Preparation Of Magnetic Nanoparticles With High Contentof Amino Groups By Molecular Self-assembly And Enzyme Immobilization

A new method to fabricate amino-functionalized polymer coated Fe3O4nanoparticles was reported in this paper. The Fe3O4nanoparticles which werefabricated by chemical co-deposition method were covered with molecules of bilayeroleic acid at first. After having washed by ethanol and water several times,single-layer molecules of oleic acid covered Fe3O4nanoparticles were obtained. Theprepared nanoparticles were separated by ultrasonic method in water/ethanol solution.The fabricated nanoparticles were of hydrophobic surfaces, and they can induceself-assembly of4-vinylaniline dispersed in medium. Then, the centered Fe3O4nanoparticles coated with4-vinylaniline with the style of amino groups outwards andvinyl groups inwards were formed. Next in-situ polymerization among the moleculesof4-vinylaniline was occurred after the addition of the initiator and the polymer layerproduced was coated on the surface of Fe3O4nanoparticles. The nanoparticles werecharacterized by TGA, TEM, VSM and conductivity titration. The results indicatedthat the prepared about20nm magnetic nanoparticles possess high content of aminogroups of0.848mmol/g, magnetic capacity of75.6%and saturation magnetization of44.508emu/g. The influence of polarity of dispersing medium on the process ofself-assembly was also discussed to obtain optimum functional nanoparticles bypolarity-regulating molecular self-assembly. The kinetic and thermodynamics ofself-assembly was investigated and the experimental datas yielded well fits withFreundlich isotherm model and the second order model. The adsorption capacity wasmeasured to be127mg/g when the nanoparticles were interacted with α-chymotrypsin.The Langmuir isotherm model fits the experimental data better than Freundlichisotherm model in the process of immobilization. The immobilization kinetic datacorrelates well with the second order equation compared with the first order equation.