(426d) Immiscible Liquid-Coated Materials for Bioseparations

Bioseparations, such as liquid and aerosol filtration, are most often performed with the use of porous materials. However, porous materials can be prone to biofouling and other types of surface adsorption. In this work, we present bio-inspired liquid-coated surfaces as a new approach to separation materials that resist fouling. Liquid-coated filters can be created by immobilizing a water immiscible liquid on the surface of commercially available synthetic filtration membranes. By chemically matching the infusing liquid to the filtration membrane, the stable liquid layer that is formed produces a dynamic, mobile surface that resists the adhesion of contaminants. For water purification, 0.45 µm pore diameter polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) filters were tested using omniphobic perfluoropolyether coating liquids. We measured the continuity of the surface liquid layer by testing how easily a water droplet could begin to move the surface, as well as the anti-adhesion properties of the surface liquid layer through quantifying the speed of droplet movement at a static angle of inclination. The results indicate that the PTFE membranes could sustain a more consistent functional liquid layer, with an approximately 75% lower sliding angle and 70% faster droplet movement at a fixed angle than the PVDF. For aerosol filtration, we tested liquid-coated commercial PTFE and HEPA filters for their efficiency in capturing and releasing aerosolized Escherichia coli for analysis. We determined that bacteria trapped on the liquid-coated filters could be removed with increased efficiency compared to bare controls. The use of liquid coated materials in bioseparations opens new doors for the creation of dynamic filtration strategies.