ISSN 2075-1133, Inorganic Materials: Applied Research, 2011, Vol. 2, No. 1, pp. 85–90. © Pleiades Publishing, Ltd., 2011. Original Russian Text © A.Yu. Fedotov, V.S. Komlev, V.V. Smirnov, I.V. Fadeeva, S.M. Barinov, V.M. Ievlev, S.A. Soldatenkov, N.S. Sergeeva, I.K. Sviridova, V.A.Kirsanova, S.A. Akhmedova, 2011, published in Materialovedenie, 2010, No. 7, pp. 41–46. 85 INTRODUCTION Volumetric polymer foam structures are promising for application as 3D matrices, on which cells (includ- ing stem ones) can be cultured and subsequently implanted in damaged tissues (osteal and cartilagi- nous) for their regeneration [1, 2]. With time, the matrix is gradually replaced by a de novo formed tis- sue. This method, which has been actively developing in medicine for the last decade, is known as tissue engineering. The material of a matrix should be bio- compatible with the body’s medium; have the kinetics of biological degradation (resorption) corresponding to that in the formation of new tissue; and be elastic for supporting tight attachment to a recipient base and filling of a defect, as well as osteoconductive, i.e., capable of maintaining cell vitality, physiological flows, and vascularization. Furthermore, an addi- tional requirement was recently formulated in the pro- cess of clinical trials of one novel biopolymer—if a material for repairing a defect is applied in a milled form (granule, crumb, etc.), it is expedient to intro- duce it in a complex with a binding agent to reduce the risk of microtraumas to surrounding tissues and pre- vent the material from going beyond the localization of the defect in the postoperative period [3, 4]. We would like to consider, as an example of the most prospective materials, some highly porous hybrid composite mate- rials (CMs) based on biopolymers—chitosan and gel- atin, reinforced with calcium phosphate particles [5]. The composites are biocompatible and elastic, while the reinforcing phosphates add the desired mechanical and biological properties. This work presents the results of studies on the technology of hybrid CMs, reinforced with nanoparticles and granules of hydroxyapatite (HA) and its carbonate-substituted form (CHA), and their properties. EXPERIMENTAL Porous biopolymer matrices were fabricated by blending a 5% acetic acid solution of medium-molec- ular chitosan (50 to 190 kDa) and a 10% aqueous solu- tion of gelatin in the chitosan-to-gelatin mass ratios of 100/0, 90/10, 70/30, 50/50, 30/70, 10/90, and 0/100 until a homogeneous blend was formed. Then a foam- ing agent—ammonium carbonate—was added. The resulting dense suspension was placed inside a poly- ethylene cylinder-shaped mold (diameter of 12 mm, height of 40 mm) and frozen until ice crystals were formed at –18°C or –180°C. The frozen material was subjected to sublimated drying to remove ice. The dried samples were placed in ethyl alcohol for replac- ing acetic acid residues contained in the sample with alcohol. Then the samples were dried at 60°C in air until the liquid phase was completely removed. The initial HA and CHA powders were synthesized by the reaction Hybrid Composite Materials Based on Chitosan and Gelatin and Reinforced with Hydroxyapatite for Tissue Engineering A. Yu. Fedotov a , V. S. Komlev a , V. V. Smirnov a , I. V. Fadeeva a , S. M. Barinov a , V. M. Ievlev b , S. A. Soldatenkov b , N. S. Sergeeva c , I. K. Sviridova c , V. A. Kirsanova c , and S. A. Akhmedova c a Baikov Institute of Metallurgy and Materials Science, Russian Academy of Sciences, Moscow, Russia e-mail: barinov@imet.ac.ru b Voronezh State University, Voronezh, Russia c Herzen Oncology Research Institute, Rosmedtekhnologii, Moscow, Russia Received April 1, 2010 Abstract—The fundamentals of the technology are developed for the fabrication of hybrid composite chito- san/gelatin–hydroxyapatite materials aimed for medical applications as porous matrices in regenerating damaged bone tissues, and the properties of the above materials are investigated. They are elastic, having a porosity of up to 90% and pores of up to 700 μm in size; possess controlled dissolution kinetics; contain up to 90 wt % hydroxyapatite or carbonate-substituted hydroxyapatite in the form of nanodisperse powders or granules with a size of up to 500 μm; and are characterized by no cytotoxicity. Their introduction into the site of a bone defect considerably accelerates the process of regeneration in a bone tissue. Keywords: biomaterials, composite materials, biopolymers, calcium phosphates, tissue engineering, oncology. DOI: 10.1134/S2075113311010072