Ternary biocomposites of dicalcium phosphate (DCP), calcium sulfate (CS), and poly(amino acid) copolymer (PAA) could be used as a promising degradable biomimic bone substitute. Using an in vitro degradation model, we evaluated the influence of polymerization conditions, initial amino acids, and (DCP + CS)/PAA ratio on the degradation of the resulting materials. PAA degradation was affected by both the polymerization conditions and the initial amino acids, and the degradation of the DCP/CS/PAA composites was affected by the (DCP + CS)/PAA ratio. Using a certain initial amino acids (75% ε‐aminohexanoic acid, 19% γ‐aminobutanoic acid, 4% l‐proline, and 2% l‐lysine) and polymerization conditions (i.e., 210°C for 2.5 h) as the polymeric phase, (DCP + CS)/PAA biocomposites were prepared with 70%, 60%, and 40% PAA. All of the biocomposites were degradable, which resulted in the release of ions/amino acids and a slight pH fluctuation of 6.76 to 7.20. In addition, these biocomposites were biocompatible based on the proliferation of L929 but varied with the degradation rates. These results suggest the potential to control the degradation rates of (DCP + CS)/PAA biocomposites for bone regeneration. POLYM. COMPOS., 39:E122–E131, 2018. © 2016 Society of Plastics Engineers

In vitro cytocompatibility of ternary biocomposite of dicalcium phosphate (DCP) and calcium sulfate (CS) containing 40 wt% poly (amino acid) (PAA) was evaluated using L929 fibroblasts and MG-63 osteoblast-like cells. Thereafter, the biocompatibility of biocomposite in vivo was investigated using an implantation in muscle and bone model. In vitro L929 and MG-63 cell culture experiments showed that the composite and PAA polymer were noncytotoxic and allowed cells to adhere and proliferate. The scanning electron microscope (SEM) confirmed that two kinds of cells maintained their phenotype on all of samples surfaces. Moreover, the DCP/CS/PAA composite showed higher cellular viability than that of PAA; meanwhile, the cell proliferation and ALP activity were much higher when DCP/CS had added into PAA. After implanted in muscle of rabbits for 12 weeks, the histological evaluation indicated that the composite exhibited excellent biocompatibility and no inflammatory responses were found. When implanted into bone defects of femoral condyle of rabbits, the composite was combined directly with the host bone tissue without fibrous capsule tissue, which shown good biocompatibility and osteoconductivity. Thus, this novel composite may have potential application in the clinical setting.

In this study, we focused on the surface modification of a novel poly(amino acid) (PAA)/hydroxyapatite/calcium sulfate composite and the effect of its surface modification on cellular responses. The surface modification was performed by sandblasting (sample S2), calcium chloride ethanol saturated solution etching (sample S3), and formic acid etching (sample S4) followed by in vitro culturing of osteoblast‐like cells. The obtained results indicate that a new interface of the composite was formed during the modification, and the modified surface was changed with respect to its surface morphology by physical abrasion. The calcium chloride ethanol saturated solution etchant etched PAA selectively whereas forming rich calcium‐phosphate (Ca–P) apatite on the surface of S3. The formic acid etchant attacked the inorganic component without changing the PAA state. Cell attachment and cell proliferation were improved by the treatments of S2 and S3 in comparison with no treatment and the treatment of S4 © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42427.

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