Fax: (+) 82-42-350-2810 haeshin@kaist.ac.kr, Homepage: http://web.mac.com/haeshin. NIH Public Access Author ManuscriptAngew Chem Int Ed Engl. Author manuscript; available in PMC 2011 December 3. NIH-PA Author ManuscriptNIH-PA Author Manuscript NIH-PA Author ManuscriptA bio-inspired approach for superhydrophobic surface modification was investigated. Hydrophilic conversion of the superhydrophobic surface was easily achieved through this method, and the superhydrophobic-hydrophilic alternating surface was generated by the method combined with soft-lithography. The resulting patterned surface showed high water adhesion property in addition to superhydrophobic property. KeywordsSuperhydrophobicity; Surface modification; Bio-inspired coating; Soft-lithography; High-water adhesion Mussels, a promiscuous, underwater fouling organism, attach to virtually any natural or synthetic organic/inorganic substrates. Major components of mussels' adhesive pads include proteins that contain the unusual amino acid, 3,4-dihydroxy-L-phenylalanine (DOPA Despite the large effort to develop methods to prepare superhydrophobic surfaces and to seek useful applications, few strategies to tailor the superhydrophobic surface properties have been developed. In particular, a facile strategy to modify superhydrophobic surfaces that can be integrated with widely implemented soft-lithographic techniques has not been achieved.Herein, we report a one-step, solution-based surface chemistry that modifies superhydrophobic surfaces (Scheme 1). The surface chemistry to enable this innovation is inspired by adhesion mechanisms of marine mussels, and is compatible with the established soft-lithography techniques. By immersing substrates into a solution containing dopamine, a mussel-mimetic adhesive molecule, the superhydrophobic surface is immediately transformed into a hydrophilic substrate. By partial exposure of the substrate via a softlithographic technique, micromolding in capillaries (MIMIC),[12] the micropatterned surface remained superhydrophobic but was found to be adhesive to water. Similar to the mechanism of water collection by a desert beetle, Stenocara sp., the modified surface can be used to capture, guide, and collect water droplets.[13]We hypothesized that polydopamine formed by oxidative self-polymerization of dopamine could modify superhydrophobic surfaces as it demonstrated functionalization of all other tested surfaces. For preparation of superhydrophobic surfaces, anodic aluminum oxide (AAO) membranes were utilized as templates on which fluorosilane was coated by a gasphase deposition.[14] The resulting AAO superhydrophobic surfaces were immersed into the dopamime solution to test the hypothesis. The superhydrophobic surface became hydrophilic with the dramatic decrease in contact angle from 158.5±2.8° to 37.3±2.6° after 18 hr polydopamine functionalization ( Figure 1A). The partially modified surface prepared by half immersion of the superhydrophobic substrate into the dopamine solution showed drastic differences in the beh...

Heparin immobilization on surfaces has drawn a great deal of attention because of its potential application in enhancing blood compatibility of various biomedical devices such as catheters, grafts, and stents. Existing methods for the heparin immobilization are based on covalent linkage formation and electrostatic interaction between substrates and heparin molecules. However, complicated multistep procedures and uncontrolled desorption of heparin are limitations of these methods. In this work, we report a new heparin derivative that exhibits robust adhesion on surfaces. The derivative, called hepamine, was prepared via conjugation of dopamine, a mussel-inspired adhesive moiety, onto a heparin backbone. Immersion of poly(urethane) substrates into an aqueous solution of hepamine resulted in robust heparin coating of the poly(urethane), the most widely used polymeric material for blood-contacting medical devices. The hepamine-coated poly(urethane) substrate showed significant inhibition of blood coagulation and platelet adhesion. The use of hepamine for surface modification is advantageous for several reasons: for example, no chemical pretreatment of the substrates is necessary, and surface functionalization is a simple, one-step procedure. Thus, the heparin immobilization method described herein is an excellent alternative approach for the introduction of heparin molecules onto surfaces.

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This study reports methods for general preparation of superhydrophobic surfaces on any type of material surface using musselinspired poly(dopamine) (pDA). The use of pDA presents several advantages over conventional superhydrophobic fabrication methods: development of superhydrophobicity in a material-independent manner, enhancement of mechanical stability, decreases in angle hysteresis, and applicability to 3D objects.

This article is a brief overview of the emerging microfluidic systems called surface-tension-confined microfluidic (STCM) devices. STCM devices utilize surface energy that can control the movement of fluid droplets. Unlike conventional poly(dimethylsiloxane)-based microfluidics which confine the movement of fluids by three-dimensional (3D) microchannels, STCM systems provide two-dimensional (2D) platforms for microfluidics. A variety of STCM devices have been prepared by various micro-/nanofabrication strategies. Advantages of STCM devices over conventional microfluidics are significant reduction of energy consumption during device operation, facile introduction of fluids onto 2D microchannels without the use of a micropump, increased flow rate in a special type of STCM device, among others. Thus, STCM devices can be excellent alternatives for certain areas in microfluidics. In this Minireview, fabrication methods, operating modes, and applications of STCM devices are introduced.