The Development and Study of Some Composite Membranes Based on Polyurethanes and Iron Oxide Nanoparticles.

To improve the performance of composite membranes, their morphology can be tailored by precise control of the fabrication methods and processing conditions. To this end, the aim of this study was to develop novel high-performance composite membranes based on polyurethane matrix and magnetic nanoparticles with the desired morphology and stability, by selecting the proper method and fabrication systems. These well-prepared composite membranes were investigated from the point of view of their morphological, physico-chemical, mechanical, dielectric, and magnetic properties. In addition, their in vitro cytocompatibility was also verified by the MTT assay and their cell morphology. The results of this study can provide valuable information regarding the preparation of magnetic polyurethane-based composite membranes that could be used to design some suitable devices with tailored properties, in order to improve the image quality in magnetic resonance imaging investigations and to suppress local image artifacts and blurring.

Composite Materials Based on Gelatin and Iron Oxide Nanoparticles for MRI Accuracy.

The majority of recent studies have focused on obtaining MRI materials for internal use. However, this study focuses on a straightforward method for preparing gelatin-based materials with iron oxide nanoparticles (G-Fe2O3 and G-Fe3O4) for external use. The newly obtained materials must be precisely tuned to match the requirements and usage situation because they will be in close touch with human/animal skin. The biocompatible structures formed by gelatin, tannic acid, and iron oxide nanoparticles were investigated by using FTIR spectroscopy, SEM-EDAX analysis, and contact angle methods. The physico-chemical properties were obtained by using mechanical investigations, dynamic vapor sorption analysis, and bulk magnetic determination. The size and shape of iron oxide nanoparticles dictates the magnetic behavior of the gelatin-based samples. The magnetization curves revealed a typical S-shaped superparamagnetic behavior which is evidence of improved MRI image accuracy. In addition, the MTT assay was used to demonstrate the non-toxicity of the samples, and the antibacterial test confirmed satisfactory findings for all G-based materials.

Composite Materials Based on Iron Oxide Nanoparticles and Polyurethane for Improving the Quality of MRI.

Polyether urethane (PU)-based magnetic composite materials, containing different types and concentrations of iron oxide nanostructures (Fe2O3 and Fe3O4), were prepared and investigated as a novel composite platform that could be explored in different applications, especially for the improvement of the image quality of MRI investigations. Firstly, the PU structure was synthetized by means of a polyaddition reaction and then hematite (Fe2O3) and magnetite (Fe3O4) nanoparticles were added to the PU matrices to prepare magnetic nanocomposites. The type and amount of iron oxide nanoparticles influenced its structural, morphological, mechanical, dielectric, and magnetic properties. Thus, the morphology and wettability of the PU nanocomposites surfaces presented different behaviours depending on the amount of the iron oxide nanoparticles embedded in the matrices. Mechanical, dielectric, and magnetic properties were enhanced in the composites' samples when compared with pristine PU matrix. In addition, the investigation of in vitro cytocompatibility of prepared PU nanocomposites showed that these samples are good candidates for biomedical applications, with cell viability levels in the range of 80-90%. Considering all the investigations, we can conclude that the addition of magnetic particles introduced additional properties to the composite, which could significantly expand the functionality of the materials developed in this work.

Preparation and Characterization of Electrospun Collagen Based Composites for Biomedical Applications.

Electrospinning is a widely used technology for obtaining nanofibers from synthetic and natural polymers. In this study, electrospun mats from collagen (C), polyethylene terephthalate (PET) and a blend of the two (C-PET) were prepared and stabilized through a cross-linking process. The aim of this research was to prepare and characterize the nanofiber structure by Fourier-transform infrared with attenuated total reflectance spectroscopy (FTIR-ATR) in close correlation with dynamic vapor sorption (DVS). The studies indicated that C-PET nanofibrous mats shows improved mechanical properties compared to collagen samples. A correlation between morphological, structural and cytotoxic proprieties of the studied samples were emphasized and the results suggest that the prepared nanofiber mats could be a promising candidate for tissue-engineering applications, especially dermal applications.

Development and Performance of Bioactive Compounds-Loaded Cellulose/Collagen/Polyurethane Materials.

Here we present a new biomaterial based on cellulose, collagen and polyurethane, obtained by dissolving in butyl imidazole chloride. This material served as a matrix for the incorporation of tannin and lipoic acid, as well as bioactive substances with antioxidant properties. The introduction of these bioactive principles into the base matrix led to an increase of the compressive strength in the range 105-139 kPa. An increase of 29.85% of the mucoadhesiveness of the film containing tannin, as compared to the reference, prolongs the bioavailability of the active substance; a fact also demonstrated by the controlled release studies. The presence of bioactive principles, as well as tannins and lipoic acid, gives biomaterials an antioxidant capacity on average 40%-50% higher compared to the base matrix. The results of the tests of the mechanical resistance, mucoadhesiveness, bioadhesiveness, water absorption and antioxidant capacity of active principles recommend these biomaterials for the manufacture of cosmetic masks or patches.

Preparation and Evaluation of Nanofibrous Hydroxypropyl Cellulose and ß-Cyclodextrin Polyurethane Composite Mats.

A series of nanofibrous composite mats based on polyurethane urea siloxane (PUUS), hydroxypropyl cellulose (HPC) and ß-cyclodextrin (ß-CD) was prepared using electrospinning technique. PUUS was synthesized by two steps solution polymerization procedure from polytetramethylene ether glycol (PTMEG), dimethylol propionic acid (DMPA), 4,4'-diphenylmethane diisocyanate (MDI) and 1,3-bis-(3-aminopropyl) tetramethyldisiloxane (BATD) as chain extender. Then, the composites were prepared by blending PUUS with HPC or ßCD in a ratio of 9:1 (w/w), in 15% dimethylformamide (DMF). The PUUS and PUUS based composite solutions were used for preparation of nanofibrous mats. In order to identify the potential applications, different techniques were used to evaluate the chemical structure (Fourier transform infrared-attenuated total reflectance spectroscopy-FTIR-ATR), morphological structure (Scanning electron microscopy-SEM and Atomic force microscopy-AFM), surface properties (contact angle, dynamic vapors sorption-DVS), mechanical characteristics (tensile tests), thermal (differential scanning calorimetry-DSC) and some preliminary tests for biocompatibility and microbial adhesion.

Polyurethane/ß-cyclodextrin/ciprofloxacin composite films for possible medical coatings with antibacterial properties.

Polyurethane/ß-cyclodextrin/ciprofloxacin composite films have been prepared and structural and morphological behaviours reveal the progressive incorporation of the drug ciprofloxacin into polyurethane backbones. Spectral changes such as frequency shifts, band broadening and changes in the intensity are indicative of drug-polyurethane interactions. X-ray powder diffraction experiments demonstrate that ciprofloxacin retains its crystallinity in the polyurethane matrix. Electron microscopy and mercury porosimetry reveal open and interconnected macroporous pore morphology for the as-prepared polyurethane-drug films. Antimicrobial activity was evaluated by the agar disc diffusion method and the ciprofloxacin-polyurethane films demonstrate their potency as antibacterial medical systems. However, the ciprofloxacin-polyurethane films do not reveal antifungal properties.

Evaluation of polyurethane based on cellulose derivative-ketoprofen biosystem for implant biomedical devices.

A polyether-urethane based on polytetrahydrofuran containing hydroxypropyl cellulose for biomedical applications was tested for its biocompatibility. Ketoprofen was incorporated (3% and 6%) in the polyurethane matrix as an anti-inflammatory drug. Dynamic vapour sorption method was employed for testing the water sorption/desorption behaviour of these materials with the determination of the surface isotherms, surface parameters and the kinetic curves of sorption/desorption processes. Cytotoxicity testing in vitro for quantifying cell proliferation was employed, and the results evidence noncytotoxicity for the studied polyurethane-drug systems. In vivo biocompatibility study was performed on 200 g weight male rats. It was found that after implantation of the polyether-urethane samples a reduced acute inflammation occurred, especially for polyurethane samples with added ketoprofen.

Thermal, dynamic mechanical, and dielectric analyses of some polyurethane biocomposites.

Polymer biocomposites based on segmented poly(ester urethane) and extracellular matrix components have been prepared for the development of tissue engineering applications with improved biological characteristics of the materials in contact with blood and tissues for long periods. Thermal, dynamical, and dielectrical analyses were employed to study the molecular dynamics of these materials and the influence of changing the physical network morphology and hydrogen bond interactions accompanied by phase transitions, interfacial effects, and polarization or conductivity. All phenomena that concur in the tested materials are evaluated by cross-examination of the dynamic mechanical characteristic properties (storage modulus, loss modulus, and loss factor) and dielectric properties (relative permittivity, relative loss factor, and loss tangent) as a function of temperature. Comparative aspects were elucidated by calculating the apparent activation energies of multiplex experiments.

Segmented biopolyurethanes for medical applications.

Polyurethanes are one of the most popular groups of biomaterials applied for medical devices. Their segmented block copolymeric character endows them a wide range of versatility in terms of tailoring their physical properties, blood and tissue compatibility. Polyester- and polyether-urethanes have been modified with hydroxypropyl cellulose aiming the change of their surface and bulk characteristics to confer them biomaterial qualities. In this respect, dynamic contact angle measurements, dynamic mechanical analyses accompanied by mechanical testing have been done. Platelet adhesion test has been carried out in vitro and the use of hydroxypropyl cellulose in the polyurethane matrix reduces the platelet adhesion and therefore recommends them as candidates for biocompatible materials.