title: The degradation of the three layered nano-carbonated hydroxyapatite/collagen/PLGA composite membrane in vitro.
abstract: OBJECTIVE
  The purpose of this paper was to investigate the in vitro biodegradation of a guided tissue regeneration composite membrane, nano-carbonated hydroxyapatite/collagen/poly(lactic-co-glycolic acid) (nCHAC/PLGA). Especially for periodontal therapy, the functional graded material (FGM) nCHAC/PLGA membrane was prepared that consisted of three layers with 8 wt% nCHAC + PLGA/4 wt% nCHAC + PLGA/PLGA, where one face of the membrane is porous, thereby allowing cell growth thereon and the opposite face of the membrane smooth, thereby inhibiting cell adhesion.
  
  
  METHODS
  For evaluation, in vitro degradation specimens of nCHAC/PLGA were immersed into artificial saliva solution at 37 degrees C for 1, 2, 4, 8 and 12 weeks to detect the weight loss over the period, and set pure PLGA membrane as control to compare the degraded behaviors. pH value and calcium concentration of the residual solution were measured, and morphology change was investigated by scanning electron microscopy (SEM).
  
  
  RESULTS
  During the experimental period in vitro, the whole shape of the membrane could be kept for 4 weeks, after that it became powder at between 8 and 12 weeks. The results demonstrated that weight loss increased continuously with a reduction in mass of 23.1% after 4 weeks and 88% after 12 week for the nCHAC/PLGA three FGM layers composite membrane. The calcium concentration in the residual solution showed a significant increase after 4 weeks, which referred to the nano-carbonated hydroxyapatite degradation. Moreover, the pH value in the solution of the nCHAC/PLGA membrane was a little higher than that of the pure PLGA membrane, which demonstrated the possible neutralization effect from nCHAC composite for the acid outcome of PLGA in the solution. The pore structure of 8 wt% nCHAC + PLGA was enlarged on the porous surface, while the nonporous surface of pure PLGA also showed a small porous structure after increased time.
  
  
  CONCLUSIONS
  Degradation of the composite membrane is appropriate for practical periodontal repair. Moreover, the new mineral formation on the surface of the composite membrane referred to the possible positive effect in vivo for new bone tissue regeneration.
authors.affiliation: Graduate School of Dental Medicine, Hokkaido University, Sapporo 060-8586, Japan. liaosusan@tsinghua.org.cn
authors.forename: Susan
authors.initials: S
authors.lastname: Liao
authors.forename: Fumio
authors.initials: F
authors.lastname: Watari
authors.forename: Yuhe
authors.initials: Y
authors.lastname: Zhu
authors.forename: Motohiro
authors.initials: M
authors.lastname: Uo
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Akasaka
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Guofu
authors.initials: G
authors.lastname: Xu
authors.forename: Fuzhai
authors.initials: F
authors.lastname: Cui
mesh_terms: D020341:Absorbable Implants; D001672:Biocompatible Materials / Q000737:chemistry*; D002118:Calcium / Q000032:analysis; D003094:Collagen / Q000737:chemistry*; D017886:Durapatite / Q000737:chemistry*; D016557:Guided Tissue Regeneration, Periodontal / Q000295:instrumentation*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019344:Lactic Acid / Q000737:chemistry*; D008422:Materials Testing; D008567:Membranes, Artificial; D008855:Microscopy, Electron, Scanning; D011100:Polyglycolic Acid / Q000737:chemistry*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000737:chemistry*; D016062:Porosity; D011208:Powders; D012464:Saliva, Artificial / Q000737:chemistry; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D001672:Biocompatible Materials; D008567:Membranes, Artificial; D011108:Polymers; D011208:Powders; D012464:Saliva, Artificial; C509317:nano-hydroxyapatite-collagen; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid; D003094:Collagen; D017886:Durapatite; D002118:Calcium