Hydrophilic Modification On Polyvinyl Alcohol Membrane By Hyaluronic Acid

Corneal disease is a common and frequently occurring disease in ophthalmology.The corneal blindness is the second leading cause of blindness in the blind epidemiology survey,It was estimate that 80% corneal blindness could be treatable with corneal transplantation.However,traditional corneal transplantation has associated with problems such as donor shortages,immune rejec-tion,and reoperation.In addition,extremely hostile ocular surface environments would lead to premature allograft failure following traditional corneal transplantation.At present,artificial cornea can be divided into two major categories: tissue engineering cornea and synthetic cornea.Although tissue engineering cornea has been used in clinical practice,the effect is not ideal.The synthetic artificial cornea has provided another option to the severe corneal blindnessalthough it still has many complications,such as dry eye disease,infection,endophthalmitis,proliferative membrane and glaucoma,after implantation.Protein adsorption is the first stage of biofilm formation.The appearance of biofilm,which is difficult to remove and even become resistant to antibiotics,will lead to a series of problems such as bacterial infection and platelet adhesion resulting in thrombosis.Protein adhesion also leads to a decrease in corneal light transmission which would reduce the practical value of artificial corneal prostheses.Therefore,this paper is devoted to the study of a corneal material with strong hydrophilicity and resistance to protein adhesion.In this paper,the optical center area of artificial cornea was prepared by freeze-thaw method with polyvinyl alcohol(PVA)as the substrate.In order to increase the hydrophilicity and anti-fouling ability of the optical center area,the hyaluronic acid molecules were grafted on the surface of the optical center area by different methods.The main research contents and results are as follows:1.PVA hydrogel film is prepared by freeze-thaw method and the surface of the film is functionalized by a bridge moiety to increase the surface reactivity.The modification of hyaluronic acid enhanced its solubility and the reaction was no longer limited to the aqueous solvent system;Finally,the hyaluronic acid is grafted onto the surface of the PVA film by amidation reaction of-COOH of hyaluronic acid with-NH2 on the film.The results showed that the hydrophilicity of the membrane surface was enhanced.The water contact angle was reduced from 40.1° to the lowest 10.3°.The water content was above 68% and the water storage capacity was good.The light transmittance is above 90%,which is slightly lower than that of the pristine PVA.The capacity of anti-protein adsorption was significantly improved,the adsorption amount was reduced from the original 8.91 μg/cm2 to a minimum of 2.86 μg/cm2.In vitro cytotoxicity level was determined as grade 0 and the grafted membrane had good anti-cell adhesion property.2.The hyaluronic acid was modified by double bond containing compound(methacrylic anhydride),The double bond rate of hyaluronic acid is controlled by the ratio of hyaluronic acid to methacrylic anhydride.Then the double-bonded hyaluronic acid was polymerized and grafted onto the surface of the polyvinyl alcohol film by radical polymerization.,and.The results showed that the hydrophilicity of the membrane surface was enhanced after grafting hyaluronic acid.The contact angle decreased from 40.1° to 27.0°(the sample prepared by AIBN organic solvent system)and 11.5 °(the sample prepared by AIBI water system).The water content of the modified PVA film is over 72%.The modified film remains transparent and the transmittance is above 90%.The anti-protein adsorption capacity is significantly improved and the adsorption amount is reduced from the original 8.91 μg/cm2 to a minimum of 2.9 μg/cm2.In vitro cytotoxicity level is grade 0 or grade 1.The modified film also has good anti-cell adhesion properties.3.The cationization of PVA surface was carried out by using methacryloxyethyltrimethyl ammonium chloride.Then the polyanionic hyaluronic acid was grafted to the cationic polyvinyl alcohol by a simple ion exchange adsorption method.The results showed that the hydrophilicity of the film was enhanced after grafting hyaluronic acid.The contact angle decreased from 40.1 ° to 15.5 °.The water content was above 73%.The film remained transparent after grafting.The transmittance is above 92%.the anti-protein adsorption capacity is significantly improved and the adsorption amount is reduced from the original 8.91 μg/cm2 to a minimum of 2.7 μg/cm2.In vitro cytotoxicity level is graded 0 or 1.The surface of the modified film has good anti-cell adhesion properties.