of electromechanically stimulated rat bone marrow-derived stem cells (rt-BMSCs) on an acellular bovine pericardium (aBP) and we looked at the functioning of this engineered patch in a rat myocardial infarct (MI) model. aBP was prepared using a detergent-based decellularization procedure followed by rt-BMSCs seeding, and electrical, mechanical, or electromechanical stimulations (3 millisecond pulses of 5 V cm-1at 1 Hz, 5% stretching) to enhance cardiomyogenic differentiation. Furthermore, the electromechanically stimulated patch was applied to the MI region over 3 weeks. After this period, the retrieved patch and infarct region were evaluated for the presence of calcification, inflammatory reaction (CD68), patch to host tissue cell migration, and structural sarcomere protein expressions. In conjunction with any sign of calcification, a higher number of BrdU-labelled cells, and a low level of CD68 positive cells were observed in the infarct region under electromechanically stimulated conditions compared with static conditions. More importantly, MHC, SAC, Troponin T, and N-cad positive cells were observed in both infarct region, and retrieved engineered patch after 3 weeks. In a clear alignment with other results, our developed acellular patch promoted the expression of cardiomyogenic differentiation factors under electromechanical stimulation. Our engineered patch showed a successful integration with the host tissue followed by the cell migration to the infarct region

Detailed Characterization of Structure-Property Relationship of Polyurethanes Synthesized as Biomaterials

Development of new polyurethanes (PUs) and the modification of the existing ones are still considered as novel areas. This research deals with the preparation of PUs synthesized from its starting materials (without using any solvent, catalyst or chain extender) and examination of the structure property relation through different techniques. Series of segmented elastomeric PU films were synthesized by using different combinations of toluene diisocyanate (TDI) and polyol(polyoxypropylene/polyoxyethylene triol) without using any other ingredients and by one-shot polymerization method. The chemical, thermal and mechanical properties were examined for 2D PU films and the effects of preparation parameters on the structure-property relations were discussed in detail

Preparation of Chitosan-Coated Magnetite Nanoparticles and Application for Immobilization of Laccase

In this study, immobilization of laccase (L) enzyme on magnetite (Fe(3)O(4)) nanoparticles was achieved, so that the immobilized enzyme could be used repeatedly. For this purpose, Fe(3)O(4) nanoparticles were coated and functionalized with chitosan (CS) and laccase from Trametes versicolor was immobilized onto chitosan-coated magnetic nanoparticles (Fe(3)O(4)-CS) by adsorption or covalent binding after activating the hydroxyl groups of chitosan with carbodiimide (EDAC) or cyanuric chloride (CC). For chitosan-coated magnetic nanoparticles, the thickness of CS layer was estimated as 1.0-4.8 nm by TEM, isoelectric point was detected as 6.86 by zeta (zeta)-potential measurements, and the saturation magnetization was determined as 25.2 emu g(-1) by VSM, indicating that these nanoparticles were almost superparamagnetic. For free laccase and immobilized laccase systems, the optimum pH, temperature, and kinetic parameters were investigated; and the change of the activity against repeated use of the immobilized systems were examined. The results indicated that all immobilized systems retained more than 71% of their initial activity at the end of 30 batch uses. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123:707-716, 201

Adsorption of reactive yellow 145 onto chitosan coated magnetite nanoparticles

Removal of dyes from the industrial discharge water is an important issue for safety of the environment. In this study, magnetic (magnetite, Fe3O4) nanoparticles were coated with chitosan (CS) and the efficiency of these chitosan coated magnetic nanoparticles (Fe3O4-CS) for the adsorption of a reactive textile dye (Reactive Yellow 145, RY145) was examined first time in literature. TEM, XRD, and EPR results revealed that the thickness of the coat was about 25 nm, no phase change in the spinel structure of magnetic particles existed after coating, and particles had paramagnetic property, respectively. Adsorption of RY145 on Fe3O4-CS nanoparticles occurs according to Langmuir model in the temperature range 25 degrees C-45 degrees C with a maximum adsorption capacity of 47.62 mg g(-1) at 25 degrees C, in aqueous media. Thermodynamic parameters demonstrated that the adsorption process was endothermic and spontaneous, and the maximum desorption of the dye was 80% over a single adsorption/desorption cycle. In this study, the high efficiency of the CS coated magnetic nanoparticles in the adsorption and removal of reactive dyes from water was shown on model RY145. This type of nanoparticles can be good candidates in industrial applications for the decolorization of waste waters. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 201

Preparation and characterization of zeolite beta-polyurethane composite membranes

Incorporation of zeolite into polyurethane (PU) membranes was investigated by using as-synthesized and calcined zeolite beta particles at two different loading contents (0.1 and 1 wt %). The chemical interaction between the zeolite beta crystals and PU was observed by ATR-FTIR spectroscopy. The SEM results suggested that the calcined zeolite beta crystals were more homogeneously dispersed in the composite membranes than the assynthesized zeolite beta crystals. DMA results demonstrated that all composite membranes had higher storage modulus in the rubbery state and higher stability towards thermal and mechanical degradation with respect to the control groups. Tensile testing results also showed increased tensile strength and elongation at break for all composite membranes. This study suggests that incorporating zeolite beta in its as-synthesized or calcined forms and at different amounts can be applied as an alternative method for tailoring the mechanical properties of PU membranes without changing its structural characteristics. (c) 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3378-3387, 2007

Alpha-tricalcium phosphate (alpha-TCP): solid state synthesis from different calcium precursors and the hydraulic reactivity

The effects of solid state synthesis process parameters and primary calcium precursor on the cement-type hydration efficiency (at 37A degrees C) of alpha-tricalcium phosphate (Ca-3(PO4)(2) or alpha-TCP) into hydroxyapatite (Ca10-xHPO4(PO4)(6-x)(OH)(2-x) x = 0-1, or HAp) have been investigated. alpha-TCP was synthesized by firing of stoichiometric amount of calcium carbonate (CaCO3) and monetite (CaHPO4) at 1150-1350A degrees C for 2 h. Three commercial grade CaCO3 powders of different purity were used as the starting material and the resultant alpha-TCP products for all synthesis routes were compared in terms of the material properties and the reactivity. The reactant CaHPO4 was also custom synthesized from the respective CaCO3 source. A low firing temperature in the range of 1150-1350A degrees C promoted formation of beta-polymorph as a second phase in the resultant TCP. Meanwhile, higher firing temperatures resulted in phase pure alpha-TCP with poor hydraulic reactivity. The extension of firing operation also led to a decrease in the reactivity. It was found that identical synthesis history, morphology, particle size and crystallinity match between the alpha-TCPs produced from different CaCO3 sources do not essentially culminate in products exhibiting similar hydraulic reactivity. The changes in reactivity are arising from differences in the trace amount of impurities found in the CaCO3 precursors. In this regard, a correlation between the observed hydraulic reactivities and the impurity content of the CaCO3 powders-as determined by inductively coupled plasma mass spectrometry-has been established. A high level of magnesium impurity in the CaCO3 almost completely hampers the hydration of alpha-TCP. This impurity also favors formation of beta- instead of alpha-polymorph in the product of TCP upon firing

Evaluation of maxillary sinus volume and surface area in children with beta-thalassaemia using cone beam computed tomography

Objectives: Among children with beta-thalassaemia, skeletal changes and abnormalities, such as decreased volume or obliteration of the sinus, result primarily from hypertrophy and expansion of the erythroid marrow due to ineffective erythropoiesis. This study evaluated the volumes and surface areas of the maxillary sinuses of children with beta-thalassaemia using cone beam computed tomography (CBCT), and compared these findings with corresponding measurements in age- and sex-matched control children

Surface characterization and radical decay studies of oxygen plasma-treated PMMA films

Polymethylmethacrylate (PMMA) films were modified by RF oxygen plasma with various powers applied for different periods, and the effects of these parameters on the surface properties such as hydrophilicity, surface free energy (SFE), chemistry, and topography were investigated by water contact angle, goniometer, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy, and the types of the created free radicals and their decay were detected by electron spin resonance spectroscopy (ESR). SFE and contact angle results varied depending on the plasma parameters. Oxygen plasma treatment (100 W-30 min) enhanced the hydrophilicity of PMMA surface as shown by decreasing the water contact angle from 70 degrees to 26 degrees. XPS analysis showed the change in the amounts of the present functionalities as well as formation of new groups as free carbonyl and carbonate groups. The roughness of the surface increased considerably from similar to 2 nm to similar to 75 nm after 100 W-30 min oxygen plasma treatment. ESR analysis indicated the introduction of peroxy radicals by oxygen plasma treatment, and the intensity of the radicals increased with increasing the applied power. Significant decrease in radical concentration was observed especially for the samples treated with higher powers when the samples were kept under the atmospheric conditions. As a conclusion, RF plasma, causes changes in the chemical and physical properties of the materials depending on the applied parameters, and can be used for the creation of specific groups or radicals to link or immobilize active molecules onto the surface of a material. Copyright (C) 2012 John Wiley & Sons, Ltd

Gentamicin loaded beta-tricalcium phosphate/gelatin composite microspheres as biodegradable bone fillers

In this study, novel composite bone fillers with microspherical shape, biodegradable property, and antibacterial effect were designed and prepared. Various fillers with different beta-tricalcium phosphate (beta-TCP)/gelatin (G)/glutaraldeyde (GA) compositions were loaded with a model antibiotic, gentamicin. The effect of composition and preparation conditions on the release of gentamicin was investigated in in vitro conditions. Complete release were observed in 12 h for pure beta-TCP powder, and this period was extended up to 96 h as the gelatin content increased in the microspheres. Morphological and chemical structures of the microspheres, before and after the release studies, were investigated by scanning electron microscopy and Fourier transform infrared, respectively. Antibacterial activities were examined against Escherichia coli by using disc diffusion method and promising results were obtained. It is proposed that these novel beta-TCP/G/GA microspheres can be applied locally to prevent and/or eliminate infection that might occur around a defected region of hard tissue and supports the healing process. POLYM. COMPOS., 2012. (c) 2012 Society of Plastics Engineer

Poly(epsilon-caprolactone) composites containing gentamicin-loaded beta-tricalcium phosphate/gelatin microspheres as bone tissue supports

In this work, novel antibacterial composites were prepared by using poly(epsilon-caprolactone) (PCL) as the main matrix material, and gentamicin-loaded microspheres composed of beta-tricalcium phosphate (beta-TCP) and gelatin. The purpose is to use this biodegradable material as a support for bone tissue. This composite system is expected to enhance bone regeneration by the presence of beta-TCP and prevent a possible infection that might occur around the defected bone region by the release of gentamicin. The effects of the ratio of the beta-TCP/gelatin microspheres on the morphological, mechanical, and degradation properties of composite films as well as in vitro antibiotic release and antibacterial activities against Escherichia coli and Staphylococcus aureus were investigated. The results showed that the composites of PCL and beta-TCP/gelatin microspheres had antibacterial activities for both bacteria. (C) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 201