Gold nanocages are hollow, porous nanostructures synthesized through a galvanic replacement reaction between silver nanocubes and gold precursor solutions. This process involves the oxidation of silver and the deposition of gold on its surface, resulting in hollow structures with tunable optical and catalytic properties. The reaction is driven by the electrochemical potential difference between the two metals, with gold depositing on the silver surface while silver is oxidized and removed. The morphology of the resulting nanocages can be controlled by varying the shape of the initial silver template, leading to a range of structures including nanorings, nanoboxes, nanotubes, and nanoshells. Gold nanocages exhibit unique optical properties, particularly in localized surface plasmon resonance (LSPR), which can be tuned by adjusting the composition and size of the nanocages. Their large absorption cross-sections make them effective photothermal transducers, capable of generating heat upon light absorption, which can be used for targeted cancer therapy. Additionally, their ability to enhance light absorption and scattering makes them promising contrast agents for biomedical imaging techniques such as optical coherence tomography (OCT) and photoacoustic tomography (PAT). The nanocages can be functionalized with targeting ligands, such as antibodies, to enable specific targeting of cancer cells. In vitro studies have demonstrated their effectiveness in photothermal destruction of cancer cells, with the nanocages selectively heating and killing targeted cells. The nanocages are also being explored for their potential in biomedical applications, including cancer diagnosis and treatment, due to their biocompatibility, tunable optical properties, and ability to be surface-modified. The synthesis of gold nanocages involves a controlled galvanic replacement reaction, followed by selective etching to achieve desired morphologies. This process allows for the creation of a variety of hollow nanostructures, including nanocages, nanoboxes, and nanoframes, with precise control over their size, shape, and composition. The versatility of this method enables the development of nanocages with tailored properties for specific applications in biomedicine and catalysis. The potential of gold nanocages in biomedical applications is supported by their unique optical and thermal properties, as well as their ability to be functionalized for targeted delivery and therapeutic use.Gold nanocages are hollow, porous nanostructures synthesized through a galvanic replacement reaction between silver nanocubes and gold precursor solutions. This process involves the oxidation of silver and the deposition of gold on its surface, resulting in hollow structures with tunable optical and catalytic properties. The reaction is driven by the electrochemical potential difference between the two metals, with gold depositing on the silver surface while silver is oxidized and removed. The morphology of the resulting nanocages can be controlled by varying the shape of the initial silver template, leading to a range of structures including nanorings, nanoboxes, nanotubes, and nanoshells. Gold nanocages exhibit unique optical properties, particularly in localized surface plasmon resonance (LSPR), which can be tuned by adjusting the composition and size of the nanocages. Their large absorption cross-sections make them effective photothermal transducers, capable of generating heat upon light absorption, which can be used for targeted cancer therapy. Additionally, their ability to enhance light absorption and scattering makes them promising contrast agents for biomedical imaging techniques such as optical coherence tomography (OCT) and photoacoustic tomography (PAT). The nanocages can be functionalized with targeting ligands, such as antibodies, to enable specific targeting of cancer cells. In vitro studies have demonstrated their effectiveness in photothermal destruction of cancer cells, with the nanocages selectively heating and killing targeted cells. The nanocages are also being explored for their potential in biomedical applications, including cancer diagnosis and treatment, due to their biocompatibility, tunable optical properties, and ability to be surface-modified. The synthesis of gold nanocages involves a controlled galvanic replacement reaction, followed by selective etching to achieve desired morphologies. This process allows for the creation of a variety of hollow nanostructures, including nanocages, nanoboxes, and nanoframes, with precise control over their size, shape, and composition. The versatility of this method enables the development of nanocages with tailored properties for specific applications in biomedicine and catalysis. The potential of gold nanocages in biomedical applications is supported by their unique optical and thermal properties, as well as their ability to be functionalized for targeted delivery and therapeutic use.