(3c) Building Bioactivity and Nanostructure into Slippery Liquid-Infused Porous Surfaces

Slippery liquid-infused porous surfaces (or ‘SLIPS’) and other types of liquid-infused materials provide new approaches to prevent biofouling on commercial and industrial surfaces, including those used to design biomedical devices. Many different types of SLIPS fabricated using porous polymer matrices and hydrophobic oils have been demonstrated to resist adhesion and colonization by microorganisms. However, while SLIPS are generally good at preventing fouling on surfaces to which they are applied, they can generally do little to prevent proliferation of non-adherent organisms—e.g., to stop them from colonizing other surfaces or prevent them from engaging in other behaviors, such as virulence factor production, that could also lead to infection or fouling.

We have developed multi-functional bioactive SLIPS that address these issues and expand the potential utility of slippery surfaces in antimicrobial contexts. Our approach is based on the incorporation and controlled release of small-molecule antimicrobial agents from hydrophobic porous polymer matrices used to host infused oil phases. Our studies reveal that SLIPS designed using nanoporous coatings fabricated by covalent layer-by-layer assembly or other polymer spinning-based methods can prevent short- and longer-term colonization and biofilm formation by common fungal and bacterial pathogens. We demonstrate that both the polymer and liquid phases comprising these materials can be exploited to load and sustain the release of antimicrobial agents and other types of small- and large-molecule actives into surrounding media. Recent strategies to exploit the properties of nanostructured liquids, such as water-in-oil nanoemulsions, as infused phases and design antifouling SLIPS capable of hosting and releasing highly water-soluble agents will also be discussed. These approaches improve the inherent anti-fouling properties of these materials, enable them to more efficiently kill planktonic pathogens, and can endow them with other useful functional properties.

These approaches are modular and can be used to fabricate multi-functional, bioactive SLIPS on complex surfaces, including the luminal spaces of flexible polymer tubing of the type used to fabricate catheters. This strategy thus has the potential to be general and can be exploited to release a broad range of oil- and water-soluble cargo. We anticipate that these materials, strategies, and concepts will enable new designs of bioactive slippery surfaces with improved anti-fouling properties and open the door to new applications of slippery liquid-infused materials that host or promote the release of other types of bioactive agents. Efforts to apply these approaches to the design of anti-biofouling tubing and coatings that can identify and report on virulence phenotypes or attenuate communication in non-adherent bacteria will also be discussed.