PDLLA-Zn-nitrided Fe bioresorbable scaffold with 53-μm-thick metallic struts and tunable multistage biodegradation function
Danni Shen, Haiping Qi, Wenjiao Lin, Wanqian Zhang, Dong Bian, Xiaoli Shi, Qin Li, Gui Zhang, Wenchao Fu, Kefei Dou, Bo Xu, Zhenyuan Yin, Jiancun Rao, Mazeni Alwi, Shuhan Wang, Yufeng Zheng, Deyuan Zhang, Runlin Gao
Abstract
Balancing the biodegradability and mechanical integrity of a bioresorbable scaffold (BRS) with time after implantation to match the remodeling of the scaffolded blood vessel is important, but a key challenge in doing so remains. This study presents a novel intercalated structure of a metallic BRS by introducing a nanoscale Zn sacrificial layer between the nitrided Fe platform and the sirolimus-carrying poly(d,l-lactide) drug coating. The PDLLA-Zn-FeN BRS shows a multistage biodegradation behavior, maintaining mechanical integrity at the initial stage and exhibiting accelerated biodegradation at the subsequent stage in both rabbit abdominal aortas and human coronary arteries, where complete biodegradation was observed about 2 years after implantation. The presence of the nanoscale Zn sacrificial layer with an adjustable thickness also contributes to the tunable biodegradation of BRS and allows the reduction of the metallic strut thickness to 53 μm, with radial strength as strong as that of the current permanent drug-eluting stents.