Fluorescein-5-thiosemicarbazide is widely used in biochemical and medical research as a fluorescent labeling agent. It is particularly effective for tagging biomolecules such as proteins, peptides, and nucleic acids, enabling their visualization and tracking in various experimental setups. This compound is also employed in the study of cellular processes, including cell imaging and flow cytometry, due to its strong fluorescent properties. Additionally, it serves as a critical tool in the development of diagnostic assays and biosensors, where its ability to bind selectively to specific targets enhances detection sensitivity. In drug discovery, it aids in the identification and characterization of potential therapeutic compounds by facilitating the monitoring of interactions between drugs and biological molecules.