Preparation And Zwitterionic Modification Of Poly(Hydroxyethyl Methacrylate-co-glycidyl Methacrylate)membrane

Polyhydroxyethyl methacrylate（p HEMA）is a synthetic polymer membrane with good biocompatibility,excellent physical properties and low toxicity.It is commonly used in the preparation of contact lenses.Deposition of protein and lipidin the tears on the p HEMA hydrogelsurface may cause complications,such as bacterial infection.Itis extremely important to improvethe hydrophilicity and anti-cell adhesionproperties of p HEMA membrane surface to expand itsapplication in ophthalmology.Poly（hydroxyethyl methacrylate-co-glycidyl methacrylate）copolymer membrane（p（HEMA-co-GMA））were prepared by blue light induced-fragment chain transfer radical polymerization.Then the membranes were modifiedwithzwitterionicstructural molecules（Glycerylphosphorylcholine（GPC）,sulfobetaine（NS）and amino acid）to improve the anti-fouling ability ofmaterials.The main results are described asfollows:1.p（HEMA-co-GMA）membranes were prepared by blue light-induced electron transfer-reversible addition fragmentation radical polymerization（PET-RAFT）with（4-cyanovaleric acid）-4-dithiobenzoic acid（CPADB）as chain transfer agent and Red Y（EY）as a photocatalyst.The analysis of moisture content,contact angle and mechanical properties showed that the GMA weight content had a great influence on the properties of membranes.So the membranes with GMA mass percentage of 3%,6%,9%,12% and 15% were selected for surface modification,the illumination time was 30 h and the concentration of CPADB was 7.05 mmol/L.2.With the p（HEMA-co-GMA）membranes as a substrate,GPC was grafted onto the surface via ring opening reactionbetween hydroxyl group of GPC and epoxy groups of GMA to improve the anti-protein adsorption and anticell adhesion properties of p（HEMA-co-GMA）membrane.The hydrophilicity of the grafted p（HEMA-co-GMA）membranes were improved,the water content was above 60%,and the contact angle was reduced from 71.7° to 28.38°.After grafted zwitterions,the anti-protein adsorption capacity of p（HEMA-co-GMA）membrane was significantly increased and the lowest adsorption amount was down to 0.06129 μg·mm^-2,which is reduced about 44.60% in comparison to the blank membrane.The membranes were considered as non-toxic and had good anti-cell adhesion properties after grafted the zwitterionic.3.Sulfobetaine（NS）was synthesized by 3-dimethylaminopropylamine and 1,3-propane sultone with a molar ratio of 1:1.1（v/v: 1.3:1）in absolute ethanol.The structure of NS was characterized by IR and 1H NMR,subsequently.A sulfobetaine zwitterion was grafted on the surface of the membrane to improve the antifouling property of the p（HEMA-co-GMA）membrane under alkaline conditions by the reaction of an epoxy ring with a primary amino group.After grafting zwitterions,the water content of p（HEMA-co-GMA）film was above 62% and the contact angle was reduced from 71.7° to 27.9° compared to the blank membrane,the thermal properties after grafting decreased slightly,and the decomposition temperature was advanced to 220 °C.The anti-protein adsorption capacityof p（HEMA-co-GMA）membranes was significantly increased and the lowest adsorption amount was down to 0.06551 μg·mm^-2 compared with the blank membrane,the protein adsorption amount was reduced about 40.78%.The cytotoxicity test showed that theinitial and grafted membranes were basically considered to be non-toxic,and the surface of the membrane had good anti-cell adhesion properties after grafting the zwitterions.4.Zwitterionic amino acid（glycine,serine,aspartic acid and glutamic acid）were immobilized on the surface of p（HEMA-co-GMA）membranes via ring opening reaction between amino group in amino acid and epoxy groups of polymer chains.After grafting zwitterions,the water content of p（HEMA-co-GMA）membrane was above 61% and the contact angle decreased from 71.7°to 31.1°,29.9°,31.4°and 32.8° respectively.The thermal properties after grafting decreased slightly,and the decomposition temperature was advanced to about 310℃.After grafted zwitterions,the anti-protein adsorption capacity of p（HEMA-co-GMA）membranes was significantly increased and the lowest adsorption amount was down to 0.0609 μg·mm^-2,0.05991 μg·mm^-2,0.06148 μg·mm^-2,and 0.06379 μg·mm^-2,which reduced the protein adsorption amount by 44.94%,45.84%,44.43% and 42.34% compared with the blank membrane.Furthermore,cytotoxicity in vitro analysis demonstrated that both initial and grafted membranes were nontoxic and biocompatible.The surface of the membrane had good anti-cell adhesion properties after grafting zwitterions.