Long-term antibacterial and stable chlorhexidine-polydopamine coating on stainless steel 316L

Immobilization of chlorhexidine (CHX) coating on medical devices by utilizing a polydopamine (PDA) film as an intermediate crosslinker, demonstrates a promising value in retarding bacterial growth. However, its long-term antibacterial effect and coating stability are unknown where those features are crucial to sustain long-term application of medical devices. In this study, both properties were evaluated on the CHX-PDA coated SS316L. Greater surface roughness and coating thickness were observed on the SS-PDA-CHX20 compared to the SS-PDA. The CHX adsorption on the PDA film was increased as the CHX concentration increased. The 28 days of ageing process presented gradual coating degradation on the SS-PDA-CHX20 and SS-PDACHX30, releasing the CHX compound. The higher CHX concentration also displayed larger CHX aggregates and higher inhibition zones against E. coli and S. aureus, up to 72 h, indicating the substantivity of antibacterial effect. These properties hold a great potential in preventing bacterial growth on medical devices.