Novel degradable α-TCP/multi-(amino acid) copolymer composite: Preparation and characterization

A novel degradable α-tricalcium phosphate/multi-(amino acid) copolymer composite (α---TCP/MAACP) was prepared by the in situ copolymerization method and characterized by FTIR, XRD, SEM and in vitro degradation experiments in simulated body fluid. The results exhibit that the composite is composed of an amide copolymer and α-TCP. The composite shows a fast degradation in the primary period and 6.8% of mass loss is observed in the first week. A total of 20.1% mass is lost after 12 weeks immersion. No strong acidic degradation products are produced and the pH of soaking medium is in a range of 6.6～7.0 during the immersion period. The water absorption rate of the composite is about 11% and no significant change occurs during the soaking time. SEM analysis shows that the surface becomes smooth after 2 weeks immersion and some precipitation is observed. The precipitation increases with soaking time and covers the most part of surface at the end of 12 weeks. XRD determination shows that the precipitation is poorly crystallized hydroxyapatite, indicating the composite is bioactive. After 12 weeks soaking, compared to that of before soaking, the crystallinity of surface decreases but no significant change for that of cross section is observed, indicating that the composite may be a surface erosion material. Collectively, this composite can be potential bone substitutes for bone repair and tissue engineering.