A ratiometric fluorogenic probe for the real-time detection of SO32− in aqueous medium: application in a cellulose paper based device and potential to sense SO32− in mitochondria

A new water soluble and fluorogenic probe (L) that can demonstrate a specific ratiometric detection of a SO2 derivative (SO32−) in 100% aqueous medium and live cells has been designed and synthesized. The detection process can be visualized by the naked eye, as the orange-red fluorescence of L turns into a strong blue fluorescence upon interaction with SO32−. L displayed several beneficial attributes such as detection in complete aqueous medium, extremely fast response time along with high selectivity and sensitivity. The ratiometric sensing was attributed to the selective nucleophilic addition reaction of SO32− with L. The probe was further used to develop a low cost microfluidic sensor device (μPAD). The probe was biocompatible and its potential to sense SO32− in mitochondria was captured in live HeLa cells.