Biaxial pseudorotaxane secondary assembly for phosphorescent cellular imaging

Abstract

Herein, we report a biaxial pseudorotaxane supramolecular optical probe, which was constructed from cucurbit[8]uril (CB[8]) encapsulating a double cationic bromophenol pyridinium salt derivative (BPTN) and co-assembled with disulfide-pillar[4]arene (SSP[4]). Compared with BPTN, the biaxial pseudorotaxane obtained with a binding ratio of 1 : 2 between CB[8] and BPTN not only effectively induced the phosphorescence of BPTN through macrocyclic confinement, but also further assembled with SSP[4] leading to the quenching of phosphorescence. Interestingly, the non-phosphorescent supramolecular assembly can respond to pH 6.5 or excess glutathione (GSH) to disassemble, resulting in recovery of phosphorescence. Cell experiments showed that this process can be specifically achieved in the microenvironment of cancer cells rather than normal cells, performing as a dual-responsive phosphorescent supramolecular probe for the targeted imaging of cancer cells. Therefore, this work provides a convenient supramolecular strategy for the construction of phosphorescent probe targeting cancer cells.