Preparation And Antibacterial Properties Of Cellulose-based Composites

Cellulose,as the most abundant natural polymer in nature,has the advantages of non-toxic and pollution-free,good biocompatibility and biodegradability.Antibacterial cellulose materials are widely used in food packaging,water treatment and medical materials.Among them,the unique three-dimensional network structure of bacterial cellulose,which is formed by nanofibers,has a natural advantage in the preparation of cellulose-based antibacterial materials.In recent years,more and more researches have been made on the bacterial cellulose,especially when applied to medical dressings.Natural flexibility,super hydroscopicity allows it to engulf the wound exudate and is naturally isolated from the wound surface.In the past,cellulose antibacterial materials often have the high cost of antibacterial agents,poor biocompatibility,not suitable for mass production and other shortcomings.In order to further promote the industrialization process of antibacterial cellulose materials and expand its application in the medical field,this paper prepared a series of antibacterial cellulose composite materials based on cellulose and the specific work is as follows:(1)Preparation,characterization and antibacterial activity of nano-ZnO/cellulose composite fibers.Using wood pulp cellulose as matrix,nanolamellar ZnO via a new preparation method as antibacterial agent,ionic liquid 1-allyl-3-methylimidazolium chloride(AMIMCl)as cellulose solvent,the nanosized zinc oxide/wood pulp cellulose(ZnO/Ce)composite fibers were prepared via solution blending method.The structure,crystal form and antibacterial property of nanosized layered ZnO were analyzed.The rheological properties of composite solution and the morphology,crystal form,thermal stability,mechanical properties and antibacterial properties of composite fibers were studied.The results showed that the surfactant template method can produce long-range ordered nanolayered ZnO with a repetition period of 3.71 nm and showed excellent antibacterial activity against Staphylococcus aureus.The viscosity of cellulose solution increased with the addition of nano-layered ZnO.The nano-particles could be suspended stably in the ionic liquid system.Composite fiber showed good antibacterial activity to Staphylococcus aureus.In addition,using bacterial cellulose(BC)as matrix and nano-ZnO as antibacterial agent,ZnO/BC nanofiber composite membrane was prepared by controlled hydrolysis of zinc(II)-amine complex.The effects of experimental conditions such as reaction solution concentration and amine species on the number,size and morphology of zinc oxide crystals were studied.The morphology,structure,mechanical and antibacterial properties of ZnO/BC nanofiber composite films were analyzed.The results showed that triethanolamine was the best feedstock and the optimal reaction conditions were 25 mmol/L of the reaction solution.The ZnO/BC nanocomposites had good antibacterial activity against Staphylococcus aureus and Escherichia coli,and when the ZnO loading was 9.36 wt%,the antibacterial activity of the complex to’ Escherichia coli and Staphylococcus aureus were 96.52%and 98.57%,respectively.(2)Preparation,characterization and antibacterial activity of chitosan/cellulose antibacterial composite membranes.With chitosan as antibacterial agent,the complex ionic liquid system glycine hydrochloride/1-allyl-3-methylimidazolium chloride salt as cosolvent,chitosan/cellulose(CS/Ce)composite membrane was prepared by solution casting method.The morphology,crystal form,thermal stability,mechanical and antibacterial properties of the composite films were studied.The results showed that chitosan and cellulose were compatible in the composite ionic liquid system.The antibacterial property of the composite membrane to Escherichia coli was good at pH 6.3.At the same time,chitosan was used as antibacterial agent to impregnate to the oxidized bacterial cellulose(OBC)in the chitosan solution and then obtain the chitosan/oxidized bacterial cellulose(CS/OBC)composite membrane by ionic crosslinking.The effects of reaction conditions on the oxidation results,the morphology,structure,mechanical properties and antibacterial properties of the composite membrane were studied.The results showed that carbonate buffer solution instead of the general dropping NaOH method,with the oxidant concentration of 10 mmol/g can be effectively prepared with a high carboxyl content of OBC.The carboxyl group of OBC and the amino group of chitosan undergo a cross-linking reaction and the crystallinity and thermal stability of the composite membrane increased.The antibacterial results showed that when the content of chitosan reached above 6.6%,the antibacterial rate of the composite membrane to Escherichia coli and Staphylococcus aureus reached more than 90%.(3)Preparation,characterization and biocompatibility of bacterial cellulose matrix composites.By comparing the antibacterial properties of antibacterial materials with different type of cellulose,the results showed that the antibacterial properties of the composite were superior when bacterial cellulose was used as matrix.In order to further study the biocompatibility of cellulose materials,using bacterial cellulose as substrate,beaver rat tail collagen and nano-hydroxyapatite with nano-grooves on the surface as complexing agent to prepare collagen/oxidized bacterial cellulose(CO/OBC)and nano-hydroxyapatite/bacterial cellulose(HA/BC)composites.Their structures and morphologies were characterized.Using L929 and osteoblast MC3T3-E1 studied the biocompatibility of the two composites.The results showed that L929 cells cultured on the surface of the material,CO/OBC composite sponge showed more conducive to cell proliferation than pure BC.By CCK-8 colorimetric assay,HA/BC composites had no potential cytotoxicity and had good biocompatibility to osteoblasts MC3T3-E1.