| Cellulose,one of the most abundant polysaccharides and renewable resources on the earth,is biodegradable,biocompatible,and non-toxic in nature.The electron-rich feature of its surface hydroxyls provides cellulose with good colloidal stability in aqueous solution.On the other side,literature documents that cellulose nanocrystals exhibit reductive capability,which may be exploited for the fabrication of metal particles.Biomass-based antibacterial materials have been developed in recent years,but there are many problems,such as low efficiency caused by washability;high cost of the preparation process;narrow antibacterial spectrum and low security and stability,which could greatly limit their industrial applications.In this paper,cellulose is used as the matrix,and silver,silver chloride,Fe3O4 and other inorganic materials are used as the reinforcing materials.Various methods of hydrothermal,microwave-assisted,ultrasonic-assisted,and microwave hydrothermal-assisted methods are used to prepare a series of silver-filled cellulose composites.The inorganic particles showed uniform dispersion in the cellulose matrix.The physicochemical properties of the as-prepared cellulose-based composites were characterized,and the cytocompatibility and antibacterial properties of the materials were also investigated.The obtained data has important research significance and provides a theoretical basis for guiding the synthesis of bio-based antimicrobial materials with broad spectrum antibacterial properties,as well as high stability,and effectively reduces the cost of preparation!The results were summarized as follows:(1)Ag@microcrystalline cellulose and AgCl@microcrystalline cellulose composites were prepared by ultrasonic-assisted method using microcrystalline cellulose as matrix,NaOH/urea solution as solvent system,silver nitrate as silver source,aluminum chloride hexahydrate as chlorine source.Based on the chemical and physical effects of high-intensity ultrasonic waves,composite material in which Ag@AgCl nanoparticles are uniformly dispersed in the cellulose matrix was obtained.Since no other reducing agents were added to the experimental system,the cellulose solution treated with sodium hydroxide and urea showed significant reduction performance,it can reduce the silver ions to pure silver,and the as-prepared composite materials exhibited good stability and antimicrobial activity.(2)Ag@cellulose composite material was successfully prepared with microwave-assisted heating method using microcrystalline cellulose as a matrix,NaOH/urea solution as a solvent system for cellulose,ethylene glycol as a solvent,a microwave absorber and a reducing agent,silver nitrate as a silver source,and aluminum chloride hexahydrate as a chloride source.The experimental results show that the microcrystalline cellulose solution has a significant effect on the morphology and phase of the silver crystals dispersed in the cellulose matrix.During the reaction,the higher the concentration of the microcrystalline cellulose solution is,the stronger the reducibility will be,and it will be more favorable for the formation of silver crystals.The Ag@cellulose composite materials obtained in the experiments have good antibacterial properties against Escherichia coli(gram-negative bacteria)and Staphylococcus aureus(gram-positive bacteria).These composite materials are expected to become a promising antibacterial candidate material in the functional food packaging field.(3)Ag@cellulose composite material was synthesized by the hydrothermal method using microcrystalline cellulose as matrix.NaOH/urea solution was used as the solvent system of cellulose,silver nitrate was used as the silver source,and aluminum chloride hexahydrate was used as the chloride source.Compared with other methods,the hydrothermal synthesis method has the advantages of mild reaction conditions,enhanced reaction activity,energy saving,and the prepared product has high crystallinity,high purity,narrow size distribution,and good dispersion.During the preparation of silver,the microcrystalline cellulose solution showed a strong reduction performance.The silver crystal particles are uniformly dispersed in the cellulose matrix,and the resulting composite material has good thermal stability and excellent antibacterial properties.(4)AgX(X=Cl,Br)@cellulose composites were synthesized with the microwave-assisted method in ionic liquids using microcrystalline cellulose as matrix,ionic liquids(BmimCl;AmimCl;BmimBr)as a solvent system for cellulose,and silver nitrate as a silver source.Ionic liquids can act as solvents,microwave absorbers,and reactants at the same time,which also provide X elements for the synthesis of AgX crystals.AgCl@cellulose composites have a high percentage of AgCI crystals and relatively low thermal stability;at the same time,AgBr@cellulosic composites have a low percentage of AgBr crystals and relatively high thermal stability.The reducing agent plays an important role in the phase,shape and dispersion of AgX(X=Cl,Br)@cellulose composites.(5)Ag@AgCl@cellulose composites were synthesized by ultrasonic assisted method using microcrystalline cellulose as the matrix,LiCl/DMAc solution as the solvent of cellulose,silver nitrate as the silver source,and EG as the reducing agent.Ultrasonic time and EG volume play an important role in the morphologies of composites.By adding CTAB and SDBS into the reaction system,good dispersion of AgCl/AgBr(Ag)crystals in the cellulose matrix were achieved.The as-prepared Ag@AgCl@cellulose composite has good antibacterial properties towards Escherichia coli and Staphylococcus aureus.(6)AgCl@cellulose composites were successfully prepared in ZnCl2 solution by oil bath heating using microcrystalline cellulose as the substrate and silver nitrate as the silver source.The high concentration of ZnCl2 solution is beneficial to the increase of the AgCI crystals,and it is also beneficial to improve the thermal stability of the composite material.Antimicrobial experiment results showed that the as-synthesized silver chloride@cellulose composite material prepared by this method has excellent antibacterial effects towards Escherichia coli and Staphylococcus aureus.(7)The Ag@Fe3O4@CNC nanocomposites were successfully synthesized by the microwave hydrothermal method.The CNC showed good reduction ability and played an important role in the synthesis of silver particles.The longer the reaction time is,the more favorable it is to synthesize more and larger Ag@Fe3O4 particles.The resulting Ag@Fe3O4@CNC nanocomposites have a narrow average particle size ranging from 275±15 nm to 287±13 nm.Compared with the microwave assisted method(11.31 emu g-1)and hydrothermal method(8.95 emu g-1),the Ag@Fe3O4@CNC nanocomposites prepared by the microwave hydrothermal-assisted method have higher saturation magnetization(12.34 emu g-1).Good superparamagnetic and ferromagnetic behaviors enhance their ability to degrade dyes and increase their potential for use in waste water treatment.It also exhibits excellent antimicrobial activity against Escherichia coli and Staphylococcus aureus. |
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