Biologically Inspired Self-assembling Synthesis of Bone-like Nano-hydroxyapatite/PLGA-(PEG-ASP)_n Composite: A New Biomimetic Bone Tissue Engineering Scaffold Material

摘要

A new biomimetic bone tissue engineering scaffold material, nano-HA/ PLGA-(PEG-A_ SP)_n composite, was synthesized by a biologically inspired self-assembling approach. A novel biodegradable PLGA-(PEG-A_ SP)_n copolymer with pendant amine functional groups and enhanced hydrophilicity was synthesized by bulk ring-opening copolymerization by DL-lactide(DLLA) and glycolide(GA) with Aspartic acid (A_ SP)-Polyethylene glycol(PEG) alt-prepolymer. A Three-dimensional, porous scaffold of the PLGA-(PEG-A_ SP)_n copolymer was fabricated by a solvent casting, particulate leaching process. The scaffold was then incubated in modified simulated body fluid(mSBF). Growth of HA nanocrystals on the inner pore surfaces of the porous scaffold is confirmed by calcium ion binding analyses, SEM, mass increase measurements and quantification of phosphate content within scaffolds. SEM analysis demonstrated the nucleation and growth of a continuous bonelike, low crystalline carbonated HA nanocrystals on the inner pore surfaces of the PLGA-(PEG-A_ SP)_n scaffolds. The amount of calcium binding, total mass and the mass of phosphate on experimental PLGA-(PEG-A_ SP)_n scaffolds at different incubation times in mSBF was significantly greater than that of control PLGA scaffolds. This nano-HA/PLGA-(PEG-A_ SP)_n composite shows some features of natural bone both in main composition and hierarchical microstructure. The A_ SP-PEG alt-prepolymer modified PLGA copolymer provide a controllable high surface density and distribution of anionic functional groups which would enhance nucleation and growth of bonelike mineral following exposure to mSBF. This biomimetic treatment provides a simple method for surface functionalization and subsequent mineral nucleation and self-assembling on biodegradable polymer scaffolds for tissue engineering.