Figure 2.

Chemical structure of BMEDA (A) and ¹⁸⁸Re-BMEDA (B). Diagram (C) depicting after-loading method for liposomes containing ammonium sulfate pH gradient radiolabeled with ¹⁸⁸Re-BMEDA. The lipophilic form of BMEDA at pH 7.2 crosses the lipid bilayer. Once inside the liposome interior, BMEDA becomes protonated at pH 5.1 and trapped within the hydrophilic liposome interior as ¹⁸⁸Re-BMEDA-H⁺ form. This research was originally published in JNM [19].