Preparation And Light-Driven Antibacterial Performance Of Cellulose Fiber Materials

Pathogens including bacteria are usually the main cause of infectious diseases.Therefore,looking for novel non-specific microbial inactivation methods is one of the research hotspots in recent years.Light-driven antibacterial method could effectively inactivate bacteria,it includes antibacterial photodynamic inactivation（aPDI）and antibacterial photothermal inactivation（aPTI）.These methods reduced the using dose of conventional antibiotics and the frequency of drug-resistant bacteria.However,there are still some problems such as easy agglomeration of unimmobilized photoantimicrobial agents（Photosensitizer,PS;Photothermal Agent,PTA）,low inactivation efficiency,short functioning time and high thermal temperature.Based on the above backaground and problems,in situ growth method,Fluorescence Resonance Energy Transfer（FRET）strategy,synergistic antibacterial effect and long-lasting ion antibacterial property were used to carried out this research,one or more photoantimicrobial agents were decorated on the cellulose fiber material surface to deal with the invasion of pathoges including bacteria to humans.The main contents and conclusions of this dissertation are demonstrated:（1）Firstly,to solve the easy agglomeration problem of unimmobilized PS,pristine cotton fabric（CF）was used as the substrate in the second chapter,then Zr-based porphyrin MOF material,PCN-224 nanoparticles were fixed on the cotton fiber surface by using Tetrakis（4-carboxyphenyl）porphyrin（TCPP）,Zirconium oxychloride octahydrate（Zr OCl₂·8H₂O）and benzoic acid（BA）,achieving a cotton fabric with aPDI effect（CF@PCN-224）.The results of SEM,EDS,FT-IR,XRD and spectrum tests showed that PCN-224 nanoparticles were successfully decorated on the surface of cotton fiber.The antibacterial test results indicated that CF@PCN-224 processed broad spectrum antibacterial activity.But after two washes,the inactivation of CF@PCN-224 to E.coli decreased to 67.556%.The mechanism study presented that the type of reactive oxygen speices（ROS）that played the role of bacterial inactivation was¹O₂.In addition,CF@PCN-224 had a low cytotoxicity and could be safely used in daily life.（2）To further improve the bacterial inactivation efficiency,FRET strategy was utilized in the third chapter.Firstly,the amino group was introduced onto the surface of cotton fibers and then graphene quantum dots（GQDs）were grafted onto the surface of cotton fiber by amide bond.Finally,PCN-224 nanoparticles were further decorated by in situ growth method.The cotton fabric（CF-GQDs@PCN-224）with enhanced aPDI effect was successfully prepared.The results of SEM,EDS,FT-IR and XRD showed that cotton fiber was successfully aminated,GQDs were grafted and PCN-224 nanoparticles were decorated.The antibacterial test results showed that the aPDI efficiency was increased by 4.38 log unit（E.coli）and 4.25 log unit（S.aureus）,respectively,from the cotton fabric with FRET structure,because FRET structure enhanced the ¹O₂ production capacity of the material.Cytotoxicity test results showed that the material still had good biocompatibility.（3）In order to achieve highly efficient inactivation and long-lasting bacteriostasis effects,on the basis of CF@PCN-224,Ag NPs were further modified by in situ growth method in the fourth chapter.Multi-mode synergistic antibacterial cotton fabric with aPDI,aPTI and Ag⁺release effect was successfully prepared（CF@PCN-224-Ag）.The results of SEM,EDS,FT-IR and XRD showed that PCN-224 and Ag NPs were successfully decorated on the surface of cotton fiber.The antibacterial test results showed that CF@PCN-224-Ag exhibited stronger antibacterial activity compared with the samples modified with single kind of nanoparticle（PCN-224 or Ag）.And the Ag⁺releasing effect achieved long-lasting bacteriostasis property.The mechanism study showed that the ¹O₂ production capacity of the samples was affected by the Ag content,the ¹O₂ production initially increased and then decreased with Ag amount increasing.The reason is that local electric field effect happened between the small amount of Ag and PCN-224,promoting the generation of ¹O₂,but excessive Ag may cover the surface of PCN-224,reducing its ability to absorb light.Moreover,the introduction of Ag NPs endowed the fabric with photothermal heat and Ag⁺releasing properties.The photothermal study showed that CF@PCN-224-Ag₇ could reach to 67.6℃in 130 s.In addition,it could be seen from the ICP-MS test results that the presence of PCN-224 could accelerate Ag⁺releasing,the reason is that the oxidation property of ¹O₂ facilitated the conversion of Ag NPs into Ag ions.（4）In order to achieve multi-mode synergistic antibacterial nanofibrous materials,in the fifth chapter,bacterial cellulose（BC）nanofiber membrane was used as the substrate to achieve a cellulose nanofiber membrane with multi-mode synergistic antibacterial effects.Firstly,PCN-224 nanoparticles were decorated on the Ti₃C₂ MXene nanosheet surface by in situ growth method,and then the composites were immobilized on the surface of BC by vacuum filtration method.Finally,Ag was further deposited by magnetron sputtering.The multi-mode synergistic antibacterial cellulose nanofiber membrane（Ag-Ti₃C₂@PCN-224-BC）with aPDI,aPTI and Ag⁺releasing effect was successfully prepared.The results of SEM,TEM,EDS and XRD showed that PCN-224 nanoparticles were successfully decorated on the Ti₃C₂ MXene surface and they were successfully fixed on BC substrate surface,Ag was also successfully covered on the surface by magnetron sputtering.The antibacterial test results showed that the bacteria cells were effectively inactivated under the“three in one”effect of aPDI,aPTI and Ag⁺release.And long-lasting bacteriostasis effect was reached.The mechanism study showed that the introduce of Ti₃C₂ MXene and Ag had little effect on the ¹O₂ generation.The photothermal study showed that the surface temperature of Ag-Ti₃C₂@PCN-224-BC could reach to 48.8℃（17.6℃temperature rise）in 300 s.The results of ICP-MS showed that the ¹O₂ and photothermal heat generated by PCN-224 and Ti₃C₂ MXene would accelerate Ag⁺releasing.The cytotoxicity test results showed that Ag-Ti₃C₂@PCN-224-BC had desirable biocompatibility.（5）In order to solve the problem of excessive photothermal temperature,the sixth chapter of the study was to modify CF with PCN-224,Ti₃C₂ MXene and thermochromic dye with reversible property by in situ growth,electrostatic spraying and manual screen printing.A stimuli-responsive antibacterial CF（S-CF@PCN-224x）was successfully prepared.The results of SEM,XRD and EDS showed that the above three kinds of materials were successfully decorated on the surface of CF.The antibacterial test results showed that the material decorated with PCN-224 and Ti₃C₂ MXene showed stronger bacterial inactivation activity compared with the samples modified by single antibacterial material（PCN-224 or Ti₃C₂ MXene）.The mechanism study showed that the type of ROS is ¹O₂.With the increase of Ti₃C₂ MXene content,the production capacity of ¹O₂ was also increased.The reason may be that Ti₃C₂ MXene processed photodynamic effect which is similar to GQDs（or black phosphorus）or its Localized Surface Plasmon Resonance effect（LSPR）.The results of photothermal experiments showed that Ti₃C₂ MXene endowed CFs with photothermal effect and good photothermal cycling stability was achieved.The surface temperature of S-CF@PCN-224_0.4 could reach to 49.4℃after visible light illumination in 182 s.In addition,when the temperature rised to about 45℃,the color of the fabric would change to the naked eye,which could monitor the photothermal temperature and avoid the adverse effects.