Sandrini Enrico, Giordano Carmen, Busini Valentina, Signorelli Enrico, Cigada Alberto
Dipartimento di Chimica, Materiali e Ingegneria Chimica G.Natta, Politecnico di Milano, Milan 20133, Italy.
J Mater Sci Mater Med. 2007 Jun;18(6):1225-37. doi: 10.1007/s10856-007-0122-5. Epub 2007 Feb 3.
The modification of titanium and titanium alloy surface properties by chemical and electrochemical techniques has opened new possibilities to improve the bioactivity and, in general, the biological performance of the implants once in vivo. One of the main aims is the achievement of a surface oxide layer that stimulates hydroxylapatite mineralization and, also, shows osteoconductive properties once in the host. In the present study, two different bioactive surfaces have been prepared following the method purposed by the group of Kokubo and a new method, BioSpark, involving high voltage anodic polarisation and alkali etching both on surface mineralization potential. The aim of the present work was to evaluate and compare the mineralization capability and the early cell response of titanium modified with a new bioactive method and with a well-known and widely tested biomimetic treatment, both compared to non treated titanium. Physical and chemical (energy dispersion spectroscopy, thin film X-ray diffractometry) and morphological (scanning electron microscopy) characterisation of the novel surface features has been performed. Also the effect of the novel surface properties on both hydroxyapatite precipitation and early cellular response has been investigated using in vitro models. The results have shown that both treatments produce an active outer layer on titanium but do not impair cells activity and support osteoblasts processes. BioSpark showed high bioactivity and good mineral phase deposition even after early incubation time, these properties were found in Kokubo's surface as previously published. Mineralisation mechanisms of the two materials were different, and while this mechanisms was well characterised and reported for Kokubo's surface, it was still unclear for BioSpark. In this paper an explanation was given and catalytic properties of the latter surface was bound to both well known crystal titanium oxide exhibiting anatase lattice and a certain level of calcium and phosphorus doping, which promoted chemical and physical variation in anatase properties. At the same time early osteoblasts response to Kokubo's and BioSpark's surface was characterised and, no significant differences was found.
通过化学和电化学技术对钛及钛合金表面性能进行改性，为改善植入物在体内的生物活性及总体生物学性能开辟了新的可能性。主要目标之一是获得一种表面氧化层，该氧化层能刺激羟基磷灰石矿化，并且在宿主体内还具有骨传导特性。在本研究中，按照Kokubo团队提出的方法以及一种新的BioSpark方法制备了两种不同的生物活性表面，BioSpark方法涉及高电压阳极极化和碱蚀刻，二者均作用于表面矿化电位。本工作的目的是评估和比较用新的生物活性方法改性的钛与一种广为人知且经过广泛测试的仿生处理方法改性的钛的矿化能力和早期细胞反应，并将二者与未处理的钛进行比较。已对新型表面特征进行了物理和化学（能量色散光谱、薄膜X射线衍射）以及形态学（扫描电子显微镜）表征。还使用体外模型研究了新型表面特性对羟基磷灰石沉淀和早期细胞反应的影响。结果表明，两种处理方法均在钛表面产生了活性外层，但不损害细胞活性并支持成骨细胞的生长过程。即使在早期孵育时间后，BioSpark仍显示出高生物活性和良好的矿相沉积，这些特性如先前发表的那样也存在于Kokubo的表面。两种材料的矿化机制不同，虽然Kokubo表面的矿化机制已得到很好的表征和报道，但BioSpark的矿化机制仍不清楚。本文给出了解释，后者表面的催化性能与具有锐钛矿晶格的著名晶体二氧化钛以及一定水平的钙和磷掺杂有关，这促进了锐钛矿性能的化学和物理变化。同时对早期成骨细胞对Kokubo和BioSpark表面的反应进行了表征，未发现显著差异。
