Nanoshells are spherical nanoparticles composed of a dielectric core coated with a thin layer of metal, typically gold or silver. They exhibit unique optical properties, particularly tunable surface plasmon resonance, which can be adjusted by altering their size and composition. Applications of nanoshells span various fields, including biomedical imaging, drug delivery, and photothermal therapy for cancer treatment, where they absorb specific wavelengths of light to generate localized heat, effectively targeting and destroying cancer cells. Additionally, they are utilized in sensors and diagnostic tools, enhancing the sensitivity and accuracy of various detection methods.