In Vitro Degradation of PLLA/nHA Composite Scaffolds

Abstract

Porous Poly-L-lactide (PLLA) scaffolds and PLLA/nanohydroxyapatite (nHA) composite scaffolds with interconnected pore networks and a porosity of over 90% were fabricated with lyophilization techniques. In this study, the degradation behavior of PLLA and PLLA/nHA composite scaffolds is investigated over 8 weeks in phosphate buffer solution at 37 C. Thermal analysis using differential scanning calorimetry (DSC) showed that the percent crystallinity of all the samples increased by approximately 10%, which represents a considerable increase in the glass transition temperature. The melting range enthalpy of the scaffolds did not change to lower temperatures as would be expected. The spectroscopic analysis performed by Fourier transform infrared spectroscopy suggested that nHA particles should not appreciably affect the absorbance pattern when evenly mixed with the PLLA. This is consistent with the analysis of the scaffold microstructure and morphology with scanning electron microscopy, which drew a low content of nHA with no significant effect on solvent crystallization or pore structure. The compressive modulus and the yield strength of the scaffolds were investigated in conjunction with the study of their degradation rates. In comparison with the mechanical properties of the PLLA scaffolds, which remained largely unchanged, those of the PLLA/nHA composite scaffolds decreased as the degradation progressed. POLYM. ENG. SCI., 54:2571–2578, 2014. VC 2013 Society of Plastics Engineers