D-Luciferin sodium salt is widely used in bioluminescence imaging (BLI) for studying biological processes in live organisms. It serves as a substrate for the enzyme luciferase, which is often genetically engineered into cells or organisms. When luciferin reacts with luciferase in the presence of oxygen and ATP, it emits light, allowing researchers to track cellular activities, gene expression, and disease progression in real-time. This application is particularly valuable in cancer research, drug development, and monitoring therapeutic efficacy. Additionally, it is utilized in molecular biology to study protein-protein interactions and in vivo imaging of small animals, providing non-invasive and high-sensitivity detection.