German scientists have created a material based on calcium phosphate cement with carbon fibres that can withstand shock loadings up to 1.9 kilojoules per square meter. The material was able to heal cracks of up to ten microns in its structure in solution simulating the blood plasma, and the presence of polymer capsules salt with phosphate of sodium to allow the material to regenerate itself and in the water. The results of a study published in the journal Scientific Reports.
In nature one can often find the materials capable of self-restoration of its structures: skin and bones, for example. The damaged bone is restored with the help of calcium ions and phosphates contained in the blood plasma, the bones and teeth. In clinical practice already used a self-healing polymeric biomaterials and hydrogels.
As the inorganic material for implants often use calcium phosphate. A paste of cement of powdered calcium phosphate with the liquid phase can provide a reliable contact of bone and implant, biocompatible, and it is possible to add various medications. However, such cements are very fragile.
Anna Boehm (Boehm V. Anne) with colleagues from University of Jena Friedrich Schiller created on the basis of the Apatite calcium phosphate cement samoklejushchiesja biocompatible solid material, in cement by adding carbon fiber as a reinforcing component and a polymer capsule with crystals of phosphate of sodium. Solidified cement at high humidity for seven days. The self-healing in vitro , the researchers tested, observing the healing of cracks in the mortar, which is the composition of simulated inorganic part of human blood plasma.
The toughness of cement with carbon fiber amounted to almost two kilojoules per square meter, which is 100 times higher than the value corresponding to pure calcium phosphate cement. The presence of polymer capsules as improved impact toughness, and the ability of fractures to heal in a liquid medium. The formation of cracks up to ten microns, the polymer shell was broken releasing the phosphate ion, which caused local supersaturation and crystallization of Apatite in the crack. Materials that do not contain capsule to heal the cracks, but if the solution was the calcium ions and phosphate, that is, in the medium solution, the composition simulates the blood plasma.
Materials after the healing was for mechanical properties no worse than samples without defects even after three cycles of formation and healing of cracks. According to the authors, the ability to withstand high loads and restore the structure will allow to use these materials to create implants bone experiencing frequent load.
The ability of calcium phosphate to crystallize in the defective areas is used to increase the strength of other parts of the human body. About a year ago, scientists from China have restored natural tooth enamel using ion clusters of calcium phosphate.