Identification and Detection of Intracellular Reactive Sulfur Species Using a Reaction-Mediated Dual-Recognition...

Reactive sulfur species (RSS) are emerging as a potential key gasotransmitter in diverse physiological processes linking two signaling molecules H₂S and SO₂. However, the exact roles of H₂S and SO₂ remain unclear. A major hurdle is the shortage of accurate and robust approaches for sensing of H₂S and SO₂ in biological systems. Herein, we report a reaction-mediated dual-recognition strategy-based nanosensor, silver nanoparticles (AgNPs)-loaded MIL-101 (Fe) (ALM) hybrids, for the simultaneous detection of H₂S and SO₂ in a living cell. Upon exposure to H₂S, AgNPs can be oxidized to form Ag₂S, causing a decrease of surface enhanced Raman spectroscopy (SERS) signals of p,p'-dimercaptoazobenzene. Moreover, SO₂ reacts with the amino moiety of MIL-101 to form charge-transfer complexes, resulting in an increment of fluorescent (FL) intensity. The ALM with dual-modal signals can simultaneously analyze H₂S and SO₂ at a concentration as low as 2.8 × 10^-6 and 0.003 μM, respectively. Most importantly, the ALM sensing platform enables targeting mitochondria and detection multiple RSS simultaneously in living cells under external stimulation, as well as displays indiscernible crosstalk between SERS and FL signals, which is very beneficial for the comprehension of physiological issues related with RSS.