Near-infrared fluorescent probe for hydrogen sulfide: high-fidelity ferroptosis evaluation in vivo during stroke

Ferroptosis is closely associated with cancer, neurodegenerative diseases and ischemia-reperfusion injury and the detection of its pathological process is very important for early disease diagnosis. Fluorescence based sensing technologies have become excellent tools due to the real-time detection of cellular physiological or pathological processes. However, to date the detection of ferroptosis using reducing substances as markers has not been achieved since the reducing substances are not only present at extremely low concentrations during ferroptosis but also play a key role in the further development of ferroptosis. Significantly, sensors for reducing substances usually consume reducing substances, instigating a redox imbalance, which further aggravates the progression of ferroptosis. In this work, a H(2)S triggered and H(2)S releasing near-infrared fluorescent probe (HL-H(2)S) was developed for the high-fidelity in situ imaging of ferroptosis. In the imaging process, HL-H(2)S consumes H(2)S and releases carbonyl sulfide, which is then catalyzed by carbonic anhydrase to produce H(2)S. Importantly, this strategy does not intensify ferroptosis since it avoids disruption of the redox homeostasis. Furthermore, using erastin as an inducer for ferroptosis, the observed trends for Fe(2+), MDA, and GSH, indicate that the introduction of the HL-H(2)S probe does not exacerbate ferroptosis. In contrast, ferroptosis progression was significantly promoted when the release of H(2)S from HL-H(2)S was inhibited using AZ. These results indicate that the H(2)S triggered and H(2)S releasing fluorescent probe did not interfere with the progression of ferroptosis, thus enabling high-fidelity in situ imaging of ferroptosis.