title: Aminopropyltriethoxysilane-mediated surface functionalization of hydroxyapatite nanoparticles: synthesis, characterization, and in vitro toxicity assay.
abstract: BACKGROUND
  We report on aminopropyltriethoxysilane (APTS)-mediated surface modification of nanohydroxyapatite with different surface functional groups for potential biomedical applications. In this study, nanohydroxyapatite covalently linked with APTS (n-HA-APTS) was reacted with acetic anhydride or succinic anhydride to produce neutralized (n-HA-APTS. Ac) or negatively charged (n-HA-APTS.SAH) nanohydroxyapatite, respectively. Nanohydroxyapatite formed with amine, acetyl, and carboxyl groups was extensively characterized using Fourier transform infrared spectroscopy, transmission electron microscopy, (1)H nuclear magnetic resonance spectroscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectroscopy, and zeta potential measurements.
  
  
  RESULTS
  In vitro 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide colorimetric assay revealed that the slight toxicity of the amine-functionalized n-HA-APTS could be eliminated by post-functionalization of APTS amines to form acetyl and carboxyl groups. Blood compatibility assessment demonstrated that the negligible hemolytic activity of the pristine nanohydroxyapatite particles did not appreciably change after APTS-mediated surface functionalization.
  
  
  CONCLUSIONS
  APTS-mediated functionalization of nanohydroxyapatite with different surface groups may be useful for further functionalization of nanohydroxyapatite with biologically active materials, thereby providing possibilities for a broad range of biomedical applications.
authors.affiliation: State Key Laboratory for Modification of Chemical Fibers and Polymer Materials, Shanghai, People's Republic of China.
authors.forename: Shige
authors.initials: S
authors.lastname: Wang
authors.forename: Shihui
authors.initials: S
authors.lastname: Wen
authors.forename: Mingwu
authors.initials: M
authors.lastname: Shen
authors.forename: Rui
authors.initials: R
authors.lastname: Guo
authors.forename: Xueyan
authors.initials: X
authors.lastname: Cao
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
authors.forename: Xiangyang
authors.initials: X
authors.lastname: Shi
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D017886:Durapatite / Q000737:chemistry* / Q000633:toxicity; D004912:Erythrocytes / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006651:Histocytochemistry; D006801:Humans; D051379:Mice; D053758:Nanoparticles / Q000737:chemistry* / Q000633:toxicity; D011437:Propylamines; D012821:Silanes / Q000737:chemistry* / Q000633:toxicity; D017550:Spectroscopy, Fourier Transform Infrared; D013499:Surface Properties; D014961:X-Ray Diffraction
chemical_list: D011437:Propylamines; D012821:Silanes; D017886:Durapatite; C477625:amino-propyl-triethoxysilane