Beijing Advanced Innovation Center for Materials Genome Engineering & School of Materials Science and Engineering, Peking University, Beijing, 100871, P. R. China.
School of Engineering Medicine, Beihang University, Beijing, 100191, P. R. China.
Adv Mater. 2023 May;35(19):e2301074. doi: 10.1002/adma.202301074. Epub 2023 Mar 28.
To reduce incidences of in-stent restenosis and thrombosis, the use of a thinner-strut stent has been clinically proven to be effective. Therefore, the contemporary trend is toward the use of ultrathin-strut (≤70 µm) designs for durable stents. However, stents made from biodegradable platforms have failed to achieve intergenerational breakthroughs due to their excessively thick struts. Here, microalloying is used to create an ultrathin-strut (65 µm) zinc (Zn) scaffold with modified biodegradation behavior and improved biofunction, by adding lithium (Li). The scaffold backbone consists of an ultrafine-grained Zn matrix (average grain diameter 2.28 µm) with uniformly distributed nanoscale Li-containing phases. Grain refinement and precipitation strengthening enable it to achieve twice the radial strength with only 40% of the strut thickness of the pure Zn scaffold. Adding Li alters the thermodynamic formation pathways of products during scaffold biodegradation, creating an alkaline microenvironment. Li CO may actively stabilize this microenvironment due to its higher solubility and better buffering capability than Zn products. The co-release of ionic zinc and lithium enhances the beneficial differential effects on activities of endothelial cells and smooth muscle cells, resulting in good endothelialization and limited intimal hyperplasia in porcine coronary arteries. The findings here may break the predicament of the next-generation biodegradable scaffolds.
为了降低支架内再狭窄和血栓形成的发生率，临床已经证明使用更薄的支架梁是有效的。因此，目前的趋势是使用超薄支架梁（≤70µm）设计用于耐用支架。然而，由于可生物降解支架梁的厚度过大，其使用并未实现代际突破。在这里，通过添加锂（Li），微合金化被用来制造一种超薄支架梁（65µm）锌（Zn）支架，其具有改性的生物降解行为和改进的生物功能。支架的骨架由超细晶 Zn 基体（平均晶粒直径 2.28µm）和均匀分布的纳米级含 Li 相组成。晶粒细化和析出强化使其在仅为纯 Zn 支架梁厚度 40%的情况下，实现了两倍的径向强度。添加 Li 改变了支架生物降解过程中产物的热力学形成途径，创造了碱性微环境。LiCO3 可能由于其比 Zn 产物更高的溶解度和更好的缓冲能力而积极稳定这种微环境。离子锌和锂的共同释放增强了对内皮细胞和平滑肌细胞活性的有益差异效应，导致猪冠状动脉良好的内皮化和有限的内膜增生。这一发现可能打破了下一代可生物降解支架的困境。
