Lindgren M, Astrand M, Wiklund U, Engqvist H
Department of Engineering Sciences, Materials Science, Uppsala University, Uppsala, Sweden.
J Mater Sci Mater Med. 2009 Jul;20(7):1401-8. doi: 10.1007/s10856-009-3709-1. Epub 2009 Feb 28.
To improve the clinical outcome of metal implants, i.e. earlier loading and reduction of the incidence of revision surgery, better bone bonding ability is wanted. One method to achieve this is to change the surface chemistry to give a surface that facilitates bone bonding in vivo, i.e. a bioactive surface. Crystalline titanium oxide has recently been proven to be bioactive in vitro and is an interesting option to the more common hydroxylapatite (HA) coatings on implants. A materials possible in vitro bioactivity is tested through soaking in simulated body fluid and studies of possible HA formation on the surface. For bioactive materials, the formed HA layer can also be used as a coating. The aim of the current paper is to investigate some boundary conditions for HA formation on crystalline titanium oxide surfaces regarding influence from coating thickness, soaking time and soaking temperature. The influence from soaking time and temperature on the HA growth were investigated on oxidised Ti samples, (24 h at 800 degrees C) resulting in a rutile surface structure. The oxidised samples were tested at three temperatures (4, 37 and 65 degrees C) and four times (1 h, 1 day, 1 week and 4 weeks). The influence from titanium coating thickness on the HA growth was investigated via depositing thin films of crystalline titanium dioxide on Ti plates using a reactive magnetron sputtering process. Four different PVD runs with coating thicknesses between 19 and 74 nm were tested. The soaking temperature had an effect on the HA formation and growth on both rutile surfaces and native oxide on Ti substrates. Higher temperatures lead to easier formation of HA. It was even possible, at 65 degrees C, to grow HA on native titanium oxide from soaking in PBS. The coating quality was better for HA formed at 65 degrees C compared to 37 degrees C. All PVD-coatings showed HA growth after 1 week in PBS at 37 degrees C, thus even very thin coatings of crystalline titanium oxide coatings are bioactive.
为改善金属植入物的临床效果，即实现更早负重并降低翻修手术发生率，需要更好的骨结合能力。实现这一目标的一种方法是改变表面化学性质，以获得在体内促进骨结合的表面，即生物活性表面。最近已证明结晶二氧化钛在体外具有生物活性，对于植入物上更常见的羟基磷灰石（HA）涂层来说，它是一个有趣的选择。通过将材料浸泡在模拟体液中并研究表面上可能形成的HA，来测试材料可能的体外生物活性。对于生物活性材料，形成的HA层也可用于涂层。本文的目的是研究在结晶二氧化钛表面形成HA的一些边界条件，包括涂层厚度、浸泡时间和浸泡温度的影响。研究了浸泡时间和温度对在800℃氧化24小时得到的具有金红石表面结构的钛样品上HA生长的影响。将氧化后的样品在三个温度（4℃、37℃和65℃）和四个时间点（1小时、1天、1周和4周）下进行测试。通过使用反应磁控溅射工艺在钛板上沉积结晶二氧化钛薄膜，研究了钛涂层厚度对HA生长的影响。测试了四种不同的物理气相沉积（PVD）涂层，涂层厚度在19至74纳米之间。浸泡温度对金红石表面和钛基底上的天然氧化物上的HA形成和生长都有影响。温度越高，HA形成越容易。在65℃时，甚至有可能通过在磷酸盐缓冲盐水（PBS）中浸泡在天然氧化钛上生长HA。与37℃相比，在65℃形成的HA涂层质量更好。所有PVD涂层在37℃的PBS中浸泡1周后都显示出HA生长，因此即使是非常薄的结晶二氧化钛涂层也具有生物活性。
