Preparation Of Silver Loaded Antibacterial Fibers And Particle Size Control Research Of Nano-silver

With the improvement of medical and health care level in our country,the demand for antibacterial materials is increasing.In this study,environmental friendly cellulosic materials were used as raw materials,and silver nanoparticles loaded cellulosic fiber composite antibacterial materials were successfully obtained.Specifically,with softwood fibers as raw materials,dialdehyde cellulosic fibers were firstly prepared.Secondly,silver nanoparticles were in situ reduced on surface of the dialdehyde cellulosic fibers with silver nitrate as silver precursor and without outer joined reductant.Finally,the shape and size control of silver nanoparticles on cellulosic fibers were studied by the method of adding separate sodium citrate or adding both sodium citrate and ethanol.The results of dialdehyde cellulosic fibers preparation showed that aldehyde group content of softwood fibers was increased gradually as the time extension of sodium periodate oxidation,and the increase of aldehyde group content was larger in the early reaction stage.The inner structure of cellulose molecules was becoming more and more loose,and gradually turning into amorphism.After sodium periodate oxidation,the surface of fibers became more smooth,and there was obvious vertical stripes or crack on surface of softwood fibers with prolonged oxidation time.Silver nanoparticles loaded dialdehyde cellulosic fibers were prepared with dialdehyde cellulosic fibers and silver nitrate without outer joined reducing agent.Results illustrated that the characteristic absorption peaks of silver nanoparticles at 428 nm were appeared in silver nanoparticles loaded dialdehyde cellulosic fibers.With reaction time extended,the yellow coloured light of fibers deepened.Silver nanoparticles distributed uniformly on surface of fibers without obvious phenomenon of flocculation.The average size of silver nanoparticles produced by 2.5 h of reaction was about 50 nm.After reducing silver ions into silver nanoparticles,the aldehyde group on dialdehyde cellulosic fibers was oxidized into carboxyl.Silver nanoparticles loaded dialdehyde cellulosic fibers exhibited good antibacterial ability on both escherichia coli and staphylococcus aureus,and possessed broad-spectrum antibacterial properties.The results of shape research of silver nanoparticles on fibers indicated that smaller spherical silver nanoparticles were mainly formed on the surface of dialdehyde cellulosic fibers before 20 h.Between 20 h and 60 h,the spherical silver nanoparticles were gradually grown and transformed into triangular prism induced by citrate,and finally triangular prism silver nanoparticles were in situ formed on the surface of fibers.When the reaction time was more than 20 h,characteristic diffraction peaks of cellulose I and silver nanoparticles with face-centered cubic structure were observed in XRD spectra of samples.From 30 h to 60 h,the size of silver nanoparticles increased from 10.67 nm to 12.20 nm.The antibacterial properties of silver nanoparticles were not significantly affected in the process of inducing spherical silver nanoparticles into triangular prism shape.Silver nanoparticles loaded dialdehyde cellulosic fibers still exhibited good antibacterial ability on both escherichia coli and staphylococcus aureus.The results of particle size research of silver nanoparticles on fibers indicated that the particle size of silver nanoparticles was affected by the reaction temperature and time.The higher the temperature and the longer the time,the larger the average grain size of silver nanoparticles.After adding the second end capping agent-ethanol,the average grain size of silver nanoparticles was smaller than that of without ethanol under the same conditions.Thus ethanol,as a second end capping agent,can be used to stabilize the size distribution of silver nanoparticles.