The influence of mechanochemical treatment of sintered submicrocrystalline corundum substrates on the structure of bioglass composites

The influence of mechanochemical treatment of submicrocrystalline sintered corundum on the structure of bioglass composites containing α-Al₂O₃ and CaO-SiO₂-P₂O₅ glasses was examined in the context of the possibility to form hydroxyapatite after being immersed in the simulated body fluid solution. Measurements of specific surface area and size and X-ray analysis of submicrocrystalline sintered corundum were conducted. Bioglass composites were obtained by placing submicrocrystalline sintered corundum grains in the CaO-SiO₂-P₂O₅ sol system, gelling and sintering at 800°C. The specimens were examined under a scanning electron microscope before and after immersion in the simulated body fluid solution for 24 and 120 h. Using the VCS algorithm, calculations of thermodynamic stability of compounds occurring in these bioglass composites were carried out, verifying the X-ray analysis. Original Russian Text ? B. Staniewicz-Brudnik, S. Szarska, K. Gamrat, 2008, published in Sverkhtverdye Materialy, 2008, Vol. 30, No. 6, pp. 40–48.     

生物凝胶玻璃陶瓷的体内外生物学性能研究

采用溶胶凝胶自蔓延法制备生物凝胶玻璃粉,采用冷等静压法压制成圆片状和圆柱状,对经过烧结处理的两种生物凝胶玻璃陶瓷样品在体外、体内环境中的生物学行为进行了研究.试验结果表明:两试样均具有很好的体外生物活性和体内组织相容性,其中,硅含量较低的试样的体外生物活性优于硅含量较高的试样;而硅含量较高的试样的组织相容性较好且具有一定的骨诱导能力.试验证明:体外试验与体内试验的结果具有一定相关性,但对体内植入试验只起到一定的指导性所用.     

Phosphate content affects structure and bioactivity of sol-gel silicate bioactive glasses

Bioactive glasses can heal bone defects and bond with bone through formation of hydroxyl carbonate apatite (HCA) surface layer. Sol-gel derived bioactive glasses are thought to have potential for improving bone regeneration rates over melt-derived compositions. The 58S sol-gel composition (60 mol% SiO₂, 36 mol% CaO, and 4 mol% P₂O₅) has appeared in commercial products. Here, hydroxyapatite (HA) was found to form within the 58S glass during sol-gel synthesis after thermal stabilization. The preformed HA may lead to rapid release of calcium orthophosphate, or nanocrystals of HA, on exposure to body fluid, rather than the release of separate the calcium and phosphate species. Increasing the P₂O₅ to CaO ratio in the glass composition reduced preformed HA formation, as observed by XRD and solid-state NMR. Instead, above 12 mol% phosphate, a phosphate glass network (polyphosphate) formed, creating co-networks of phosphate and silica. Nanopore diameter of the glass and rate of HCA layer formation in simulated body fluid (SBF) decreased when the phosphate content increased.     

Chitin and chitosan in selected biomedical applications

Chitin (CT), the well-known natural biopolymer and chitosan (CS) (bio-based or “artificial polymer”) are non-toxic, biodegradable and biocompatible in nature. The advantages of these biomaterials are such that, they can be easily processed into different forms such as membranes, sponges, gels, scaffolds, microparticles, nanoparticles and nanofibers for a variety of biomedical applications such as drug delivery, gene therapy, tissue engineering and wound healing. Present review focuses on the diverse applications of CT and CS membranes and scaffolds for drug delivery, tissue engineering and targeted regenerative medicine. The chitinous scaffolds of marine sponges’ origin are discussed here for the first time. These CT based scaffolds obtained from Porifera possess remarkable and unique properties such as hydration, interconnected channels and diverse structural architecture. This review will provide a brief overview of CT and CS membranes and scaffolds toward different kinds of delivery applications such as anticancer drug delivery, osteogenic drug delivery, and growth factor delivery, because of their inimitable release behavior, degradation profile, mucoadhesive nature, etc. The review also provides an overview of the key features of CT and CS membranes and scaffolds such as their biodegradability, cytocompatibility and mechanical properties toward applications in tissue engineering and wound healing.     

用于治疗癌症的生物玻璃

生物玻璃是重要的无机生物医用材料之一,具有良好的生物活性和生物相容性,各国对其研究非常活跃。本文论述了此类玻璃用作内辐射治癌用的射线载体材料和热磁疗法中用的热种子的研究现状及发展方向。     

新型骨-软骨一体化修复支架材料的制备

利用可降解聚合物微球的相互粘结制备了一种新型的组织工程支架材料, 可用于软骨和软骨下骨损伤的修复。采用光学显微镜、 扫描电镜对支架的表面形貌、 内部结构进行了表征, 同时研究了支架材料的力学性能, 此外还研究了微球的粒径对支架材料孔隙率的影响。结果显示, 该材料在结构上分为乳酸-羟基乙酸共聚物(PLGA)层和PLGA/生物活性玻璃(BG)层; 材料的孔隙三维连通、 分布均匀; 采用粒径为150~200μm微球所制备的支架孔隙率为(53.37±4.39)%, 在10%的应变下材料压缩强度便已达到了0.9MPa, 显示了较强的力学性能; 随着微球粒径的变小, 材料孔隙率逐渐增大。这种微球支架在骨-软骨组织缺损修复方面有着很大的研究价值和应用价值。      

羟基磷灰石/生物玻璃复合涂层的研究

设计了适合在Ti6Al4V金属基体上制备涂层的生物玻璃，通过电泳沉积以及后续热处理在Ti6Al4V合金上制备了羟基磷灰石／生物玻璃复合涂层，实现了底层致密表层多孔的结构梯度。利用平底锥头法对涂层剪切强度进行了测试；利用SEM观察了其表面形貌；利用EPMA分析了复合涂层断面结构和组成。     

卵磷脂对生物活性玻璃表面改性的研究

采用卵磷脂对生物活性玻璃粉体表面进行改性处理, 并研究了生物活性玻璃与卵磷脂的相互作用. 热分析(TG/DSC)、傅立叶变换红外光谱（FTIR）分析表明, 卵磷脂在生物活性玻璃表面附着,通过氢键等弱键相互作用. 表面改性后的生物活性玻璃粉体与壳聚糖复合后, 复合材料的力学强度与未处理的相比有明显提高. 扫描电子显微镜(SEM)结果显示, 经处理后的生物活性玻璃粉体在壳聚糖中分散均匀, 两者结合紧密, 表明卵磷脂改性可以有效地提高生物活性玻璃粉体与壳聚糖有机基质的界面结合强度.     

生物玻璃涂层植入材料的动物实验研究

本文利用扫描电镜、电子探针等手段,研究分析了生物玻璃涂层植入动物骨组织后,涂层表面与骨界面的显微变化及元素分布,生物实验结果,羟脯氨酸和氨基已糖含量与骨折后羟脯氨酸和氨基已糖含量变化的趋势一致。     

喷雾干燥可控制备生物玻璃微球及其体外生物活性研究

CaO-SiO₂-P₂O₅体系生物玻璃(Bioglass,BG)微球具有良好的生物活性和骨传导性,在骨组织修复领域得到广泛研究与应用。传统熔融法制备BG粉体的能耗大、粉体形貌不可控、生物活性相对较低;溶胶–凝胶法制备BG粉体则需大量溶剂、制备周期长、不易量产。为快速、规模化制备形貌、粒径、化学组成可控的BG微球,本研究以水溶液为溶剂,以正硅酸四乙酯、磷酸三乙酯、四水硝酸钙为原料,采用喷雾干燥前驱体溶液方法制备BG微球,探讨喷雾干燥过程中进气风量、前驱体溶液浓度和进料速率等工艺参数对BG微球粒径的影响;前驱体溶液化学组成对BG微球的体外诱导磷灰石沉积能力的影响。结果表明,BG微球的粒径范围在40μm以下可控,且粒径随前驱体溶液浓度增大而增大,随进气风量增大而减小,进料速率则对微球粒径影响较小。不同化学组成的BG微球都具有良好的体外诱导磷灰石沉积能力,而且随CaO含量的增加而提高。