CIRIMAT, INPT-CNRS-UPS, Université de Toulouse, Université Paul Sabatier, Toulouse, France.
Langmuir. 2013 Feb 19;29(7):2224-32. doi: 10.1021/la3046548. Epub 2013 Feb 4.
Bisphosphonates (BPs) are well established as successful antiresorptive agents for the prevention and treatment of bone diseases such as osteoporosis and Paget's disease. The aim of this work was to clarify the reaction mechanisms between a BP molecule, tiludronate, and the nanocrystalline apatite surface. The adsorption of tiludronate on well-characterized synthetic biomimetic nanocrystalline apatites with homogeneous but different compositions and surface characteristics was investigated to determine the effect of the nanocrystalline apatite substrate on the adsorption behavior. The results show that the adsorption of tiludronate on nanocrystalline biomimetic apatite surfaces varies over a large range. The most immature apatitic samples exhibited the highest affinity and the greatest amount adsorbed at saturation. Maturation of the nanocrystals induces a decrease of these values. The amount of phosphate ion released per adsorbed BP molecule varied, depending on the nanocrystalline substrate considered. The adsorption mechanism, although associated with a release of phosphate ions, cannot be considered as a simple ion exchange process involving one or two phosphate ions on the surface. A two-step process is proposed consisting of a surface binding of BP groups to calcium ions associated with a proton release inducing the protonation of surface orthophosphate ions and their eventual solubilization.
双膦酸盐（BPs）是预防和治疗骨质疏松症和 Pagets 病等骨骼疾病的成功抗吸收剂。本工作旨在阐明 BP 分子替鲁膦酸与纳米晶磷灰石表面之间的反应机制。研究了替鲁膦酸在具有均匀但不同组成和表面特性的合成仿生纳米晶磷灰石上的吸附，以确定纳米晶磷灰石基底对吸附行为的影响。结果表明，替鲁膦酸在纳米晶仿生磷灰石表面上的吸附范围很大。最不成熟的磷灰石样品表现出最高的亲和力和最大的饱和吸附量。纳米晶的成熟诱导这些值降低。每吸附一个 BP 分子释放的磷酸离子量取决于所考虑的纳米晶基底而有所不同。尽管吸附机制与释放磷酸离子有关，但不能将其视为涉及表面上一个或两个磷酸离子的简单离子交换过程。提出了一个两步过程，包括 BP 基团与钙离子的表面结合以及质子释放，质子释放诱导表面正磷酸离子的质子化及其最终的溶解。
