ALBERT

Notes: Natural bone is a typical example of an “organic matrix-mediated” biomineralizationprocess which constituted of hydroxyapatite(HA) nanocrystals orderly grown in intimate contactwith collagen fibers. Bone morphogenetic protein 2 (BMP2) is the most powerful osteogenic factor.But it is extremely difficult to be manufactured in large scale. In previous study, we have designed anovel oligopeptide (P24) derived from BMP2 knuckle epitope and it contained abundantAsp(aspartic acid) and phosphorylated Ser(serine) which may be helpful for self-assamblybiomineralization and osteogenesis. Previous In vivo experiments have shown that this noveloligopeptide had excellent osteoinductive and ectopic bone formation property which was similar tothat of BMP2. In this study, PLGA-(PEG-ASP)n scaffolds were modified with P24 and a newbiomimetic bone tissue engineering scaffold material with enhanced bioactivity was synthesized bya biologically inspired mineralization approach. Peptide P24 was introduced intoPLGA-(PEG-ASP)n scaffolds using cross-linkers. Then the P24 modified scaffolds and the simplePLGA-(PEG-ASP)n scaffolds were incubated in modified simulated body fluid (mSBF) for 10 days.Growth of HA nanocrystals on the materials was confirmed by observation SEM and measurementsEDS and XRD. SEM analysis demonstrated the well growth of bonelike HA nanocrystals on P24modified PLGA-(PEG-ASP)n scaffolds than that of the control scaffolds. The main component ofmineral of the P24 modified scaffolds was hydroxyapatite containing low crystalline nanocrystals,and the Ca/P ratio was nearly 1.60, similar to that of natural bone, while that of the control scaffoldswas 1.52. The introduction of peptide P24 into PLGA- (PEG- ASP)n copolymer provides abundantactive sites to mediate the nucleation and self- ssembling of HA nanocrystals in mSBF. the resultedpeptide P24 modified- HA/PLGA- (PEG- ASP)n composite shows some features of natural boneboth in main composition and and hierarchical microstructure. This biomimetic treatment providesa simple method for surface functionalization and subsequent biomineralization on biodegradablepolymer scaffolds for tissue engineering