Processing and Characterization of Coatings for Polymeric Implants

描述(申请人提供)：该项目解释了一种在聚合物基板上处理羟基磷灰石(HA)涂层的新方法，特别是聚醚醚酮(PEEK)，以改善组织相容性，增强体内植入物的骨对接和性能。在对各种类型的金属基材进行涂层的多年经验之后，一位著名的脊柱外科医生问我们是否可以在聚合物基板上沉积一层HA涂层，用于脊柱植入物。我们面临的问题是，考虑到聚合物的熔点通常低于HA的结晶温度，如何在不损害基材的情况下对聚合物植入物进行涂层和热处理。我们简要地探索了两种方法：(A)在聚醚醚酮(PEEK)上沉积HA，使其具有良好的结合强度；(B)在不损害衬底的情况下，采用不同的技术对其进行热处理。我们还探索了聚合物和HA涂层之间的中间层在热处理过程中进一步保护基材的作用。我们很高兴地在这份申请书中报告，这些努力是成功的，表明我们的做法是可行的。值得注意的是，我们选择PEEK作为我们的第一个候选者，因为它比其他聚合物具有更高的熔点。证实我们可以成功地修饰PEEK的表面性质，这让我们有信心将这种方法应用于其他聚合物，包括超高相对分子质量聚乙烯。在这项研究中，我们建议使用离子束辅助沉积(IBAD)在室温下在聚合物植入物上制备HA涂层，然后使用微波技术进行沉积后热处理。该技术的优点是：涂层薄而致密，具有很高的抗裂性，适用于各种生物医学装置和植入物。晶体的结晶度 通过本研究提出的新型热处理方法，可以对涂层进行精确控制。微波和激光技术允许热量集中在小厚度的薄膜中，而不会对聚合物基板造成任何损害。同时，在室温下沉积涂层将消除聚合物植入物的任何潜在热降解。涂层的化学成分可以精确控制。HA和基材之间的热障涂层的存在将进一步保护基材免受任何过热和热降解。它还将有助于HA晶体在热处理过程中成核，加速这一过程。早期和长期的骨骼反应都将在兔子模型中进行评估。这项拟议的研究调查了一种新的聚合物设备涂层技术，该技术将对下一代聚合物植入物的发展产生重大影响，并将成为生物医学涂层技术的重大创新。它有可能极大地提高在以前被认为不切实际的应用中使用低模数聚合物的可行性，因为人们担心未涂层材料的组织集成度较差。

DESCRIPTION (provided by applicant): This project explains a new approach towards processing Hydroxyapatite (HA) coating on polymeric substrates in general and PEEK (polyetheretherketone) in particular to improve tissue compatibility, enhance bone apposition and performance of the implant in the body. After many years of experience with coating various types of metallic substrates, we were asked by a well-known spine surgeon if we can deposit an HA coating on a polymeric substrates for application in spine implants. The question for us was how to coat a polymeric implant and heat treat the coating without damaging the substrate, considering the fact that the melting point of polymers is normally lower than the crystallization temperature of HA. We briefly explored methods to (a) deposit HA on PEEK with good bonding strength of the coating and (b) heat-treat it using different techniques without damaging the substrate. We have also explored the effect of an intermediate layer between the polymer and HA coating to further protect the substrate during the heat-treatment. We are pleased to report in this application that these efforts were successful in showing the feasibility of our approach. t is notable that we selected PEEK as our first candidate because it has a higher melting point compared to other polymers. Confirmation that we can successfully modify the surface properties of PEEK has given us confidence that we can adapt this approach to other polymers, including ultra-high molecular weight polyethylene. In this study we propose to produce the HA coating on polymeric implants using an Ion Beam Assisted Deposition (IBAD) at room temperature followed by a post deposition heat-treatment using microwave technique. The advantages of the proposed technology are: The coating is a thin and dense layer with high fracture resistance suitable for all sorts of biomedical devices and implants. The crystallinity of the coating can be controlled precisely through the novel heat treatment approach (proposed in this study). The microwave and laser techniques allow the heat to be focused in a small thickness of the film without any damage to the polymeric substrate. At the same time, depositing the coating at room temperature will eliminate any potential thermal degradation of the polymeric implant. The chemical composition of the coating can be precisely controlled. The presence of the thermal barrier coating layer between the HA and substrate will further protect the substrate from any excessive heat and thermal degradation. It will also help the nucleation of HA crystals during heat-treatment expediting the process. Both early and long-term bone responses will be assessed in a rabbit model. The proposed study investigates a new technique for coating polymeric devices that can have a great impact on the development of the next generation of polymeric implants and a significant innovation in biomedical coating technology. It has the potential to dramatically enhance the feasibility of using low-modulus polymers in applications that were previously considered impractical because of concerns over the poor tissue integration of uncoated materials.