A dual-emission ratiometric fluorescence probe for highly selective and simultaneous detection of tetracycline and ferric ions in environmental water samples based on a boron-doped carbon quantum dot/CdTe–Eu3+ composite

Abstract

A dual-emission ratiometric fluorescence probe for the simultaneous detection of tetracycline (TC) and Fe³⁺ in aqueous solution was fabricated based on a boron-doped carbon quantum dot (B-CQD)/CdTe–Eu³⁺ composite. Green-emitting CdTe QDs were modified by Eu³⁺; the fluorescence of CdTe QDs was quenched owing to the aggregation via Eu³⁺ and could be restored by the addition of TC. The fluorescence response of CdTe–Eu³⁺ is quite sensitive and selective to TC, which can be used as a turn on–off–on fluorescence probe for ultrasensitive and selective detection of TC. By introducing the blue-emitting B-CQDs with specific fluorescence response to Fe³⁺, a dual-emission ratiometric fluorescence probe of B-CQD/CdTe–Eu³⁺ was thus fabricated for the simultaneous detection of TC and Fe³⁺. At the excitation wavelength of 270 nm, the dual-emission fluorescence peaks are at 410 and 530 nm. A good linearity between the fluorescence intensity ratio (F₅₃₀/F₄₁₀ or F₄₁₀/F₅₃₀) and the concentrations of TC and Fe³⁺ in the range of 0.01–2.0 μM for TC and 0.1–15.0 μM for Fe³⁺ was shown. The limits of detection (LODs, 3σ/k) are ultrasensitive for TC (4.2 nM) and Fe³⁺ (53.0 nM). The dual-emission ratiometric fluorescent probe was successfully applied for the simultaneous determination of TC and Fe³⁺ in environmental water samples. The possible luminescence and fluorescence quenching/restoring mechanisms of the composite probe were also discussed in detail. This study can provide a new approach for fabricating a multifunctional fluorescent probe and a prospective application in environmental and food analysis.