Abstract: Resonant nanostructures (RNSs) are provided in one embodiment of the present invention. RNSs may be nano- to micro-scale structures that resonate at specific frequencies through the application of an electromagnetic or acoustic stimulus. Resonant nanostructures provide new tools for diagnosing and treating disease. Resonant activation (RA) is also provided. RA may be a method of stimulating targeted chemical compounds, or nano- or micro-scale structures, in vivo and/or in vitro, to induce a response therefrom. Some RNSs include cavities that are configured to carry a payload. The resonant response of the target may include resonating, fracturing of the structure, and exposing or releasing of a payload. Targets may be changed or engage in various interactions as part of the resonant response.