Gold nanoparticles in image-guided cancer therapy

► We focus on the use of gold nanoparticles as a computed tomography (CT) contrast agent. ► We describe the use of gold-iron oxide hybrid nanoparticles for dual imaging modality. ► We describe the use of aptamer-conjugated gold nanoparticles for cancer theranosis. ► We describe a colorimetric sensor for calcium ion based on gold nanoparticles.