Hydroxyapatite/poly-L-lactide (HAp/PLLA) is a ceramic/polymer composite, whose application as a resorbable biomaterial for the substitution and repair of hard bone tissue is widely promising in orthopedic, oral, maxillofacial, and reconstructive surgery. Hot processing is a necessary step for obtaining HAp/PLLA composite blocks with mechanical properties similar to those of bones. In this article, the changes in structure and physicochemical properties of HAp/PLLA composite, hot pressed for different pressing times (5, 15, 30, 45, and 60 min), were studied. Because the morphology of HAp/PLLA composite biomaterial is very sensitive to this procedure, its surface microstructure was analyzed by scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray (EDX) detector system. Structural changes occurring in the material, mostly changes in crystallinity of PLLA, were studied by wide-angle X-ray structural analyses (WAXS) and infrared (FTIR) spectroscopy. Using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC), the influence of hot pressing on the properties, crystallization kinetics, and decomposition of HAp/PLLA composite biomaterial was analyzed.

Besides its high osteoinductive properties, hydroxyapatite (HAp) exhibits a relatively low mechanical strength. In order to improve the mechanical properties and reliability of HAp based composites, the addition of selected polymers is highly recommended. The main objective of this work is to study the microstructural characteristics of HAp/poly-L-lactide (PLLA) composites obtained by cold or hot processing. The composites were prepared from a mixture of a chloroform solution of poly-L-lactide with granulated HAp. After elimination of chloroform by vacuum evaporation, dense compacts were obtained by cold or hot pressing. The pressing pressure ranged from 98.10 to 294.3 MPa for both cold and hot pressing. The hot pressing was performed in the temperature region 293-457 K for a time period of 15-60 min. Depending on the PLLA amount and the pressing procedure it is possible to obtain highly porous or nearly fully dense composites. The scanning electron microscopy examination of fracture as well as of free surfaces revealed that the final porosity and wetting are affected to a great extent by the synthesis conditions and amount of polymer added. An increase in temperature to 457 K for a longer period of time results in fully dense compacts. The formation of a nearly continuous polymer network that leads to the hardening of HAp has also been observed. However, it should be pointed out that some layers of HAp may be free of polymer film since PLLA penetrates more deeply into the porous HAp.

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Based on the model polyimide systems the principal nonlinear optical features, such as laser induced refractive indices changes, nonlinear refraction and third order susceptibility have been established during their doping with fullerenes, shungites, carbon nanotubes, carbon nanofibers, quantum dots, etc. The evidence of the correlation between laser induced refractive indices and charge carrier mobility has been obtained. The features of new nanocomposites for their possible optoelectronics, laser techniques and solar energy applications have been considered.

Biphasic calcium phosphate-poly-DL-lactide-co-glycolide composite biomaterial with and without biostimulative agents (protein-rich plasma or fibrin) was synthesised in the form suitable for reconstruction of bone defects. The composite used as filler was obtained by precipitation in solvent-non-solvent systems. The material, calcium phosphate granules covered by polymer, was characterised by wide-angle X-ray structural analysis, scanning electron microscopy, infrared spectroscopy and differential scanning calorimetry. Reparation of bone tissue damaged by osteoporosis was investigated in vivo on rats. The method applied enabled production of granules of calcium phosphate-poly-DL-lactide-co- glycolide composite biomaterial of average diameter 150-200 mum. Histological analysis confirmed recuperation of the alveolar bone, which osteoporosis-induced defects were repaired using composite biomaterial. By addition of biostimulative agents, intensity of osteogenesis increases accompanied by the formation of regular, new bone structure.

In this article, synthesis and application of calcium phosphate/poly-DL-lactide-co-glycolide (CP/PLGA) composite biomaterial in particulate form, in which each CP granule/particle is coated with PLGA, are described. Two types of the particulate material having different particle sizes were synthesized: one with an average particle diameter between 150 and 250 mum (micron-sized particles, MPs) and the other with an average particle diameter smaller than 50 nm (nanoparticles, NPs). A comparative in vivo analysis was done by reconstructing defects in osteoporotic alveolar bones using both composites. The material, CP granules/particles covered with polymer, was characterized using X-ray structural analysis, scanning electron microscopy, and atomic force microscopy. Changes in reparatory functions of tissues affected by osteoporosis were examined in mice in vivo, using these two kinds of composite materials, with and without autologous plasma. Having defined the target segment, histomorphometric parameters-bone area fraction, area, and mean density-were determined. The best results in the regeneration and recuperation of alveolar bone damaged by osteoporosis were achieved with the implantation of a mixture of nanoparticulate CP/PLGA composite and autologous plasma. After the implantation of microparticulate CP/PLGA, in the form of granules, mixed with autologous plasma, into an artificial defect in alveolar bone, new bone formation was also observed, although its formation rate was slower.

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