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

We demonstrated the fabrication of size controlled two-dimensional iron oxide nano-dots derived 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 of ferritin molecules and amino terminal functional groups of 3-APMS. Heat-treatments were performed at 400 °C for 60 min to fabricate two-dimensional nano-dots based on ferritin cores, a heat-treatment at was performed. XPS and FT-IR results clearly indicate that ferritin shells were composed 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 was tunable in the range of 0 ~ 5 (± 0.75) nm by in situ reactions of iron ion chelators with ferritin molecules immobilized on substrates before heat-treatment