Preparation And Properties Of Novel Soft Contact Lens Material Based On Hydrogel Containing Zwitterionic Betaine

Currently,the materials commonly used for the fabrication of SCLs include the homopolymer hydrogel of 2-hydroxyethyl methacrylate(HEMA),pHEMA,and the copolymer hydrogels using HEMA as a main comonomer.However,most of SCLs made of these materials still suffer the adhesion of proteins and bacteria in the tear fluid to some extent,thereby decreasing the optical transmittance,oxygen permeability and wearing comfort of SCLs,and even causing the ophthalmic inflammation and complications.Therefore,the construction of novel protein-resistant SCLs hydrogel material is of great significance for improving the consumer’s wearing comfort and reducing the risk of ophthalmic inflammation and enriching the material system of SCLs.Inspired by the chemical composition and character of cell outer membrane,people found that zwitterionic polymers are a kind of material which possesses anti-protein-fouling performance.They mainly contain phosphorylcholine(PC),sulfobetaine(SB)and carboxybetaine(CB).Among them,the synthesis of monomers or reactive compounds bearing SB or CB groups is relatively simple and the starting reactants are available and inexpensive.Therefore,it is expected to construct a novel SCLs material with good hydrophilicity and antiprotein-fouling property by introducing zwitterionic macromolecule chains containing SB or CB groups into hydrogel system.Based on the above study,a series of copolymer hydrogels containing zwitterionic betaine were prepared through introducing SB or CB compound as comonomer into the conventional poly(methyl methacrylate-N-vinylpyrrolidone)hydrogel systems via radical copolymerization.The chemical composition and structural morphologies of the prepared copolymer hydrogels were characterized by Fourier transform infrared spectroscopy(FTIR)and scanning electron microscopy(SEM),respectively;and their swelling property,dehydrated property,surface wettability,transparency,mechanical properties and antiprotein-fouling performance were investigated.Furthermore,the structure-activity relationship between the composition,structure and properties of the copolymer hydrogels was established through the contrastive analyses of experimental data.The research results have laid a solid theoretical and experimental foundation for the design and preparation of novel antibioadhesive materials used for SCLs.The main comtents and results of this work are described follows.(1)First,the zwitterionic carboxybetaine monomer,CBMAA-1,was synthesized by quaternization reaction.And then a series of copolymer hydrogels Poly(HEMA-NVPCBMAA-1)were prepared by copolymerization of HEMA,NVP and CBMAA-1.The prepared copolymer hydrogels exhibited good hydrophilicity.Specifically,the WCA and EWC decreased and increased with the increase of CBMAA-1 content,respectively.The results of BSA protein adsorption tests showed that the prepared hydrogel also possessed a certain anti-protein-fouling ability.Comparing with CBMAA-1-free hydrogel,HNC-0,when the content of CBMAA-1 reached 5.0 wt %,the adsorbed protein amount on the surface of the hydrogel decreased about 32 %,only 0.65 μg/cm2.However,the light transmittance and mechanical properties of the copolymer hydrogels decreased with increasing CBMAA-1 content.(2)Using hydroxyethyl methacrylate(HEMA),N-vinyl pyrrolidinone(NVP)and sulfobetaine methacrylate(SBMA)as comonomers,several copolymer hydrogels with different SBMA contents,Poly(HEMA-NVP-SBMA),were synthesized via radical copolymerization in an aqueous phase.With increasing SBMA content in the comonomer mixture,WCA and EWC of the prepared copolymer hydrogel tended to decrease and increase,respectively,and light transmittance slightly increased,but their tensile mechanical properties declined.The amounts of protein BSA adsorbed onto the surfaces of the copolymer hydrogels and commercially available EASY DAY? SCLs as a control were also determined by protein adsorption tests.The amount of BSA adsorbed on the surface of the copolymer hydrogel decreased with increasing SBMA content.For the hydrogel prepared using the comonomer mixture with 5.0 wt % SBMA,the amount of adsorbed BSA was 0.42 μg/cm2,which corresponded to only 43.0 % of the amount adsorbed on the surface of EASY DAY? SCLs.(3)First,the zwitterionic sulfobetaine monomer,DMAPMAPS,was synthesized by ringopening reaction.And then a series of copolymer hydrogels Poly(HEMA-NVP-DMAPMAPS)with different DMAPMAPS content were prepared by copolymerization of HEMA,NVP and DMAPMAPS using EGDMA as a crosslinker.With increasing DMAPMAPS content,the hydrophilicity of the copolymer hydrogel increased,the dehydration rate of the hydrogel slowed down which meant the water retention capacity was enhanced,and the light transmittance of the hydrogel increased,while the mechanical properties decreased.With increasing the amount of EGDMA,the hydrophilicity and transmittance of the hydrogel decreased and the mechanical properties improved.The results of BSA adsorption showed that the amount of BSA adsorbed on the surface decreased and increased with increasing DMAPMAPS and EGDMA content,respectively.When the content of DMAPMAPS is 5.0 wt % and the amount of EGDMA ranged from 1.0 to 2.0 wt %,the prepared hydrogel exhibited excellent overall performance which was expected to be SCLs material with excellent anti-protein-fouling property.Specifically,the adsorbed BSA amount is in the range of 0.38 ~ 0.52 μg/cm2,and it has excellent light transmittance and mechanical properties.