Calcium phosphate can be described as a calcium salt of phosphoric acid having a chemical formula, as Ca3(PO4)2. It can also be called Tricalcium Phosphate or Calcium phosphate tribasic.
Calcium phosphate compound appears to be either crystalline or white amorphous powder that is tasteless and odorless. It is insoluble in acetic acid and ethanol but soluble in hydrochloric acid and dilute nitric acid. Also, it slightly dissolves in water and is found in milk, bones, teeth, and ground.
Characteristics of Calcium Phosphate
Apatite is a mineral rock that is a complex and impure form of calcium phosphate that produces tribasic calcium phosphate.
Apatite is a form of phosphorite that contains calcium phosphate, which is mixed with other compounds.
Calcium phosphates are the important materials of Geology, Biology, Medicine, Dentistry, and Industry.
Its functions, applications, and formation, depends on its composition, solubility, stability, and structure.
Calcium Phosphate Preparation
It is also produced by reacting the phosphoric acid (H3PO4) with solid calcium hydroxide Ca(OH)2.
The chemical equations can be given as below:
3Ca(OH)2 + 2H3PO4 → Ca3(PO4)2 + 6H2O (Balanced Equation)
Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O (Unbalanced Equation)
Dibasic-calcium phosphate is made in the calcium phosphate reaction with an aqueous solution of calcium hydroxide. In contrast, the monobasic calcium phosphate can be obtained by adding the excess phosphoric acid to either a dibasic solution or a tribasic calcium phosphate solution and permitting it to evaporate.
Structure of Ca3(PO4)2
(image will be uploaded soon)
Properties of Calcium Phosphate - Ca3(PO4)2
Solubility of Calcium Phosphate Ca3(PO4)2
Solubility is the most important characteristic of calcium phosphate salts. Solubility can be defined by the course of various reactions involving calcium phosphates such as precipitation, hydrolysis, phase transformation, and absorption. The solubility of calcium phosphate also plays a primary role in the biological processes, including resorption, hard tissue formation, and pathological calcification.
The bone graft replacements (mostly hydroxyapatite or tricalcium phosphate) based on the calcium phosphate are bioceramics having the greatest resemblance to bone minerals. This makes the calcium phosphate excellent biodegradability, osteoconductivity, and biocompatibility.
Occurrence of Calcium Phosphate
Phosphorus and Calcium make up the bulk of animal mineral nutrient requirements (to fulfill both milk needs and body tissue). Therefore, the DCPD is a popular and commonly used animal supplement. Also, Dicalcium Phosphate Dihydrate is mainly considered because it is the most soluble of barely soluble crystals of calcium phosphate, making it a good choice for the rock phosphate dissolution tests. The DCPD fate in the soil is rather temporary.
Usually, mineral phosphorus is applied to the soil in a water-soluble form, such as diammonium phosphate or triple superphosphate. Since the phosphorus dissolves at a high concentration of a solution (suppose as ‘P’), the precipitation reactions are mostly preferred. Calcium phosphates can be found naturally in many ways, and they are the primary minerals for phosphate fertilizer manufacture and a variety of phosphorus compounds.
Health Hazards of Calcium Phosphate
When the doses of ingested toxins become more than 2 gms/kg, there is an unusual skin sensitization. Consumption of it can cause chemical pneumonitis. Also, calcium phosphate is used in most of the products in biomedicine, including cosmetics and dentistry.
It can be found in nanoparticle form in some situations, either on purpose, after mechanical abrasion, or degradation. Some possible issues are referred to as the biological impact of these nanoparticles.
An in-depth literature review represents that calcium phosphate nanoparticles, as such, do not have inherent toxicity but can lead to an intracellular calcium concentration increase following lysosomal degradation and endosomal uptake. However, within a few hours, the cells can remove calcium from the cytoplasm unless huge doses of calcium phosphate are used.
The cytotoxicity observed in a few cell culture studies, especially for the unfunctionalized particles, is likely because of the subsequent sedimentation and particle agglomeration on the cell layer, leading to very high local particle concentration, subsequent cell death, and high absorption of particles.
The nanoparticles of calcium phosphate can reach the bloodstream by inhalation. Still, there are no harmful effects that have been noticed, except for the extended exposure to doses of high particles. Whereas the nanoparticles of calcium phosphate within the body don't pose a risk since they are resorbed and destroyed normally by macrophages and osteoclasts.