You are given two sets of thin samples in which one set is very hydrophobic and

Question

You are given two sets of thin samples in which one set is very hydrophobic and one set is very hydrophilic. Each sample is 1 cm2 in surface area. You can ignore the depth of the material

e. If you adsorb albumin for 24 hours and then expose fibrinogen to high molecular weight kininogen (HMWK) at a very high concentrated, predict and explain the likely outcome of albumin for both type of surfaces? (4 pts) If you adsorb fibrinogen to the samples after one minute, predict and explain the attachment of platelets for both samples? (4 pts) If you adsorb fibrinogen to the samples after 24 hours, predict and explain the attachment of platelets for both samples? (4 pts) f. g.

Explanation / Answer

Ans e. studying the adsorption of Fibrinogen on a surface in contact with blood plasma, first done by Vroman also called Vroman effect. For more you may read: L. Vroman, Nature, 1962, 196, 476–477

Naturally albumin globular proteins are hydrophilic and they readily adsorb to hydrophilic surfaces. But upon drying they become more hydrophobic (relatively more hydrophobic than fibrinogen and gamma globulin). As we are adsorbing albumin for 24 hours it should turn more hydrophobic and should adsorb very well to hydrophobic sample (like attracts like). Then added fibrinogen, it should attach to hydrophobic surface of albumin which is already strongly attached to hydrophobic surface (as per research fibrinogen prefers hydrophobic albumin than hydrophilic albumin). Kininogen especially high molecular weight removes fibrinogen from albumin both invitro and invivo. Upon exposure to HMWK fibrinogen will be removed (this is brought about by increasing the hydrophilicity of albumin, hence fibrinogen can no more attach to albumin)    

f: From the clarity of the question fibrinogen dried for 1 minute and applied to hydrophobic and hydrophilic sample? Or added to both samples and allowed to dry? Fibrinogen is also a hydrophilic protein but upon drying becomes hydrophobic but comparatively less hydrophobic than albumin. As adsorption time is one minute (drying time is less) hence fibrinogen attaches most favourably to hydrophilic sample. Platelets tend to attach to relatively hydrophobic surfaces, as we are not allowing fibrinogen to dry and become relatively hydrophobic, attachment of platelets to hydrophilic sample will be less.

g. From the clarity of the question fibrinogen dried for 24 hours and applied to hydrophobic and hydrophilic sample? Or added to both samples and allowed to dry for 24 hours? As adsorption time is 24hours (drying time is more) hence fibrinogen attaches most favourably to hydrophobic sample. Platelets tend to attach to relatively hydrophobic surfaces, as we are allowing fibrinogen to dry for 24 hours it should become relatively hydrophobic, hence attachment of platelets to hydrophobic sample should be more.

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