Luminescent nanomaterials are materials that emit light when stimulated or excited by an external energy source, such as light or heat. These materials have gained significant attention due to their unique optical and electronic properties, as well as their potential applications in a wide range of fields, including biomedical imaging, optical sensing, and display technology. There are several types of luminescent nanomaterials, including quantum dots, upconversion nanoparticles, and fluorescent dyes. Quantum dots are semiconductor nanocrystals that exhibit unique electronic and optical properties due to their small size and quantum confinement effects. Upconversion nanoparticles, on the other hand, can absorb low-energy photons and emit high-energy photons, allowing for efficient energy conversion. Fluorescent dyes are organic molecules that absorb and emit light at specific wavelengths. One of the most promising applications of luminescent nanomaterials is in biomedical imaging, where they can be used for in vitro and in vivo imaging of cells and tissues. For example, quantum dots have been used to label cells for tracking and monitoring cell behavior. Upconversion nanoparticles have been used in bioimaging applications due to their low cytotoxicity and high photostability. Fluorescent dyes have also been widely used for in vivo imaging due to their ability to target specific tissues and cells.