Sanli Movafaghi

Superhydrophobic Coatings with Edible Materials.

We used FDA-approved, edible materials to fabricate superhydrophobic coatings in a simple, low cost, scalable, single step process. Our coatings display high contact angles and low roll off angles for a variety of liquid products consumed daily and facilitate easy removal of liquids from food containers with virtually no residue. Even at high concentrations, our coatings are nontoxic, as shown using toxicity tests.

Free-Standing, Flexible, Superomniphobic Films

Fabrication of most superomniphobic surfaces requires complex process conditions or specialized and expensive equipment or skilled personnel. In order to circumvent these issues and make them end-user-friendly, we developed the free-standing, flexible, superomniphobic films. These films can be stored and delivered to the end-users, who can readily attach them to virtually any surface (even irregular shapes) and impart superomniphobicity. The hierarchical structure, the re-entrant texture, and the low solid surface energy render our films superomniphobic for a wide variety of liquids. We demonstrate that our free-standing, flexible, superomniphobic films have applications in enhanced chemical resistance and enhanced weight bearing.

Hemocompatibility of Superhemophobic Titania Surfaces

The hemocompatibility of superhemophobic surfaces is investigated and compared with that of hemophobic surfaces and hemophilic surfaces. This analysis indicates that only those superhemophobic surfaces with a robust Cassie-Baxter state display significantly lower platelet adhesion and activation. It is envisioned that the understanding gained through this work will lead to the fabrication of improved hemocompatible, superhemophobic medical implants.

Fabrication of Nanostructured Omniphobic and Superomniphobic Surfaces with Inexpensive CO2 Laser Engraver

Superomniphobic surfaces (i.e., surfaces that are extremely repellent to both high surface tension liquids like water and low surface tension liquid like oils) can be fabricated through a combination of surface chemistry that imparts low solid surface energy with a re-entrant surface texture. Recently, surface texturing with lasers has received significant attention because laser texturing is scalable, solvent-free, and can produce a monolithic texture on virtually any material. In this work, we fabricated nanostructured omniphobic and superomniphobic surfaces with a variety of materials using a simple, inexpensive and commercially available CO2 laser engraver. Further, we demonstrated that the nanostructured omniphobic and superomniphobic surfaces fabricated using our laser texturing technique can be used to design patterned surfaces, surfaces with discrete domains of the desired wettability, and on-surface microfluidic devices.

Superhemophobic titania nanotube array surfaces for blood contacting medical devices

Hemocompatibility of blood-contacting medical devices is necessary to prevent device failure. As soon as a material encounters blood, proteins and platelets will adsorb and attach to its surface. This leads to thrombosis and clot formation on the surfaces, restricting blood flow and in some cases leading to inflammation and device failure. To avoid these complications, patients receiving blood-contact devices are prescribed blood thinning medications, which must be taken for the rest of the patients life. Some devices can be pre-clotted to improve hemocompatibility, but the benefits will not last the devices entire life. Enhancing hemocompatibility has been a focus of recent research. Proposed methods have included diamond-like carbon surfaces, heparin-based surface coatings, modified polymer surfaces, and titania nanotube arrays. These methods have all shown some enhancement of hemocompatibility initially, but no approach has proven durable over long periods of time. Superhemophobic surfaces are a new approach to improving hemocompatibility, but the interactions of blood components with these surfaces have not been studied in depth. In this study, we have developed superhemophobic surfaces by modifying the surface topography and surface chemistry of titanium. The surface topography was modified by creating titania nanotube arrays through a well-documented anodization technique. Superhemophobicity was induced by modifying the titania nanotube arrays with two different silanes using chemical vapor deposition. The investigations of blood interactions with superhemophobic surfaces showed reduced protein adsorption and platelet adhesion/activation, indicating this a potential approach for enhancing material hemocompatibility.

Antibacterial activity on superhydrophobic titania nanotube arrays

Bacterial infections are a serious issue for many implanted medical devices. Infections occur when bacteria colonize the surface of an implant and form a biofilm, a barrier which protects the bacterial colony from antibiotic treatments. Further, the anti-bacterial treatments must also be tailored to the specific bacteria that is causing the infection. The inherent protection of bacteria in the biofilm, differences in bacteria species (gram-positive vs. gram-negative), and the rise of antibiotic-resistant strains of bacteria makes device-acquired infections difficult to treat. Recent research has focused on reducing biofilm formation on medical devices by modifying implant surfaces. Proposed methods have included antibacterial surface coatings, release of antibacterial drugs from surfaces, and materials which promote the adhesion of non-pathogenic bacteria. However, no approach has proven successful in repelling both gram-positive and gram-negative bacteria. In this study, we have evaluated the ability of superhydrophobic surfaces to reduce bacteria adhesion regardless of whether the bacteria are gram-positive or gram-negative. Although superhydrophobic surfaces did not repel bacteria completely, they had minimal bacteria attached after 24 h and more importantly no biofilm formation was observed.