Immersion behaviour of calcium polyphosphate in simulated body fluid

This work documents an investigation into the immersion behaviour of calcium polyphosphate (CPP) in simulated body fluid (SBF) for various periods. The results showed that with the increase of soaking time in SBF, a number of tiny particles were observed on the surface of samples by scanning electron microscope (SEM). The results of X-ray diffraction (XRD) indicated that the particles were contributed to apatite. And the changes of PO43− and Ca2+ concentrations in SBF were detected by phospho–vanado–molybdate method and inductively coupled plasma atomic emission spectroscopy (ICP) methods respectively. The results indicated that the concentrations of PO43− and Ca2+ in SBF reached the maximum value after 25 days of immersion, and then decreased with further increase of the soaking time. It is suggested that the degradation and ion exchange of CPP samples are dominant during the early stage of soaking, and then the precipitates begin to form and increase gradually as the soaking time increases. This study has demonstrated that apatite could be formed on the surface of CPP samples, and CPP would be used as bone substitution material.