Processing and Characterization of Coatings for Polymeric Implants

描述（由申请人提供）：该项目解释了一种新的方法，用于处理聚合物基质上的羟基磷灰石（HA）涂层，特别是PEEK（聚醚醚酮），以改善组织相容性，增强骨沉积和体内植入物的性能。在对各种类型的金属基质进行涂层的多年经验之后，一位著名的脊柱外科医生询问我们是否可以在聚合物基质上存款HA涂层，以应用于脊柱植入物。我们面临的问题是如何涂覆聚合物植入物并对涂层进行热处理而不损坏基底，考虑到聚合物的熔点通常低于HA的结晶温度。我们简要探讨了（a）在PEEK上存款HA并使涂层具有良好结合强度的方法，以及（B）使用不同技术对其进行热处理而不损坏基底的方法。我们还探索了聚合物和HA涂层之间的中间层的效果，以进一步保护在热处理过程中的基板。我们很高兴地报告，在这个应用程序中，这些努力是成功的，表明我们的方法的可行性。值得注意的是，我们选择PEEK作为我们的第一个候选材料，因为它与其他聚合物相比具有更高的熔点。确认我们可以成功地改变PEEK的表面性能，这让我们有信心将这种方法应用于其他聚合物，包括超高分子量聚乙烯。在这项研究中，我们建议在室温下使用离子束辅助沉积（IBAD），然后使用微波技术进行沉积后热处理，在聚合物植入物上产生HA涂层。所提出的技术的优点是：涂层是一个薄而致密的层，具有高的抗断裂性，适用于各种生物医学设备和植入物。的结晶度 涂层可以通过新的热处理方法（在本研究中提出）精确控制。微波和激光技术允许热量集中在小厚度的膜中，而不会对聚合物基材造成任何损坏。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。在HA和基底之间存在热障涂层将进一步保护基底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的成核，从而加速该过程。将在兔模型中评估早期和长期骨反应。这项拟议的研究调查了一种新的技术，用于涂层聚合物设备，可以有很大的影响下一代聚合物植入物的发展和生物医学涂层技术的重大创新。它有可能显着提高使用低模量聚合物在应用中的可行性，以前被认为是不切实际的，因为对无涂层材料的不良组织整合的关注。 公共卫生相关性：在许多生物医学应用中，聚合物比金属和合金具有显著的优势。虽然聚合物广泛用于关节面，但由于其在体内倾向于刺激纤维而非骨质生长，因此其用作固定面的情况较为复杂。本研究旨在研究一种新的技术，即用羟基磷灰石涂层涂覆生物医学聚合物，以促进早期骨长入和加速植入物固定。将使用PEEK作为试验基质，在体外和体内确定这种新型HA涂层的安全性和有效性。从临床角度来看，在生物医学聚合物上成功开发生物活性和机械坚固的涂层有可能大大提高这些材料在骨科、脊柱外科和牙科中的使用。

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. PUBLIC HEALTH RELEVANCE: Polymers offer significant advantages over metals and alloys for many biomedical applications. Although polymers are widely used for articulating surfaces, their use as fixation surfaces is complicated by the fact that they tend to incite fibrous rather than osseous ongrowth in vivo. The proposed study investigates a new technique for coating biomedical polymers with a hydroxyapatite coating to facilitate early bone ingrowth and accelerated implant fixation. The safety and efficacy of this new HA coating will be determined in vitro and in vivo using PEEK as the test substrate. From a clinical perspective, successful development of a bioactive and mechanically robust coating on biomedical polymers has the potential to dramatically enhance the use of these materials in orthopedics, spine surgery and dentistry.