The Preparation And Photo-induced Antibacterial Properties Of The Heterostructure Of Conjugated Polymer

At present,water pollution has become a major concern worldwide.Among various pollutants,AZO dyes have already lead high chroma to water and destroyed aquatic ecosystem,while pathogenic microorganisms in water（such as E.coli,Staphylococcus aureus and Salmonella）have caused millions of death in the past few decades.Photocatalysts,as a potential materials for the treatment of dyes and bacteria in wastewater,has been widely studied.Inorganic catalysts are the most widely used catalysts.However,there are still some disadvantages in the application of inorganic photocatalysts,such as the narrow absorption spectrum and the easy recombination of electron-hole pairs.In recent years,visible-light-responsive photocatalyst has gradually become a research hotspot.One of the potential materials is organic material,which have many unique properties,such as flexible preparation,low cost,visible-lightresponse,wide light absorption band and high absorption coefficient.Currently,the application of photocatalyst in biological field has also gradually increased.In this paper,Fe³⁺-doped PTCDI-PANI heterostructure was prepared with polyaniline（PANI）and perylenediimide（PTCDI）,and it was used for the subsequent degradation of dyes and antibacterial experiments.In addition,preliminary researches were done on the potential application of polypyrrole composite material UCNPs@MSNs-Fe₃O₄@PPy,which is a multi-functional materials and will be employed in the subsequent research work of photodynamic and photo-thermal therapy in our group.The specific content is as follows:（1）Polyaniline was prepared by free radical polymerization,followed by the doping of Fe3+,and PTCDI-PANI（Fe（Ⅲ））heterostructure was prepared by improved amidation reaction.The morphology,chemical structure,and photoelectricity of the prepared materials were systematically characterized,and the results showed that the PTCDI-PANI（Fe（Ⅲ））was well synthesized.Under the irradiation of visible light,the photocatalytic degradation of methyl blue and free radical trapping experiments were carried out with PANI,PTCDI,PTCDI-PANI,PTCDI-PANI（Fe（Ⅲ））.The results showed that PTCDI-PANI（Fe（Ⅲ））had the best photocatalytic activity,and the grafting of polyaniline could significantly promote the generation of hydroxyl radicals.Then under the irradiation of visible light,the sterilization experiments of E.coli and Staphylococcus aureus were carried out by PTCDI,polyaniline,and PTCDI-PANI（Fe（Ⅲ））,respectively.The results showed that bactericidal effect of PTCDI-PANI（Fe（Ⅲ））against E.coli and S.aureus was the best.When the concentration of PTCDIPANI（Fe（Ⅲ））was 128 μg/m L,the bactericidal rates of PTCDI-PANI（Fe（Ⅲ））against E.coli and S.aureus were 95.8% and 99.3% respectively.PANI（Fe（Ⅲ））grafting can enhance the photobacterial antibacterial properties of PTCDI,mainly due to:（a）Polyaniline has a narrow band gap and a strong absorption of visible light;（b）The higher conduction band position of PANI（-2.1 e V）promotes the reaction of O₂+e^-→·OH;（c）The amide bond between PTCDI and PANI enhances the separation efficiency of photogenerated electron-hole pairs;（d）Compared with PTCDI,the surface of PTCDI-PANI（Fe（Ⅲ））is relatively rougher and the specific surface area is larger,which improves the adhesion of bacterium;（e）Doped iron ions act as conductive tunnels and promote charge transfer between polyaniline and PTCDI.Finally,the mechanism of antibacterial was discussed.Through the observation of the morphology of bacteria in the transmission electron microscope and the measurement of the concentration of potassium ions in the culture medium,it was considered that the antibacterial mechanism of the material is killing mechanisms that photocatalysis causes cell wall destruction.（2）Composite nanoparticles of UCNPs@MSNs-Fe₃O₄@PPy were prepared successfully.Their morphology,composition,structure and magnetic properties were characterized.It was initially confirmed that the composite material of UCNPs@MSNs-Fe₃O₄@PPy was successfully synthesized.The performance meets the requirements of the following experiments.