Preparation Of Magnetic Nanocomposite Particles And Their Applications In Antibacterial Activity And Capturing Staphylococcus Aureus

Bacterial disease,as a type of disease caused by bacterial infection,has become one of the main diseases threatening human public health.The methods of preventing,detecting and diagnosing bacterial diseases have always attracted the attention of researchers,and progresses have been made.In the treatment of bacterial diseases,the most common method at present is to use antibiotics.Although this is usually a rapid and effective solution,due to the long-term and extensive use of antibiotics,the resistance of bacteria has gradually become a problem that can't be ignored,the development of a new type of high-efficiency antibacterial program cannot be delayed.In terms of bacterial detection,current detection methods are mainly divided into bacteriological detection and serological detection.Routine bacteriological testing often requires multiple steps of processing the sample to be tested,which takes a long time and requires high personnel and equipment.In some testing situations,it may even take several days to obtain results.Therefore,it is very necessary to develop a fast and accurate method for detecting bacteria.With the rapid development of nanotechnology in the past ten years,the performance of nanomaterials has also been greatly improved.Among them,magnetic nanomaterials represented by Fe₃O₄have stable properties,high biocompatibility,and excellent electromagnetic properties,which make it an ideal material for separation,imaging and magneto-calorific therapy in life science research In this research,we combined magnetic materials and nanomaterials with other new technologies,And got the following results:?1?A magnetic nano composite antibacterial particle was prepared.With Fe₃O₄nanoparticles as the magnetic core,the surface of which was then coated with a silica layer to improve the dispersion stability and benefit for further functional modification.Finally,the silver nitrate reduction was conducted to modify silver nanoparticles on the surface of the composite particles in situ for sterilization.The results show that when the concentration of the particles is 1 mg/m L and the number of bacteria is 10²CFU,the sterilization efficiency of Escherichia coli,Shigella flexneri and Salmonella can reach 100%.Moreover,the particles have strong magnetic properties and are easy to use,the particles can be quickly separated from the sterilization system after the sterilization operation is completed.Therefore,the nano composite particles can provide a new method for quick and easy sterilization operations in a liquid environment.?2?A magnetic composite particle capable of capturing Staphylococcus aureus efficiently,quickly and specifically was prepared.The surface of Fe₃O₄particles is coated with a polymeric nano-fibers layer for further modification of the nucleic acid aptamer that can specifically bind to Staphylococcus aureus to achieve efficient capture of the target bacteria.This novel nano-fibers structure can enhance the target bacteria capture ability of the magnetic composite particles.Experimental results show that the composite particles can selectively separate Staphylococcus aureus with the interference of other bacteria.When the particle concentration is 500?g/m L,the capture efficiency of Staphylococcus aureus with a viable count of less than 10³CFU can reach 100%.Even increasing the sample volume to 100m L,only 0.5 mg magnetic beads needed to enrich and capture the target bacteria completely.It can be anticipated that by replacing the corresponding affinity aptamers,the composite particles can theoretically capture various types of bacteria efficiently and specifically,and have great potential in the field of rapid screening of specific bacteria.