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Although the degradation of polylactide has been relatively well understood, there is still a lack of reliable data on the behavior of its composites at specific temperatures. This paper studies the hydrolytic degradability of polylactide/not activated smectite clay nanocomposites in the 6 weeks accelerated degradation at 80 °C which has not been widely documented so far. The composites with 3 wt%, 5 wt% and 10 wt% of smectite filler content obtained by injection molding were investigated and compared to the neat polylactide matrix material. The results of degradation at 80 °C were referred to the hydrolytic degradation at 25 °C and 37 °C. Macroscopic changes in the nanocomposites, their molecular weight and pH of medium was monitored during the degradation time. The influence of clay addition on the crystallization, glass transition and the melting temperature was also studied by differential scanning calorimetry (DSC). The DSC results show that the presence of smectite clay results in a shift of the onset peak for the melting temperatures towards higher values while for the glass transition towards the lower ones. A significant difference in degradation rate between the polylactide matrix and the polylactide/clay nanocomposites was also noted. The shortened degradation time of the nanocomposites increases their potential for use in biomedical applications, but also in disposable thermoplastic products which are increasingly used. [ABSTRACT FROM AUTHOR]

Polymer-based nanocomposites containing biocompatible and bioactive nanocomponents seem to be excellent materials that could be used in many biomedical applications. The aim of this study was biological evaluation of resorbable polymer-based nanocomposites (PLA, PCL) and their modifications with ceramic nanoparticles (silica - SiO2, montmorylonit - MMT) or carbon nanotubes. The nanocomposites were seeded with the human osteoblast-like MG 63 cells. After 1, 3 and 7 days of incubation, Trypan blue exclusion test was used to determine the viability and number of cells. The cell population density depending on incubation time and cell population doubling time was calculated. The cell proliferation abilities on the all applied nanocomposites and on control material (polystyrene cell culture plate) were also compared. The number of cells growing on the nanocomposite surfaces increased with the incubation time. The cell viability was not decreased for all applied materials during the entire study (97-100%). The ceramic nanoparticles and carbon nanotubes modified the bone cell growth and proliferation rate. Results of this study confirm that all types of the nanocomposites are appropriate to the growing and proliferation of human osteoblast-like cells. [ABSTRACT FROM AUTHOR]

Nanocomposite polymer scaffolds for tissue engineering were prepared using leaching method. As a porogen there were used phosphate salts with different grain size (100-400 μm). Nanocomposite materials based on polylactide (PL/DLA) containing 2 wt% of ceramic bioactive nanoadditives (SiO2) were prepared. The nanoadditive was characterized by dynamic light scatering (DLS) (size) and the Brunauer-Emmett-Teller (specific surface area) methods. Morphology of the nanoparticles was observed using the transmission electron microscopy. The optimal concentration of the nanofiller in the polymer matrix was evaluated on the basis of in vitro tests of the nanocomposite foils contacted with osteoblast-like human cells of MG63 line. The morphology and porosity of the scaffold after leaching was evaluated using scanning electron microscopy and hydrostatic weighing. The bioactivity test made on the scaffolds demonstrated ability to nucleation of apatite structure on the material. [ABSTRACT FROM AUTHOR]

Abstract: Novel materials for regenerative medicine are usually composites or nanocomposites. Their main task is to stimulate damaged tissue for faster regeneration caused by enhanced activity of cells prone to intense proliferation within the defect area. One of the main requirements for such materials is bioactivity, which accelerates fixation between the material and surrounding tissue. After implanting into the body, bioactive materials create new physicochemical bonds between the material and the surrounding tissue. In their case apatite layers are formed on the implant surface without inducing growth of fibrous tissue around them. Some differences in bioactivity phenomena observed on the surface of materials depend on the mechanism of bonding and/or time required to create a new bonding and its strength. In the case of some polymers, especially with highly porous or fibrous structures, the bioactivity phenomenon is initiated by local increase in concentration of calcium and phosphate ions which become nuclei of apatite crystallization. The work presents time-dependent results of interactions between nanocomposite foils and simulation body fluid solution (SBF). Nanocomposite foils were produced from chitosan (CS) and montmorillonite (MMT). The obtained foils, CS and CSM (CS+MMT) were subjected to bioactivity tests by incubation in SBF for different time. FTIR measurements were carried out on an Excalibur spectrometer using ATR method in the wave number region from 550cm−1 to 4000cm−1. The reaction between foils and SBF was analyzed by 2D IR correlation spectroscopy The data obtained show local supersaturation of some characteristic groups in CS-MMT material which seems to be the result of apatite nucleation. [Copyright &y& Elsevier]