Department of Materials Science and Engineering, Missouri University of Science and Technology, Rolla, MO 65409, USA.
J Mater Sci Mater Med. 2011 Mar;22(3):579-91. doi: 10.1007/s10856-011-4250-6. Epub 2011 Feb 3.
Hollow hydroxyapatite (HA) microspheres were prepared by reacting solid microspheres of Li(2)O-CaO-B(2)O(3) glass (106-150 μm) in K(2)HPO(4) solution, and evaluated as a controlled delivery device for a model protein, bovine serum albumin (BSA). Reaction of the glass microspheres for 2 days in 0.02 M K(2)HPO(4) solution (pH = 9) at 37°C resulted in the formation of biocompatible HA microspheres with a hollow core diameter equal to 0.6 the external diameter, high surface area (~100 m(2)/g), and a mesoporous shell wall (pore size ≈ 13 nm). After loading with a solution of BSA in phosphate-buffered saline (PBS) (5 mg BSA/ml), the release kinetics of BSA from the HA microspheres into a PBS medium were measured using a micro bicinchoninic acid (BCA) protein assay. Release of BSA initially increased linearly with time, but almost ceased after 24-48 h. Modification of the BSA release kinetics was achieved by modifying the microstructure of the as-prepared HA microspheres using a controlled heat treatment (1-24 h at 600-900°C). Sustained release of BSA was achieved over 7-14 days from HA microspheres heated for 5 h at 600°C. The amount of BSA released at a given time was dependent on the concentration of BSA initially loaded into the HA microspheres. These hollow HA microspheres could provide a novel inorganic device for controlled local delivery of proteins and drugs.
中空羟基磷灰石 (HA) 微球是通过将固体 Li(2)O-CaO-B(2)O(3) 玻璃微球（106-150 μm）在 K(2)HPO(4) 溶液中反应而制备的，并作为一种模型蛋白质牛血清白蛋白 (BSA) 的控制释放装置进行了评估。玻璃微球在 0.02 M K(2)HPO(4) 溶液（pH = 9）中在 37°C 下反应 2 天，导致形成具有中空核直径等于 0.6 外直径、高表面积（~100 m(2)/g）和介孔壳壁（孔径约为 13nm）的生物相容性 HA 微球。用磷酸盐缓冲盐水（PBS）（5 mg BSA/ml）中的 BSA 溶液加载后，使用微比色法（BCA）蛋白测定法测量 BSA 从 HA 微球释放到 PBS 介质中的释放动力学。BSA 的释放最初随时间线性增加，但在 24-48 小时后几乎停止。通过使用受控热处理（600-900°C 下 1-24 小时）来修饰所制备的 HA 微球的微观结构来实现 BSA 释放动力学的修饰。通过在 600°C 下加热 5 小时的 HA 微球实现了 7-14 天的 BSA 持续释放。在给定时间释放的 BSA 量取决于最初加载到 HA 微球中的 BSA 的浓度。这些中空 HA 微球可为蛋白质和药物的控制局部递送提供新颖的无机装置。
