Amorphous Se: A New Platform for Synthesizing Superparamagnetic Colloids with Controllable Surfaces

Abstract

We have successfully incorporated iron oxide nanoparticles into monodispersed amorphous selenium (a-Se) colloids by regulating the reaction temperature during the synthesis of a-Se. The surfaces of these a-Se colloids could be coated with conformal and smooth shells made of Pt and SiO₂. The Se cores could then be removed by etching with hydrazine. The spherical morphology and superparamagnetism were maintained in all these synthetic steps. The presence of Pt and SiO₂ on the outer surfaces of these colloidal particles allows one to control their surface functionalities through the formation of alkanethiolate and siloxane monolayers, respectively.