Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, Japan.
Colloids Surf B Biointerfaces. 2010 Mar 1;76(1):226-35. doi: 10.1016/j.colsurfb.2009.10.039. Epub 2009 Nov 1.
Recently, much attention has been paid to hydroxyapatite (HA) particles as protein drug carriers. HA is biological substance like tooth and bone, and HA has biodegradable and biocompatible property. Also HA has high affinity for versatile substances, such as proteins. The aim of this study was to prepare HA particles and to evaluate the effects of various experimental conditions on particles properties (i.e. shape and amount of protein adsorption to HA). HA particles were prepared by three methods including solvent diffusion methods, the method using sintering porous HA microgranules, and homogeneous precipitation method. Complicated spiky crystals were prepared by solvent diffusion method, whereas spherical amorphous agglomerates were prepared by sintering of porous HA granules. Spherical particles were obtained by homogeneous precipitation method and were well dispersed. The spherical particles were composed of minute spiky crystals. The temperature and time duration of the producing process and the amount of additives, such as urea and EDTANa(2), strongly affected the particle shape and size. When the production process is kept under low temperature, tiny crystals were not mutually sintered and also their aggregation was not deposited. Also, inhomogeneous crystal growth occurred when the reaction time was long. Addition of enough amount of EDTANa(2) to reaction solution made the small and spherical HA particles. Bovine serum albumin (BSA) or lysozyme hydrochloride (LSZ)-adsorbed HA particles were prepared. The affinity of HA particles and release profile of proteins from the particles were evaluated. X-ray powder diffraction measurements suggested that the surface area ratio of a plane against total surface area of HA crystal became smaller by decreasing EDTANa(2) concentration. The surface of plane a is positively charged but that of plane c is negatively charged. HA particle size decreased as EDTANa(2) concentration increased. The amounts of BSA and LSZ adsorbing onto HA particle surface were different, since BSA was negatively charged and LSZ was positively charged in the solution. Therefore BSA seems to adsorb onto plane c, whereas LSZ adsorb onto plane a. The differences of the ratio of surface a plane against the total surface area of HA particles and particles size influenced the amount of protein adsorption. The sustained release of BSA and LSZ from HA particles were observed for two weeks.
最近，人们对羟基磷灰石（HA）颗粒作为蛋白质药物载体给予了极大关注。HA 是一种类似于牙齿和骨骼的生物物质，具有可生物降解和生物相容性。此外，HA 对各种物质具有高亲和力，例如蛋白质。本研究的目的是制备 HA 颗粒，并评估各种实验条件对颗粒性质（即蛋白质吸附到 HA 的形状和数量）的影响。HA 颗粒通过溶剂扩散法、烧结多孔 HA 微球的方法和均相沉淀法三种方法制备。溶剂扩散法制备复杂的刺状晶体，而烧结多孔 HA 颗粒制备球形无定形团聚体。均相沉淀法制备的球形颗粒分散良好，由微小的刺状晶体组成。制备过程的温度和时间持续时间以及添加剂（如尿素和 EDTANa(2)）的量强烈影响颗粒的形状和尺寸。当生产过程保持在低温下时，微小的晶体不会相互烧结，并且它们的聚集也不会沉积。此外，当反应时间较长时，会发生不均匀的晶体生长。向反应溶液中添加足够量的 EDTANa(2)可得到小而球形的 HA 颗粒。制备了牛血清白蛋白（BSA）或溶菌酶盐酸盐（LSZ）吸附的 HA 颗粒。评估了 HA 颗粒的亲和力和蛋白质从颗粒中的释放情况。X 射线粉末衍射测量表明，随着 EDTANa(2)浓度的降低，HA 晶体总表面积与平面面积之比减小。HA 晶体的平面 a 表面带正电荷，而平面 c 表面带负电荷。随着 EDTANa(2)浓度的增加，HA 颗粒的粒径减小。由于 BSA 在溶液中带负电荷而 LSZ 带正电荷，因此吸附到 HA 颗粒表面的 BSA 和 LSZ 的量不同。因此，BSA 似乎吸附在平面 c 上，而 LSZ 吸附在平面 a 上。HA 颗粒表面 a 平面与总表面积之比和颗粒尺寸的差异影响蛋白质的吸附量。观察到 BSA 和 LSZ 从 HA 颗粒中的持续释放长达两周。
