Fabrication And Properties Of Silk Fibroin Based Bioadhesives

Recently,some natural or synthetic biopolymer materials have been used to prepare bioadhesives,such as silk fibroin.Silk fibroin is widely used as biomedical materials due to its certain mechanical strength,good biocompatibility and degradability.Bioadhesives used in clinical trials still have certain problems in terms of adhesive strength,curing mode and speed,biocompatibility,biodegradability,etc.Therefore,it's still challenging to develop a wound repairing adhesive with good biocompatibility,high adhesive strength and strong water resistance.This study reports a facile approach for the synthesis of silk fibroin-based bioadhesives with the assistance of polyethylene glycol.Based on polyethylene glycol which can promote silk fibroin self-assembly,the silk fibroin bioadhesive(SFB)is prepared under the induction of protons.And the effects of silk fibroin content,pH,temperature,time and environment on the adhesive strength of SFB were investigated.Self-crosslinking silk fibroin bioadhesive(NESFB)was carried out by the use of a biocompatible cross-linking agent NHS/EDC.Furthermore,dopamine was grafted onto the silk fibroin macromolecule to prepare a dopamine/silk fibroin bioadhesive(NESFB-Dopa)with strong water resistance.The cytotoxicity of silk fibroin-based bioadhesives was evaluated by MTT assay.The leaching solution of the materials was co-cultured with Hela cells to evaluate the biocompatibility.In vitro degradation evaluation of silk fibroin-based bioadhesives was executed using protease XIV.The research contents and results are as follows:1.The preparation of silk fibroin bioadhesive(SFB)and the characterizationSFB was prepared by proton induction in polyethylene glycol solution.The adhesive strength of SFB was tunable by controlling the reaction parameters such as silk fibroin content,pH,temperature and time.And its structure and morphology were characterized.Fluorescent labeling was used to trace the formation of SFB.It was found that polyethylene glycol promoted silk fibroin self-assembly to form nanoparticles and agglomerated into gel blocks under the action of protons.The adhesion properties of SFB prepared under different conditions were studied by conducting a lap-shear testing.The results showed that SFB had good adhesive strength in both dry and wet conditions.2.The preparation of dopamine/silk fibroin bioadhesive and the characterizationSelf-crosslinking silk fibroin bioadhesive(NESFB)was prepared by NHS/EDC action.The adhesive strength of NESFB-Doap for pigskin tissue was greatly enhanced when a little mount of dopamine was grafted(about 5 wt%).Successful grafting of dopamine on silk fibroin macromolecules was demonstrated by IR and UV tests.The optimum adhesive strength of NESFB-Dopa was explored by changing the amount of polyethylene glycol,crosslinker and dopamine,and the effect of curing time on the adhesive strength was monitored.The lap-shear testing results showed that NESFB-Dopa still maintained high adhesive strength under wet condition.After 42 hours immersion in water,its adhesive strength was 503.32±16.54 kPa,which indicated that it had good water resistance.So NESFB-Dopa has great potential in wound repairing.3.Cytotoxicity evaluation and in vitro degradation of silk fibroin-based bioadhesivesThe extraction of SFB,NESFB and NESFB-Dopa were co-cultured with Hela cells.The toxicity levels of the three materials were determined by MTT method.The results showed that they were all no cytotoxicity and even NESFB-Dopa could promote cell proliferation.Confocal laser scanning microscope was used to observe the cells.The results showed that the cells were normal in shape and well adhered.These results indicated that silk fibroin-based bioadhesives had good biocompatibility.And silk fibroin-based bioadhesives also had good degradation.