Magnetic nanocomposites with complex structures and surface functionalities show the unique physical and chemical properties. Their applications in the drug carrier, bio-detection, in vivo imaging and catalysts are very promising. In this review, several typical magnetic composites with complex architectures, including Janus structure, Yolk-Shell shape and mesoporous structure composite are thoroughly discussed, the progresses in preparation method and biomedical applications are reviewed. The outlook of improvement of fabrication technology and potential applications are also concerned.

Contents
1 Introduction
2 The study of Janus magnetic composites
2.1 Inorganic-inorganic magnetic Janus particles
2.2 Inorganic-organic magnetic Janus particles
3 The study of Yolk-Shell magnetic composites
4 The study of magnetic mesoporous composites
4.1 Core-Shell mesoporous composites
4.2 Janus mesoporous composites
4.3 Yolk-Shell mesoporous composites
4.4 Other mesoporous composites
5 The application of magnetic composites
5.1 The application of Janus magnetic composites
5.2 The application of Yolk-Shell magnetic composites
5.3 The application of magnetic mesoporous compo-sites
6 Conclusions