Construction of a Dual-Mode Sensing Platform for Ultra-fast Detection of Bisulfite in Food and Environmental Systems.

Sulfur dioxide (SO₂) is widely used in food processing to extend the shelf life of food. However, excessive intake of SO₂ and its derivatives (HSO₃^- and SO₃^2-) can cause oxidative damage to the body, and result in several diseases. How to construct probes for rapid real-time detection of HSO₃^- in the field is beneficial to the developmental needs of practical applications, but it is also very challenging. Here we report a dual-mode fluorescent probe Rh-QL for ultrafast detection of HSO₃^-, which undergoes a specific 1,4-Michael addition reaction with HSO₃^- to achieve near-infrared fluorescence turn-on. Probe Rh-QL can rapidly (< 5 s) respond to HSO₃^- with a color change from purple to green and a strong fluorescence emission at 725 nm. The probe Rh-QL has been used for the detection of HSO₃^- in real sugar samples and can be prepared as a portable sensing kit for the detection of HSO₃^- in the environment due to its high efficiency, rapidity and accuracy. In addition, the probe Rh-QL is able to target label Gram-negative bacteria after reacting with HSO₃^-, which has the potential to identify the type of pathogenic bacteria.