title: Manipulating the bioactivity of hydroxyapatite nano-rods structured networks: effects on mineral coating morphology and growth kinetic.
abstract: BACKGROUND
  Nano-hydroxyapatite particles have better bioactivity than the coarse crystals. So, they can be utilized for engineered tissue implants with improved efficiency over other materials. The development of materials with specific bioactive characteristics is still under investigation.
  
  
  METHODS
  The surface properties of four hydroxyapatite materials templated by different micelle-polymer structured network are studied. The synergistic interaction of each block copolymer in contact with CTAB rod-like micelles results in crystalline HAp nano-rods of 25-50nm length organized in hierarchical structures with different micro-rough characteristics.
  
  
  RESULTS
  It was observed that the material in vitro bioactivity strongly depends on the surface structure while in a minor extent on their Ca/P ratio. So, MIII and MIV materials with Skewness parameter Rsk>2.62 favored the formation on their surfaces of net-like phase with a high growth kinetic constant; while MI and MII (Rsk≤2.62) induced the appearance of spherulitic-like structures and a growth rate 1.75 times inferior. Material biocompatibility was confirmed by interaction with rat calvarial osteoblasts.
  
  
  CONCLUSIONS
  The different structures growth is attributed to a dissimilar matching of crystal planes in the material and the apatite layer formed. In specific synthesis conditions, a biocompatible material with a Ca/P ratio close to that for the trabecular bone and a morphology that are considered essential for bone-bonding was obtained.
  
  
  CONCLUSIONS
  The creation of implantable devices with a specific bioactive characteristic may be useful to manipulate the attachment of cells on mineral coating directly affecting the stability and life of the implant.
authors.affiliation: Department of Chemistry, Universidad Nacional del Sur, INQUISUR-CONICET, (8000) Bahía Blanca, Argentina.
authors.forename: Noelia L
authors.initials: NL
authors.lastname: D'Elía
authors.forename: A Noel
authors.initials: AN
authors.lastname: Gravina
authors.forename: Juan M
authors.initials: JM
authors.lastname: Ruso
authors.forename: Juan A
authors.initials: JA
authors.lastname: Laiuppa
authors.forename: Graciela E
authors.initials: GE
authors.lastname: Santillán
authors.forename: Paula V
authors.initials: PV
authors.lastname: Messina
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry* / Q000494:pharmacology*; D002478:Cells, Cultured; D020099:Coated Materials, Biocompatible / Q000737:chemistry* / Q000494:pharmacology*; D017886:Durapatite / Q000737:chemistry* / Q000494:pharmacology*; D007700:Kinetics; D008823:Micelles; D043942:Nanotubes / Q000737:chemistry*; D010006:Osteoblasts / Q000187:drug effects; D011108:Polymers / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D013329:Structure-Activity Relationship; D013499:Surface Properties; D023822:Tissue Engineering / Q000379:methods
chemical_list: D001672:Biocompatible Materials; D020099:Coated Materials, Biocompatible; D008823:Micelles; D011108:Polymers; D017886:Durapatite
keywords: Bioactivity; Hydroxyapatite; Nano-rods; Osteoblast viability; Sol–gel method; Trabecular bone