Abstract: Methods are provided for making caged gold nanostars (C-GNSs). In one method, a layer of gold is deposited on the silver layer of bimetallic nanostar (BNS) particles in a galvanic replacement-free reaction and the silver is subsequently removed via hydrogen peroxide etching. In another method, gold ions are exchanged with the silver atoms of the BNS particles in a galvanic replacement reaction. Both methods result in a hollow gold shell around a gold nanostar core that enables loading with dyes for in vitro and in vivo detection of the C-GNSs and provides an internal standard in sensing. The C-GNS particles have a greater local electric field enhancement from the visible to the NIR spectral range relative to plasmonic-active GNSs of similar diameter that lack the hollow gold shell. Dye-loaded C-GNS particles are demonstrated for in vivo hyperspectral imaging and as photothermal transducers in the treatment of solid tumors.