Study On The Adsorption And Desorption Behavior Of Fibrinogen On Poly(2-methyl-2-oxazoline)/poly(Acrylic Acid) Mixed Brushes

Fibrinogen is a highly abundant blood plasma glycoprotein synthesized in the liver by hepatocytes,playing a vital role in coagulation,platelet activation,inammatory response,and leucocyte binding.Fibrinogen has a molecular weight of 340 kDa,and an IEPprotein=5.8.Fibrinogen is a kind of protein with strong adhesion,which is easy to adsorb on the materials surface(such as silicon,gold).The adsorption of the fibrinogen monolayer on the substrate or various synthetic materials can induce platelet adhesion,thereby affecting the function of the material surface.The selective adsorption and release behavior of fibrinogen can be achieved by grafting a binary mixed polymer brush with stimulus-responsive capability on the material surface.In this paper,the binary mixed polymer brushes which combine the anti-protein adsorption properties of poly(2-methyl-2-oxazoline)(PMOXA)and the pH and ionic strength(I)stimulus-responsive properties of poly(acrylic acid)(PAA)were prepared,and the adsorption and desorption behavior of fibrinogen on the mixed brushes was studied.The specific work is as follows:Firstly,the mixed polymer brushes which combine PMOXA with different chain lengths and PAA were prepared on the material surfaces(including glass,silicon,and gold)by using polydopamine(PDA)as an anchor.Then the surface chemical composition and thickness of the mixed brushes were characterized by X-ray photoelectron spectroscopy(XPS)and variable angle spectroscopic ellipsometry(VASE).Water contact angle(WCA)results showed that when the environmental pH and I change from pH 9 and I=0.01 M to pH 9 and I=0.15 M,the surface of the mixed brushes would change from a relatively hydrophobic state to hydrophilic state.Studies on the adsorption and desorption behavior of fibrinogen by fluorescence microscopy and surface plasmon resonance(SPR)showed that increasing the degree of polymerization of PMOXA would reduce the amount of protein adsorption of the mixed brushes,and would also significantly improve the protein desorption percentage of the mixed brushes.SPR experiment indicated that the mixed brush prepared by sequential grafting PMOXA with a degree of polymerization of 60 and PAA with a degree of polymerization of 90 in a mass ratio of 3:2 achieved the best desorption percentage of 83.5%for fibrinogen.