Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), UMR 7504 CNRS, Université de Strasbourg , 23 rue du Loess BP 43, 67034 Strasbourg, France.
Department of Basic and Applied Sciences for Engineering (BASE), Sapienza University of Rome , Via Antonio Scarpa 16, 00161 Rome, Italy.
ACS Appl Mater Interfaces. 2018 Feb 14;10(6):5967-5977. doi: 10.1021/acsami.7b17008. Epub 2018 Jan 30.
Titanium (Ti) is the most widely used metal in biomedical applications because of its biocompatibility; however, the significant difference in the mechanical properties between Ti and the surrounding tissues results in stress shielding which is detrimental for load-bearing tissues. In the current study, to attenuate the stress shielding effect, a new processing route was developed. It aimed at growing thick poly(methyl methacrylate) (PMMA) layers grafted on Ti substrates to incorporate a polymer component on Ti implants. However, the currently available methods do not allow the development of thick polymeric layers, reducing significantly their potential uses. The proposed route consists of an alkali activation of Ti substrates followed by a surface-initiated atom transfer radical polymerization using a phosphonic acid derivative as a coupling agent and a polymerization initiator and malononitrile as a polymerization activator. The average thickness of the grown PMMA layers is approximately 1.9 μm. The Ti activation-performed in a NaOH solution-leads to a porous sodium titanate interlayer with a hierarchical structure and an open microporosity. It promotes the covalent grafting reaction because of high hydroxyl groups' content and enables establishing a further mechanical interlocking between the growing PMMA layer and the Ti substrate. As a result, the produced graduated structure possesses high Ti/PMMA adhesion strength (∼260 MPa). Moreover, the PMMA layer is (i) thicker compared to those obtained with the previously reported techniques (∼1.9 μm), (ii) stable in a simulated body fluid solution, and (iii) biocompatible. This strategy opens new opportunities toward hybrid prosthesis with adjustable mechanical properties with respect to host bone properties for personalized medicines.
钛（Ti）由于其生物相容性而成为生物医学应用中最广泛使用的金属；然而，Ti 与周围组织之间机械性能的显著差异导致了应力屏蔽，这对承重组织是有害的。在本研究中，为了减轻应力屏蔽效应，开发了一种新的加工路线。其旨在在 Ti 基底上生长厚的聚甲基丙烯酸甲酯（PMMA）层，以在 Ti 植入物上引入聚合物成分。然而，目前可用的方法不允许开发厚的聚合物层，从而大大降低了它们的潜在用途。所提出的路线包括 Ti 基底的碱活化，然后使用膦酸衍生物作为偶联剂和聚合引发剂以及丙二腈作为聚合活化剂进行表面引发原子转移自由基聚合。生长的 PMMA 层的平均厚度约为 1.9μm。在 NaOH 溶液中进行的 Ti 活化导致具有分级结构和开放微孔的多孔钛酸钠中间层。由于高羟基含量，它促进了共价接枝反应，并能够在生长的 PMMA 层和 Ti 基底之间建立进一步的机械联锁。结果，所产生的渐变结构具有高的 Ti/PMMA 粘附强度（约 260MPa）。此外，与以前报道的技术相比，PMMA 层（i）更厚（约 1.9μm），（ii）在模拟体液溶液中稳定，（iii）具有生物相容性。该策略为具有与宿主骨性质可调机械性能的混合假体开辟了新的机会，以实现个性化药物。
