title: Bioactive rosette nanotube-hydroxyapatite nanocomposites improve osteoblast functions.
abstract: Inspired from biological systems, small synthetic organic molecules expressing the hydrogen bonding arrays of the DNA bases guanine and cytosine were prepared, and their self-assembly into rosette nanotubes (RNTs) was investigated. Due to their unique biological, physicochemical, and mechanical properties, RNTs could serve as the next generation of injectable orthopedic materials. In this study, a self-assembling module (termed twin base linkers or TBL) was synthesized, and the corresponding RNTs were used as bioactive components in composites of poly (2-hydroxyethyl methacrylate) (pHEMA) and hydroxyapatite (HA) nanoparticles (termed TBL/HA/pHEMA). The properties of these composites were characterized for solidification time, surface morphology, mechanical properties, and cytocompatibility. The experimental conditions were optimized to achieve solidification within 2-40 min, offering a range of properties for orthopedic applications. Composites with 20 wt% HA nanoparticles had a compressive strength (37.1 MPa) and an ultimate tensile stress (14.7 MPa) similar to that of a natural vertebral disc (5-30 MPa). Specifically, the TBL (0.01 mg/mL)/HA(20 wt%)/pHEMA composites improved long-term functions of osteoblasts (or bone-forming cells) in terms of collagen synthesis, alkaline phosphatase activity, and calcium deposition. Moreover, this composite inhibited fibroblast adhesion, thus decreasing the potential for undesirable fibrous tissue formation. In summary, this in vitro study provided evidence that TBL/HA/pHEMA composites are promising injectable orthopedic implant materials that warrant further mechanistic and in vivo studies.
authors.affiliation: School of Engineering, Brown University, Providence, RI 02912, USA.
authors.forename: Linlin
authors.initials: L
authors.lastname: Sun
authors.forename: Lijie
authors.initials: L
authors.lastname: Zhang
authors.forename: Usha D
authors.initials: UD
authors.lastname: Hemraz
authors.forename: Hicham
authors.initials: H
authors.lastname: Fenniri
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Webster
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D002448:Cell Adhesion / Q000187:drug effects; D002452:Cell Count; D016923:Cell Death / Q000187:drug effects; D048430:Cell Shape / Q000187:drug effects; D003094:Collagen / Q000378:metabolism; D019245:Compressive Strength / Q000187:drug effects; D017886:Durapatite / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006801:Humans; D008422:Materials Testing; D008856:Microscopy, Fluorescence; D053761:Nanocomposites / Q000737:chemistry* / Q000648:ultrastructure; D043942:Nanotubes / Q000737:chemistry* / Q000648:ultrastructure; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000201:enzymology; D011102:Polyhydroxyethyl Methacrylate / Q000737:chemistry; D051381:Rats; D013718:Tensile Strength / Q000187:drug effects
chemical_list: D001672:Biocompatible Materials; D011102:Polyhydroxyethyl Methacrylate; D003094:Collagen; D017886:Durapatite; D000469:Alkaline Phosphatase; D002118:Calcium