Molecular Cages as Probes in Indicator Displacement Assays: The Case of Scopolamine Detection

Abstract

Abstract A study of the Pd‐based molecular cage C1 host–guest properties against fluorescein and the drug scopolamine is reported. C1 forms an interpenetrated structure C1 2 in the presence of ≥40% water in H 2 O/DMSO solvent mixtures. The presence of fluorescein (FL) induces the disassembly of the C1 2 structure to form the [FL 2 ⊂C1] complex. Moreover, the addition of scopolamine (SCOP, a drug typically involved in drug‐facilitated sexual assaults) to [FL 2 ⊂C1] results in fluorescein release and the formation of [ SCOP⊂C1 2 ], obtaining a fluorescence signal proportional to the concentration of scopolamine with a limit of detection as low as 59.4 µg mL −1 . A good selectivity for scopolamine against other drugs such as MDMA, cocaine, GBL, and ketamine is observed. This is the first scopolamine detection method described to date using a molecular cage and one of the very few examples of the use of cages in indicator displacement assays. Similar concepts could be applied to the design of other molecular cage‐based sensors for the detection of target analytes.