Study on adsorption mechanism of proteins onto synthetic calcium hydroxyapatites through ionic concentration measurements
Study on adsorption mechanism of proteins onto synthetic calcium hydroxyapatites through ionic concentration measurements
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DOI：
10.1007/s00223-004-0102-4
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发表时间：
2005-03-01
影响因子：
4.2
通讯作者：
Ishikawa, T
中科院分区：
文献类型：
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作者：
Kandori, K;Masunari, A;Ishikawa, T
为了阐明蛋白质在羟基磷灰石（Hap）钙上的吸附机理，在15 ℃下检查了在不存在和存在蛋白质的情况下合成Hap颗粒的溶解和离子交换性质的动力学研究。在不存在蛋白质的情况下，Hap颗粒轻微溶解，在KCl、CaCl 2、BaCl 2和AlCl 3溶液中产生少量的钙离子（[Ca 2 +] = 0.09-0.14 μ mol m（-2））和磷酸根离子（[PO 43-] = 0.01-0.08 μ mol m（-2））。随着Ca/P比值的增加，[Ca 2 +]增加，[PO 43-]减少。[Ca ~（2+）]和[PO_（43-）]与离子强度无关。Ba ~（2+）和Al ~（3+）离子在2小时内与Hap晶格中的Ca ~（2+）离子完全交换，Hap表面OH ~-离子溶解后，溶液pH值升高1.1-1.8。在牛血清白蛋白（BSA）的存在下，Hap颗粒溶解略快于没有蛋白质的系统。这一事实被解释为溶解的离子的BSA的功能基团的络合。BSA的吸附导致水溶液中[Ca ~（2+）]和[PO ~（4 3-）]的还原，在BSA吸附达到饱和之前，[Ca ~（2+）]和[PO ~（4 3-）]的浓度出现极小值。该结果表明，BSA在Hap上的吸附受[Ca 2 +]离子与BSA分子的络合（结合效应）以及[Ca 2 +]离子通过溶解OH-离子暴露在Hap表面上的操作（所谓的“C-位点”）控制。BaCl_2和AlCl_3的加入，使BSA在初始吸附阶段的吸附量（n（BSA））急剧增加，这是由于这些二价和三价阳离子在BSA和Hap之间的强结合作用。然而.通过离子交换反应将这些阳离子从Hap表面去除后，结合作用消失，BSA I和n（BSA）降低。由于功能团的数量是小的，只有轻微的反离子的结合效果检测到的系统与二价和三价离子的吸附系统的溶菌酶（LSZ）。
To clarify the adsorption mechanism of proteins onto calcium hydroxyapatite (Hap), the kinetic studies of dissolution and ion-exchange properties of synthetic Hap particles in the absence and presence of proteins were examined at 15 degrees C. In the absence of proteins, Hap particles slightly dissolved to give low amounts of calcium ([Ca2+] = 0.09-0.14 mu mol m(-2)) and phosphate [PO43-] = 0.01-0.08 mu mol m(-2)) ions in KCl, CaCl2, BaCl2 and AlCl3 solutions. The [Ca2+] increased with increase in the Ca/P ratio of Hap, while the [PO43-] decreased. The [Ca2+] and [PO43-] were independent of the ionic strength. Ba2+ and AI(3+) ions were completely ion-exchanged with calcium ions in Hap lattice within 2 hr. The solution pH was increased by 1.1-1.8 after the dissolution of OH- ions on the Hap surface. In the presence of bovine serum albumin (BSA), the Hap particles dissolved slightly faster than the systems without protein. This fact was explained by a complexation of dissolved ions to functional groups of BSA. The adsorption of BSA induced a reduction of [Ca2+] and [PO43-] in the aqueous medium and minima appeared on [Ca2+] and [PO43-] profiles before the BSA adsorption reached a saturation. This result suggests that the adsorption of BSA onto Hap is governed by [Ca2+] ions complexing to BSA molecules (binding effect) together with the operation of [Ca2+] ions exposing on the Hap surfaces by dissolution of OH- ions, so-called "C-sites". The addition of BaCl2 and AlCl3, BSA steeply increased the amounts of adsorbed BSA (n(BSA)) at the initial adsorption step by the strong binding effect of these di- and trivalent cations between BSA and Hap. However. after eliminating these cations from the Hap surface by the ion-exchange reaction, the binding effects disappeared BSA I and n(BSA) decreased. Since the number of functional groups is small, the binding effect of the counter ions was only slightly detected for the systems with di- and trivalent ions on the adsorption systems of lysozyme (LSZ).