Endothelial Cytotoxicity of Drug‐Doped Polypyrrole Coatings on Biodegradable Iron for Stent Applications

Conducting polymers, such as polypyrrole (PPy), are promising coatings for biodegradable vascular implants due to their electrical conductivity and drug‐loading capacity. However, their compatibility with cells is not well understood, especially under different synthesis conditions toward endothelial cells. In this study, the effects of deposition parameters and dopants on the viability of human umbilical vein endothelial cells (HUVECs) are systematically examined. PPy coatings are applied to iron substrates using pyrrole (Py, 0.1–0.3 m ) and doped with salicylate (SS, 0.1–0.3 m ) or dexamethasone (DEX, 0.1–3 m m ), with potentials from 1.0 to 1.6 V and deposition charges up to 2.4 C. Coatings prepared at 1.2 V with 0.1 m Py and 0.1 m SS demonstrate the highest biocompatibility conversely, higher voltages or charges produced overoxidized, less conductive films with increased cytotoxicity. SS causes dose‐dependent toxicity, while DEX enhanced biocompatibility and reduces surface roughness. HUVECs with low confluence (proliferative) are more sensitive than high‐confluence (quiescent) cells. The results reveal a self‐powered drug release mechanism driven by Fe/PPy microgalvanic coupling and redox‐triggered dopant elution. These findings underscore the importance of optimizing synthesis conditions to balance conductivity, adhesion, and cytocompatibility for safe endothelial applications.