Ratiometric fluorescence detection of Hg²⁺ based on gold nanocluster/carbon quantum dots nanohybrids

Ratiometric fluorescence sensing methods are widely used in analysis and detection due to their high sensitivity and stability. In this work, a ratiometric fluorescence method for sensitive detection of Hg²⁺ was established using a gold nanoclusters/carbon quantum dots (AuNCs/CQDs) nanohybrid probe. The AuNCs/CQDs nanohybrids probe were simply constructed by mixing blue-light-emitting gold nanoclusters (AuNCs) with an orange-emissive carbon quantum dots (CQDs). The probe had two fluorescence emission peaks at 434 nm and 561 nm when the excitation wavelength was 375 nm. With the addition of Hg²⁺, the fluorescence at 434 nm decreased and the fluorescence at 561 nm remained unchanged; the fluorescence intensity ratio Δ(F₄₃₄/F₅₆₁) and Hg²⁺ concentration have a good linear relationship in the range of 8.32 × 10^-7 to 7.69 × 10^-5 mol L^-1, and the limit of detection (LOD) is 3.58 × 10^-7 mol L^-1. The method was applied in the detection of Hg²⁺ in cosmetics and wastewater, and has potential applications for detecting Hg²⁺ in other samples.