Application Of Magnetic Nanoparticles In Molecular Biology And Its Cell Toxicity

Magnetic nanoparticles has many particular characterizations,such as volume effect,surface effect,quanta size effect,macroscopical quanta tunnel effect and so on.As a new functional material, magnetic particles have developed quickly in recent years.Magnetic nanoparticles containing another shell have attracted much interest from material science.The shell structure can improve the physical and chemical properties and have many applications because the shell can overcome the magnetic nanoparticles’ problems of lack of functional groups and tendency of agglomeration.It’s applications in molecular biology lead to a new idea for bioseparation and detection.The characteristics,types,and main synthesis methods of magnetic nanoparticles were described in this paper,and its application in nucleic acid separation,cell separation,protein purification,virus detection,drug targeted therapy were explained.In the present work,the preparation,characterization,application of magnetic nanoparticles in molecular biology and its cell toxicity were studied.The supurparamagnetic iron oxide nanoparticles were prepared by co-precipitation method. Then the magnetic nanoparticles were coated with silica on the surface by sol-gel method and alkali catalyzing hydrolysis of TEOS.Some physics and chemical characterizations of synthesized particles were further determined,the appearance and size distribution analysis by TEM,the crystal structure analysis by X-ray diffraction,paramagnetism data collected by vibrating sample magnetometer,chemical composition analysis by FT-IR spectrum.The results showed the particles were global and with good dispersity,Fe₃O₄ Magnetic nanoparticles’ diameter is 10nm,the silica-coated magnetic nanoparticles with average particle size of 20 nm,the saturation magnetization is 11.67emu/g.This work developed a simple and reliable method for the rapid isolation of plasmid DNA from crude cell lysates with the silica-coated magnetic nanoparticles.Plasmid DNA could be bind to the silica surface in the presence of special agents easily.The magnetic particles coated with silica respond very strongly and rapidly to a magnetic field,this response made the separation to become very simple.The effect of concentration and pH of buffer,temperature,time of elution,and amount of particles on recovery and purity of eluted plasmid DNA were investigated.The results indicated that at room temperature,13μg of high pure plasmid DNA could be harvested from 1.5mL of over night culture under concentration of Gu·HCl 4mol/L,solution C pH 4.The protocol is not involving the conventional centrifugation procedure or the use of hazardous agents,and starting from the preparation of bacterial lysate and ending with purified plasmids takes less than 20min.Magnetic separation technology offers benefits over traditional phenol/chloroform method and column-based purifications.Plasmid DNA purified using silica-coated magnetic nanoparticles performed successfully in downstream applications including restriction enzyme digestion,transformation and sequencing, which indicating that the isolated plasmid DNA retains excellent biological activity,the DNA purification method based on silica-coated magnetic nanoparticles was reliable.We detected the effects of magnetic nanoparticles and silica-coated nanoparticles on the growth of A549 cells by SRB method,and plasmid DNA pGEX-4T-EGFP purified by silica-coated magnetic nanoparticles was transformed into E.coli DH5αbacterial cells,the overnight cell culture expressed strong fluorescence.The results showed the magnetic nanoparticles have no cell toxicity, and the biological activities of plasmid DNA were retained after purified by silica-coated magnetic particles.