Provided are novel nanostructures comprising hollow nanospheres (HGNs) and nanotubes for use as chemical sensors, molecular specific photothermal coupling agents, and photothermal ablation compounds. The nanostructures can be used in electromagnetic radiation-induced phototherapy for treatment of cancer and other disorders. The nanostructures can also be used as a sensor that detects molecules. The nanostructures are of particular use in the fields of clinical diagnosis, clinical therapy, clinical treatment, and clinical evaluation of various diseases and disorders, manufacture of compositions for use in the treatment of various diseases and disorders, for use in molecular biology, structural biology, cell biology, molecular switches, molecular circuits, and molecular computational devices, and the manufacture thereof. The hollow gold nanospheres have a unique combination of spherical shape, small size, and strong, tunable, and narrow surface plasmon resonance absorption covering the entire visible to near IR region.
 This invention was made under the auspices of U.S. Department of Energy by University of California Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48 and partly using funds from the National Cancer Institute (NIH) research Grant No. R01 CA119387 and National Science Foundation (NSF) research Grant number SC20040178/ECS-041206. The Federal Government has rights to this invention.