Background: Angiogenic and osteogenic activities are two major problems with biomedical titanium (Ti) and other orthopedic implants used to repair large bone defects.
Purpose: The aim of this study is to prepare hydroxyapatite (HA) coatings on the surface of Ti by using electrochemical deposition (ED), and to evaluate the effects of nanotopography and silicon (Si) doping on the angiogenic and osteogenic activities of the coating in vitro.
Materials and Methods: HA coating and Si-doped HA (HS) coatings with varying nanotopographies were fabricated using two ED modes, ie, the pulsive current (PC) and cyclic voltammetry (CV) methods. The coatings were characterized through scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS), and atomic force microscopy (AFM), and their in vitro bioactivity and protein adsorption were assessed. Using MC3T3-E1 pre-osteoblasts and HUVECs as cell models, the osteogenic and angiogenic capabilities of the coatings were evaluated through in vitro cellular experiments.
Results: By controlling Si content in ∼ 0.8 wt.%, the coatings resulting from the PC mode (HA-PC and HS-PC) and CV mode (HA-CV and HS-CV) had nanosheet and nanorod topographies, respectively. At lower crystallinity, higher ionic dissolution, smaller contact angle, higher surface roughness, and more negative zeta potential, the HS and PC samples exhibited quicker apatite deposition and higher BSA adsorption capacity. The in vitro cell study showed that Si doping was more favorable for enhancing the viability of the MC3T3-E1 cells, but nanosheet coating increased the area for cell spreading. Of the four coatings, HS-PC with Si doping and nanosheet topography exhibited the best effect in terms of up-regulating the expressions of the osteogenic genes (ALP, Col-I, OSX, OPN and OCN) in the MC3T3-E1 cells. Moreover, all leach liquors of the surface-coated Ti disks promoted the growth of the HUVECs, and the HS samples played a more significant role in promoting cell migration and tube formation than the HA samples. Of the four leach liquors, only the two HS samples up-regulated NO content and expressions of the angiogenesis-related genes (VEGF, bFGF and eNOS) in the HUVECs, and the HS-PC yielded a better effect.
Conclusion: The results show that Si doping while regulating the topography of the coating can help enhance the bone regeneration and vascularization of HA-coated Ti implants.



中文翻译：

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纳米形貌调控和硅掺杂对钛植入物羟基磷灰石涂层的血管生成和成骨活性的影响。

背景：血管生成和成骨活性是生物医学钛 (Ti) 和其他用于修复大骨缺损的骨科植入物的两个主要问题。
目的：本研究旨在通过电化学沉积 (ED) 在 Ti 表面制备羟基磷灰石 (HA) 涂层，并评估纳米形貌和硅 (Si) 掺杂对涂层的血管生成和成骨活性的影响。体外。
材料和方法：使用两种 ED 模式，即脉冲电流 (PC) 和循环伏安法 (CV) 方法制造具有不同纳米形貌的 HA 涂层和 Si 掺杂 HA (HS) 涂层。通过扫描电子显微镜（SEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FT-IR）、X射线光电子能谱仪（XPS）和原子力显微镜（AFM）对涂层进行表征，并在评估了体外生物活性和蛋白质吸附。使用 MC3T3-E1 前成骨细胞和 HUVECs 作为细胞模型，通过体外细胞实验评估了涂层的成骨和血管生成能力。
结果：通过将 Si 含量控制在 ~ 0.8 wt.%，由 PC 模式（HA-PC 和 HS-PC）和 CV 模式（HA-CV 和 HS-CV）产生的涂层分别具有纳米片和纳米棒形貌。在较低的结晶度、较高的离子溶解度、较小的接触角、较高的表面粗糙度和更负的 zeta 电位下，HS 和 PC 样品表现出更快的磷灰石沉积和更高的 BSA 吸附能力。体外细胞研究表明，Si掺杂更有利于增强MC3T3-E1细胞的活力，但纳米片涂层增加了细胞扩散的面积。在四种涂层中，具有Si掺杂和纳米片形貌的HS-PC在上调MC3T3-E1细胞中成骨基因（ALP、Col-I、OSX、OPN和OCN）的表达方面表现出最佳效果。而且，表面涂覆的钛盘的所有浸出液都促进了 HUVECs 的生长，并且 HS 样品在促进细胞迁移和管形成方面的作用比 HA 样品更显着。在四种浸出液中，只有两种 HS 样品上调了 HUVECs 中 NO 含量和血管生成相关基因（VEGF、bFGF 和 eNOS）的表达，并且 HS-PC 产生了更好的效果。
结论：结果表明，Si 掺杂在调节涂层形貌的同时有助于增强 HA 涂层钛植入物的骨再生和血管化。