Bio-inspired porous metallic scaffolds have tremendous potential to be used as artificial bone substitutes. In this work, a radially graded lattice structure (RGLS), which mimics the structures of natural human bones, was designed and processed by laser powder bed fusion of martensitic Ti-rich TiNi powder. The asymmetric tension-compression behaviour, where the compressive strength is significantly higher than the tensile strength, is observed in this Ti-rich TiNi material, which echoes the mechanical behaviour of bones. The morphologies, mechanical properties, deformation behaviour, and biological compatibility of RGLS samples were characterised and compared with those in the uniform lattice structure. Both the uniform and RGLS samples achieve a relative density higher than 99%. The graded porosities and pore sizes in the RGLS range from 40%-80% and 330-805 μm, respectively, from the centre to the edge. The chemical etching has significantly removed the harmful partially-melted residual powder particles on the lattice struts. The compressive yield strength of RGLS is 71.5 MPa, much higher than that of the uniform sample (46.5 MPa), despite having a similar relative density of about 46%. The calculated Gibson-Ashby equation and the deformation behaviour simulation by finite element suggest that the dense outer regions with high load-bearing capability could sustain high applied stress, improving the overall strength of RGLS significantly. The cell proliferation study suggests better biological compatibility of the RGLS than the uniform structures. The findings highlight a novel strategy to improve the performance of additively manufactured artificial implants by bio-inspiration.

作为一种新型的荧光探针, 量子点(QD)已经受到越来越多的重视, 制备工艺也显得格外重要。水相中合成的量子点效率低, 油相中的量子点经过转相以后效率也大大衰减。本论文利用再沉淀包覆的方法制备了具有良好的水溶性的掺杂绿光CdSe@ZnS的纳米颗粒G-NPs(534 nm)和掺杂红光CdSe@ZnS的纳米颗粒R-NPs(610 nm), 具有窄的半峰宽(G-NPs ~29 nm, R-NPs ~31 nm), 较小的粒径(45 nm), 并在此基础上通过发射光谱与荧光衰减研究了量子点之间的能量传递现象。该方法保留了量子点原来的性质, 基于其优良的光学性质, 对人类肝细胞肝癌细胞株(HepG2)进行了荧光标记, 从共聚焦成像实验结果看出, 纳米颗粒得到了良好的吞噬效果。

以聚乙烯吡咯烷酮(PVP)为表面活性剂, 利用溶剂热法合成了NaYF4∶20%Yb3+, 3%Er3+(摩尔分数)的上转换发光纳米粒子。利用扫描电子显微镜对粒子的形貌进行了表征, 结果表明纳米颗粒的尺寸在30～40 nm, 分布比较均匀。在980 nm红外光的激发下, 样品能够发出肉眼可见的明亮的黄色上转换荧光。样品可以较好地分散在水溶液中形成透明澄清的溶液。利用MTT实验测量了不同给药浓度下NaYF4纳米粒子是否对HeLa细胞具有生物毒性。结果表明: PVP修饰的NaYF4∶Yb3+/Er3+上转换发光纳米粒子具有较好的生物兼容性, 对HeLa细胞无生物毒性, 在生物荧光标记领域具有潜在的应用价值。