Nanoparticles targeting cancer cells. Illustration showing porous silica nanoparticles (upper left) encapsulated by lipid bilayers targeting a cancer cell (lower right). This is an example of a nanoparticle platform being used for targeted cellular delivery of chemicals such as drugs to cancer cells. This work (called 'Protocell') was carried out by researchers at the University of New Mexico Cancer Nanotechnology Platform Partnership (CNPP) and Cancer Nanoscience and Microsystems Training Center (CNTC), USA. Illustration produced in 2012.