Effect of microgravity and a high magnetic field on hydroxyapatite deposition and implications for bone loss in space

The microgravity and high magnetic field simulated by a superconducting magnet were used to investigate the dynamics of deposition mechanisms of hydroxyapatite (HAp) on the surface of Ti-6Al-4V samples. The HAp coatings were derived by a self-assembly-induced biomineralization method in simulated body fluid. The experimental results showed that the amount and growth rate of HAp deposition in the simulated microgravity condition were far less than those in the gravity field, as were those in the high magnetic field compared with those outside the magnet. This may provide insight into the bone loss of astronauts in spaceflight from the viewpoint of the dynamic balance between HAp nucleation, deposition and decomposition on the surface of substrates.