When orthopedic joints coated by hydroxyapatite(HA) were implanted in the human body, they release wear debris into the surrounding tissues. The generation and accumulation of wear particles will induce aseptic loosening. However, the potential bioeffect and mechanism of HA-coated orthopedic implants on bone cells are poorly understood. In this study, defect-related luminescent bur-like hydroxyapatite(BHA) microspheres with the average diameter of 7–9 μm which are comparable to that of the wear-debris particles from aseptically loosened HA implants or HA debris have been synthesized by hydrothermal synthesis and the MC3 T3-E1 cells were set as a cells model to study the potential bioeffect and mechanism of BHA microspheres. The studies demonstrated that BHA microspheres could be taken into MC3 T3-E1 cells via endocytosis involved in micropinocytosisand clathrin-mediated endocytosis process, and exert cytotoxicity effect. BHA microspheres could induce the cell apoptosis by intracellular production of reactive oxygen species(ROS), which led to not only an increase in the permeability of lysosome and release of cathepsins B, but also mitochondrial dysfunction and DNA damage. Our results provide novel evidence to elucidate their toxicity mechanisms and might be helpful for more reasonable applications of HA-based orthopaedic implants in the future.
Yi JinShizhu ChenNan LiYajing LiuGong ChengCuimiao ZhangShuxiang WangJinchao Zhang
Color-tunable phosphors Sr0.94MoO4：xEu^3＋, （0.06 - x）Tb^3＋ were synthesized rapidly by microwave ra- diation method with active carbon particle as microwave absorbent. The synthesized phosphors were investigated by X-ray powder diffraction （XRD） and fluorescence spec- trophotometer. The effects of the ratio of Eu^3＋ and Tb^3＋ on the phase structure and luminescent properties of the phos- phors were discussed. The results show that Eu^3＋,Tb^3＋-doped samples can be well indexed to the pure tetragonal scheelite- type SrMoO4, indicating that Eu^3＋ and Tb^3＋ are effectively doped into the SrMoO4 host lattices. The as-synthesized Sro.94MoO4：xEu^3＋,（0.06 - x）Tb^3＋ phosphors have two luminescent centers （Eu^3＋ and Tb^3＋）, which can show red and green emissions under ultraviolet light excitation, respec- tively. Doping concentration of Eu^3＋ and Tb^3＋ has great effect on the intensity of emission peaks and the chromaticity of the samples, and the full color between green and red light can be achieved by adjusting the relative concentration of Eu^3＋ and Tb^3＋.
A new white luminescent material Dy3＋ doped ZnWO4 was synthesized by hydrothermal route followed by calcining proc- ess. The phase structure, morphology and luminescent properties of as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and fluorescence spectrophotometry, respectively. The results indicated that the sample was pure ZnWO4：Dy3＋ only when the pH value of the reaction system was 6. The ZnWOa：Dy3＋ sample was composed of spherical particles, and the particle size was about 80-130 nm. The excitation spectrum consisted of a broad band ascribed to the charge transfer transi- tion from oxygen ligand to tungsten ion. The emission spectrum of ZnWO4：Dy3＋ was composed of two major parts： the broad band attributing to the intrinsic emission of WO42- and the 4F9/2→6H15/2 transition of Dy3＋, and the sharp emission peak corresponding to the 4F9/2→61-113/2 transition of Dy3＋. The optimal emission intensity of the Zn1-xWOa：Dy3＋x phosphors was realized when x= 1.5 mol. %. Moreover, all of the ZnI_xWOa：Dy3＋ （x=0.5 mol.%, 1 mol.%, 1.5 mol.%, 2 mol.%） phosphors could exhibit white light emission, which could be potentially applied in white lighting-emitting diodes.
