Straightforward phase-transfer route to colloidal iron oxide nanoparticles for protein immobilization

Abstract

We report for the first time the effective transfer of hydrophobic oleate-capped iron oxide nanoparticles to an aqueous phase upon treatment with a base bath cleaning solution. We discuss the mechanism of the phase transfer, which involves the elimination of the organic capping agent followed by ionic stabilization of the nanoparticles due to negatively charged Fe–O⁻ surface species. The resultant superparamagnetic aqueous nanocolloid shows excellent protein immobilization capability.