Study On The Preparation,Properties And Biological Applications Ofmagnetic Nanoparticles(MNPs) With Different Size

Fe₃O₄ magnetic nanoparticles?MNPs?have beenwildly applied to various biological fields owning to their excellent properties.Different experiment conditions result in MNPs with different size,MNPs with different size show different properties,so understanding that what is the effect of different experiment conditions on the size of MNPs is meaningful.This paper prepared MNPs with different size through different experiment conditions,tested related performances,get the relationship between experiment conditions with properties of MNPs.At last,some experiment of surface modification and biological detection were done.?1?By thermal decomposition method,we prepared 4,10,20,30,60,and 80nm MNPs through changing different experiment conditions.The results show that,increasing the reaction time from 30 min to 2 h,the size of MNPs changed from 20nm to 30 nm,PDI changed from 0.098 to 0.510.Decreasing the amount of the solvent from 20 ml to 10 ml,the size of MNPs changed from 60 nm to 80 nm,PDI changed from 0.433 to 0.456.Changing the solvent from 1-octadecene to dibenzyl ether,the size of MNPs increased from 10 nm to 60 nm,PDI decreased from 0.182 to 0.433.Adding the other surfactant,1,2-hexadecanediol,the size of MNPs decreased from 10nm to 4 nm,PDI decreased from 0.493 to 0.182.Changing the heating rate from 3.3?/min to 20?/min,the size of MNPs increased from 20 nm to 60 nm,PDI increased from 0.098 to 0.433.?2?we further characterized MNPs with different size prepared under different condition by SEM,VSM,AM etc.It turned out that the composition of MNPs is Fe₃O₄,surface groups match well with the experiment conditions.MNPs of 4 nm is paramagnetism,MNPs of 10 and 20nm is superparamagnetism,saturation magnetization is 60 and 46 emu/g,respectively.MNPs of 60 and 80 nm is ferromanetism,saturation magnetization is 92 and 105 emu/g,coercivity is 81 ang77.351 G.Remanence signal of 20,60,80 nm MNPs is 4,1224,1020 pt/ug,respectively.?3?MNPs of 20nm transferred from water phase to oil phase successfully using DHCA to exchange the surface groups,modified MNPs of 20 nm with streptavidin?SA?through amide reaction.We further labeled the cell with hydrophilic MNPs,achieving excellent sensitivity,60 pt.At last,using microfluidic technology,we combined the MNPs with PS,prepared the magnetic PS microspheres,remanence signal is 100pt/ug,one times better than commercial used M280 low-field probe.