A novel Near-Infrared rhodamine-derivated turn-on fluorescence probe for sensing SO32− detection and their bio-imaging in vitro and in vivo

Abstract

Sulfur dioxide (SO2) is an important marker in the human body, and maintaining its balance is very significant for human health. The high concentration of SO2 will cause harm to human health because of the transient nature of SO2. To measure the level of SO2, it is urgent to find a suitable detection method for the real-time monitoring of sulfite. Herein, we designed and exploited a Near-Infrared (NIR) turn-on fluorescent probe L derived from rhodamine for the detection of SO32− in living cells and zebrafish. The addition of sulfite would attack the 4-position of the carbonyl group of levulinic acid, resulting in the cleavage of the ester bond and the formation of the fluorophore. The intramolecular charge transfer (ICT) was restored thus the monitoring system emitted the corresponding long NIR fluorescence at 646 nm. Probe L had high selectivity, a short response period within 10 min, and the detection limit of 0.6 μM. Besides, Probe L had a long excitation wavelength (>580 nm), which was in favor of more deeply biological imaging properties. Moreover, Probe L had low cell cytotoxicity through MTT assay, thus it was confirmed with good biocompatibility. In addition, probe L could successfully real-time monitor exogenous and endogenous sulfite in living cells, and be applied in zebrafish. The confocal results suggested that probe L had strong potential application prospect of outstanding capabilities for detecting sulfite in clinical diagnostics.