Consider a material for a vascular graft application with proteins adsorbed to its surface and a second material with proteins covalently attached to its surface. For which material would you expect the protein layer to be more stable under flow conditions similar to those found in a blood vessel? Why?

Answer is given below :

Explanation:

Individual-specific proteins are placed on the graft material so that the body does not recognize the graft as a foreign substance and treats it as a part of the body’s natural tissue structure. If the body recognizes the graft as a foreign substance, it produces an immune response against it and leads to a graft rejection reaction by the body. In order for these proteins to attach to grafts, a covalent bond for absorption must be preferred. Absorption is a reversible process and, if used, can lead to de-absorption of bound proteins, including blood, after dissolving by turbulence and pulling to the grafting material by blood flow (velocity up to 40 cm/sec). The remaining infectious tissue is detected foreignly, activating the immune response.  On the other hand, covalent bonding is irreversible in nature and vascular flow does not have a disruptive effect on the bond between the graft and the protein, reducing the stable state of the graft and the possibility of rejection.