Surface Solutions
Surface Solutions
Surface Solutions
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  • Generic Examples

    1) Covalent Bioactive Metal Complex Attachment: one-step

    Samples were prepared of a covalently bound bioactive metal complex, which were then dip-coated on a PMMA surface and dried overnight at 60°C. Metal counts were obtained from the samples after drying and washing, after soaking overnight and for three weeks in water.

    Binding is maintained through prolonged soaking. There may actually be more metal available with longer exposures due to reorientation of the metal within the dried coating resin.

    2) Covalent protein attachment: two-step

    Glass slides were primed with a functional primer resin. One slide was treated with linker and the other was left with primer only. A flow coat of fluorescamine-labeled bovine serum albumin (BSA) was applied to the glass slides and dried. Fluorescence was observed after drying and after washing under running water for 10 minutes. Slides were observed under an appropriate light source. Both dried slides fluoresced, but after washing, only the linker-treated slide showed fluorescence of the BSA.

    Sustained attachment of a protein is observed with this mechanism.

    3) Covalent heparin attachment: one-step

    A) Clotting times

    ID of a polysulfone tube was coated with a covalently bound water-based heparin coating.
    Modified Lee-White clotting time test from NAMSA on Steam-sterilized parts:

    control (uncoated) clotted 30% faster than system control (blank)
    Sample set A n=2 clotted 13% faster than system control
    Repeat set A n=3 clotted 15% faster than system control

     

    Clotting times < 20% faster than system control are significant. This information combined with uncoated data suggests that the Surface Solution samples did reduce clotting time.

    B) Thrombin times of human plasma: one-step

    Two samples of coating resins were prepared. In one, heparin was bound covalently to the supporting resin through a linker and in the other the heparin was not bound. Films 3 mils thick were cast on PE sheets and removed. A control of benzalkonium heparin was prepared by casting the coating resin on PE and post-dipping in the ionic heparin solution. Films were soaked in saline for 24 hours and then removed and placed in fresh saline. Thrombin times for soak solutions, based on a pooled human plasma, yielded IU data shown below.

    Plots indicate sporadic and ineffective release with the benzalkonium heparin coating. Substantial improvement is noted in heparin release when it is incorporated in the film for diffusion release. Logarithmic improvements are noted when the heparin is covalently bound.

    Sample

    Time to lost effectiveness (< 1 IU/24 hr)

    Benzalkonium heparin–dipped film – control

    less than 12 hours

    Unbound heparin

    Approx. 1 day

    Bound heparin retained

    2 weeks minimum

     

    Bound heparin is sustained and effectively released over at least 14 days by
    this method.
     

    C2G00033

     

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