Calcium Orthophosphates in Nature, Biology and Medicine

Abstract

The present overview is intended to point the readers’ attention to the important subject of calcium orthophosphates. These materials are of the special significance because they represent the inorganic part of major normal (bones, teeth and dear antlers) and pathological (i.e. those appearing due to various diseases) calcified tissues of mammals. Due to a great chemical similarity with the biological calcified tissues, many calcium orthophosphates possess remarkable biocompatibility and bioactivity. Materials scientists use this property extensively to construct artificial bone grafts that are either entirely made of or only surface-coated with the biologically relevant calcium ortho-phosphates. For example, self-setting hydraulic cements made of calcium orthophosphates are helpful in bone repair, while titanium substitutes covered by a surface layer of calcium orthophosphates are used for hip joint endoprostheses and as tooth substitutes. Porous scaffolds made of calcium orthophosphates are very promising tools for tissue engineering applications. In addition, technical grade calcium orthophosphates are very popular mineral fertilizers. Thus ere calcium orthophosphates are of great significance for humankind and, in this paper, an overview on the current knowledge on this subject is provided.

In vitro degradation of calcium phosphates: Effect of multiscale porosity, textural properties and composition

“…Figure 7A also displays the results for the degradation behavior of β-TCP samples at the different L/P. It is interesting to note that, in spite of having a much higher solubility, with a solubility product of 28.9 (-log K PS ) [11], [58] and larger pore sizes (Fig. 6), its degradation was lower than that of CDHA, which can be explained by the much smaller SSA.…”

Ostrich Eggshell as an Alternative Source of Calcium Ions for Biomaterials Synthesis

“…The appearance of this phase indicates that the precipitated powder was a calcium-deficient Hydroxyapatite (d-HA). Obtaining a calcium deficient HA is a common characteristic of the wet chemical precipitation, even in ideal conditions 6 .…”

“…Its Ca/P ratio is 1.5, slightly smaller the HA. β-TCP can not be precipitated from aqueous solutions, it is only prepared from the calcination of Ca-deficient HA or by solid state reactions 6 .…”

Structure and mechanical properties of selected protective systems in marine organisms

“…Non-stoichiometric hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ), where 4-6% of the phosphate groups are replaced by carbonate groups [52], constitutes the biomineral phase of bone, teeth and most fish scales [13,[53][54][55][56]. Given its presence in the bones and teeth of humans, it has garnered a significant amount of research in the biomedical field, producing a number of bioinspired designs with a focus on biomedical materials and implants [9,[57][58][59][60][61].…”