title: Biomimetic growth of apatite on hydrogen-implanted silicon.
abstract: Hydrogen in silicon has been widely applied in semiconductor fields. In this paper, the application of hydrogen-implanted silicon wafer in biomedical fields was explored by investigating its bioactivity. Hydrogen implanted silicon wafers were prepared using plasma immersion ion implantation. The surface structures of the 1.4 x 10(17) cm(-2) hydrogen-implanted silicon wafers were investigated using atomic force microscopy and transmission electron microscopy (TEM). The hydrogen depth profiles were acquired by SIMS and the crystal quality of the as-implanted silicon was studied by channeling Rutherford backscattering spectrometry (RBS). The bioactivity of the implanted silicon was evaluated using the biomimetic growth of apatite on its surface after it was soaked in simulated body fluid for a period of time. The TEM, SIMS and RBS results indicate the formation of an amorphous hydrogenated silicon (a-Si:Hx) layer has been formed on the surface of the hydrogen-implanted silicon wafer. After immersion in SBF for 14 days, bone-like apatite is observed to nucleate and grow on the surface. With longer soaking time, more apatite appeared on the surface of the hydrogen implanted silicon but our control experiments did not reveal any apatite formation on the surface of the un-implanted silicon wafer, hydrogenated crystalline silicon wafer (with hydrogen, but no amorphous surface), or argon-implanted silicon wafer (amorphous surface but without hydrogen). Our results indicated that the bioactivity of silicon wafer can be improved after hydrogen implantation and the formation of the amorphous hydrogenated silicon (a-Si:Hx) surface also plays a synergistic role to improve the bioactivity.
authors.affiliation: Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong.
authors.forename: Xuanyong
authors.initials: X
authors.lastname: Liu
authors.forename: Ricky K Y
authors.initials: RK
authors.lastname: Fu
authors.forename: Ray W Y
authors.initials: RW
authors.lastname: Poon
authors.forename: Peng
authors.initials: P
authors.lastname: Chen
authors.forename: Paul K
authors.initials: PK
authors.lastname: Chu
authors.forename: Chuanxian
authors.initials: C
authors.lastname: Ding
mesh_terms: D000512:Alpha Particles; D001031:Apatites / Q000032:analysis / Q000138:chemical synthesis*; D040761:Biomimetic Materials / Q000032:analysis / Q000138:chemical synthesis*; D002118:Calcium / Q000032:analysis; D002254:Carbonates / Q000032:analysis; D006801:Humans; D006859:Hydrogen / Q000737:chemistry*; D008274:Magnesium / Q000032:analysis; D018625:Microscopy, Atomic Force; D046529:Microscopy, Electron, Transmission; D010710:Phosphates / Q000032:analysis; D010949:Plasma / Q000737:chemistry; D011188:Potassium / Q000032:analysis; D012542:Scattering, Radiation; D012825:Silicon / Q000032:analysis / Q000737:chemistry*; D012964:Sodium / Q000032:analysis; D018629:Spectrometry, Mass, Secondary Ion; D013052:Spectrometry, X-Ray Emission; D017550:Spectroscopy, Fourier Transform Infrared; D014961:X-Ray Diffraction
chemical_list: D001031:Apatites; D002254:Carbonates; D010710:Phosphates; D006859:Hydrogen; D012964:Sodium; D008274:Magnesium; D011188:Potassium; D002118:Calcium; D012825:Silicon