Ethylene-plasma coated

Senior J, Delgado C, Fisher D, Tilcock C, Gregoriadis G. Influence of surface hydiophilicity of liposomes on their interaction with plasma-protein and clearance from the circulation— studies with poly(ethylene glycol)-coated vesicles. Biochim Biophys Acta 1991 1062 ... 

Polyperfluorohexane-coated sulfur floats on ethylene glycol for hours, whereas sulfur samples coated with the other two polymers sink after minutes, especially acrylic-acid-coated sulfur. As the surface energy of sulfur after encapsulation with a plasma polymer is brought closer to those of the rubbers, better compatibility with these rubbers is to be expected. 

In this context plasma is a gas containing free electrons, ions, and neutral particles and may be created by applying external excitation to the gas. When used to polymerize ethylene a plasma can give coatings of higher molecular weight, cross-linked and without pores—and provide relatively impermeable barrier layers on blow mouldings. 

Blattler, T. M. Covalent Immobilization of Poly(L-lysine)-g-poly(ethylene glycol) onto Aldehyde Plasma Polymer Coated Surfaces. Diploma Thesis, University of South Australia, 2004. 

Hydroxyethylation of starch, which is obtained from starch and ethylene oxide. This compound has been utilized in papermaking for sizing and coating, in textile manufacturing, and as a blood plasma extender. Hydroxypropylated starch has also practical applications. 

Stancell et. al. ( 0) reported the possible use of ultrathin films deposited onto relatively permeable substrates as permselective membranes. Ultrathin and highly crosslinked coatings effectively distinguish between molecules of different sizes and increase the permselectivity of the substrate film. Chang et. al. ( ) demonstrated that the permeability coefficient of silicone rubber to oxygen decreased noticeably after depositing a plasma-polymerized ethylene film on the surface. Colter, et. al. (92.93) found similar effects of plasma polymerized films as diffusion barriers in controlled-released drug delivery systems. 

The wettability of plasma deposited coatings can be compared with poly(tetrafluoroethylene) and poly(ethylene). When the cosine of contact angles obtained with non-hydrogen bonding liquids are plotted against their surface tension, extrapolation of the resulting straight line to cos 0=1 yields a term called the critical surface tension (CST) which is characteristic of that surface (ll). 

Several polymers were evaluated in the form of a surface coating on glass beads packed in columns to determine their ability to retain platelets when whole human blood passes over the surface. This ability was measured as the platelet retention index p, the fraction of platelets retained on the column. Lowest values of p were found for poly(ethylene oxide), polypropylene oxide), poly(tetramethylene oxide) (in the form of polyurethanes), and polydimethylsiloxane. Highest values (around 0.8) were found for cross-linked poly(vinyl alcohol) and the copolymers of ethylenediamine with diisocyanates. Intermediate values were found for polystyrene and its copolymers with methyl acrylate, for polyacrylate, and for poly(methyl methacrylate). The results are interpreted in terms of possible hydrophobic and hydrogen bonding interactions with plasma proteins. 

Figure 7.1-3. The ideal synthetic (nonviral) gene delivery vector. After dense DNA packaging is accomplished (e.g., by protamine sulfate), the surface of synthetic particles (which is usually positively charged) needs to be shielded (e.g., by poly (ethylene-glycol) [PEG]) so that they do not attach to blood elements or to each other and, therefore, have an extended circulating plasma half-life (1) (passive targeting to leaky vessels ). The surface of the particles will contain specific ligands for active targeting to selected cells/ tissues (2). By engineering viral fusion proteins to the particle coat, cell entry is facilitated...

Tubular blood-contacting polymeric materials were modified by plasma polymerization and evaluated in animals (baboons) with respect to th r c iadty to induce acute and chronic arterial thrombosis. Nine plasma polymers based on tetrafluoro-ethylene, hexafluoroethane, hexafluwoethane/H, and methane, when deposited on silicone rubber, consumed platetets at rates ranging from l.l-5.6x 10 platelets/on day. Since these values are close to the lower detection limit for this test system, tl plasma polymers were considered relatively nonthrombogenk. Thus, artificial blood tube made of polyesters, having the inner side coated with plasma-pcrfymerized tetra-fluoroethylene, is now commercially available. 

The structures that have evolved for ablative-mode optical discs make use of interference effects to minimize the reflectance (R) of the disc in the absence of a hole. A typical ablative-mode optical disc has the structure shown in Figure 5.51. The substrate is an optically transparent material such as polycarbonate, poly(methyl methacrylate), poly(ethylene terephthalate), or poly(vinyl chloride), topped by a subbing layer to provide an optically smooth (to within a fi-action of a nanometer) surface for the recording layer. A metal reflector (typically aluminum) is then incorporated next to a transparent dielectric medium such as spin-coated poly(a-methyl styrene) or plasma-polymerized fluoropolymers. This dielectric spacing layer serves both to satisfy the quarter-wave (2/4) antireflection conditions and to insulate thermally the A1 reflector from the top absorbing layer where the information pits are created. 

---