Polymer-Nanoparticle Interaction as a Design Principle in the Development of a Durable Ultrathin Universal Binary Antibiofilm Coating with Long-Term Activity.

Bacterial attachment and biofilm formation pose major challenges to the optimal performance of indwelling devices. Current coating methods have significant deficiencies including the lack of long-term activity, easy of application, and adaptability to diverse materials. Here we describe a coating method that could potentially overcome such limitations and yield an ultrathin coating with long-term antibiofilm activity. We utilized the interaction between polydopamine (PDA) nanoaggregates/nanoparticles and ultrahigh molecular weight (uHMW) hydrophilic polymers to generate stable coatings with broad spectrum antibiofilm activity. We used a short-term bacterial adhesion assay as an initial screening method to identify coating compositions that give superior performance and found that only selected polymers (out of 13 different types) and molecular weights gave promising antifouling activity. Optimization of PDA self-assembly, polymer-PDA interaction, and deposition on the surface using uHMW poly( N,N-dimethylacrylamide) (PDMA) (∼795 kDa) resulted in a stable ultrathin coating (∼19 nm) with excellent antifouling and antibiofilm properties (>4 weeks) against diverse bacteria (∼108 CFU/mL) in shaking and flow conditions. The ultrathin coating is effective on diverse substrates including metals and polymeric substrates. The uHMW PDMA is stabilized in the coating via supramolecular interactions with PDA and generated a surface that is highly enriched with PDMA in aqueous conditions. Based on the surface analyses data, we also propose a mechanism for the stable coating formation. The molecular weight of PDMA is a crucial factor, and only uHMW polymers generate this property. An attractive feature of the coating is that it does not contain any antimicrobial agents and has the potential to prevent biofilm formation for diverse applications both short- and long-term.