A lysosome specific ratiometric fluorescent probe for detection of bisulfite ion based on hybrid coumarin-benzimidazolium compounds

An Acid-Activatable Fluorescent Probe for Sulfur Dioxide in Traditional Chinese Medicines and Living Cells

Excessive sulfur dioxide (SO₂) disturbs physiology of lysosomes causing diseases and threatening human health. A fluorescent probe has been regarded as one of the most attractive approaches, which is compatible with living cells and possesses high sensitivity. However, most of fluorescent probes' reaction sites are activated before they reach the destination. In this work, an acid-activatable fluorescent probe PT1 was synthesized, characterized, and used for SO2 detection. The introduction of oxazolines in PT1 enables the intelligent response of probe to release the activation stie for SO2 derivatives through Michael addition upon exposure to acid. In vitro studies showed a remarkable selectivity of PT1 to SO₂ derivatives than other biothiols with a limit of detection as low as 62 nM. By using this acidic pH-controlled fluorescence responsiveness to SO₂, precise spatiotemporal identification of lysosomal SO2 fluctuations has been successfully performed. Furthermore, probe PT1 can be applied for monitoring SO₂ derivatives in traditional Chinese medicines.

An Imidazo[1,5-a]pyridine Benzopyrylium-Based NIR Fluorescent Probe with Ultra-Large Stokes Shifts for Monitoring SO2

A mitochondria-targeted NIR probe based on the FRET mechanism was developed. It shows ultra-large Stokes shifts (460 nm) and emission shifts (285 nm). Furthermore, we also realized the imaging of SO₂ in living SKOV-3 cells, zebrafish and living mice which may be useful for understanding the biological roles of SO₂ in mitochondria and in vivo.