Surface chemical reactivity of diamond-like carbon films

类金刚石碳膜的表面化学反应性

• 批准号: 463121443
• 负责人: Professor Dr. Claus-Peter Klages
• 金额: --
• 依托单位: Institut für Oberflächentechnik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/463121443?language=en
• 关键词: Surface; chemical; reactivity; diamond; like

Owing to their outstanding properties, diamond-like carbon (DLC) films have found applications in fields as diverse as mechanical engineering on the one hand and biomaterials on the other. Worldwide research activities on DLC films have resulted in profound knowledge and understanding of its bulk microstructure and properties, as well as physical surface characteristics such as surface free energy, wetting and adhesion properties. Knowledge about the chemical nature of DLC film surfaces and especially about their chemical reactivity, on the other hand, is very poorly developed. In a few studies reported in literature, XPS analyses were used in conjunction with standard chemical derivatization in order to gain information about the temporal development of surface chemistry during aging under ambient conditions, generally resulting in oxygen uptake (autoxidation) and formation of oxygen-containing electrophilic functional groups. From these reports, however, no conclusions can be drawn about the ability of DLC surfaces to react under smooth conditions with organic molecules, especially biomolecules carrying nucleophilic functional groups. For this reason the main objective of the proposal is to advance substantially the knowledge and understanding of surface chemistry in general and reactivity specifically on aging hydrogen-free and hydrogenated DLC films, a-C and a-C:H, respectively. A powerful combination of immersion-IRRAS (ImIRRAS) and XPS, together with non-standard chemical derivatization techniques, will provide so far unavailable information regarding the autoxidation mechanism itself as well as the emerging reactive groups. These functional groups are of importance in biomedical applications where DLC surfaces interact with biomolecules, primarily proteins. Due to their size of typically 3 to 10 nm, very small densities of reactive functional groups, down to 0.01 nm2, may suffice to bind a monolayer. Preliminary studies have shown that ImIRRAS can quantify such low densities. This holds also true for hydroperoxy groups, presumed central intermediates in the oxidation process. Results of the project will be of fundamental interest, filling a gap in the knowledge about DLC films. Understanding the aging of DLC films is important for a more general comprehension of their physico-chemical surface properties. Presumably, however, surface functional groups of DLC also play an important role for its outstanding properties as a hemocompatible coating. Therefore the relation between surface chemical reactivity and several properties allowing a first rating of blood compatibility will be explored in this project: Using FTIR-ATR spectroscopy in situ, the presence of reactive groups on a-C:H or a-C will be correlated with the ability of the surfaces to adsorb or immobilize proteins playing a major role for the hemocompatibility of a surface. These studies will be complemented by investigations of platelet deposition and by blood clotting tests.

类金刚石薄膜由于其优异的性能，在机械工程和生物材料等领域得到了广泛的应用。世界范围内对DLC薄膜的研究活动已经对其本体微观结构和性能以及物理表面特性（如表面自由能、润湿性和粘附性）有了深刻的了解和理解。另一方面，关于DLC膜表面的化学性质，特别是关于它们的化学反应性的知识非常少。在文献中报告的一些研究中，XPS分析与标准化学衍生结合使用，以获得有关环境条件下老化期间表面化学随时间发展的信息，通常导致氧吸收（自氧化）和含氧亲电官能团的形成。然而，从这些报道中，无法得出关于DLC表面在光滑条件下与有机分子，特别是携带亲核官能团的生物分子反应的能力的结论。出于这个原因，该提案的主要目标是大幅提高对一般表面化学和反应性的认识和理解，特别是对老化的无氢和氢化DLC膜，a-C和a-C：H。一个强大的组合，浸泡IRRAS（ImIRRAS）和XPS，连同非标准的化学衍生技术，将提供迄今为止无法获得的信息，关于自氧化机制本身以及新兴的反应基团。这些官能团在生物医学应用中具有重要意义，其中DLC表面与生物分子（主要是蛋白质）相互作用。由于它们的尺寸通常为3至10 nm，非常小密度的反应性官能团（低至0.01 nm 2）可能足以结合单层。初步研究表明，ImIRRAS可以量化这种低密度。这也适用于氢过氧基团，假定在氧化过程中的中心中间体。该项目的结果将具有根本意义，填补了DLC薄膜知识的空白。了解DLC膜的老化对于更全面地理解其物理化学表面性质是重要的。然而，据推测，DLC的表面官能团对于其作为血液相容性涂层的优异性能也起着重要作用。因此，本项目将探索表面化学反应性与允许血液相容性的第一等级的几个属性之间的关系：使用原位FTIR-ATR光谱，a-C：H或a-C上反应基团的存在将与表面吸附或吸附蛋白质的能力相关，蛋白质对表面的血液相容性起主要作用。这些研究将通过血小板沉积研究和凝血试验进行补充。