Over the last two decades, nanotechnology has become one of the most dynamically evolving fields of research. Various types of nanoparticles are widely exploited to extend our understanding of biological interactions at the molecular level. They are actively engaged in the biomedical research for imaging, biosensing, drug delivery and/or concurrent therapy. Recent progress on this field is briefly reviewed here with an emphasis on the wide imaging applications of nanoparticles. Collectively, this field will no doubt make a greater impact after we gradually address any potential risk of nanoparticles.