Size control for two-dimensional iron oxide nanodots derived from biological molecules

We demonstrated the fabrication of size controlled two-dimensional iron oxide nano-dotsderived from the heat-treatment of ferritin molecules self-immobilized on modified silicon surfaces.Ferritin molecules were immobilized onto 3-aminopropyltrimethoxysilane (3-APMS)modified silicon surfaces by electrostatic interactions between negatively charged amino acids offerritin molecules and amino terminal functional groups of 3-APMS. Heat-treatments wereperformed at 400 °C for 60 min to fabricate two-dimensional nano-dots based on ferritin cores, aheat-treatment at was performed. XPS and FT-IR results clearly indicate that ferritin shells werecomposed of amino acids and 3-APMS modifiers on silicon surfaces were eliminated by heattreatment.Nano-dots on substrate surfaces corresponded to iron oxides. The size of nano-dots wastunable in the range of 0 ~ 5 (± 0.75) nm by in situ reactions of iron ion chelators with ferritinmolecules immobilized on substrates before heat-treatment