Biomimetic Mineralization of Collagen with Bifunctional Polymer-Stabilized Calcium Phosphate Nanoparticles

Bones are composed of collagen fibers and inorganic hydroxyapatite, and the mineralization of collagen fibers in bone repair materials has attracted much attention. Increasing the concentration of calcium and phosphate ions and ensuring their effective integration with collagen fibers are key research focus. Through the structural design of polymers, the combination of summarization and ability and collagen mineralization is combined to prepare bifunctional polymers. Through the optimization of calcium phosphate nanoparticle preparation, the preparation process is simplified and multifunctional. RAFT synthesis of polyacrylamide-block-poly(N-(3-aminopropyl)methacrylamide) copolymer followed by diethylenetriaminepentaacetic acid (DTPA) grafting yields the dual-functional copolymer DTPA-grafted polyacrylamide-b-poly(3-aminopropyl)methacrylamide copolymer (PPD). The polymer was stabilized Ca2+ and PO43– to prepare an inorganic–organic nanoparticle (DCAP) interacting with collagen for high mineralization. Studies on the mineralization of collagen fibers indicated that this nanoparticle stabilized by PPD promotes the mineralization of collagen fibers, forming internally mineralized collagen fibers. In vitro study indicated that the DCAP material had good biocompatibility. The osteogenic activity of MC3T3-E1 cells was enhanced at 7 and 14 days, with the gene expression of ALP and OPN increasing significantly by 2-fold within 14 days. The nanoparticles demonstrate providing an example of periodic mineralization of collagen fibers.