710
Z. Voitko et al.
Fig. 1 Structure of the HA elementary cell: a Ca 1 coordination surrounding taking into account
the crystallographic direction (100), b Ca 1 coordination surrounding taking into account the
crystallographic direction (001), c, d coordination surrounding of the Ca 2 ions
HA structure (Fig. 1a, b) [2]. Ca 1 ions are bound to PO 4 tetrahedra. In this case, Ca 1
has surrounding close to the octahedral structure and is surrounded by nine oxygen
ions, also belonging to the PO 4 -groups. Ca 2 ions form an axial channel and are
surrounded by oxygen ions from PO 4 -groups and OH-groups. (Fig. 1c, d). The Ca 2
atoms form a triangle in a plane perpendicular to the c-axis, the triangles rotated 60°
relative to each other along that axis. Thus, the refined formula for the HA structure
can be represented as Ca( 1 ) 4 Ca( 2 ) 6 (PO 4 ) 6 (OH) 2 [2].
Biomaterials synthesis based on HA has long become a priority direction in
modern medical materials science. HA is widely used: in clinical practice because it
has high biocompatibility, devoid of immunogenic, and allergenic activity; as a major
component of therapeutic and prophylactic pastes and gels; for the repair of defects
and treatment of bone pathologies, etc. Since natural bone tissue is a composite material, the use of HA is the most promising in the form of composite materials. Bone
tissue is known to consist of HA, collagen, water and other components (proteins,
salts, etc.). By introducing appropriate additives into HA-based composites, their
mechanical and biological characteristics and, first their biocompatibility with the
tissue of a living organism can be improved. In addition to collagen, such additives
Z. Voitko et al.
Fig. 1 Structure of the HA elementary cell: a Ca 1 coordination surrounding taking into account
the crystallographic direction (100), b Ca 1 coordination surrounding taking into account the
crystallographic direction (001), c, d coordination surrounding of the Ca 2 ions
HA structure (Fig. 1a, b) [2]. Ca 1 ions are bound to PO 4 tetrahedra. In this case, Ca 1
has surrounding close to the octahedral structure and is surrounded by nine oxygen
ions, also belonging to the PO 4 -groups. Ca 2 ions form an axial channel and are
surrounded by oxygen ions from PO 4 -groups and OH-groups. (Fig. 1c, d). The Ca 2
atoms form a triangle in a plane perpendicular to the c-axis, the triangles rotated 60°
relative to each other along that axis. Thus, the refined formula for the HA structure
can be represented as Ca( 1 ) 4 Ca( 2 ) 6 (PO 4 ) 6 (OH) 2 [2].
Biomaterials synthesis based on HA has long become a priority direction in
modern medical materials science. HA is widely used: in clinical practice because it
has high biocompatibility, devoid of immunogenic, and allergenic activity; as a major
component of therapeutic and prophylactic pastes and gels; for the repair of defects
and treatment of bone pathologies, etc. Since natural bone tissue is a composite material, the use of HA is the most promising in the form of composite materials. Bone
tissue is known to consist of HA, collagen, water and other components (proteins,
salts, etc.). By introducing appropriate additives into HA-based composites, their
mechanical and biological characteristics and, first their biocompatibility with the
tissue of a living organism can be improved. In addition to collagen, such additives