Biotium developed SDIP/Eu3 as an alternative to DPA/Tb3 (80104), which is used for vesicle fusion assays. Similar to DPA/TB 3 assay, one population of vesicles can be loaded with the chelator SDIP while another population of vesicles can be loaded with EuCl3. Intense red fluorescence is produced when the two types of vesicles fuse as a result of formation of the SDIP/Eu3 complex. The main advantage of SDIP/Eu3 over DPA/TB3 is that the SDIP/Eu3 generates fluorescent emission with brighter intensity and much longer wavelength. Each set of products contain 10 mg SDIP and 25 mg EuCl3 in two separate vials.