Study On Preparation And Properties Of Recyclable N-halamine-based Antibacterial Nanocomposites

In recent years,health problems caused by bacteria and other microorganisms frequently appear,arousing people's attention.Study and development of antimicrobial materials which are new,efficient and without secondary pollution have become one of the research hotspots.N-halamine-based antibacterial material is widely used in medical devices,food packaging,water purification system and other fields due to its excellent antibacterial effect,high stability,non-toxic,low-cost,renewable and other characteristics.Magnetic nanoparticles with unique magnetism can achieve separation and recovery of materials.Therefore,it has been widely used in catalysis,biology,medicine and other fields.In this paper,the following two works are mainly carried out based on the antibacterial N-halamine nanocomposite:?1?Preparation and antibacterial properties of Fe₃O₄@SiO₂ nanoparticles modified by quaternarized halamine polymer.In order to prepare an efficient antimicrobial nanocomposite,quaternarized halamine polymer-modified Fe₃O₄@SiO₂ nanoparticles were designed based on the contact oxidation mechanism of N-halamine and the electrostatic affinity of quaternary ammonium salt during the sterilization.Firstly,3-bromopropyl-5,5-dimethylhydantoin was synthesized and grafted on the surface of Fe₃O₄@SiO₂ modified with polyethyleneimine.And then,the Fe₃O₄@SiO₂ nanoparticles modified by quaternarized halamine polymer were obtained after chlorination.The optimum reaction conditions were discussed by adjusting the reaction time and temperature of quaternization.The structure,morphology,dispersion and magnetism of the samples were characterized by ¹H NMR,SEM,TEM,FTIR,XRD,Zeta potential analyzer,TGA and vibration magnetometer.The sample has obvious core-shell structure,relatively uniform particle size and narrow particle size distribution range.The magnetic test showed that the sample was super-paramagnetic and it could be separated quickly by the aid of an external magnetic field.And it can still maintain a high recovery rate after repeated recovery.The antimicrobial performance was studied by the minimal inhibitory concentration?MIC?method.The results of antibacterial tests showed that the antibacterial mechanism of chlorinated samples was synergistic with quaternary ammonium salt and halamine and the antibacterial property was better than the one without chlorination.100%of S.aureus and E.coli were inactivated within 30 min of contact.?2?Preparation and antibacterial properties of Fe₃O₄@SiO₂@TiO₂ nanoparticles modified by halamineTiO₂ has good UV shielding effect.In order to improve the stability of N-halamine under ultraviolet light,TiO₂ nanoparticles were introduced to prepare Fe₃O₄@SiO₂@TiO₂-halamine?F@S@T-Cl?antibacterial nanocomposite.The microtopography,structure and magnetic property of the samples were characterized by SEM,TEM,BET,FTIR,XRD,XPS and VSM.The samples are with obvious core-shell structure and relatively uniform particle size.The thickness of TiO₂ shell was adjusted by changing the amount of tetrabutyl titanate?TBOT?.BET results showed that the sample introduced 0.4 ml TBOT had the maximum specific surface area and uniform mesoporous structure,which greatly improved the contact area between the samples and bacteria.Magnetic tests showed that the magnetic saturation strength of F@S@T-Cl was 22.58emu/g,which was lower than that of Fe₃O₄,but it did not affect the normal magnetic recovery process.The samples could be separated well in solution.F@S@T-Cl showed good antibacterial property agaist staphylococcus aureus and escherichia coli,and the minimum inhibition concentrations were 256 and 512 g/mL,respectively.The residual amount of Cl⁺was observed by changing the time of UV irradiation.It was found that the introduction of TiO₂ could effectively improve the UV stability of N-halamine.After 24hours of UV irradiation,the residual of Cl⁺only decreased 52.78%wich still had antibacterial activity.