PH tolerant metal ion controlled luminescence behaviour of supramolecular assembly and its application in bioimaging and supramolecular logic gate

Abstract

Developing intelligent supramolecular assemblies endowed with highly tunable optical properties has been a challenge. Herein, we demonstrate pH tolerant metal ion controlled highly tunable optical properties of a fluorescence quenched supramolecular assembly composed of sulfated-β-cyclodextrin (SβCD) templated acridine orange (AO+) aggregates by using an external stimulus, aluminium (Al3+), a well-known neurotoxic metal ion. The addition of Al3+ ion to the AO+-SβCD complex provides a strong screening effect, resisting the electrostatic interaction between the AO+ and SβCD host, which triggers significant changes in the absorption and fluorescence characteristics of the AO+-SβCD complex along with a favorable fluorescence turn-On response. Additionally, the fluorescence On-Off-On switching of AO+ activated by SβCD and Al3+ ion was successfully utilised to construct an uncommon supramolecular-based two-input IMPLICATION logic gate. Finally, we could also monitor the fluorescence On-Off-On switching events of AO+ in more complex live MCF-7 cancer cells, suggesting the potential of the current system in real-time monitoring of in-vivo biosensing and drug delivery applications.