A novel highly sensitive dual-channel chemical sensor for sequential recognition of Cu2+ and CN− in aqueous media and its bioimaging applications in living cells

Abstract

A simple and unique dual-channel chemical probe (DH) was designed and synthesized, which not only realized sequential recognition of Cu²⁺ and CN⁻ by colorimetric and fluorometric methods, but also realized fluorescence detection of CN⁻. When different cations (Co²⁺, Mg²⁺, Ni²⁺, Cd²⁺, Hg²⁺, Al³⁺, Ag⁺, Cu²⁺, Pb²⁺, Fe³⁺, Zn²⁺ and Ca²⁺) were added into the solution containing the probe molecule DH, only Cu²⁺ induced an observable change in the UV-vis and fluorescence spectra, indicating that the probe molecule can be applied for specific recognition of Cu²⁺. The anti-interference experiment of DH to Cu²⁺ showed that DH has good selectivity for detecting Cu²⁺, with a detection limit of 7.05 × 10⁻⁷ M. In particular, the fluorescence “ON–OFF–ON” process can be recycled by sequentially adding Cu²⁺ and EDTA, and the fluorescence intensity remained unchanged after ten times. This observation suggested that DH can achieve reversible highly sensitive response to Cu²⁺ and EDTA, and can be used as a hypersensitive logic gate for Cu²⁺ detection. More interestingly, when different anions (CH₃COO⁻, SO₃²⁻, H₂PO₄⁻, ClO₄⁻, NO₃⁻, HSO₄⁻, I⁻, Cl⁻, F⁻, Br⁻, N₃⁻ and CN⁻) were added into the solution containing DH and Cu²⁺, only CN⁻ induced color change of the solution from red to yellowish green, and the fluorescence intensity greatly enhanced, indicating that DH-Cu²⁺ has a specific response to CN⁻. The anti-interference experiment showed that DH-Cu²⁺ has good selectivity for CN⁻, with a detection limit of 8.11 × 10⁻⁶ M. Moreover, the probe molecule DH can detect CN⁻, with a detection limit of 7.61 × 10⁻⁶ M. Experimental and theoretical methods were applied to deeply study the detection mechanism of DH, present great potential in practical application for ion test strips and HeLa cell imaging reagents.