Jia Zhaojun, Xiong Pan, Shi Yuying, Zhou Wenhao, Cheng Yan, Zheng Yufeng, Xi Tingfei, Wei Shicheng
Center for Biomedical Materials and Tissue Engineering, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, China.
J Mater Chem B. 2016 Apr 14;4(14):2498-2511. doi: 10.1039/c6tb00117c. Epub 2016 Mar 23.
The design of functional biomaterials that respond intelligently to external stimuli has become a rapidly growing area with widespread interest. This work contributes to the development of a feedback-active anticorrosion system with intriguing self-healing ability to protect magnesium (Mg) from biocorrosion. The system was constituted by an inner micro/nano-porous, ceramic-like pre-coating developed readily from the substrate, and an outermost inhibitor (nanosized cerium (Ce) oxides) containing chitosan (CS) multilayers. Here, the pre-coating acted as both an "anchoring" and a "barrier" layer to acquire structural integrity and improved impedance, respectively. Green CS served as cargo for Ce to be entrapped, harnessing Ce-NH complexation chemistry. The coating barrier properties were evaluated by electrochemical impedance spectroscopy. The active corrosion inhibition was assessed by immersion degradation tests with respect to Mg release, pH alteration, crack development, and scanning Kelvin potential. To our delight, the coatings effectively protected the substrate from biocorrosion in vitro compared with bare alloys. Putatively, the pH-triggered formation of Ce oxide precipitation, along with the pH-buffering activity and movable swelling capacity of CS macromolecules, should have contributed to restraining the anodic activity and healing the cracks/defects dynamically. Furthermore, the coated substrate had the biocompatibility to elicit better attachment and growth of osteoblasts.
设计能对外部刺激做出智能响应的功能性生物材料已成为一个迅速发展且广受关注的领域。这项工作有助于开发一种具有有趣自愈能力的反馈活性防腐系统，以保护镁（Mg）免受生物腐蚀。该系统由一个易于从基底形成的内部微/纳米多孔、类陶瓷预涂层和一个含有壳聚糖（CS）多层膜的最外层抑制剂（纳米级铈（Ce）氧化物）组成。在此，预涂层分别作为“锚固”层和“阻挡”层，以获得结构完整性并提高阻抗。绿色CS作为捕获Ce的载体，利用Ce-NH络合化学。通过电化学阻抗谱评估涂层的阻隔性能。通过关于Mg释放、pH变化、裂纹发展和扫描开尔文电位的浸泡降解试验评估活性腐蚀抑制作用。令我们高兴的是，与裸合金相比，这些涂层在体外有效地保护了基底免受生物腐蚀。据推测，pH触发的Ce氧化物沉淀的形成，以及CS大分子的pH缓冲活性和可移动的膨胀能力，应该有助于抑制阳极活性并动态修复裂纹/缺陷。此外，涂覆的基底具有生物相容性，能促进成骨细胞更好地附着和生长。
