European School of Molecular Medicine, IFOM-IEO, Milan, Italy.
PLoS One. 2011;6(9):e25029. doi: 10.1371/journal.pone.0025029. Epub 2011 Sep 26.
Bacterial infection of implants and prosthetic devices is one of the most common causes of implant failure. The nanostructured surface of biocompatible materials strongly influences the adhesion and proliferation of mammalian cells on solid substrates. The observation of this phenomenon has led to an increased effort to develop new strategies to prevent bacterial adhesion and biofilm formation, primarily through nanoengineering the topology of the materials used in implantable devices. While several studies have demonstrated the influence of nanoscale surface morphology on prokaryotic cell attachment, none have provided a quantitative understanding of this phenomenon. Using supersonic cluster beam deposition, we produced nanostructured titania thin films with controlled and reproducible nanoscale morphology respectively. We characterized the surface morphology; composition and wettability by means of atomic force microscopy, X-ray photoemission spectroscopy and contact angle measurements. We studied how protein adsorption is influenced by the physico-chemical surface parameters. Lastly, we characterized Escherichia coli and Staphylococcus aureus adhesion on nanostructured titania surfaces. Our results show that the increase in surface pore aspect ratio and volume, related to the increase of surface roughness, improves protein adsorption, which in turn downplays bacterial adhesion and biofilm formation. As roughness increases up to about 20 nm, bacterial adhesion and biofilm formation are enhanced; the further increase of roughness causes a significant decrease of bacterial adhesion and inhibits biofilm formation. We interpret the observed trend in bacterial adhesion as the combined effect of passivation and flattening effects induced by morphology-dependent protein adsorption. Our findings demonstrate that bacterial adhesion and biofilm formation on nanostructured titanium oxide surfaces are significantly influenced by nanoscale morphological features. The quantitative information, provided by this study about the relation between surface nanoscale morphology and bacterial adhesion points towards the rational design of implant surfaces that control or inhibit bacterial adhesion and biofilm formation.
植入物和假体装置的细菌感染是植入物失效的最常见原因之一。生物相容性材料的纳米结构表面强烈影响哺乳动物细胞在固体基底上的黏附和增殖。观察到这一现象促使人们加大力度开发新策略来防止细菌黏附和生物膜形成，主要是通过对植入装置所用材料的拓扑结构进行纳米工程处理。虽然有几项研究表明纳米级表面形态对原核细胞黏附的影响，但没有一项研究提供对此现象的定量理解。我们使用超声速团束沉积法分别制备了具有可控和可重复纳米级形态的纳米结构化二氧化钛薄膜。我们通过原子力显微镜、X 射线光电子能谱和接触角测量来表征表面形态、组成和润湿性。我们研究了蛋白质吸附如何受物理化学表面参数的影响。最后，我们研究了大肠杆菌和金黄色葡萄球菌在纳米结构化二氧化钛表面的黏附。我们的结果表明，表面孔径纵横比和体积的增加与表面粗糙度的增加有关，这改善了蛋白质吸附，从而抑制了细菌黏附和生物膜形成。当粗糙度增加到约 20nm 时，细菌黏附和生物膜形成增强；进一步增加粗糙度会导致细菌黏附显著减少并抑制生物膜形成。我们将观察到的细菌黏附趋势解释为形态依赖性蛋白质吸附引起的钝化和平整效应的综合作用。我们的研究结果表明，纳米结构化氧化钛表面上的细菌黏附和生物膜形成受到纳米级形态特征的显著影响。本研究提供的关于表面纳米级形态与细菌黏附之间关系的定量信息，为控制或抑制细菌黏附和生物膜形成的植入物表面的合理设计提供了依据。
