Theranostic nanomedicine is emerging as a promising therapeutic strategy. Magnetic iron oxide nanoparticle-based theranostic nanomedicine takes advantage of nanotechnology to load both nanoparticle and therapeutic agent into one nanoparticle. The resulting nanosystem is composed of three main components: an iron oxide nanoparticle core, coating, and multifunction moieties. These nanoparticles are expected to play a significant role in personalized medicine for their capability of diagnosis, visualizing drug delivering and monitoring therapeutic response in real-time. In this review, we summarize the synthesis, surface modification, multifunction and biomedicine application of magnetic iron oxide nanoparticle, especially focused on the part of surface modification and multifunction, which are associated with the multimodality and multifunctionality theranostics. At last, the challenges of the application of nanomedicine in personalized medicine are presented.

Contents
1 Introduction
2 Synthesis of MNPs
3 The compounds commonly used in the surface modification of MNPs
3.1 Polymers
3.2 Inorganic shells
3.3 Small organic molecules
4 Surface functionalization of MNPs
4.1 Targeting modification of MNPs
4.2 Multifunction of MNPs
5 Application of theranostic nanomedicine based on MNPs
6 Challenge of theranostic nanomedicine in clinic