Controlled Synthesis and Stability of Co@SiO2 Aqueous Colloids

Abstract

Magnetic nanoparticles have emerged as an important class of functional nanostructures with potential applications of magnetic resonance imaging, drug targeting, and bio‐conjugation. We have developed a modified sol–gel approach to synthesize stable and well‐dispersed magnetic Co@SiO2 nanoparticles with improved control over shell thickness and larger core diameters. These well‐defined Co@SiO2 core–shell nanoparticles exhibit useful magnetic properties, and the protective silica shell allows them to be surface modified for bioconjugation for various biomedical applications. The core–shell nanoparticles were characterized by transmission electron microscopy, energy‐dispersive spectroscopy, elemental mapping, and the line compositional analyses to demonstrate that uniform individually isolated core–shell nanoparticles are obtained through the improved synthetic route.