Nanocalcium-deficient hydroxyapatite–poly (ε-caprolactone)–polyethylene glycol–poly (ε-caprolactone) composite scaffolds

Zhiwei Wang,* Ming Li,* Baoqing Yu, Liehu Cao, Qingsong Yang, Jiacan Su

Department of Orthopedics, Shanghai Hospital, Second Military Medical University, Shanghai, People's Republic of China

*These authors contributed equally to this work

Abstract: A bioactive composite of nano calcium-deficient apatite (n-CDAP) with an atom molar ratio of calcium to phosphate (Ca/P) of 1.50 and poly(ε-caprolactone)–poly(ethylene glycol)–poly(ε-caprolactone) (PCL–PEG–PCL) was synthesized, and a composite scaffold was fabricated. The composite scaffolds with 40 wt% n-CDAP contained well interconnected macropores around 400 µm, and exhibited a porosity of 75%. The weight-loss ratio of the n-CDAP/PCL–PEG–PCL was significantly greater than nano hydroxyapatite (n-HA, Ca/P = 1.67)/PCL–PEG–PCL composite scaffolds during soaking into phosphate-buffered saline (pH 7.4) for 70 days, indicating that n-CDAP-based composite had good degradability compared with n-HA. The viability ratio of MG-63 cells was significantly higher on n-CDAP than n-HA-based composite scaffolds at 3 and 5 days. In addition, the alkaline phosphatase activity of the MG-63 cells cultured on n-CDAP was higher than n-HA-based composite scaffolds at 7 days. Histological evaluation showed that the introduction of n-CDAP into PCL–PEG–PCL enhanced the efficiency of new bone formation when the composite scaffolds were implanted into rabbit bone defects. The results suggested that the n-CDAP-based composite exhibits good biocompatibility, biodegradation, and osteogenesis in vivo.

Keywords: nano calcium-deficient apatite, composite scaffold, degradability, cell responses, osteogenesis