Effect of Hydrolysis Pretreatment on the Formation of Bone-like Apatite on Poly(L-lactide) by Mineralization in Simulated Body Fluids

Abstract

A bone-like apatite-coated surface that mediates a positive interaction between materials and bone is key to the development of desirable bone substitute materials. To incorporate apatite-coating on poly(L-lactide) (PLLA) surfaces, the effect of the hydrolysis of PLLA surfaces on the formation ability of bone-like apatite was investigated in this study.PLLA films and porous PLLA scaffolds were hydrolyzed for different time periods in alkaline solution and the hydrolyzed PLLA surfaces were characterized with X-ray photoelectron spectroscopy, atomic force microscopy, contact angle, and the measurement of carboxyl density. An apatite coating was formed by mineralizing the hydrolyzed PLLA in simulated body fluids (SBF) for 3 weeks and characterized. The hydrolyzed PLLA surfaces were rich in COOH and OH; the hydrophilicity, surface roughness, and carboxyl density increased with the hydrolysis time. After the incubation in SBF, a bone-like apatite layer with different morphology and composition was formed on the PLLA surfaces. The apatite formation on PLLA surfaces was promoted by the hydrolysis pretreatment and this increases with hydrolysis time. In addition, the compression module of the apatite-coated PLLA scaffolds increased compared with the pure PLLA scaffolds and increased with the hydrolysis time. The hydrolysis pretreatment was important in functionalizing the PLLA surfaces, facilitating subsequent apatite nucleation and apatite growth.