The effect of polymeric chain-like structure on the degradation and cellular biocompatibility of calcium polyphosphate

Three-dimensional porous calcium polyphosphate (CPP) scaffolds were fabricated in the present work. We investigated the degradation mechanism of CPP from the viewpoint of polymeric structure and the effects of different polymeric structure on cell viability. By controlling the sintering temperature and altering the proportion of hydrolytic groups (Q1 groups) in polyphosphate chain, CPP can be obtained respectively with different degradation rate. The results suggested that with increasing sintering temperature, the proportion of Q1 groups in polyphosphate chain decreased. CPP sintered at 550 °C had 15.1% Q1 groups in polyphosphate chain, while CPP sintered at 650 °C and 750 °C exhibited 10.5 and 8.3%, respectively. During immersion in simulated body fluid (SBF) for 30 days, the weight loss of CPP sintered at 550 °C was about 80%, while CPP sintered at 650 °C and 750 °C degraded by only 8% and 5%. Cell viability test results showed that the porous CPP did not exert cytotoxicity effect on the cells after being cultured 6 days. Due to the lower degradation rate, CPP sintered at 750 °C showed better cell attachment and proliferation as well as higher cell density. These findings may provide an approach to study and achieve controllable degradation of CPP, and explore more biomedical applications.