Construction And Performance Of Silver Nanoparticles/Polysaccharide Antibacterial Composite Materials

In daily life,bacteria seriously endanger people's health.In order to inhibit the growth of bacteria,antibacterial agents have been widely used.Silver nanoparticles(Ag NPs)are the most widely used in the field of antibacterial materials due to its large specific surface area,unique physical and chemical properties and excellent antibacterial properties.There are many methods for preparing silver nanoparticles.In recent years,more attention has been paid to the preparation of antibacterial composite materials by using polysaccharides as reducing agents and stabilizers to synthesize silver nanoparticles.This paper mainly studied the construction and properties of silver nanoparticles/polysaccharide composite materials.Firstly,soluble soybean polysaccharide(SSPS)was used as a reducing agent and stabilizer to synthesize silver nanoparticles antibacterial composite materials,and to characterize the structure and properties of silver nanoparticles.Based on the growth kinetics of Escherichia coli and Staphylococcus aureus,the antibacterial properties of the soluble soybean polysaccharide stabilized silver nanoparticles suspension were evaluated.Then,it was applied to kraft paper as coating materials.The results of the inhibition zone experiment showed that the kraft paper coated with silver nanoparticles/soybean polysaccharide had strong inhibitory effect on the growth of the above-mentioned various bacteria.This paper also studied the influence of silver nanoparticles/polysaccharide coating barrier properties and micro-morphology of kraft paper.The results showed that silver nanoparticles synthesized from soluble soybean polysaccharides had great application potential in the field of antibacterial materials.Secondly,the soluble soybean polysaccharide-stabilized silver nanoparticles suspension was directly prepared into films by the casting method,and the structure and properties of the composite films were studied.The optical properties of the polysaccharide films were characterized by UV-vis spectrophotometer and colorimeter.The crystal structure of silver nanoparticles and the interaction between polysaccharide and silver nanoparticles were analyzed by XRD and FTIR,respectively.The composite films had good antibacterial properties against both gram-negative and gram-positive bacteria,and could be used in food packaging to extend its shelf life.Thirdly,in order to further improved the performance of the antibacterial films,the composite films were prepared by compounding carrageenan and silver nanoparticles/soybean polysaccharide.The mechanical properties and morphology of films were characterized by texture analyzer and FESEM.FTIR results showed that there were strong interaction between soluble soybean polysaccharide,carrageenan and silver nanoparticles.The addition of carrageenan improved the water resistance and water vapor barrier properties of the composite films.The antibacterial experiment results showed that the silver nanoparticles/carrageenan/soybean polysaccharide composite films had excellent antibacterial properties.The experimental results of packaging applications showed that the composite films helped to extend the shelf life of food.Finally,in order to control the release rate of silver nanoparticles to achieve longterm antibacterial effect,antibacterial composite materials based on microfibrillated cellulose were constructed.A layer of polydopamine was modified on the surface of microfibrillated cellulose,and silver nanoparticles was grown and fixed in situ by using the reducing and cohesive properties of polydopamine.The structure and properties of silver nanoparticles/microfibrillated cellulose nanomaterials were characterized.The results showed that silver nanoparticles with a face-centered cubic crystal plane structure were randomly fixed on the surface of the microfibrillated cellulose and had excellent storage stability.The results of atomic absorption spectroscopy showed that the silver ion release rate of this composite materials were very slow,and it has excellent long-term antibacterial properties.This part also studied the application of silver nanoparticles/microfibrillated cellulose as coating and filling materials.The test results showed that the silver nanoparticles/microfibrillated cellulose coating and filling respectively endowed kraft papers and carrageenan films with great antibacterial properties.