In situ construction of Ag NPs in bio-inspired multilayer films for long-term bactericidal and biofilm inhibition properties

Bacteria can easily adhere on the surface of implants and subsequently form biofilm which lead to serious critical issues in the application. In the current work, poly(acrylic acid) (PAA) was firstly modified with dopamine (dopa) into dopa-PAA and was self-assembled with poly(ethylenimine)-AgNO3 (PEI-AgNO3) into multilayer films via layer-by-layer self-assembly technique. AgNO3 were in situ reduced into silver nano particles (Ag NPs) in the process of multilayer film self-assembling using bio-inspired dopa as reducing agent. The morphology of the Ag NPs was characterized using transmission electron microscopy. In vitro, the (dopa-PAA/PEI-Ag NPs)n multilayer films showed a long-term sustained release of Ag+ in PBS buffer. Zone of inhibition assays and the bacterial LIVE/DEAD staining methods demonstrated the high efficient and long-term bactericidal properties of the multilayer films. For the in vivo subcutaneous antibacterial tests in New Zealand white rabbits, the wound appearance and the histopathology analysis showed that implantation of the antibacterial coating modified PDMS promoted wound healing and showed good anti-inflammatory effect. The multilayer films also proved to be low cytotoxicity towards human lens epithelial cells, which can potentially be widely used to modify biomedical implants.