Preparation of monosized spherical particles for bio-ceramic cement

具有相同大小的小颗粒，通常被称为单粒粉末，现在在许多科学领域发现了越来越多的需求。它们在一些医学应用中非常有趣，例如用于制备可分解骨替代品的起始材料，用于持续药物输送的可分解系统，或用于分化哺乳动物细胞培养的支持。对于生物医学应用，处理尺寸在0.05 ~ 0.5mm范围内的单分散球形颗粒是理想的。根据应用的不同，致密的固体颗粒、空心球体或孔隙度可控的多孔球体都是优选的。颗粒可以由磷酸三钙（TCP）、羟基磷灰石（HAp）或两者的混合物组成，这取决于所需材料的生物可吸收性。在任何情况下，关键问题是将初始磷酸钙粉末塑造成具有所需尺寸分布的球体。考虑到医用级粉末的成本相对较高，一种制备单分散球形颗粒的方法将非常有吸引力。在微米范围内（溶胶-凝胶，控制沉淀）和毫米范围内（膏体挤出，球化）制备颗粒已经建立了良好的技术，但没有一种技术能够在0.05 ~ 0.5mm范围内正常工作。本文采用脉冲孔喷射法制备了孔径在200 ~ 500μm范围内具有多孔空心结构的磷酸三钙（β-TCP）单尺寸球形颗粒。该装置设计用于通过压电致动器的传压膜片的剪切动作从一个小孔口喷出磷酸钙陶瓷悬浮液。每个脉冲压力产生一个液滴，其大小几乎等于孔直径。已研制出陶瓷悬浮液，可在该装置上加工；对配方进行了粉末特性优化（粒度、团聚程度、固液比、分散剂、流变添加剂和粘合剂的性质和浓度）。少

Small particles having the same size, often called as monosized powder, have now been finding increased needs in a number of scientific fields. They are very interesting in several medical applications, such as starting materials for the elaboration of resolvable bone substitutes, resolvable systems for sustained drugs delivery, or supports for differentiated mammalian cell cultures. For biomedical applications, it would be desirable to dispose of monodisperse spherical particles in the size range of 0.05〜0.5mm. Depending on the application, either dense solid particles, hollow spheres, or porous spheres with controlled porosity would be preferable. The particles may consist of tricalcium phosphate (TCP), hydroxyl apatite (HAp) or mixtures there of, depending on the desired bioresorvability of the material. In any case, a key issue is to shape the starting calcium phosphate powders into spheres with the desired size distribution. Given the relatively high cost of medical-grade powders, … More a method allowing to prepare monodisperse spherical granules would be highly appealing. Already well established techniques exist for the preparation of particles in the micrometer rage (sol-gel, controlled precipitation) and in the millimeter range (paste extrusion, spheronization) but none of them is able to work properly in the 0.05〜0.5mm range.In this study, monosized spherical particles of tricalcium phosphate (β-TCP) with porous and hollow structure have been successfully prepared by pulsated orifice ejection method in the 200〜500μm range. The apparatus was devised for ejecting suspensions of calcium-phosphate ceramics from a small orifice by a clipping action of a pressure transmitting diaphragm by a piezoelectric actuator. Each pulse pressure produced one liquid droplet having a size almost equal to the orifice diameter. Ceramic suspensions have been developed, which can be processed with the apparatus; for mulations have been optimized with respect to powder characteristics (granulometry, degree of agglomeration, solid/liquid ratio, nature and concentration of dispersants, theological additives and binders). Less