Influences of degradability,bioactivity, and biocompatibility of the calcium sulfate content on a calcium sulfate/poly(amino acid) biocomposite for orthopedic reconstruction

The inorganic content in a bioceramic/polymer composite is considered to play an important role in promoting bone healing after implantation in vivo. In this study, two calcium sulfate/poly(amino acid) (CS/PAA) composites with CS content proportions of 50% (mass fraction, 50CS/PAA) and 65% (65CS/PAA) were synthesized via the in situ melting polymerization method, and the degradability, bioactivity, and biocompatibility of the composites were evaluated. The results indicated that 41.5% of weight loss of the 50CS/PAA was observed after soaking in simulated body fluid (SBF) for 16 weeks, whereas 56.2% of weight loss of the 65CS/PAA was observed. These results suggested that the CS content in the composite affected the degradability of the composite. After being soaked in SBF for 1 week, formation of an apatite layer was observed on the surfaces of both composites without obvious differences. The co‐culture results of the composites and the MG‐63 cells confirmed that 65CS/PAA exhibited higher proliferation and a higher alkaline phosphatase (ALP) activity than did 50CS/PAA. The implantations in bone defects of rabbits for 3 months revealed that both composites had good biocompatibility and were capable of guiding new bone formation without causing any inflammation. However, faster degradability of the 65CS/PAA composite was observed in vivo, indicating that the higher CS content in the composite results in higher degradability. In conclusion, the CS content in the composite for orthopedic reconstruction has distinct effects on the degradability, OD value, and ALP activity of the composites, whereas it has little effect on the bioactivity and bone formation. POLYM. COMPOS., 37:1886–1894, 2016. © 2015 Society of Plastics Engineers