title: Single-crystal apatite nanowires sheathed in graphitic shells: synthesis, characterization, and application.
abstract: Vertically aligned one-dimensional hybrid structures, which are composed of apatite and graphitic structures, can be beneficial for orthopedic applications. However, they are difficult to generate using the current method. Here, we report the first synthesis of a single-crystal apatite nanowire encapsulated in graphitic shells by a one-step chemical vapor deposition. Incipient nucleation of apatite and its subsequent transformation to an oriented crystal are directed by derived gaseous phosphorine. Longitudinal growth of the oriented apatite crystal is achieved by a vapor-solid growth mechanism, whereas lateral growth is suppressed by the graphitic layers formed through arrangement of the derived aromatic hydrocarbon molecules. We show that this unusual combination of the apatite crystal and the graphitic shells can lead to an excellent osteogenic differentiation and bony fusion through a programmed smart behavior. For instance, the graphitic shells are degraded after the initial cell growth promoted by the graphitic nanostructures, and the cells continue proliferation on the bare apatite nanowires. Furthermore, a bending experiment indicates that such core-shell nanowires exhibited a superior bending stiffness compared to single-crystal apatite nanowires without graphitic shells. The results suggest a new strategy and direction for bone grafting materials with a highly controllable morphology and material conditions that can best stimulate bone cell differentiation and growth.
authors.affiliation: Energy Materials and Convergence Research Department, Korea Institute of Energy Research, 71-2 Jang-dong, Yuseong-gu, Daejeon 305-343, Republic of Korea.
authors.forename: Namjo
authors.initials: N
authors.lastname: Jeong
authors.forename: Misun
authors.initials: M
authors.lastname: Cha
authors.forename: Yun Chang
authors.initials: YC
authors.lastname: Park
authors.forename: Kyung Mee
authors.initials: KM
authors.lastname: Lee
authors.forename: Jae Hyup
authors.initials: JH
authors.lastname: Lee
authors.forename: Byong Chon
authors.initials: BC
authors.lastname: Park
authors.forename: Junghoon
authors.initials: J
authors.lastname: Lee
mesh_terms: D001031:Apatites / Q000737:chemistry*; D018786:Bone Substitutes / Q000138:chemical synthesis*; D016025:Bone Transplantation / Q000295:instrumentation*; D002454:Cell Differentiation; D002478:Cells, Cultured; D003460:Crystallization / Q000379:methods; D055119:Elastic Modulus; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D046911:Macromolecular Substances / Q000737:chemistry; D008422:Materials Testing; D059630:Mesenchymal Stem Cells / Q000166:cytology*; D008968:Molecular Conformation; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure; D010006:Osteoblasts / Q000166:cytology*; D010012:Osteogenesis / Q000502:physiology; D013499:Surface Properties; D023822:Tissue Engineering / Q000295:instrumentation; D054457:Tissue Scaffolds
chemical_list: D001031:Apatites; D018786:Bone Substitutes; D046911:Macromolecular Substances; D006108:Graphite