Biomimetic lipid bilayers on solid surfaces: models for biological interactions

Biomimetic lipid bilayer platforms on solid supports, or solid-supported lipid bilayers (SLBs), are important model membrane systems for studying the fundamental properties of biological membranes and their constituent lipid and protein molecules. SLBs with different properties and functionalities can be designed by changing their lipid content (charged, uncharged, saturated, etc.), adding various membrane components (glycolipids, cholesterol, etc.) or incorporating membrane proteins (receptors, ion channels, etc.). They allow the usage of surface-sensitive characterization techniques such as atomic force spectroscopy, surface plasmon resonance (SPR) and the use of acoustic sensors such as quartz crystal microbalance with dissipation monitoring (QCM-D). Both QCM-D and SPR can supply information about binding events on surfaces and the properties of the resulting lipid films in real time by using frequency-dissipation changes and refractive index shift, respectively. In recent years, the potential of SLBs in numerous practical applications, such as the construction of drug screening or cancer cell detection platforms, has been explored. These platforms address some of the important challenges faced in cell membrane and membrane protein research and make membrane-related applications possible. </jats:p

Alteration of PTFE Surface to Increase Its Blood Compatibility

The aim of this study is to increase the blood compatibility of polytetrafluoroethylene (PTFE), one of the preferred materials for soft-tissue application, by a two-step procedure: first, the surface was activated by hydrogen plasma followed by acrylamide attachment and, secondly, hirudin, a potent antithrombogenic protein from leeches, was immobilized to the surface. Plasma treatment conditions were optimized and different surfaces were characterized by water contact angle measurements, ATR-FT-IR and X-ray photoelectron spectroscopy (XPS). It was seen that the contact angle of the PTFE decreased from 126 degrees to 55 degrees in optimum conditions. Acrylamide (25% (w/v) in ethanol/acetone (50%, v/v)) was grafted to the surface by the help of argon plasma treatment (1 min, 50 W, 13 Pa). The water contact angle was further decreased to 33 degrees with acrylamide grafting and amide groups, which were subsequently used in protein immobilization, and could be detected both by ATR-FT-IR and XPS analysis. In the second part, hirudin was attached to these amide groups on PTFE surface by an optimized EDC/NHS activation procedure. Then a thrombo-genicity test was done to detect hirudin activity. The results showed that there is a significant decrease in the clot formation compared with the untreated PTFE samples and ca. 0.3-0.4 ATU/cm(2) (22-29 ng/cm(2)) of hirudin was enough to prevent the clot formation. A preliminary study showed that the hirudin immobilized membranes keep their antithrombogenic activity for at least 40 days in 37 degrees C in PBS (0.1 M, pH 7.4). As a result, the blood compatibility of PTFE surfaces was ameliorated by plasma-induced monomer grafting and hirudin immobilization, and an alternative material was obtained to be used in medical applications such as vascular grafts, catheters, etc. (C) Koninklijke Brill NV, Leiden, 201

Investigating of interactions between statin-based cholesterol lowering drugs with p-glycoprotein membrane protein by molecular modeling

European Biotechnology Congress -- SEP 28-OCT 01, 2011 -- Istanbul, TURKEYWOS: 000295310800398European Biotechnol Themat Network Asso