A facile and versatile superhydrophilic coating on biodegradable PLA stent with stepwise assembly of metal/phenolic networks for mimicking endothelium function

Abstract

The achievement of the desired hemocompatibility, anti-inflammatory, and rapid endothelialization properties has significantly contributed to the success of implantable blood-contacting materials, especially vascular stents. In this study, we constructed a facile and versatile superhydrophilic coating via the stepwise deposition of metal/phenolic networks (MPNs) using a layer-by-layer assembly technique. Tannic acid and copper ions were employed for the fabrication of MPNs, and the surface roughness and the number of hydrophilic phenolic groups were gradually increased, ultimately leading to the generation of a superhydrophilic coating, where the copper ions were also effectively incorporated. Owing to the superhydrophilicity of the coating, the binding of serum adhesion proteins, such as albumin and fibrinogen, to the surface was strongly inhibited, thereby conferring a potent antithrombotic ability. In addition, a potent antioxidant and anti-inflammatory effects were achieved through the deposition of a large amount of residual phenolic hydroxyl groups on the surface. The incorporated copper ions could also mimic endothelial function through the continuously catalyzed decomposition of endogenous S-nitrothiols (RSNOs) to release nitric oxide (NO) in situ in a controlled manner. The synergistic contribution effect of NO and superhydrophilicity, further inhibited the adhesion/activation of platelets. The optimized coating significantly inhibited the adhesion and activation of platelets, selectively supported the adhesion of endothelial cells, and suppressed the proliferation of smooth muscle cells. Such superhydrophilic coating with the incorporation of copper ions adequately addressed the basic requirements of vascular stents, in terms of antithrombosis, anti-restenosis, and enhanced endothelialization in vivo, demonstrating a promising approach for the clinical application of vascular implants.