Fluorometric sensing of Pb2+ and CrO42− ions through host–guest inclusion for human lung cancer live cell imaging

Abstract

The formation of an inclusion complex between 1,5-dihydroxyanthraquinone (1,5-DHAQ; 1) and β-cyclodextrin (β-CD) in aqueous media has been studied by UV-visible and fluorescence spectroscopy. A solid inclusion complex (β-CD:1,5-DHAQ; 2) has been prepared and characterized by FT-IR, XRD, DSC and SEM analyses. The chemosensor probes 1 and 2 showed selective recognition and sensing ability towards the Pb²⁺ and CrO₄²⁻ ions. The association constants (K_a) of 2·Pb²⁺ and Stern–Volmer quenching constant (K_sv) of 2·CrO₄²⁻ were obtained to be 1.6 × 10³ M⁻¹ and 1.9 × 10⁶ M⁻¹ in water, and the corresponding detection limits were calculated to be 9.0 × 10⁻⁸ and 3.9 × 10⁻⁸ M according to fluorescence titration analysis. Theoretical studies on molecular docking and density functional theory (DFT) calculations have been performed to prove the binding of Pb²⁺ and CrO₄²⁻ ions with chemosensor probes 1 and 2. Furthermore, bio-imaging indicated that these probes 1 and 2 have good cell permeability and are suitable for monitoring intracellular uptake of Pb²⁺ and CrO₄²⁻ ions in living cells (human lung cancer A549) by confocal microscopy.