Multifunctional gold nanocomposites, which were designed as dendrimer-entrapped gold nanoparticles functionalized with gadolinium, cyanine dye (Cy5.5), and folic acid, were synthesized to be used as the first dendrimer-based clinical nanoprobes for targeted X-ray computed tomography/magnetic resonance/optical trimodal imaging in vitro and in vivo of human non-small cell cancer cells.