Preparation Of Silver Nanoparticles Based On Bamboo Hemicelluloses And Evaluating Their Antibacterial Activity

In recent decades,large quanties of antibiotics used in many fields have led to more and more bacteria developing resistance to antibiotics.Therefore,new antibacterial agent which shows excellent and wide-spectrum antibacterial activity has become one of the hot research topics in food industry,medicine,etc.Compared with the triditional antibacterial agents,such as antibiotics,silver nanoparticles exhibit highly efficient antibacterial activity and wide-spectrum antibacterial activity.Meanwhile,almost all bacterials can not develop resistence to silver nanoparticles.Thus,silver nanoparticles used as antibacterial agent would have great potential in the future.Contrasting with the traditional preparation methods of silver nanoparticles,biosynthesis of silver nanoparticles has attracted much attention because of high security,high economic,and envitromentally friendly.In the present study,silver nanoparticles were prepared using the polysaccharides of bamboo hemicelluloses with low molecular weight of 3748 g/mol as stabilizing agent,and glucose as reducing agent.The storage stability and antibacterial activity of the synthesized nanoparticles using bamboo hemicelluloses had been evaluated.The conclusions obtained would provide a meaningful support and theoritical base for the further utilization of the silver nanoparticles based on bamboo hemicelluloses in food package,medicine,etc.The results showed that bamboo hemicellulose polysaccharides presented excellent function of stabilizing agent,and silver nanoparticles with particle size smaller than 10 nm were obtained.The reduction rate of Ag⁺to Ag⁰was not high.The stabilizing function of hemicelluloses to silver nanoparticles increased with the increase of hemicellulose dosage.The surface of silver nanoparticles presented electronegativity according to the Zeta-potential analysis results.The formation rate of silver nanoparticles could be accelerated when hemicelluloses and AgNO₃with high concentration were used to synthesize the silver nanoparticles at high temperature.A large quantity of silver nanocrystallines with silver atoms less than seven were also found in the prepared samples of silver nanoparticles,However,the number of the silver nanocrystallines decreased during the storage at 4?.The particle sizes of silver nanoparticles synthesized under different reaction conditions increased during storage process at 4?,resulting in the absorbance of the surface plasma resonance of silver nanoparticles to increase with the increase of storage time.There was a linear relationship between the absorbance strength of the surface plasma resonance of silver nanoparticles and the storage time.The silver nanoparticles would be more stable at 4? when high hemicellulose concentration,low reaction temperature and long reaction time were adopted to prepare the silver nanoparticles.The silver nanoparticles exhibited weaker stability at 25? when low concentration of AgNO₃was used.Generally,the prepared silver nanoparticles synthesized using bamboo hemicelluloses with small molecular weight of 3748 g/mol as stabilizer showed good storage stability.The silver nanoparticles,which were prepared under different reaction conditions including AgNO₃concentration,hemicelluloses dosage,and glucose concentration,performed strong antibacterial activity against Bacillus subtilis?G-positive?and Pseudomonas aeruginosa?G-negative?.The antibacterial activity of the silver nanoparticles was greatly affected by the dosage of the silver nanoparticles and the inhibition time.With the increase of the dosage of silver nanoparticles and the inhibition time,more bacteria were killed.On the other hand,there was no obvious relationship between antibacterial activity of silver nanoparticles and the hemicellulose concentration adopted to prepare the silver nanoparticles.Silver nanoparticles caused the damage of cell membrane of bacteria.After 12 h of treatment,all the cell membrane of bacteria was damaged.Furthermore,silver nanoparticles induced the formation of active oxygen species?ROS?during bacteria inactivation process,and the amount of ROS was affected by the addition amount of the silver nanoparticles.More ROS would be released when the dosage of the silver nanoparticles increased.B.subtilis and P.aeruginosa would grow well again if the free radical scavenging agent of histidine and silver nanoparticles were simultaneously added into the nutrient soltion of bacteria.ROS was possibly one of the key factors causing the death of bacteria.P.aeruginosa?G-negative?was more sensitive to the silver nanoparticles synthesized using bamboo hemicelluloses than B.subtilis?G-positive?.