Significant progress has been made in understanding the main biological processes that underlie many diseases. However, it remains a major challenge for the biomedical scientific community to reach comparable achievements in the detection, diagnosis, and treatment of these diseases. The main shortcoming lies in the fact that most clinical therapeutic or imaging agents do not efficiently accumulate in the target cell and/or tissue due to their unspecific distribution throughout the body (Shi et al. 2010). As a consequence, conventional therapeutic and imaging agents require high doses and result in significant side effects (Ferrari 2005). Nanomaterials open up the potential to overcome many of these issues and have received noteworthy attention as platforms for therapeutic and imaging applications (K. Cho et al. 2008; Davis, Chen, and Shin 2008; Farokhzad and Langer 2009; Peer et al. 2007). Nanoparticulateplatforms exhibit remarkable advantages compared to conventional materials, including tunable size, high agent-loading tailoredsurface properties, controllable or stimuliresponsive drug release kinetics, improved pharmacokinetics, and biocompatibility (Shi et al. 2010; Alexis et al. 2008). Nanoparticles can be specifically targeted to certain regions of the body (i.e., unhealthy cells/tissues) by conjugation with targeting ligands. They can also be designed to contain multiple agents, such as imaging and therapeutic agents, for real-time monitoring of the drug uptake and/or therapeutic responses.