For the past decade, a variety of inorganic nanoparticles have been newly created or modified to provide superior materials properties with functional versatility. Simultaneously, due to their size features similar to biological species (e.g. genes, proteins, viruses) and potential advantages over existing chemical imaging agents or drugs, these nanoparticles have been examined for their uses as new tools not only for investigation of biological processes but also for sensing and treating diseases. Upon addition of specific biological functionalities such as DNAs and peptides to the nanoparticles, these nanoparticle-conjugates have shown a number of new promises and breakthroughs in the biomedical fields. Accordingly, a new research area called ‘nanomedicine’ is rapidly emerging.