Regulating Endoplasmic Reticulum localization of a fluorescent NBD adamantane conjugate by Cucurbit [7]uril

Abstract Intracellular localization of small molecule organic fluorescent probes by supra-molecular control is a fascinating approach. Here we report an adamantine conjugated nitrobenzoxadiazole (NBD-Ad)-based fluorescent probe that efficiently labels the endoplasmic reticulum (ER) in living cells. Alongside, we have chosen cucurbit [7]uril (CB7), a water-soluble and biocompatible macrocyclic host as a supramolecular cavity having a strong micromolar binding affinity to the NBD-Ad probe. The photophysical properties of NBD-Ad and the binding studies with CB7 have been performed using various spectroscopic techniques. After confirming the ER-specific sub-cellular localization of the probe, the internalization has been studied in presence of CB7 in a time-dependent manner. The reduction in the fluorescence signal along with loss in specificity for ER with increasing CB7 treatment period highlights the controlled sub-cellular localization and transport of small molecule.