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A dansyl-quinolinium-based ratiometric fluorescent probe for detecting HSO3-/SO32- in living cells
Feng-Ting Liu1, Xian-Fang Liu2, Zhi Jin3
1School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, PR China; Laboratory of Immunology for Environment and Health, School of Pharmaceutical Sciences, Shandong Analysis and Test Center, Qilu University of Technology (Shandong Academy of Sciences), Jinan, PR China.
Background:
Sulfur dioxide (SO2) is recognized as a major atmospheric pollutant and its excessive emissions can pose a great threat to the environment, flora and fauna, and human health. Long-term exposure to excessive SO2 can cause chronic poisoning, leading to neurological disorders and cardiovascular diseases. However, there are two sides to everything. SO2 is an important in vivo reactive sulfur small molecule involved in many physiological activities such as antioxidant, signaling and immunomodulatory effects. Therefore, the development of efficient assays for SO2 derivatives is critical and urgent.
Results:
In this research, we constructed the ratiometric fluorescent probe DQQ based on FRET (Förster resonance energy transfer) mechanism to detect SO2 derivatives with dansyl as the donor fluorophore and quinolinium as the acceptor fluorophore. Based on the designed FRET structure, DQQ could effectively detect SO2 derivatives with large Stokes shift, stable fluorescence signals, low detection limit, high sensitivity and selectivity. DQQ itself had a strong red fluorescence at 620 nm. Following the HSO3-/SO32- addition process at the CC double bond response site, the conjugated structure in DQQ molecule was disrupted and the fluorescence was blue-shifted to 535 nm. DQQ had a good linear response in the amount range between 5.15 and 100 μM with excellent selectivity and sensitivity. Crucially, DQQ tracked changes in HSO3-/SO32- in cells in addition to detecting HSO3-/SO32- in real water samples.
Significance:
We developed a FRET-based ratiometric probe, DQQ, utilizing dansyl derivatives as the donor and quinolinium as the acceptor to detect SO2 derivatives. DQQ could not only be made into simple, sensitive and portable test strips for the detection of SO2 derivatives, but also monitor SO2 derivatives in real water samples with excellent recoveries. Importantly, DQQ exhibited low toxicity and excellent photostability, enabling fluorescence imaging of HSO3-/SO32- in cells.
