The Study On The Interactions Of Functionalized Magnetic Nanoparticles With Bacteria

In recent years,with the development of nanotechnology,nano-materials developed rapidly in the field of science and technology.In all nanomaterials,the magnetic materials combined with nano-technology to form magnetic nano-materials,has been widely concerned and applied,of which the performance of Fe₃O₄ magnetic nanoparticles is particularly prominent.Compared with traditional materials,magnetic iron oxides,especially magnetic nanoparticles?MNPs?possess unique physical,chemical and biological properties.These properties make MNPs a promising material in developing medical and diagnostic applications as well as solving environmental problems.Almost all these applications are based on direct interactions between MNPs and molecules or biological systems.Therefore,a detailed understanding of the interaction between magnetic nanoparticles and biological systems contributes to the better use of magnetic nanomaterials.The bacteria as a class of simple and common biological cells in biological system,is very important in human's production and living.It is very meaningful to study the interaction between functionalized magnetic nanoparticles and bacteria.The aim of this paper is to develop a kind of suitable functionalized magnetic nanoparticle and to explore the mechanism of its interaction with bacteria.This study lays a theoretical foundation for the subsequent application of magnetic nanoparticles.The main research contents are as follows:?1?So far there are many researches on the preparation of functional magnetic nano-materials.The magnetic core is prepared and then modify in the two-step modification method.However,the coating or synthesizing procedures as complicated with large amounts of waste of the reagents.In this paper,we applied a simple and efficient one-step modified oxidative hydrolysis method to prepare polyethyleneimine functionalized Fe₃O₄ MNPs by using FeSO_4?7H₂O as the sole Fe soure.The morphology and properties of Fe3O4@PEI MNPs were characterized by scanning electron microscope?SEM?,Fourier transform infrared?FT-IR?,X-ray powderdiffraction?XRPD?,vibratingsamplemagnetometry?VSM?,thermogravimetric analysis?TGA?,and zeta-potential measurement.The results show that Fe3O4@PEI MNPs is successfully prepared,and the particle size distribution is about 56.1±0.6 nm.The crystal form is a face-centered cubic spinel structure with high saturation magnetization of 75emu/g,coercivity and remanence of 150 Oe and10 emu/g,respectively.As prepared MNPs have positive surface charge in a broad range of pH from 3 to 10.?2?The interaction between Fe₃O₄@PEI MNPs and Gram-negative bacteria/Gram-positive bacteria was studied.The prepared Fe3O4@PEI MNPs were mixed with bacteria and they can be removed by external magnetic force after interaction.The results showed that the nanoparticles can adsorb and capture the bacteria,and the Fe3O4@PEI MNPs were investigated by field emission scanning electron microscopy,UV spectrophotometer and thermogravimetric analysis.The mechanism of the interaction between the magnetic nanoparticles and the bacteria was also studied by treating bacteria cells with ethanol and trypsin.It is found that Fe₃O₄@PEI MNPs can capture the bacteria with high concentration quickly and efficiently.The interaction between Fe3O4@PEI MNPs and bacteria is mainly electrostatic adsorption.Negatively charged groups of molecules such as LPS,proteins,peptidoglycan may play important roles in the interaction between Fe₃O₄@PEI MNPs and bacterial cells.