Study On The Controllable Preparation And Mechanical Properties Of Silk Fibroin Hydrogel

As a new type of polymer materials,hydrogels have extensive prospect in biology and medicine due to it good environmentally friendly and biocompatible.Silk fibroin(SF)is a natural biomaterial with excellent biocompatibility.And exhibits some special properties,such as bioactivity,PH-sensitivity and tissue adhesion.Hence,SF based hydrogel have attracted widespread attentions,and show promising applications potential in biomedical field of tissue engineering and drug release.However,the poor mechanical properties and formability just as SF hydrogel are serious impediments for practical application.Therefore,it has an important scientific significance to prepare silk fibroin hydrogel with excellent mechanical properties and controllable shape.In the present work,we designed a photopolymerized hydrogel PEGDA/SF,PEGDA/SF hydrogel consists of polyethylene glycol diacrylate(PEGDA),silk fibroin(SF)and photoinitiator 2-hydroxyl-4'-(2-hydroxyethoxy)-2-methylpropiophenone(Irgacure 2959).The hydrogel is polymerized by UV light.The influence of silk fibroin content on the mechanical properties of composite hydrogel PEGDA/SF was also investigated.Moreover,the composite hydrogel was patterned with UV by using a shadow mask and the micropatterned hydrogels were successfully prepared.its biocompatibility is studied by cell encapsulation experiments.On the other hand,silk fibroin was used as main material and combination of microfluidic technology to prepare hydrogel fibers for biological printing.Qualitative and quantitative physicochemical properties of hydrogel fibers were also analyzed.The main result are as follows:(1)The PEGDA/SF prepolymer solution with different content of silk fibroin was prepared,and the photoinitiator I-2959 was added to the prepolymer solution,which can turner into composite hydrogel by light polymerization under a 365 nm ultraviolet light.The effects of silk fibroin content on swell ratio?mechanical properties? internal structure of hydrogel samples and the formation mechanism of composite hydrogels were discussed.The experiment results indicated that a photocrosslinkable,interpenetrating PEGDA/SF composite hydrogel was synthesized with this method,and as the content of silk fibroin increases,the mechanical property of the composite hydrogel has been improved.(2)By using a shadow mask under UV light,the composite hydrogel was patterned.The biocompatibility of the composite hydrogel was studied.The experimental results show that a grid pattern with a size of 100 ?m can be obtained through the used method.Moreover,the composite hydrogel was proved to have good biocompatibility by encapsulating mouse pre-osteoblast MC3T3-E1 in composite hydrogel,the results of the cell experiment indicated that composite hydrogel can maintain the normal growth of cell.(3)Base on simple single emulsion capillary microfluidic device,SF/SA composite hydrogel fibers can be prepared with size controllable.The mixed solution of Ca Cl2 and PEG 400 is the outer phase,and the mixed solution of silk fibroin and sodium alginate(SA)is the internal phase.The physical and chemical properties of the composite hydrogels were also investigated,the result show that distribution of silk fibroin and sodium alginate is in a core/shell structure,and the silk fibroin is mainly inside the fiber with ?-sheet conformation.In addition,the mechanical property of the composite hydrogel fibers still needs to be improved.(4)In addition,the above-mentioned microfluidic device is also used to preparation of silk fibroin hydrogel fiber.Aqueous solution of silk fibroin and mixed solution of methanol/PEG400 are used as inner phase and outer phase,respectively.The physicochemical properties of the hydrogel fiber were also investigated.The study showed that the elongation at break of the fibroin hydrogel fiber was obviously enhanced than that of the natural fiber,but the fracture strength decreased.