Fathi A M, Ahmed M K, Afifi M, Menazea A A, Uskoković Vuk
Physical Chemistry Department, National Research Centre, Dokki, Giza 12622, Egypt.
Department of Physics, Faculty of Science, Suez University, Suez 43518, Egypt.
ACS Biomater Sci Eng. 2021 Jan 11;7(1):360-372. doi: 10.1021/acsbiomaterials.0c01105. Epub 2020 Dec 18.
Coating with hydroxyapatite (HAP) presents a mainstream strategy for rendering bioinert titanium implants bioactive. However, the low porosity of pure HAP coatings does not allow for the infiltration of the surface of the metallic implant with the host cells. Polymeric scaffolds do enable this osseointegration effect, but their bonding onto titanium presents a challenge because of the disparity in hydrophilicity. Here, we demonstrate the inability of a composite scaffold composed of carbonated HAP (CHAP) nanoparticles interspersed within electrospun ε-polycaprolactone (PCL) nanofibers to bind onto titanium. To solve this challenge, an intermediate layer of graphene nanosheets was deposited in a pulsed laser deposition process, which facilitated the bonding of the scaffold. The duration of the deposition of graphene (0, 5, 10, 15, and 20 min) and the thickness of its mesolayer affected numerous physical and chemical properties of the material, including the surface atomic proportion of carbon bonds, the orientation and interlinking of the polymeric nanofibers, and the surface roughness, which increased in direct proportion with the thickness of the graphene mesolayer. Because the polymeric scaffold did not adhere onto the surface of pure titanium, no cells were detected growing on it . In contrast, human fibroblasts adhered, spread, and proliferated well on all the substrates sputtered with both graphene and the composite scaffold. The orientations of cytoskeletal filopodia and lamellipodia were largely determined by the topographic orientation of the nanofibers and the geometry of the surface pores, attesting to the important effects that the presence of a scaffold has on the cellular behavior. The protection of titanium from corrosion in the simulated body fluid (SBF) was enhanced by coating with graphene and the composite scaffold, with the most superior resistance to the attack of the corrosive ions being exhibited by the substrate subjected to the shortest duration of the graphene deposition because of the highest atomic ratio of C-C to C-O bonds detected in it. Overall, some properties of titanium, such as roughness and wettability, were improved monotonously with an increase in the thickness of the graphene mesolayer, while others, such as cell viability and resistance to corrosion, required optimization, given that they were diminished at higher graphene mesolayer thicknesses. Nevertheless, every physical and chemical property of titanium analyzed was significantly improved by coating with graphene and the composite scaffold. This type of multilayer design evidently holds a great promise in the design of biomaterials for implants in orthopedics and tissue engineering.
用羟基磷灰石（HAP）涂层是使生物惰性钛植入物具有生物活性的一种主流策略。然而，纯HAP涂层的低孔隙率不允许宿主细胞渗入金属植入物表面。聚合物支架确实能实现这种骨整合效应，但由于亲水性的差异，它们与钛的结合存在挑战。在这里，我们证明了由散布在静电纺丝ε-聚己内酯（PCL）纳米纤维中的碳酸化HAP（CHAP）纳米颗粒组成的复合支架无法与钛结合。为了解决这一挑战，在脉冲激光沉积过程中沉积了一层石墨烯纳米片中间层，这促进了支架的结合。石墨烯沉积的持续时间（0、5、10、15和20分钟）及其中间层的厚度影响了材料的许多物理和化学性质，包括碳键的表面原子比例、聚合物纳米纤维的取向和相互连接以及表面粗糙度，表面粗糙度与石墨烯中间层的厚度成正比增加。由于聚合物支架没有粘附在纯钛表面，因此未检测到有细胞在其上生长。相比之下，人成纤维细胞在所有溅射有石墨烯和复合支架的基底上均能良好地粘附、铺展和增殖。细胞骨架丝状伪足和片状伪足的取向在很大程度上由纳米纤维的形貌取向和表面孔隙的几何形状决定，这证明了支架的存在对细胞行为具有重要影响。通过用石墨烯和复合支架涂层，增强了钛在模拟体液（SBF）中的抗腐蚀能力，由于在其中检测到的C-C与C-O键的原子比最高，因此石墨烯沉积持续时间最短的基底表现出对腐蚀性离子侵蚀的最强抵抗力。总体而言，钛的一些性质，如粗糙度和润湿性，随着石墨烯中间层厚度的增加而单调改善，而其他一些性质，如细胞活力和抗腐蚀性，则需要优化，因为在较高的石墨烯中间层厚度下它们会降低。然而，通过用石墨烯和复合支架涂层，分析的钛的每一项物理和化学性质都得到了显著改善。这种多层设计显然在骨科和组织工程植入物生物材料的设计中具有很大的前景。
