Laboratoire des Matériaux Céramiques et Procédés Associés, Université de Valenciennes et du Hainaut-Cambrésis, Valenciennes, France.
J Mech Behav Biomed Mater. 2013 Jul;23:133-48. doi: 10.1016/j.jmbbm.2013.03.010. Epub 2013 Apr 10.
Bioactive glasses are able to bond to bone through formation of carbonated hydroxyapatite in body fluids, and fluoride-releasing bioactive glasses are of interest for both orthopaedic and, in particular, dental applications for caries inhibition. However, because of their poor strength their use is restricted to non-load-bearing applications. In order to increase their mechanical properties, doping with nitrogen has been performed on two series of bioactive glasses: series (I) was a "bioglass" composition (without P2O5) within the quaternary system SiO2-Na2O-CaO-Si3N4 and series (II) was a simple substitution of CaF2 for CaO in series (I) glasses keeping the Na:Ca ratio constant. The objective of this work was to evaluate the effect of the variation in nitrogen and fluorine content on the properties of these glasses. The density, glass transition temperature, hardness and elastic modulus all increased linearly with nitrogen content which indicates that the incorporation of nitrogen stiffens the glass network because N is mainly in 3-fold coordination with Si atoms. Fluorine addition significantly decreases the thermal property values but the mechanical properties of these glasses remain unchanged with fluorine. The combination of both nitrogen and fluorine in oxyfluoronitride glasses gives better mechanical properties at much lower melting temperatures since fluorine reduces the melting point, allows higher solubility of nitrogen and does not affect the higher mechanical properties arising from incorporation of nitrogen. The characterization of these N and F substituted bioactive glasses using (29)Si MAS NMR has shown that the increase in rigidity of the glass network can be explained by the formation of SiO3N, SiO2N2 tetrahedra and Q(4) units with extra bridging anions at the expense of Q(3) units. Bioactivity of the glasses was investigated in vitro by examining apatite formation on the surface of glasses treated in acellular simulated body fluid (SBF) with ion concentrations similar to those in human blood plasma. Formation of a bioactive apatite layer on the samples treated in SBF was confirmed by grazing incidence X-ray diffraction and scanning electron microscopy (SEM) combined with energy dispersive X-ray spectroscopy (EDS). The crystallinity of this layer decreases with increasing N content suggesting that N may decrease bioactivity slightly.
生物活性玻璃能够通过在体液中形成碳酸羟基磷灰石与骨骼结合，而释放氟的生物活性玻璃对于骨科，特别是牙科的龋齿抑制应用具有重要意义。然而，由于其强度较差，它们的应用仅限于非承重应用。为了提高它们的机械性能，已经对两种系列的生物活性玻璃进行了氮掺杂：系列（I）是在四元系统 SiO2-Na2O-CaO-Si3N4 内的“生物玻璃”组成（不含 P2O5），而系列（II）是简单地用 CaF2 替代系列（I）玻璃中的 CaO，保持 Na:Ca 比不变。这项工作的目的是评估氮和氟含量的变化对这些玻璃性能的影响。密度、玻璃化转变温度、硬度和弹性模量都随氮含量线性增加，这表明氮的掺入使玻璃网络变硬，因为 N 主要与 Si 原子以三配位的形式存在。氟的加入显著降低了热性能值，但这些玻璃的机械性能随氟的加入而保持不变。在氧氟氮化物玻璃中同时加入氮和氟，可以在低得多的熔融温度下获得更好的机械性能，因为氟降低了熔融温度，允许更高的氮溶解度，并且不会影响因氮掺入而产生的更高机械性能。使用（29）Si MAS NMR 对这些氮和氟取代的生物活性玻璃进行的表征表明，玻璃网络的刚性增加可以用 SiO3N、SiO2N2 四面体和 Q(4)单元的形成来解释，这些单元在牺牲 Q(3)单元的情况下带有额外的桥接阴离子。通过在类似于人血浆离子浓度的无细胞模拟体液（SBF）中处理玻璃来研究玻璃的生物活性，在体外检查玻璃表面上形成的磷灰石。用掠入射 X 射线衍射和扫描电子显微镜（SEM）结合能量色散 X 射线光谱（EDS）证实了在 SBF 中处理的样品上形成了生物活性磷灰石层。该层的结晶度随氮含量的增加而降低，这表明氮可能略微降低生物活性。
