Preparation And Application Of Multifunctional Silk Fibroin Composite Materials

Our country is the world’s largest producer of sericulture,and silkworm cocoons account for 75%or more of the world’s output.Silk fibroin（SF）,which is extracted from natural silk fibers,has excellent biocompatibility,biodegradability,colorless and non-toxic,and has attracted extensive attention from material researchers.Different forms of SF materials can be applied in various fields such as food packaging and biomedical materials.Due to the layered structure and fixed diameter of SF fibers,in addition to the application of traditional processing methods,pure SF films prepared by drying from dissolved silk fibroin have low flexibility,poor water resistance,and are easily contaminated by microorganisms,making it difficult to be directly applied to other applications.In this study,a dual-functional coating and packaging film material was prepared for packaging by using cellulose nanocrystals（CNC）as a reinforcing agent,glycerin to improve flexibility and SF composite;and the combination of electro spun silk fibroin film（SF）and ultra-viscous hydrogel（CTFG）,the bilayer composite material（CTFG@S）is applied to the biological field.The specific research content is as follows:（1）Preparation and performance study of SF/CNC composite materials.In order to improve the efficacy of fruit preservation materials,this chapter is prepared by SF/CNC as"tough"unit,glycerin as plasticizer and natural aloe-emodin powder（AE）.Two common fruit preservation materials（edible coating SCA-CS;packaging film SCA-PF）and four different fruits were used for this strategy.The results showed that the SCA-CS material formed an ultra-thin layer with a thickness of 7.7μm on the fruit surface,which was easy to clean,had antibacterial and antioxidant activities,and could prolong the shelf life of bananas and strawberries,respectively.In addition,SCA-CS has good biosafety,and the discharge will not pose a threat to plant health.SF film should have good flexibility（103.5%）,optical properties（91%）,and water vapor barrier properties(17g mm m^-2 day^-1)when used in food packaging.This multifunctional composite material is expected to be applied in the packaging field.（2）Preparation and application exploration of Fe induced super adhesive CNC/SF composite materials.In order to explore the application of composite materials in high-end fields such as smart packaging,this chapter uses waste regenerated silk fibroin film as the base material,prepared by electrospinning technology,and after being treated with 1%glycerin and 75%ethanol,discovered poor flexibility of SF spinning film,not suitable for the field of intelligent packaging.Inspired by natural mussels,we therefore evaluated bilayer composites（CTFG@S）for biological applications.This chapter presents a modification of CNC surface by tannic acid（TA）,exploiting the synergy between metal ions and TA-CNC was used to rapidly prepare hydrogel（6 s）,which did not require tedious preparation processes such as prolonged heating and ultraviolet radiation.The gel has good swelling rate（153.4%）,transparency,antibacterial property,stretchability（CTFG-6,850%）,excellent self-recovery,fatigue resistance and ultraviolet shielding ability（UV spectral transmittance,0.05%）,using the combination of hydrogel adhesion and SF electro spun membrane to prepare a double-layer composite material has good UV barrier properties（UV spectral transmittance,0.05%）,simulated blood A absorption（CTFG-6,0.4 g/g）,Stretchability（CTFG@S-6,800%）.These results demonstrate the high potential of bilayer composites for wound dressing applications.