Proto-SLIPS: Slippery Liquid-Infused Surfaces that Release Highly Water-Soluble Agents

Slippery liquid-infused porous surfaces (or "SLIPS") can prevent bacterial surface fouling, but they do not inherently possess the means to kill bacteria or reduce cell loads in surrounding media. Past reports show that the infused liquids in these materials can be leveraged to load and release antimicrobial agents, but these approaches are generally limited to the use of hydrophobic agents that are soluble in the infused oily phases. Here, we report the design of so-called "proto-SLIPS" that address this limitation and permit the release of highly water-soluble (or oil-insoluble) agents. This approach involves the physical patterning of small, dried spots of hydrophilic drugs on the surfaces of hydrophobic porous materials and leads to analogs of conventional SLIPS that contain drug-patterned regions that can dissolve and disperse on exposure to water. We show that proto-SLIPS fabricated by patterning the antibiotic gentamicin on model porous PTFE membranes release drug rapidly, followed by a rapid process of self-healing in which oil from surrounding areas is transported to regions vacated by the drug. This healing process leads to uniform oil-infused surfaces with inherent antibiofouling properties similar to those of conventional SLIPS. The results of microbiological studies demonstrate that gentamicin-patterned proto-SLIPS can kill the common human bacterial pathogen <i>Staphylococcus aureus</i> on the surfaces of hydrogels or in liquid culture media and then transform to substantially reduce further bacterial surface fouling. This approach is modular and has the potential to enable the design of slippery surfaces that can release a wide variety of highly water-soluble and/or oil-soluble agents. In support of this goal, we demonstrate bases for the design of proto-SLIPS that release antifungal peptides, new dual-release coatings that release two agents targeted against different bacterial species, and the integration of concepts from the field of controlled release that provide additional measures of control over drug loading and release. We conclude that this proto-SLIPS strategy presents a new and useful approach to the design of drug-eluting SLIPS, with the potential to improve inherent antibiofouling behaviors and open the door to new applications of liquid-infused coatings in healthcare and other areas.