One-pot Synthesis of Size Controllable Amine-Functionalized Core-Shell Magnetic Nanoparticles for Use in Microfluidic Flow Separators

Silica coating of magnetic nanoparticles has been widely used as a surface modification strategy to endow various surface functionalization and fast magnetic respond for application in molecular separation and purification. A simple one-pot synthesis of amine functionalized core-shell magnetic nanoparticles with a tunable shell thickness has been prepared in a reverse microemulsion system. The morphologies and sizes of resulting nanoparticles were confirmed by PXRD spectroscopy and TEM imaging. Nanoparticles prepared by this method are single-core dominated and highly monodisperse, and show great potential for use in a closed-cycle microfluidic magnetic purification system. To demonstrate this idea, fluorescein was used as a model carboxylate molecule to demonstrate the potential separation ability of Fe 3 O 4 @SiO 2 -NH 2 nanoparticles towards cationic targets via UV-VIS spectroscopy. The results show that fluorescein molecules can be quickly and quantitatively associated with the magnetic nanoparticles via electrostatic binding, resulting in an average of 2.73 x 10 3 adsorbed target molecules per nanoparticle. In addition, covalent binding of target molecules to the nanoparticles is also demonstrated.