National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China.
National Engineering Research Center for Biomaterials, Sichuan University, Chengdu 610064, China.
Biomaterials. 2018 Jul;170:116-126. doi: 10.1016/j.biomaterials.2018.04.014. Epub 2018 Apr 11.
Weak osteointegration affects the long-term stability of polyaryletherketone (PAEK) implants. Surface modification provides a potential solution to improve the osteointegration property of PAEKs. Polyetheretherketone (PEEK) and polyetherketoneketone (PEKK) are two representative PAEK materials, but the latter has more ketone groups and better potential for surface chemical modification than the former. In this work, porous PEKK (PEKK-P) and PEEK (PEEK-P) were fabricated by a porogen leaching method. The samples were treated with 80% sulfuric acid (PEKK-SP and PEEK-SP) and then simulated body fluid (SBF) incubation (PEKK-BSP and PEEK-BSP). More micropores and higher hydrophilic SOH groups were found on PEKK-SP than PEEK-SP. Likely, more bone-like apatite crystals deposited on PEKK-BSP than PEEK-BSP. To evaluate their osteointegration properties, the samples were implanted in femoral condyle defects (Φ3 × 4 mm) of rat models, and micro-computed tomography (μ-CT), histology and mechanical analyzes were performed on the retrieved specimens. For control groups, i.e. the dense samples (PEKK-D and PEEK-D), only a handful of bone creeping growth on the implant surface was seen on them. However, with the interconnected macropores, surface micro/nano topography and bone-like apatite, notable bone growth into the inner pores was observed on PEKK-BSP and PEEK-BSP. Furthermore, quantitative analyses confirmed that the newly formed bone in PEKK-BSP was nearly more than doubled than that in PEEK-BSP. The push-out force testing results (PEKK-D ≈ PEEK-D < PEKK-P ≈ PEEK-P < PEEK-BSP < PEKK-BSP) suggested that the surface chemical modification (sulfonation treatment followed by SBF incubation) along with build-in porous structure played more important role in enhancing the mechanical stability of both PAEK materials than just the physical structure change. Our results revealed that PEKK with more ketone groups allowed easier sulfonation and better bone-like apatite deposition than PEEK, thus endowing PEKK-BSP with better osteointegration and mechanical stability than PEEK-BSP. Therefore, surface modified PEKK could be potential candidate for spinal and orthopedic applications requiring good osteointegration property.
骨整合较弱会影响聚芳醚酮（PAEK）植入物的长期稳定性。表面改性为改善 PAEK 的骨整合性能提供了一种潜在的解决方案。聚醚醚酮（PEEK）和聚醚酮酮（PEKK）是两种代表性的 PAEK 材料，但后者的酮基数更多，表面化学改性的潜力也比前者更大。在这项工作中，通过造孔剂浸出法制备了多孔 PEKK（PEKK-P）和 PEEK（PEEK-P）。将样品用 80%硫酸（PEKK-SP 和 PEEK-SP）处理，然后用模拟体液（SBF）孵育（PEKK-BSP 和 PEEK-BSP）。PEKK-SP 上的微孔和更高的亲水性 SOH 基团比 PEEK-SP 上的多。同样，PEKK-BSP 上沉积的类骨磷灰石晶体比 PEEK-BSP 上的多。为了评估它们的骨整合性能，将样品植入大鼠股骨髁缺损（Φ3×4mm）中，并对取出的标本进行微计算机断层扫描（μ-CT）、组织学和力学分析。对于对照组，即致密样品（PEKK-D 和 PEEK-D），仅在其表面观察到少量骨爬行生长。然而，由于具有相互连通的大孔、表面微/纳米形貌和类骨磷灰石，在 PEKK-BSP 和 PEEK-BSP 上观察到明显的骨向内孔生长。此外，定量分析证实，PEKK-BSP 中新形成的骨几乎是 PEEK-BSP 的两倍。推出力测试结果（PEKK-D≈PEEK-D<PEKK-P≈PEEK-P<PEEK-BSP<PEKK-BSP）表明，表面化学改性（磺化处理后再进行 SBF 孵育）与内置多孔结构对增强两种 PAEK 材料的机械稳定性比单纯的物理结构变化更为重要。我们的结果表明，具有更多酮基数的 PEKK 比 PEEK 更容易磺化，并且更容易沉积类骨磷灰石，因此，PEKK-BSP 具有比 PEEK-BSP 更好的骨整合和机械稳定性。因此，表面改性的 PEKK 可能是需要良好骨整合性能的脊柱和矫形应用的潜在候选材料。
