Antimicrobial efficacy and optimized cell adhesion from defined plasma polymerised multilayer structures involving zinc acetylacetonate and allylamine

Abstract

Plasma polymer-based zinc release systems combined with a biocompatible surface layer are discussed, which together allow for optimum antimicrobial properties towards pathogenic bacteria such as Staphylococcus aureus while at the same time show excellent cytocompatibility and biocompatibility. The surfaces developed consist of a multilayer system in which each layer exhibits a particular function. The antimicrobial layer shows a burst release of zinc within approximately 24 hours. A top-coating of plasma polymerised allylamine acts as a barrier layer that reduces the diffusion of zinc out of the layers for up to 2 weeks and at the same time induces cytocompatibility. The properties of the deposits were analysed using InfraRed Reflection Absorption Spectroscopy (IRRAS), Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES), cell culturing and different bacterial assays. A structure was developed that showed antimicrobial efficacy towards Methicillin Susceptible Staphylococcus aureus (MSSA), while at the same time human endothelial cells (HUVECs) and fibroblast readily adhered to the surface. Antimicrobial properties could be tuned to last from a few days to two weeks, which corresponds to a typical time frame required to reduce the risk of infection in postoperative wounds.