________________________________________________________________Countless lives have been saved by implantable medical devices (e.g., total artificial hearts, ventricular assist devices, pacemakers, cardioverterdefibrillators, and central lines) and extracorporeal devices that flow whole human blood outside the body through indwelling catheters and external circuits, during cardiopulmonary bypass (CPB), hemodialysis, and extracorporeal membrane oxygenation (ECMO) 1,2 . However, the need to co-administer soluble anticoagulant drugs, such as heparin, with many of these procedures, significantly reduces their safety and hampers their effectiveness 3,4 . Without systemic anticoagulation, these extracorporeal and indwelling devices can rapidly occlude due to thrombosis because clots form when fibrin and platelets in the flowing blood adhere to the surfaces of these artificial materials 5 . Unfortunately, heparin causes significant morbidity and mortality including post-operative bleeding, thrombocytopenia, hypertriglyceridemia, hyperkalemia and hypersensitivity 6 , and its use is contraindicated in several patient populations 7 . In fact, the majority of drug-related deaths from adverse clinical events in the UnitedStates are due to systemic anticoagulation 8 .This need to prevent blood clotting while minimizing administration of anticoagulant drugs has led to the search for biomaterial surface coatings that can directly suppress blood clot formation. The most successful approach to date has been to chemically immobilize heparin on blood-contacting surfaces to reduce thrombosis and lower anticoagulant administration 9,10 . Although this approach has been widely adopted, major limitations persist because the surface-bound heparin leaches, resulting in a progressive loss of anticoagulation 24,25 . Importantly, the TP continues to retain the free LP as a thin mobile liquid layer even when the surface is challenged with a flowing immiscible fluid, such as blood (Fig. 1a). We refer to this unique anti-thrombogenic bilayer composed of the TP and LP coating as a Tethered-Liquid Perfluorocarbon (TLP) surface. RESULTS A generic blood repellent surface coatingTo test the anti-adhesive properties of the TLP coating method, we examined surface adhesion of fresh whole human blood on an acrylic surface sloped at an angle of 30 degrees, with or without a TLP coating composed of tethered perfluorohexane and liquid perfluorodecalin. Blood droplets immediately adhered to the control uncoated acrylic surface and left a trail of blood components over the course of 5 sec (Fig. 1b, top, Supplementary Fig. 1 and Supplementary Movie 1).In contrast, when the same surface was coated with TLP, the blood droplet almost immediately slid off the surface (< 0.3 sec), and remarkably, there was no evidence of any residual blood trail (Fig. 1b, Supplementary Fig. 1 and Supplementary Movie 2). We quantified blood adhesion to surfaces by measuring the minimum angle required to cause a droplet to slide ("sliding angle") ( Fig. 1c). Control uncoated s...

Omniphobic coatings are designed to repel a wide range of liquids without leaving stains on the surface. A practical coating should exhibit stable repellency, show no interference with color or transparency of the underlying substrate and, ideally, be deposited in a simple process on arbitrarily shaped surfaces. We use layer‐by‐layer (LbL) deposition of negatively charged silica nanoparticles and positively charged polyelectrolytes to create nanoscale surface structures that are further surface‐functionalized with fluorinated silanes and infiltrated with fluorinated oil, forming a smooth, highly repellent coating on surfaces of different materials and shapes. We show that four or more LbL cycles introduce sufficient surface roughness to effectively immobilize the lubricant into the nanoporous coating and provide a stable liquid interface that repels water, low‐surface‐tension liquids and complex fluids. The absence of hierarchical structures and the small size of the silica nanoparticles enables complete transparency of the coating, with light transmittance exceeding that of normal glass. The coating is mechanically robust, maintains its repellency after exposure to continuous flow for several days and prevents adsorption of streptavidin as a model protein. The LbL process is conceptually simple, of low cost, environmentally benign, scalable, automatable and therefore may present an efficient synthetic route to non‐fouling materials.

Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectious bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella salina, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.

The stability and longevity of surface-stabilized lubricant layers is a critical question in their application as low-and non-fouling slippery surface treatments in both industry and medicine. Here, we investigate lubricant loss from surfaces under flow in water using both quantitative analysis and visualization, testing the effects of underlying surface type (nanostructured versus flat), as well as flow rate in the physiologically-relevant range, lubricant type, and time. We find lubricant losses on the order of only ng/cm 2 in a closed system, indicating that these interfaces are relatively stable under the flow conditions tested. No notable differences emerged between surface type, flow rate, lubricant type, or time. However, exposure of the lubricant layers to an air/water interface did significantly increase the amount of lubricant removed from the surface, leading to disruption of the layer. These results may help in the development and design of materials using surface-immobilized lubricant interfaces for repellency under flow conditions.