[Show abstract][Hide abstract] ABSTRACT: Bioceramics are used to treat bone defects but in general do not induce formation of new bone, which is essential for regeneration process. Many aspects related to bioceramics synthesis, properties and biological response that are still unknown and, there is a great need for further development. In the most recent research efforts were aimed on creation of materials from biological precursors of apatite formation in humans. One possible precursor is octacalcium phosphate (OCP), which is believed not only to exhibit osteoconductivity, but possesses osteoinductive quality - the ability to induce bone formation. Here we propose a relatively simple route for OCP ceramics preparation with a specifically designed microstructure. Comprehensive study for OCP ceramics including biodegradation, osteogenic properties in ortopic and heterotopic models and limited clinical trials were performed that demonstrated enhanced biological behaviour. Our results provide a possible new concept for the clinical applications of OCP ceramics.
[Show abstract][Hide abstract] ABSTRACT: The synthesis of calcium phosphate particles on cellulose fibers of cotton fabric is developed. The possibility of obtaining particles homogeneously distributed over the fiber surface through synthesis including the procedures of cellulose phosphorylation in orthophosphoric acid solution and treatment in calcium salts followed by treatment in ammonium hydrophosphate is established. The method can serve as a basis for the development of the technology of antiburn wound-healing bandages.
[Show abstract][Hide abstract] ABSTRACT: Biocompatible ceramic fillers are capable of sustaining bone formation in the proper environment. The major drawback of these scaffolding materials is the absence of osteoinductivity. To overcome this limitation, bioengineered scaffolds combine osteoconductive components (biomaterials) with osteogenic features such as cells and growth factors. The bone marrow mesenchymal stromal cells (BMMSCs) and the β-tricalcium phosphate (β-TCP) are well-known and characterized in this regard. The present study was conducted to compare the properties of novel octacalcium phosphate ceramic (OCP) granules with β-TCP (Cerasorb(®)), gingiva-derived mesenchymal stromal cells (GMSCs) properties with the BMMSCs and osteogenic and angiogenic properties of a bioengineered composite based on OCP granules and the GMSCs. This study demonstrates that GMSCs and BMMSСs have a similar osteogenic capacity. The usage of OCP ceramic granules in combination with BMMSCs/GMSCs significantly affects the osteo- and angiogenesis in bone grafts of ectopic models.
[Show abstract][Hide abstract] ABSTRACT: The developments of three-dimensional printing of osteoconductive ceramic matrices based on tricalcium phosphate for tissue engineering constructions intended for acceleration of the reparative processes and effective osteointegration with tissues of the living body are studied in the present work.
[Show abstract][Hide abstract] ABSTRACT: Tetracalcium phosphate (TeCP) bone cements are
promising for repairing bone defects . A major lim
itation of their clinical use is low mechanical charac
teristics of these materials . It is known that treat
ment of building concretes and cements with gases in
the supercritical state, in particular, with carbon diox
ide, promotes hardening processes and improves their
mechanical characteristics . However, control of
calcium phosphate cement hardening by means of
treatment with supercritical CO2 (scCO2) has not
been studied thus far. This study deals with specific
features of microstructure formation and properties of
TeCP bone cement after its treatment with supercriti
[Show abstract][Hide abstract] ABSTRACT: The technological foundations are developed and the properties of porous composite materials with a ceramic framework reinforced by polymer impregnation and used as porous matrices in medicine to regenerate injured bone tissues are investigated. Composite materials have interconnected pores, porosity from 50 to 75%, and size of coarse pores up to 500 μm and fine pores down to 2 μm. Infiltration by chitosan allows one to increase the material compression strength by up to seven times and decrease strength sensitivity to porosity by up to two times.
[Show abstract][Hide abstract] ABSTRACT: Results are presented from a study of how the thermomechanical properties of specimens of a ceramic based on sodium polyaluminate with the structure of Na-β″-alumina are affected by the ceramic’s microstructure, chemical composition, and phase composition. The range of critical pressure gradients that sharply reduce the strength and service characteristics of specimens of the solid electrolyte is determined. Quantitative estimates are made of the relative change in fracture toughness after thermal shock, the sensitivity of the material to defects, and the degree to which defects accumulate at the root of a notch during thermal shock.
Refractories and Industrial Ceramics 01/2013; 53(5). · 0.19 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have studied a process for the preparation of apatite precursors through calcium carbonate conversion into dicalcium phosphate dihydrate, which is then hydrolyzed to octacalcium phosphate. The process enables the preparation of both phase-pure octacalcium phosphate and calcium phosphate mixtures with variable dicalcium phosphate dihydrate : octacalcium phosphate and hydroxyapatite : octacalcium phosphate ratios.
[Show abstract][Hide abstract] ABSTRACT: The nature of precursor phase during the biomineralization process of bone tissue formation is still controversial. Several phases were hypothesized, among them octacalcium phosphate. In this study, an in situ monitoring of structural changes, taking place upon the octacalcium phosphate bone cement hardening, was carried out in the presence of biopolymer chitosan and Simulated Body Fluid (SBF). Several systems with different combination of components were studied. The Energy Dispersive X-Ray Diffraction was applied to study the structural changes in real time, while morphological properties of the systems were investigated by the Scanning Electron Microscopy. The obtained results evidence that final hydroxyapatite phase is formed only in the presence of chitosan and/or SBF, providing new insights into the in vivo biomineralization mechanism and, consequently, favouring the development of new approaches in biomaterials technology.
[Show abstract][Hide abstract] ABSTRACT: Spontaneous explosive crystallization in a selenium/copper bilayer nanofilm has been experimentally studied. It has been shown that the formation of a microcrack network in the selenium film is a decisive factor for spontaneous explosive crystallization. The microcrack network is an efficient channel for the relaxation of the collected energy of elastic stresses in the selenium film. The relaxation of this energy accelerates crystallization and transfers it to the explosive regime. It has been found that crystalline phases appearing in the products of the reaction after spontaneous explosive crystallization depend on the ratio of the thicknesses of the copper and selenium films.