Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany.
ACS Appl Mater Interfaces. 2010 Aug;2(8):2421-8. doi: 10.1021/am1004305.
Titanium that is covered with a native oxide layer is widely used as an implant material; however, it is only passively incorporated in the human bone. To increase the implant-bone interaction, one can graft multifunctional phosphonic compounds onto the implant material. Phosphonate groups show excellent adhesion properties onto metal oxide surfaces such as titanium dioxide, and therefore, they can be used as anchor groups. Here, we present an alternative coating material composed of phosphonate surface-functionalized polystyrene nanoparticles synthesized via free radical copolymerization in a direct (oil-in-water) miniemulsion process. Two types of functional monomers, namely, vinylphosphonic acid (VPA) and vinylbenzyl phosphonic acid (VBPA), were employed in the copolymerization reaction. Using VBPA as a comonomer leads to particles with a higher density of surface phosphonate groups in comparison to those obtained with VPA. VBPA-functionalized particles were used for the coating formation on the titanium surface. The particles monolayer was investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM) employing titanium and silicium tip with the native OH groups. Force versus distance curves proves the strong adhesion between the phosphonated particles and the titanium (or silicium) surfaces in contrast to the nonfunctionalized polystyrene particles. Finally, as a proof of concept, the particles adhered to the surface were further used to nucleate hydroxyapatite, which has high potential for bioimplants.
钛金属表面覆盖有天然氧化层，被广泛用作植入材料；然而，它只能被动地与人体骨骼结合。为了增强植入物与骨骼的相互作用，可以将多功能膦酸化合物接枝到植入材料上。膦酸基团在二氧化钛等金属氧化物表面表现出优异的附着力，因此可以用作锚固基团。在这里，我们提出了一种替代的涂层材料，由通过自由基共聚在直接（油包水）细乳液工艺中合成的膦酸基表面功能化聚苯乙烯纳米粒子组成。两种类型的功能单体，即乙烯基膦酸（VPA）和乙烯基苯膦酸（VBPA），被用于共聚反应。与 VPA 相比，使用 VBPA 作为共聚单体可得到表面膦酸基团密度更高的粒子。VBPA 功能化的粒子用于在钛表面形成涂层。通过扫描电子显微镜（SEM）和原子力显微镜（AFM），使用带有天然 OH 基团的钛和硅尖端研究了粒子的单层。与非功能化的聚苯乙烯粒子相比，力与距离曲线证明了膦酸化粒子与钛（或硅）表面之间的强附着力。最后，作为概念验证，附着在表面上的粒子进一步用于诱导羟基磷灰石的成核，这对生物植入物具有很高的潜力。
