Dissolution behavior of simultaneous vapor deposited calcium phosphate coatings in vitro

Solubility is one of the most important properties in the field of biomaterial. The present paper evaluated the dissolution behavior of simultaneous vapor deposited calcium phosphate coatings in vitro. The coatings were immersed in calcium-free Hank's solution at different periods of time. Characterization of the coatings was performed using scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and Rutherford backscattering spectroscopy, prior to and after immersion. Amorphous coatings showed complete dissolution. Crystalline coatings showed that alpha tricalcium phosphate (α-TCP) phase dissolved steadily throughout the testing time leaving the stable hydroxyapatite phase undegraded. The increased in calcium and phosphate ions due to dissolution of α-TCP provided the means for reprecipitation of apatite on the coating, which became apparent after 7 days of immersion.