Dual-channel fluorescent probe for detecting SO2 and Hg2+, and dynamic imaging SO2 under Cd2+ in alfalfa (Medicago sativa)

Background

As an antioxidant, SO₂ plays a critical role in maintaining the plant's redox balance. At the same time, Hg²⁺ as heavy metals, will accumulate in plants through soil, often disrupting physiological processes in plants. However, few studies have been reported to examine changes in Hg²⁺ and SO₂ in plants. Here, we developed a dual-channel fluorescent probe NYD, which can differentiate between the detection of Hg²⁺ and SO₂.

Results

The probe exhibits high sensitivity (LOD, 44 nM for Hg²⁺ and 26 nM for SO₂). When Hg²⁺ and HSO₃⁻ deprotect and attack the double bond by nucleophilic addition, significant emission of fluorescence at 475 nm and 574 nm with blue and red fluorescence respectively. In addition, NYD has the capability to detect the levels of Hg²⁺ and SO₂ in cells and alfalfa seedlings. Meanwhile, the findings indicated that alfalfa seedlings were exposed to Cd²⁺, which led to redox imbalance and increased endogenous SO₂ production.

Significance

We anticipate that this research will contribute to a better understanding of the functions of SO₂ under oxidative stress induced by Cd²⁺.